Fuel problem - Long post

[wlsnoops]

1995 S-10 Blazer 4.3L V-6 4WD
The vehicle had been hard to start and finally quit starting all together. Cranked over just fine.
My nephew, who is a mechanic, ran a fuel pressure test at the service port (Schrader valve) and got nothing. He then disconnected the fuel line in front of the fuel filter (closest to engine). Turned key on and gasoline squirted out. Fuel pump appeared to be working. He could not check the pressure at that connection as he did not have the correct fitting.
Had Blazer towed to a reputable shop around the corner. They said they were able to get the car started by hitting the bottom of the gas tank. They also ran a fuel pressure test and said it had about 40 PSI. In their opinion, the fuel pump was at fault.
I had the fuel pump replaced and tank cleaned out at a Chevy dealer back in December, so the pump was still under warranty.
Got car started and drove to Chevy dealer. They had car most of day and called me and said the car was not showing any problems. Said fuel pressure was good. Started everytime. I picked up Blazer and drove around, did some errands and it started everytime.
Saturday morning, I'm back to square one. Doesn't start. So it'll be back to Chevy dealer on Monday for sure.
Any thoughts on this?

[blazes9395]

Fuel Pump.

Check and make sure all wiring conections up to the pump are good. If in fact it is a pump, check the wiring to the pump, make sure is clean and not corroded. Make sure the ground to the pump is good and strong.

[muddog321]

Also for cold start these require min 60 psi for injectors to shoot a rich mix in. 95 and earlier have had leak down problems with teh reg and nut kit (lines) under the upper intake as they age. Then if fuel press good when was the last tuneup and especially the cap/rotor - cheap to replace and rule out before GM may have to do it! Assume no SES light or codes.

[wlsnoops]

Originally Posted by muddog321

Also for cold start these require min 60 psi for injectors to shoot a rich mix in. 95 and earlier have had leak down problems with teh reg and nut kit (lines) under the upper intake as they age. Then if fuel press good when was the last tuneup and especially the cap/rotor - cheap to replace and rule out before GM may have to do it! Assume no SES light or codes.

The last tune-up was a year ago this month, included plugs, cap and wires. No SES light or troublecodes to report.
If I'm laying under the vehicle, will I be able to see the wires for the fuel pump? I would like to check them to see if they are secure.
...Will

[MT-2500]

Fuel pressure specs on the code Z 4.3 is 55/61

Take it back to the dealer and ask for a full fuel pressure test cold after sitting overnight and warm and hot and driving on the road.
Also ask for a factory trained tech to check it.
If dealer refuses that request ask for your money back and find another dealer.
Tip on going to the dealer
Ask that only a factory certified gasoline engine performance specialist work on your car.
Not all dealerships are concerned with how repairs are dispatched, and not all dealership techs bother to take advantage of the training offered by factory (the vast majority of which is paid training). If the dealer is uncooperative, ask for your money back and call around for a dealer that will accommodate you.


You fuel pressure is to low.
Specs on it is 55/62 lbs of pressure
Here is some guide lines of fuel pressure checking.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 55-66 fuel pressure.
On your 95 4.3 code Z
Cold start should be 55/61 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/62 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back your fuel pressure readings.
MT

[kpring]

This is all good info, just posted the same problem three days ago, changed out the fuel pump I replaced 1 1/2 years ago and fixed the problem.Sounds like the dealer doesn't know whats going on if the fuel pressure says 40 and it needs 60, which is what I'm getting now on my 2001 4.3 Jimmy.

[wlsnoops]

Took vehicle back to Chevy dealer. Told them everything I read here. They installed new fuel pump and it STILL wouldn't start. The problem was a pinched fuel line.