Aftermarket "Stock like" fuel pumps

[Lunchbox]

So i've been doing a bit of research and realize the stock fuel pump has a "jet pump" or venturi built in which syphons in fuel to the basket. I'm looking to replace the stock one with a much higher flow pump but keep the stock like function and i'm finding there aren't many options.

Racetronix offers a 340LPH Pump which drops in place and is good for what appears to be up to about 600hp.
https://www.racetronix.biz/p/340lph-jet-pump-high-pressure-volume/rxp340j

Im looking for something however that support about 700-800 range or maybe even more. Now, I realize I can probably throw a boost-a-pump on a racetronix and squeeze a little more out of it but i'm not really a fan of doing that.
i'm a fan of simplicity and less parts or systems to have potential problems or maintenance.

I recently found this adapter which bolts to the bottom of a walbro 450/525lph in tank pump. Holley discontinued it but many sites out there still have a these in stock.
https://www.holley.com/products/discontinued_product/parts/16-136

Are there any sort of 6AN venturi style fittings that exist? if not i'm sure something could be machined probably. Is there any reason why something like this wouldn't work assuming a proper venturi style fitting either exists or is machined?

[SuperSaiks]

haha I also just found the racetronix one as well and I am trying to confirm if its the exact same size for 96-98 vipers.

https://www.racetronix.biz/p/340lph-jet-pump-high-pressure-volume/rxp340j

I am waiting for racetronix to confirm as I sent them pics of the original Walbro P/N 4848563 (chrysler part #) that I have. However someone back in 2017 posted in these forums that its a direct fit.

[dave6666]

I use a Gen 4 module in my Gen 2. Good for ~750 hp according to Dan Lesser.

[Lunchbox]

haha I also just found the racetronix one as well and I am trying to confirm if its the exact same size for 96-98 vipers.

https://www.racetronix.biz/p/340lph-jet-pump-high-pressure-volume/rxp340j

I am waiting for racetronix to confirm as I sent them pics of the original Walbro P/N 4848563 (chrysler part #) that I have. However someone back in 2017 posted in these forums that its a direct fit.

Please post pics of the stock pump! I pulled mine a year ago and, I either tossed it or lost it somewhere in the garage. Kicking myself for that now. Would be good to see bottom of it and the ports.

[Lunchbox]

I use a Gen 4 module in my Gen 2. Good for ~750 hp according to Dan Lesser.

Close to a direct drop in? I can't imagine it just fits and works, but that would be nice if it did! I'm looking at 650-750 range probably and this would check the box and potentially make things easier. Hopefully sending unit attaches and works without much hassle.

[dave6666]

Dan made 1" extensions for the module and a custom swing arm for the float. Not sure if he took notes or made a drawing of the swing arm. The electrical hook up is identical. I ran a new #8 line and used one of the Russell adapters at the module. I have zero of the factory fuel delivery system feeding the manifold on my car short of the wires going to the module. I got a leaky gas tank from RSI and sectioned it to have access to the inside to design the float swing arm and review the module mounting depth. Not sure if Dan still has the cut up tank. I did send it to him to do all the work. I just installed it all and financed it. The spacers are visible in the 2nd pic.

50017

50018

50019

[Lunchbox]

Thanks Dave. Based on a few other pics of the fuel pump module/assembly from a Gen 4 floating around online, the float arm looks about the same from what i could tell compared to the picture you posted.
However, these pump modules are pricey brand new and the only way to go would be to buy it new anyway. Used is too much of a gamble unless its low mileage and clean from a known car.

[GTS Dean]

Serious warning on fuel line "upgrades":

A friend's TT Viper burned and was totaled because the "upgraded" stainless fuel line inner tubes were not compatible with with 10% ethanol from every pump in San Antonio. The hose liner disintegrated and leaked enough to flash.

If you truly upgrade your fuel lines, they need to have TEFLON liners. These hoses can be successfully hand-made, but the brass ferrules that install between the outer braid and the inner tube take some practice and patience to install properly for a reliable assembly. One thing you definitely don't want is an unreliable fuel line!

[Lunchbox]

Good info Dean. I'm still not sure on what i'm going to do fuel wise just yet but if i start replacing lines i'll be sure to keep this in mind.

Called Racetronix today just to check on availability and price if i decide to go this route, and it appears they wont have the 340LPH pump available until January at the earliest. I Don't believe anyone else but them carries it either.

[dave6666]

Thanks Dave. Based on a few other pics of the fuel pump module/assembly from a Gen 4 floating around online, the float arm looks about the same from what i could tell compared to the picture you posted.
However, these pump modules are pricey brand new and the only way to go would be to buy it new anyway. Used is too much of a gamble unless its low mileage and clean from a known car.

I spent over $4k on my fuel system if that makes you feel any better. But it has performed flawlessly for about a decade now.

[Lunchbox]

I was entertaining the idea of either machining an adapter type piece for the bottom of a walbro450/525 to adapt a venturi/jet pump style inlet, but.... seems like quite a bit of work. Someone really should attempt this though or make one if they have the time and material. More cars than just the viper are affected by the lack of a jet pump option. They could easily re-coupe costs and sell plenty.

I did a little cross referencing and it seems that through TI Automotive (company that makes pumps on behalf of walbro or is partnered with them) has the Gen 2 fuel pump module listed on their website. They also give specs for the stock pump and it appears that its basically a walbro255 stock roughly. Going from memory here i believe it was 66GPH which roughly translates to 255lph. So, its no wonder a boost a pump on a stock pump can reach fairly high levels.

I think im going to end up going with the Racetronix 340Lph pump and plug and play harness when its available again and a kenne bell boost a pump probably. As much as i don't like adding another piece of electronics and wiring to the car, i don't have much of an option in the way of a drop in pump that isn't going to cost me 3-4x what the racetronix and BAP combined costs. Plus replacement parts if the pump kicks the bucket are likely to be around since the same 340lph pump is also roughly the same setup for the c5 vette guys from what I understand. Additionally i don't plan on hitting power levels over 750 since this is a cast piston motor and id be lucky to see power in that range probably anyway. I simply want to eliminate the fact that i could ever have fuel supply issues which overall eliminates another possibility off the drawing board of going down the path of detonating/cracking a few ring lands on the pistons and torching the motor. The tune and injectors really are the only other factor keeping it all together beyond that.

Thanks for the input Dave. Looks like an awesome fix to the problem but, I dont think I could justify getting a used sending unit, and the new ones are a quite steep still from some looking. A little research about the 750 claim from Dan that i found somewhere, he mentions needing a BAP anyway to hit the 750 level with the gen 3 OR 4 pump assembly/module. Not sure if he made a statement beyond that stating it was rated for higher without?! Either way.

[GTS Dean]

Any updates on this yet Jeff? I suddenly find myself in the market for a new fuel pump...

[Lunchbox]

Any updates on this yet Jeff? I suddenly find myself in the market for a new fuel pump...

So, the best I think that can be done that I’ve found is the racetronix 340lph drop in pump which has a Venturi built in just like the factory pump. Beyond that I believe a boost a pump is the next step on top of the racetronix 340lph pump to squeeze more if needed. Unfortunately I think that’s really it unless custom lines or pump module setups come into play or even new tank setup to accommodate for a modified feed/return setup.

Another option for a factory size pump I think is to grab a wallbro 255 setup for a 2500 ram I believe which is basically same size as the factory viper pump from what I found. They do have them with a Venturi setup and I believe I posted in a thread somewhere here recently linking to one.

Edit: here is the link I was referring to.

https://www.summitracing.com/parts/vpn-gca760-2?seid=srese1&gclid=Cj0KCQiA-qGNBhD3ARIsAO_o7ynv8QVu7PiBRb6LJNsDnBi0yWCnF2G88_U POvMl2Dyw2hx-9OkkAL4aAn1AEALw_wcB

You obviously wont be using all the parts in the kit, except for maybe the blue o-ring/grommet and pump itself probably. The rest i'm guessing would have to be re-used or new if you can find it somewhere else. It's atleat the same quality as oem and same brand so i cant
imagine this would be any downgrade, but it certainly wouldn't flow more than factory probably.

[Lunchbox]

Just another update.

Racetronix basically told me in december that they would have these in january, i've now been told "due to covid" we wont have pumps until april or may. Fucking joke basically.
If you can get one, good luck.

I guess this is one last bump to see if there is anything else out there.

[Lunchbox]

So i've come across a potential solution but, still needs a lot more investigation and research. Also waiting on measurements here before i'll pull the trigger.

My quest here is to get MORE fuel using a single in tank pump all while not losing the jet pump feature from the stock pump. Since thats not really a possibility im looking at an alternative that should alleviate the issues
that the jet pump solves. The stock pump with a boost-a-pump will put out 600-650ish from my understanding. The stock pump is basically a walbro255 in terms of flow and the only known drop in replacement pump is a racetronix 340LPH Jet pump which it seems is impossible to buy and they dont know when they'll have it again.

My thoughts are using the following parts to basically get a larger walbro 450 single in tank pump in the stock basket and not run into issues with fuel pickup below 1/4 tank and to be able to use most if not all of that fuel.
Holley hydramat (24x15) part number 16-109
Holley 16-136 - Holley HydraMat Fuel Pump Adapter (fits walbro 450-525 lph pumps)
Either 16-204 (mounting boss with magnets) or the 16-201 (studs that can be epoxied into poly fuel tanks)

More than likely its going to require some modification potentially of the bottom of the fuel bucket, however its entirely possible it might not need it. Won't know until I get in there.
I'm more inclined to use super strong magnets through the bottom of the poly fuel tank and the magnetic mounting studs to install this, as it can be reversed and there are some pretty strong magnets out there.
I don't know how thick the tank is however so that is another thing.

Downsides to this setup are that, its going to be a mega pain in the ass to remove it and install it, but it SHOULD help pickup all the fuel in the tank and the bled off fuel from the regulator should cover the mat and help.
Also the hydramat is basically a larger fuel pump filter/sock. Replacement wont be cheap WHEN it needs servicing. Also, no telling how long holley will make this stuff....

Thoughts, input? Id love to hear if this is worth the trip down the rabbit hole with. Also if anyone has measurements of the stock 00-02 tank, please let me know!

[Lunchbox]

So I decided to take the plunge and order a few parts to implement the idea.

As you can see I had to hack the bottom off the stock bucket to fit the pump in with fitting above the hydramat itself. The process evolved quite a bit. I attempted to just cut out the circular portion where the snap in screen goes at the bottom of the basket first to see if i might have some luck getting the right clearance to pass a line through to the hydramat but had no real luck. The next step was to cut off just the bottom which did free up some room for flexibility, but ultimately i needed to take off more material (shorten the length of the bucket) to get it to clear the hose and fittings properly. The cut was basically made just below the mount for the sending unit float arm ultimately. I will say even cut its still a pretty solid and rigid. I did have to completely get rid of the plastic membrane adapter that was used for the stock pump and cut the bar off that went over the top of that hole as well. Its probably not able to be seen clearly in these pictures. The fabulous zip ties however hold the pump in very very well and its very solid and isnt going to move.

The stock regulator should return fuel back on top of the mat through the bucket since the bottom is wide open now. The hydramat perfectly covers the bottom of the stock fuel tank (almost as if it was made for it). I did not end up using magnets or literal super glue (yes they recommend this) to hold down the corners of the mat to the tank. Just way too difficult to actually do in car and magnets i dont think would be strong enough to hold in place through the tank and and any other stuff in the way. However, I believe this is going to allow reliable and enough fuel supply for a low boost application using a modified bucket/ assembly and also allow me to use all the fuel in my tank without worry of running below 1/4 tank due to removal of the siphon jet-pump feature that was built into the stock fuel pump. Its not a pretty solution and it hasn't been put through the paces just yet so you'll all have to wait for feedback.

[jasond29]

The hydromat is a great solution, I used it in my application as well. didnt work for me mainly because of the pump I was using, long story but its a great product. The only other real solution to the jetpump issue is to use a surge tank like Radium offers. You can ditch all the evap stuff under the passenger wheel well and put it there. Only issue with that is you are adding more points of failure to the system.

[Lunchbox]

The hydromat is a great solution, I used it in my application as well. didnt work for me mainly because of the pump I was using, long story but its a great product. The only other real solution to the jetpump issue is to use a surge tank like Radium offers. You can ditch all the evap stuff under the passenger wheel well and put it there. Only issue with that is you are adding more points of failure to the system.

Yeah i wanted something as simple as possible without adding more points of failure if possible. There are obviously compromises made here and there but, overall i think i got away pretty cheap here keeping functionality and upgrading fuel supply to support low boost. Would love to see others build on the idea and do it better. WIth 3d printing now available, it would be really cool to see a bucket made that has a built in venturi setup built in that can support a few types of drop in pumps to make a drop in solution. I don't know how far materials have come with 3D printing and plastics these days in terms of durability with fuels and such though, could be a pipe dream.

[jasond29]

I totally agree. I looked at 3D printing as well. I havent looked recently to see if there is a material that can be used to hold up against fuel. Obviously there is a plastic that withstands fuel (OEM bucket is plastic) but I dont know if it is available for 3d printing.

I think your setup will work great. The only other option I was going to do, as last resort, build a complete fuel tank with baffles.

[Lunchbox]

I totally agree. I looked at 3D printing as well. I havent looked recently to see if there is a material that can be used to hold up against fuel. Obviously there is a plastic that withstands fuel (OEM bucket is plastic) but I dont know if it is available for 3d printing.

I think your setup will work great. The only other option I was going to do, as last resort, build a complete fuel tank with baffles.

I thought about the entire fuel tank option but didn't want to pull the trigger on that unless i had some reason to take the fuel tank out. Since the rear hatch area (fiberglass) hasn't ever been cut to remove the tank, i didn't want to start now without another reason. Sounds silly, but i feel if the stock tank is working fine, might as well just use it as is until it needs replacement. Plus saves a lot of time/money from finding a clouse out panel and also cutting the old out and doing the whole tank swap/build.

Truly though, going for anything more than a walbro 525lph pump in stock tank is probably going to require a custom tank or at the very least a custom sending unit that has been 3d printed out of nylon (is that at thing for DIYers?) or perhaps cnc machined.

[GTS Dean]

I pulled mine out yesterday. Getting the upper/lower apart was pretty simple. The PITA was getting the pump out of the lower basket without ruining the whole thing. That took over an hour before I figured out where the lock was. Now, off to try and find a new, high capacity jet pump and an old-style regulator.

[Lunchbox]

It's pretty interesting to see how radically different the pump assemblies are between late 90s and early 2000s era on the GEN2 vipers. It doesnt look like they give you room to do much of anything on those buckets (not even a little bit).

[GTS Dean]

Apparently, they put the filler vent and roll-over protection valve on the tank itself on later production models. There's a whole lot going on at the top of the earlier modules like mine. I searched high and low and found a regulator with the correct pressure rating. Getting the old one out was a bit nerve-racking.

I called Racetronix for a status report on the 340J pump and it is not good. The main problem is Canada and Trudeau's government restrictions. The second is some unspecified bugs with current units in stock and they are not allowed to sell. Upgrades for E85 compatibility underway with no estimate on availability.

[Lunchbox]

Apparently, they put the filler vent and roll-over protection valve on the tank itself on later production models. There's a whole lot going on at the top of the earlier modules like mine. I searched high and low and found a regulator with the correct pressure rating. Getting the old one out was a bit nerve-racking.

I called Racetronix for a status report on the 340J pump and it is not good. The main problem is Canada and Trudeau's government restrictions. The second is some unspecified bugs with current units in stock and they are not allowed to sell. Upgrades for E85 compatibility underway with no estimate on availability.

Yep, this is the same issue I ran into. I called over a span of... 2-3 months but never was able to get anything more than "covid" as an answer to why they were not able to get the units in stock and sell them, which led me to give up on them overall.

https://www.highflowfuel.com/genuine-walbro-ti-automotive-gca760-2-255lph-fuel-pump-dodge-ram-2500-pickup-5-9l-8-0l-1995-2002/

This is the closest stock replacement i've seen. It will atleast get you up and running if you replace the pump and any other useful gaskets the kit comes with that can be swapped over. Its also a genuine Walbro pump so its oem in terms of parts.

I think for upgrades however, its going to require hacking the bucket and doing something like I did, or going with a full on tank replacement that is custom and setup for its own pump assembly and such. Honestly, its a little more than its worth if you just need a pump replacement or slight upgrade. Id only really consider that if you had a leaking tank somehow or were cutting up the rear for something else. Those rear closeout panels i cant imagine are easy to find anymore anyhow.

[GTS Dean]

Measure and cut carefully. The same piece can go back in with a flat flange surround riveted on. Or, use the removed panel as a pattern for a sheet metal replacement.

[GTS Dean]

After striking out on a higher flow jet pump, I installed a spare OE takeout and I'm rolling again. My car makes a little under 500 rwhp and that's about the limit the stocker will support. It was a very frustrating search to try and keep the OE bucket inlet arrangement with anything besides the unavailable Racetronix pump.

Also frustrating was finding out that the pressure regulator is not produced by anyone now. Standard Motor Products was the OE supplier and the original part number is a PR322. It is very similar to the 323 and 324 used on Dodge trucks, but smaller in diameter to fit the tight confines of the module top.

[GTS Dean]

Racetronix.com

It took 6 phone calls over several days, but I finally have a 340lph jet pump on the way. The kit will have a pump, new silicone lower grommet, new inlet filter sock, a new hose and clamps. The 340lph pump is not yet compatible with E85, but it good for E10. The revised ethanol pump will be out to market in a couple of months.

Item #: RXP340J https://www.racetronix.biz/p/340lph-...volume/rxp340j

They offer a 255lph E85 compatible pump, but don't show a jet option on the website so you may need to call and confirm availability.

[WDW MKR]

Thanks for the update, Dean. Let us know how the install goes. I’ll likely be calling for an order myself. I want more insurance with the heads/cam.

[GTS Dean]

It's been the better part of a year since I acquired the new pump, but the car's been offline since a little while after the last report mainly due to wrestling with finding parts sourcing for my leaking water pump. I had dropped an OE takeout Walbro in to get me out on track until the Racetronix was in hand and was waiting for the need. Since back on the road the last couple of weeks, I've been experiencing vapor lock-like symptoms similar to my last pump failure. Leakdown was not terrible - it took 45 min before dropping to 20 psi. Key-on brought it up to 52 within 2 cycles. I checked my idling fuel pump pressure and found the gauge needle was fluttering rapidly over about a 6-10 psi range and averaged between 50-52psi.

To get the bucket top separated from the bottom, you have to unplug the lower side of the electric connector and cut the OE tube to the regulator a little over an inch under the clamp. Once separated, mark the connector housing with a sharpie for the pump ground side, then put a mark on the fuel *sender wire* right next to the pump ground wire. Carefully jiggle and pull the terminal retainer straight out and use a fine pick to lift and disengage the plastic holder tabs for each female wire terminal and slip them out the back.

Next are the "spider" release clips that the fuel sender wires route through. Carefully pull the wires out and bend them out of the way. There may be a cylindrical release tool, but I used two metal picks under the bucket shelf to lift the tabs clear of the snap terminals, then gently worked a screwdriver to lift the spider free of the bucket.

The Racetronix pump is a true drop-in replacement for the Walbro Jet Pump. A new electrical connector and filter for inside the bucket are available on the website. There are 2 mods required to fit the Viper - 1) the polarity of the contacts on the new pump are reversed, so I had to remove the orange keeper and disengage the the lock tabs on the two spade connectors to swap the wires. 2) the new jet discharge that fills the bucket is clocked about 120* off OE and I had to carefully notch the filter attachment ring so it would fit the bucket countersink. I thought about using a Dremel to grind it out, but plastic chips could have filled the wrong side of the filter so I snipped it with dykes.

The only other concern is clocking the ear clamp on the pump discharge tube. To fit the rubber isolator back on top the pump, you have to crimp the clamp just tight enough so you can twist the tube and get the ear facing toward the electrical terminal block.

When you're ready to drop the module back into the tank, I strongly recommend that you coat the top inch and a half of the upper module barrel with engine oil. Also coat both sides of the neck gasket and the inside of the tank neck with oil. Leave the gasket down about an inch on the module and carefully feel all the way around the tank neck to be sure the gasket is not bunched up and enters the tank smoothly. If it is misaligned, you will not get it to seat correctly and the gasket may be ruined.

After wrestling with the animal for a couple weeks last year, the entire R&R process was still pretty fresh and took about 4 hours from start to finishing a 10 min road test this time. After the test drive, the pressure gauge was holding rock-solid at 57psi with no needle flutter at all. That's pretty close to the 4 Bar rating of the regulator (4 x 14.7psi = 58.8psi). The car really seems to run stronger under accel conditions and the idle is slightly smoother. All in all, a very worthwhile adventure and the pump is very reasonably priced. They sell 190, 255 and 340LPH units - all with the same form factor.

[goggles Pizano]

....
The Racetronix pump is a true drop-in replacement for the Walbro Jet Pump. A new electrical connector and filter for inside the bucket are included with the new pump...

My pump did not include the electrical connectors and the filter sock was an extra $5.

[GTS Dean]

I'll have to check my invoice. I probably meant to say they had all those parts available if needed, which is likely the case. My apologies.

[goggles Pizano]

I'll have to check my invoice. I probably meant to say they had all those parts available if needed, which is likely the case. My apologies.

No problem. just on my laptop on and saw your pictures. Damn that more stuff in that box.

[dave6666]

Viper fuel pumps are destroying the internets.

[goggles Pizano]

Can you check your invoice when you get a chance.

[GTS Dean]

I found the packing slip in the box. I ordered two complete pumps, inlet filters and discharge lines. The slip says the filters are for "C5" so they apparently sit in the Corvette bucket clocked about 120* off the Viper's. That necessitated notching the mounting collar.

I wasn't sure what diameter outlet hose to get, so I ordered both 8 and 10mm x 300mm with Oetiker clamps for both sizes. 8mm (5/16") is correct for the pump outlet, but is too large for the regulator inlet nipple which is 6mm (1/4"). To get the new line over the pump nipple, I used a heat gun (hot water is an alternative) to slightly soften the hose end for easy assembly. I ended up leaving the short OE regulator line on the nipple, then slid the 8mm over it and used a screw clamp after the bucket was reassembled. The 300mm hose length is a bit long - probably by 50-75mm.

The biggest performance bottleneck I see in the OE fuel system is probably the tiny pressure regulator inlet. Pressure gives you a consistent spray pattern at all the injectors, but diameter=flow volume=horsepower. All the later model assemblies installed the regulator *under* the module top. I have no idea what inlet diameter they have, but outlet nipples appear the same as earlier models. The G4/5 regulators and pumps are said to be good for around 800hp.

[goggles Pizano]

I found the packing slip in the box. I ordered two complete pumps, inlet filters and discharge lines....

Just checked their site, states 'THIS PUMP IS SOLD WITHOUT ANY WIRING, FILTERS OR MOUNTS. SELECT THE PARTS YOU REQUIRE IN OUR WEB STORE BASED ON YOUR APPLICATION' but the same pump for E85 states 'Standard Walbro-type electrical connector offers plug & play compatibility with pre-existing wiring. No need for extra in-line connectors found on all other E85 pumps.'

[goggles Pizano]

So do you need the connector for the rxp pump or does the factory plug in the bucket plug right in?

[GTS Dean]

It's a cafeteria order bank of discrete elements to purchase.

Based on my personal experience with the E10 pump I do not believe it is 100% "plug and play." The OE Walbro and Racetronix pumps I purchased are wired oppositely. The OE pump connector snapped into the Racetronix pump. Check yours before you put everything back together.

[RyanLS.GEN2]

i believe dan lesser had done some testing on the racetronix pump and had to me to upgrade wiring, that they pull higher amperage than the factory. i bought a racetronix jet pump, i ve had it siiting 3 years and have never instaled due to that.

[goggles Pizano]

i believe dan lesser had done some testing on the racetronix pump and had to me to upgrade wiring, that they pull higher amperage than the factory. i bought a racetronix jet pump, i ve had it siiting 3 years and have never instaled due to that.

It states that on their site including the current draw at different pressures.