1996 Passat stumbles, How to find intermittant fuel problem?

[Denny G]

My daughters 1996 Passat (2.0) has been falultering lately. Intermittantly it acts as though there is no fuel supply. The engine ueually satys running, but has nothing above idle power or speed. Then it is OK! Of course, this is a dangerous thing when the person behind you is continuing to accelerate away from the stop sign!

I am assuming it is a fuel issue, probably a failing pump. How to determine if one of the pumps momentarily stops? I hesitate to take it to the dealer, because if it doesn't act up, they will be unable to determine what has happened.

My other edaughter's 1990 Passat recently had a bad main tank pump. Her car would sputter and quit cold. In other words, it acted a bit differently than this one is acting. Since it keeps running, could it mean that the pump outside the tank is failing? (Which one is the more powerful?)

Twice the check engine light has been on. First was Idle speed out of limits, hoever, cracked vacuum lines were repaired at that time. Then, the error code was intake air too warm. Since that code was cleared, it has faultered once, but did not set a new code.

Any ideas?

Denny G

[Denny G]

I aprreciate the views, but either this problem is too trivial or too tough for a reply!!!

Ok. The problem seemed to subisde with the high summer temps until a couple of weeks ago (Novemgber now!). The fuel pump was bad - I got a Vemo pump for a lot less than a VDO pump (but the firts on only lasted 20 min. - grrrr). It seemed to be OK on the 2nd Vemo, but then it stumbled some more. My mechanic found a stretched wire going to the air mass sensor. Then it seemed OK. I got it back to my daughter, but before the afternoon was out it was back to its old ways. I do have more clues, however!

1. When it acts up the engine does not want to go past 2,000 rpm.

2. When stopped, if it will run at 3,000 rpm, a start up keeping above 3,000 rpm will run OK - but you are stuck in 1st or 2nd in town.

3. Drop below 3,000 rpm and you might not get back up to speed. It will stumble and drop down below 2K and probably die.

4. It might backfire.

5. It restarts immediately, but at idle it might die again.

Does anyone vote for air mass sensor? Some things I have read call out some of these symptoms. ANyone?

[SinisterSnowman]

Originally Posted by Denny G

I aprreciate the views, but either this problem is too trivial or too tough for a reply!!!

Ok. The problem seemed to subisde with the high summer temps until a couple of weeks ago (Novemgber now!). The fuel pump was bad - I got a Vemo pump for a lot less than a VDO pump (but the firts on only lasted 20 min. - grrrr). It seemed to be OK on the 2nd Vemo, but then it stumbled some more. My mechanic found a stretched wire going to the air mass sensor. Then it seemed OK. I got it back to my daughter, but before the afternoon was out it was back to its old ways. I do have more clues, however!

1. When it acts up the engine does not want to go past 2,000 rpm.

2. When stopped, if it will run at 3,000 rpm, a start up keeping above 3,000 rpm will run OK - but you are stuck in 1st or 2nd in town.

3. Drop below 3,000 rpm and you might not get back up to speed. It will stumble and drop down below 2K and probably die.

4. It might backfire.

5. It restarts immediately, but at idle it might die again.

Does anyone vote for air mass sensor? Some things I have read call out some of these symptoms. ANyone?

Check the Mass Airflow Sensor or Oxygen sensor. I have a 94 Passat that was doing the same thing, replacing the Oxygen sensor fixed it.