Viper died on the freeway the other night in traffic.

[Catwood]

What a ******. Diving in stop and go the thing chugs, sputters and dies. won't refire. Couple of times while cranking it sounded like the timing was way advanced, you know when it tries to stop spinning for moment. After a couple of minutes (and a few honks and lots of stares) it fired up. Drove to the offramp and it died again. Gas was low, but not that low. After a few it fired up again and I drove to the gas station and put in about 12.5 gallons.

It's done similar things before..

So now I'm wondering if I could have something in the tank that's lighter than gas. I was thinking water but that would go to the bottom of the tank. When I get to a certain point, like the last few gallons, I start picking up crap in the FP and that stalls it out.

Comments? Anyone had similar experience.

 

[Steve-Indy]

Check the battery (Vipers do funny things with low voltage...doubt that it charges well in stop/go situation), throttle position sensor (and all such connections)...then "the field".

Does the check engine light come on? Any codes?

There are several other guesses one can make...OR, try
putting a DRB III on it and see what's up...and, please let us know what you find.

 

[Catwood]

No codes that time. In the past it's given me a couple. rear O2s and high temp sensor. The O2s go off due to headers I suspect. It tends to go off with a cold start unless I give it a few revs to warm up the exhaust quickly.

The battery is only a few months old. It has drained down twice in the last few months which I think is weird when the car has not been used in a couple of weeks.

It's stumbled a few times while driving at even throttle and even did it at willow back in august. We suspected vapor lock at the time but now I'm not so sure.

I do have the nitrous trigger tied into the TPS. It's the black box that comes with the BTR system. I once had a problem at the track where the system thought the TB were at full open position. I bypassed the box and it went back to normal. That's sounding suspect now but why would it correlate to low fuel? Just a coincidence?

 

[Ulysses]

Carl, with the alarm on, it only takes a couple of weeks for the battery to drain.

 

[Catwood]

It's unlocked in the garage so I don't think the alarm is on. The first time I figured I must have left the rear glass ajar but the 2nd time it was all closed up. Perhaps having the key in the ignition (in the off position)? I now leave the keys on the center console.

 

[Ulysses]

Carl,

The first thing I would suspect is that you're battery is low. Put a charge on it and then see if it happens again. This time, though, when you put her away, hook her up to a battery tender.

The next thing I would suspect is a short.

I would also have the TPS checked out.

 

[Catwood]

I really think the battery had enough charge. Volts showed good and it cranked good even with the lights on.


Carl

 

[JGK95]

It's unlocked in the garage so I don't think the alarm is on. The first time I figured I must have left the rear glass ajar but the 2nd time it was all closed up. Perhaps having the key in the ignition (in the off position)? I now leave the keys on the center console.

Catwood,

Thanks! ...and where do you live again??

LOL!

Jay K.

 

[Ulysses]

Awright,

let's assume that the battery is good. THe other problem that a lot of people were having was a chaffed wire that ran through the tranny tunnel and over the tranny.

Also, the TPS is easy to check if you have a DVM. It's another thing that seems to be tops on the driveability problem list.

 

[joe117]

If you measure across the battery with the car not running and the battery charged, you will read just about 12 volts.

With the car running, you should measure just under 14 volts at the same point.

This will show that the battery is charging.

You can do this test from the big terminal under the hood to ground.

There will still be a possibility that the battery has a corroded terminal. That will not show up in this test if you use the terminal instead of direct to the battery.

You can make a current leakage test, with the engine off and key out, by placing an amp meter in line with the main battery cable.
You must disconnect the battery for this test. This will show if there is any sneak path that could be draining the battery while the car is sitting unused.

You shouldn't see much current flow when you make this reading. Well under 100 miliamps I'd guess, perhaps someone else knows an exact number, Make sure the doors are closed or the interior lights will be on. Everything needs to be turned off for this test.

I don't believe a short could cause this. Something would burn or blow a fuse if there were a short.

I don't think that you will find this problem to be related to crud in the fuel tank.

 

[Ulysses]

I don't believe a short could cause this. Something would burn or blow a fuse if there were a short.

I would agree with you if the path to ground were a constant path. But if it were just a chaffed wire that bounced around, intermittently making contact with the tranny, then it could cause the engine to shut down without blowing a fuse or burning something up. Not for long though.

 

[David]

One of the local So Cal Mercedes mechanics was complaining bitterly about the current fuel formulations. In older MBZ's, the fuel would vapor lock the injection if the engine compartment got hot (i.e., bad or no hot starting and sputtering in traffic). What brand of gas are you using? I switched to 76...

 

[Ulysses]

David's got a point, If it's the Shell down the street next to the freeway, I've filled up with bad fuel from them before that caused my truck to sputter and shut down when trying to accelerate.

 

[Catwood]

Awright,

let's assume that the battery is good. THe other problem that a lot of people were having was a chaffed wire that ran through the tranny tunnel and over the tranny.

Also, the TPS is easy to check if you have a DVM. It's another thing that seems to be tops on the driveability problem list.

I need more info on the DVM. I can easily check for a chaffed wire but I'm leaning more towards the TPS as I think about it.

 

[Catwood]

David's got a point, If it's the Shell down the street next to the freeway, I've filled up with bad fuel from them before that caused my truck to sputter and shut down when trying to accelerate.

I think it was probably from the new Chevron in 4S. I did fill up with Shell by Costco only because it was close after I had the problem. Most of the time I do run Union 76.

 

[Ulysses]

To test the TPS all you need is a Volt Meter. The TPS is a 3 wire variable resistance device. Power (Orange), Ground (Black/Blue) and Output (Orange/Dark Blue). 5 volts is supplied from Power. With the Key in the ON position but with the engine shut down, in the lowest throttle position, or Idle, probing the Output with a VM should yield 0-.5 Volts. With the throttle at the highest position, or WOT, probing the Output with the VM should read 3.5 Volts. Since it is a resistive device, swinging the throttle plates from Idle to WOT should yield a pretty linear curve from .5 to 3.5 Volts.

 

[Catwood]

DVM = Digital Volt Meter....

No wonder I did willow in only 1:45...I'm a little slow.

I can check that in the driveway....good deal.

Thanks!

 

[Tom F&L GoR]

Fuel:
Viper is a returnless system, so the fuel between the pump and the injector is under pressure and very unlikely to vapor lock. It would have to be able to boil under pressure. Vapor lock occured in carbureted engines because a) the fuel pump sucked on the line from tank to engine, so pressure was less than atmospheric in the fuel line, and b) the fuel would boil in the bowl, which was not pressurized (vented to atmosphere.)

Return system fuel injected cars can vapor lock, although rare. With a low fuel level, the last few gallons of fuel would get heated from the repeated contact with the warm engine, and being sent back to the tank. Fuel temperatures can get surprisingly high, like 130F or more. If the in-tank pump was up high, or if the electric pump was outside the tank, the fuel would vaporize in the fuel line between the pick up and the pump inlet.

Pardon the lecture, but a Viper could only vapor lock if the fuel was very high volatility, high temperature, and then most likely on the suction side of the pump, which is inside the tank. (And near the bottom, I think.) Given all this, it's more likely to have a leak on the suction side so that it ***** in air.

Anecdotal help: I have a Dakota that did similar things; everything fine but random stalls. Finally wouldn't start. The electric motor armature in the fuel pump was "shrink wrapped" in plastic and the plastic had started to peel off. The flap of plastic was bending over backwards and rubbing on the inside of the motor magnet. When the flap finally got long enough to not unflip when the electric motor stopped, it was permanently wedged in place and of course, no fuel.

But then again, gasoline in California is a different recipe than elsewhere. Good luck.

 

[got one]

Agreed with Tom...don't ever let it get below a quarter of a tank...and Cheveron Supreme with Techron fuel additive every time

 

[Mike Adams]

Did the car run ok after you filled up ?

 

[Joseph Dell]

Once I had something like this happen. I was driving along and was probably only down 1/2 a tank. I'd been on the highway for about 1.5 hours and for no reason, out of nowhere, the car died. I pulled off exit I was very close to (still rolling) and made it to the end of the ramp. I tried to start the car and it bucked and sputtered and managed to move enough to get me to the gas station which I could see from the end of the ramp. Then I let the car sit for 30 minutes or so, put some gas in it, and it has been fine since. that was a few years ago. very weird though. I try not to let the car run that low in gas, but sometimes it just does. i suspect bad gas, but i've never really known. It _was_ a full mood that night, however...

JD

 

[Catwood]

Did the car run ok after you filled up ?

yes....but it was a short drive.

 

[Catwood]

Based on the above comments and some PM I'm going to first test the TPS to see if the voltage is good and see if there are any opens in the TPS itself as it's moved.

2nd I'm going to take the nitrous box out of the system and see if that makes a difference over the next few weeks.

3rd..I'm thinking possible fuel pump. I did once run out or at least ran very low on gas several months ago. I'm suspect that the FP may be marginal and gets hot under load or long use and stops. I do have a pressure gauge that i could hook up to see what the FP is when it occurs next time.

Thanks all,
Carl

 

[Mike Adams]

Possible the fuel pump was too hot the fuel is also a coolant for the fuel pump or you might have water in the tank. You should put gas line antifreeze in the tank to get it out

 

[Catwood]

And I suspect it may run hotter if it's starting to fail.

 

[Tom F&L GoR]

The fuel pressure gauge may be telling. The screens on the pump inlet may be getting covered up during engine-on run time and when it plugged the inlet enough, stalling the engine, the pump will stop and the debris falls off the inlet screen... and you can start up almost right away.

Disconnect the TPS while the engine is running and see if that stalls the engine. It may not, telling you it isn't or can't be the TPS?

 

[Catwood]

ok...had a chance to work on it this weekend. I checked the voltage on the TPS and it seemed to be smooth and steady. I then started going over the wires on the nitrous system. Having thought about it more I figured to look at the things that have been worked on first. My car has the BTR650 kit installed here by a local shop by the previous owner. While running down the wires one pulled out of the crimp....fell out is more like it. I traced down where that went and it is the 5V supply for the temp sensor for fuel enrichment. It may also be tied into the fuel module.

Turns out the wire crimp was for a much larger wire. It was probably bouncing around,having momentary opens or dropped voltage. Which would explain why on occasion the car would stumble.

I put the right size lug on it and reassembled and proceeded to check the rest of the wiring. Nothing else noted. Hopefully this was it, time will tell.

Now just to figure out what's draining the battery while it sits in the garage. I need to borrow a PS from work to check the current draw.

Later,
Carl

 

[Ulysses]

I hate wire crimps. Glad you found that problem. One down, one to go.

 

[Jack B]

Catwood:

I do not think a loose connection in the IAT sensor is going to stall your car. The car will run with it unplugged. Is it possible the wire was shorting out.

 

[BIGBADCJ]

my car did that then i had to push the bastard, turns out it was the fuel pump. weird.