Mechanics

3800SC STARTS THEN DIES

1995 Buick Riviera

1995 Buick Riviera 6 cyl 65000 miles

My car starts up then dies out immediatly. It is a 3800 supercharged V6. I replaced the camshaft sensor (the magnet is on the gear) and the crankshaft sensor. I tested the injector wires for a pulse. When the car is turning over there is a light pulse on each injector. Once the engine starts, the pulse stops, then the engine dies and the test light pulses once. If I introduce fuel thru the air intake I can keep the engine running, but once I stop giving it fuel, the engine dies. I did check the ecm for corrosion but it looks brand new. Any help would be good.
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Scfiero
August 26, 2009.



Check the fuel pressure with a fuel pressure gauge could be the fuel pump -low/no pressure.

Rasmataz
Aug 26, 2009.
Fuel pressure is at 40psi. I did a check of the injector pulse and found that when he car is turning over I have a good pulse but once it starts the pulse stops, the car dies and then I get 1 last pulse at the end and thats it. Could it be the VATS.

Tiny
Scfiero
Aug 27, 2009.
If I introduce fuel thru the air intake I can keep the engine running, but once I stop giving it fuel, the engine dies

If there's a problem with injectors I don't think you can continue to make it run feathering it-

Recheck your fuell pressure its suppose to be 41-47psi also do a running test

Rasmataz
Aug 27, 2009.
The fuel pump was the first thing I replaced when this started, I also changed the fuel filter, and did complete tune up just to be sure.

I rechecked fuel pressure today w/key on got 40psi at the rail. Unfortunatly I cannot due a running test because the car only runs for a second before dieing out. After the car stops the guage stays at about 38psi. I did notice the pump kind of runs on after the car dies out. The pump sounds strong at first and then instead of just shutting off it kind of lingers and dies out slowly. Not sure if that is normal. Maybe the new pump is bad?

Tiny
Scfiero
Aug 27, 2009.
Power the fuel pump direct from the battery and see what happens.

Rasmataz
Aug 27, 2009.
I jumped the fuel pump at the relay and it ran a steady 40psi at the rail. It must be ok, it never even waivered. Possibly my guage is off by 1 or 2. Anyway it seems fine, and even with 40psi it should at least idle. I am not getting an injector pulse when the engine starts, this is why it dies out. Now I just need to find out why the injector pulse is stopping after the engine starts.

It has new pump, camshaft sensor, crankshaft sensor. Plugs and wires w/spark. Can dump fuel into air intake and keep vehicle running. Why are the injectors not firing once the engine starts?

Tiny
Scfiero
Aug 27, 2009.
Could be the injector/s ground drivers in the computer

Rasmataz
Aug 27, 2009.
I almost forgot, I even tried starting the car w/the fuel pump jumped and it still just started for a second then died out.

Tiny
Scfiero
Aug 27, 2009.
I thought that also, I opened the computer and it looks brand new, no corrosion or abnormalities that I could SEE. Does anyone test the computer alone or is there a way to bypass or jump the injectors.

Tiny
Scfiero
Aug 27, 2009.
If you have power on one side of the injectors and not pulsing think computer-

Rasmataz
Aug 27, 2009.
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