96 Tahoe dies while driving and won't start

[Nightflyer]

Hey Guys,

I'm Matthias from Bamberg, Germany. I've an 96 Tahoe (350 Vortec TBI) and a real big problem:

This is the thread from the tahoeyukonforum.com:

My car died three weeks ago while i'm driving (it was like, someone cut off the ignition) and won't start again. Nobdy in Bavaria and Germany knows why.....

- the battery is in a very good condition
- the car cranks very well but won't start
- the chevy has very good sparks
- the fuel pump is running and new
- fuel pressure at schrader-valve (is that the name?) is about 61psi and 63 while cranking
- changed the distributor cap, rotor, plugs and wires
- changed the ICM
- changed the CKP-sensor
- it misfires whit starting fluid (one time)
- the plugs are sometimes wet and you can (sometimes) smell gas
- the timing chain is okay (tested with turning the crankshaft and look at the distributor..the rotor moves

sometimes it seems like, that the chevy would like to start. it sounds like, that there is no pulse to the injectors.

btw: there are no codes stored in the PCM and all cables ok.


August,23:
Before this happend, the chevy runs very well...okay, sometimes rough idle (when it was very warm) and a little bit stumbling. but when i remember, the car ws often hard to start when the engine was hot....

I've doublechecked the spark plugs after some cranking the engine.....6 of them are dry...no fuel....

The fuel filter is new...changed it last month....

Ignition coil, cap and rotor are from delco.


August, 24:
I've spark on everthy cylinder, fuel presssure, etc..is okay.

My OBD-Software can read the ECT and TPS data...everything is fine.

It's all tested:

- there is 12V on each injector
- 0.78V at the TPS
- the EGR looks pretty good (seems to be new)
- the ECT reports the correct temperature

September, 11:

New injectors (mpfi) don't fix the problem....no fuel in the engine. All spark plugs are dry....

There are no trouble codes stored.
The ECT display the correct temperature.

September, 17:


Installed test light on each injector circuit:

Ignition on: light is lightly on
Cranking: light flickers
diconnecting VCM (red an blue): light is off

It's flickering while cranking and constantly on by ignition on.

Live data:
Now zero rpm, temperature it at 17 degrees and tps is at zero.
I've double-checked the fuel pressure...

I've tested it with another fuel pressure gauge from a friend (he has an professional one and i cant find mine)...his fuel pressure gauges reads 50psi at ignition on and engine off. While cranking it goes up to 52psi...

September, 20:

I've installed an other fuel pump...59psi at the schrader valve

Aaaand: no fuel at the injectors and no start..

The chevy wants to start with starting fluid. The first time i used too much starting fluid, so it backfires one time thru the intake..

September,21:

The distributor cap is from acdelco. The TPS is at 0% when closed.
I've tried it with the unpluged MAF and air temperature sensor...nothing...

But there is something that i've forgot: The last weeks when myy chevy works, there was something strange: when i cranked the engine, the chevy won't start. But when i stopped cranking it seems like, that the engine starts very slowly.....not all cylinders are firing. It's like one cylinder...then the other, etc. Like an old diesel.. but when the engine works, everything is fine. good idle, etc... You know what i mean? I don't know how to explain it in english, sry...



east302 from the tahoeyukonforum.com helped me soo much. Thanks to him...!!!!!

Here is the link to the thread:
http://www.tahoeyukonforum.com/threads/96-tahoe-dies-while-driving-and-wont-start.96116/

Please: could someone help me? what can i test and look for?

Best regards from Bavaria/Germany

Matthias


p.s.: soorry fpr my bad english..

 

[GarrettGmc]

Have you checked the cylinder compression?

 

[Nightflyer]

Hi Garrett,

I've never checked the cylinder compression...I've no compression gauge.

But I think the compression has nothing to do with the "no fuel issue at the injectors".....or am I wrong?

 

[east302]

He is able to get it to start with starting fluid in the TB.


Sent from my iPhone using Tapatalk

 

[GarrettGmc]

Yea read right over that, my bad.

 

[Texvet]

Check, inspect (don't just look at them - give both a good tug) and replace if necessary - the ground straps that run from the frame (passengers side by the starter) to the body and to the engine. I know this sounds low tech, but those grounds play an important role in the overall soundness of these trucks.

Note: I am not offering this a "for sure fix" to your issue. But, it is a cheap and worthwhile exercise.

 

[Nightflyer]

Okay....

The third fuel pump from Bosch. I've spark....i've fuel...the engine cranks but won't start.

spark-plug no. 2 is very dark (i cleaned it and testet them again) and light grey smoke and gas comes from the exhaust.

When i used more starter fluid, the chevy backfires thru the intake.

I think my timing chain is slipped, but not broken (because i have spark, right?)....

 

[Nightflyer]

Is the 350 vortec an interference engine? When the timing chain is jumped is the engine totally damaged?

 

[skylark]

Check, inspect (don't just look at them - give both a good tug) and replace if necessary - the ground straps that run from the frame (passengers side by the starter) to the body and to the engine. I know this sounds low tech, but those grounds play an important role in the overall soundness of these trucks.

Note: I am not offering this a "for sure fix" to your issue. But, it is a cheap and worthwhile exercise.

Ypu can do a quick check of this by usina a pair of jumper cables between the engine and the negative terminal of the battery.

 

[Nightflyer]

I've done that..the same problem...

What's about this..?:

Okay....

The third fuel pump from Bosch. I've spark....i've fuel...the engine cranks but won't start.

spark-plug no. 2 is very dark (i cleaned it and testet them again) and light grey smoke and gas comes from the exhaust.

When i used more starter fluid, the chevy backfires thru the intake.

I think my timing chain is slipped, but not broken (because i have spark, right?)....