Help 94 RT 10 wont stay running Not alarm pump battery fuses relays

[sirvelonodnarb]

Hey Everyone.

Bought my RT/10 Viper from Porsche Austin 2 weeks ago, and half of that time it's been stuck in the garage. I've spoke with the almighty Steve about bypassing the alarm as well as MANY other things. None of which worked. I'll list those things shortly.

Some background on some work done on the car about 140mi before this issue:

Compression/Leak down test
Fuel pressure confirmed and of no issue, though they didn't list what it was.
Fuel filter replaced
All fuel injectors removed/sonic cleaned/flow tested
Oil pan gasket replaced/oil change
Fuel tank filler to tank grommet replaced due to leaking
Power steering pressure line replaced
Plug wires were incorrectly routed by last owner
Ignition system tested with no faults found

With Steve, we noticed that one of the past owners disconnected from the Security box under the dash - and surprise - there was a second box plugged in? Looks like a wiring mess, but not too crazy.

There was also a rocker switch in the panel, but it only went to a ground. The other end was just dangling. We've checked some of the relays on the RH side of the engine bay, all associated fuses, we bypassed the alarm just for grins (key fob still works to disable), new battery. We checked for fuel pressure to the motor via the valve out back (need to get exact #'s).

The car acts EXACTLY the way the alarm shut off does. However, we've confirmed we dont have the dash lights nor is it active (both via fob and bypass).


Anyone willing to provide me some insight? Car is not flooded either, started it w/ full throttle to drain it. The car ran perfectly for the entire week prior. I shut the car down to get a drink and came back to these issues.

Thank you to everyone so so much. This car has been my dream since I was six and a week in it's testing me. lol.

[Steve-Indy]

This is a tough one. Fuses good, unplugged 2nd SAM and replugged...same for RKE. As noted, fob still clears alarm set light. Manual SAM reset does nothing. Air filters OK, opening throttles slightly did nothing. Fuel squirts at Schrader valve on IM (early 94 with 4 stripe IM)...but pressure unknown at present.
No CEL noted.
He pulled and reinstalled ASD relay with no change. As I recall, still needs to swap starter relay with ASD as a test.

Sounds clearly like alarm shutdown, but with an obviously rewired system we have been unsuccessful with standard "tricks"...including new battery since interior lights had been found on and may have run original battery down.

Might be helpful to see if a DRB III with OBD I cable can give any useful info such as cam and crank sensor status.

This case needs help from a fresh viewpoint.
Any suggestions appreciated.

[daveg]

Steve, does it Crank? Do you hear fuel pump when cycling key? Have spark? When you say it wont stay running, does it run as long the key's in the cranking position?

[Steve-Indy]

Hi, Dave. Yes it cranks, fires up with a roar, and immediately shuts off...just like both Gen I's and II's do with alarm in theft mode.

Puzzling part is why did someone rig a second OEM Security Alarm Module into this car instead of just replacing first module if indeed it did fail.

I suspect toggle switch that now only attaches to a ground represents an attempt to reset SAM much like the Gen II hidden switch on later Gen II's resets EEM (using 12 volts in case of Gen II). I suppose that may have either failed (or SAM went bad), and rewire of new SAM must have worked for awhile.



Final note is that car started having "driveability issues" at some point prior to current owner's purchase. No idea just what these issues were.

Any thoughts will be appreciated.

I must add that current owner is a sharp guy, is car savvy, and is a very patient man !!

[sirvelonodnarb]

update:

Swapped starter relay and ASD: Car started and ran like noted above.

Also, for grins, I plugged back into the original security alarm module, had the lights flickering and bypassed it w/ Steves recommendation. Went to start - same result as w/ the secondary SAM.


Id imagine that the fuel pump fuse (in the back of the car??) is fine being that the pump is priming?

[DanDaMan]

Hi Steve - I recall having similar issues last year shortly after I bought my 2000 RT/10. You helped me find the issue which was alarm related (thanks again!!!!!!)

So being I am somewhat familiar, did the owner confirm if he has spark, and if so did he test the injectors to confirm if they have power and if they have pulse. He needs to know which of the 3 isn't working as that points to different issues (if it is alarm related it will not have pulse - but you need to confirm that). The reason it doesn't sound as alarm for me is you state that the car starts and roars for a few seconds and then shuts off - yes this would occur the first few times if alarm (no pulse) related but after a few attempts all the left over fuel in the fuel rail would be gone and it would not even start for a second anymore.

[sirvelonodnarb]

Hey Dan,

Thanks for the input. I’m clawing to find anything I can to get my car back on the road.

How might I go about checking for pulse from injectors?

[DanDaMan]

First I would watch this video - https://www.youtube.com/watch?v=mVx_RVwPYi8&t=0s. It is a Viper where the mech shows how to diagnose if you have spark, and whether the injectors have power and whether the injectors have pulse. Goto the 6 min section to see how to test for spark, and then from 8min to 11min to test the power and pulse to the injectors.

As stated, if you have an alarm issue then you will not have any pulse, meaning the fuel pressure within the rail is not being pushed into the cylinders, and thus the engine has no fuel - if that were your case then yes the car would start for a second and then stall, and likely do it 2 to 4 more times but after that there would be no more fuel due to lack of pulse and you would only crank (no fire even for a second). Does your Viper still start for a second and then stall? If so, do it multiple times - does it still do that or do you eventually get to just crank and no fire.

Check out the video and do the tests from the 6min to 11min section and report back what you find. Need to know which of the 3 possible issues you have until we can help further

[pokeyl]

I think you need a DRB3 to plug in and see what is going on. I know you can fire coil packs and injector with it. Not sure about the security stiff. A few of us have the tester. Were are you located?

[Steve-Indy]

Thanks, guys...excellent suggestions. He has one more alarm "trick" to try...but. at this point without tools or scan devices, next step may well be professional, hands-on consultation in a shop with Viper experience. He is in Texas, and is checking options.

[sirvelonodnarb]

For what it’s worth, outside of the interior dome lights being on, the only other thing I did was rearrange my soft top and windows in the trunk. Gonna look back there and see I’m that everything is in order.

Is there a ground that may have disconnect that’s common for no start?

[sirvelonodnarb]

We have fuel delivery/pulse and power. We have spark. We jumped the fuel relay to bypass any question of it stayed running - nothing.


Any more insights?

[sirvelonodnarb]

Disconnected some of the intake vacuum to see if it’ll run.

It idles higher and for longer, but eventually shuts down. We even jumped the fuel pump to make sure it doesn’t stop. Same issue

[sirvelonodnarb]

Now w out bypass to fuel pump all c vacuums reconnected, and half throttle blips it revs steadily and for about 10-15 seconds. Then steadily dies

[Steve-Indy]

Have to wonder if fuel pump pickup is failing...there has been a lot of these issues in Gen I's. It would be nice to see if MAP sensor working properly.

[sirvelonodnarb]

W the if the pump pick up was failing, I’d think it would be a bit more intermittent and not just on and off?

Good idea on MAP.

[sirvelonodnarb]

We disconnected a single plug to see if we had spark drop off when it dies. And the car did something funny - it would drop rpms to nearly dead and then jump to to 5-700 rpm, back down and then back up a couple times w no input from me on throttle.

Weird that w one less spark plug it ran better.

[Steve-Indy]

As to the pump...I was thinking that it might be unable to keep up with the flow demand once engine running.

[sirvelonodnarb]

Well, looks like it’s the pump or associated lines within.

Everything else checked out except for this. Gonna have to look at pulling the tank and best replacements depending on what I find.

Will keep everyone up to date as it goes along.

[daveg]

Did you put a pressure gauge on it?

[Cost4133]

id be looking at pressure gauge when running. Seems to me like its a super weak pump, or a clogged filter so it builds enough pressure to fire but loses the pressure once it fires to life. Also possible to have a bad fuel line that is partially clogged,especially any rubber sections that might have deteriorated.

[sirvelonodnarb]

Pressure Gauage wouldn’t register anything, but not sure the fitting we had worked.

We fully depressed the valve w the car primed and I can tell you that it’s not 55psi as it should be.

It’s more like 5-10 if that.

It has a new fuel filter in it!

[sirvelonodnarb]

Well, we put an external tank and pump pushing 45psi right off the quick disconnect from the motor to hardline.

VOILA. She started, sounded better than ever. I suspect due to the difference in response that the car was running w/ pretty low fuel pressure until it finally died. Now, to find out what exactly the issue is. We're taking the tank out, so we're replacing everything regardless of it's age.

Thanks for everyones input - I'm infinitely more educated on some of the nuances of this vehicle and starting problems. A special shout out to Steve-Indy. His willingness to reach out and educate a newcomer to the car was reflective of the rest of the experiences I've had with the Viper community.

Thank you again. Hopefully back on the road before a few weeks!

[Steve-Indy]

Great test !! Hopefully, you will have that Beast on the road soon. Happy Spring !!

[jpmst3]

That's great to hear! I guess we were mostly wrong, but at least you will get it sorted out.
On to happy motoring!

Steve-Indy is a class act!