Mechanics

RUNS ROUGH

1999 Plymouth Voyager • 6 cylinder FWD Automatic •

My 1999 plymouth voyager van will not stay running. I have replaced the fuel pump, the vacuum lines, and egr valve. It will idle rough, and when you press on he gas it doesn't rev. Then will die, and doesn't want to restart. Is it possibley the pump is bad or maybe the fuel filter or relay?
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Onehothippiechick
December 5, 2010.



Check the fuel pressure before jumping in a replacing the least likely suspect. The most common problem with Chrysler fuel pumps is they fail to start running resulting in a no-start condition. Unlike GM pumps, Chrysler pumps rarely quit while running and don't cause many other problems.

You will never solve a running problem on a Chrysler product, other than a diesel truck, by replacing the fuel filter. It's more likely, but not often, that the pickup screen in the tank becomes plugged. The symptom will be stalling when the largest volume of fuel is being pumped, ... Which is during coasting. It will run fine at highway speeds and even better under moderate acceleration.

The best place to start is by connecting a scanner that can read live sensor data. If the Check Engine light has come on, there will be at least one diagnostic fault code stored in the Engine Computer. That code will lead to the circuit or system with the problem, not necessarily the defective part.

Also look at the MAP sensor's readings. It's values must remain between 0.5 and 4.5 volts. He has the biggest say in how much fuel enters the engine. The values it reports can be wrong but as long as they stay within the acceptable range, no fault code will be stored.

Another somewhat common problem is a cracked flex plate. It cracks a circle around the six bolts that hold it to the crankshaft. When it turns slightly, there may be no other symptoms than rotten engine performance. Related to that, a cracked core in the crankshaft position sensor can cause the symptoms you described but it's more common for it cause backfiring intermittently.

Caradiodoc

Caradiodoc
Dec 5, 2010.
What about the fuel pressure regulator? Could that be the problem?

Tiny
Onehothippiechick
Dec 5, 2010.
Also no check engine light has come on, and no fault codes?

Tiny
Onehothippiechick
Dec 5, 2010.
Extremely unlikely. GM has a huge problem with them leaking but not Chrysler. When they leak there will be raw fuel in the vacuum hose. I only had one in nine years at the dealership that turned out to have a cut o-ring around the nipple on the regulator. It lost fuel pressure within a few seconds of stopping the engine, but the engine ran perfectly. The only symptom was a very long crank time to get the pressure up before the engine would start. Took about ten seconds of cranking. All it needed was the new o-ring, a ten cent part.

Caradiodoc

Caradiodoc
Dec 5, 2010.
That DOES suggest a fuel supply problem because that is the only system that is not monitored, but incorrect readings from other sensors can cause problems too. As long as any incorrect readings fall within acceptable limits for that sensor, no codes will be set in memory.

Caradiodoc

Caradiodoc
Dec 5, 2010.