1995 S-10 Won't Start

[ohpd03]

I have a 95 S-10 Vortec V-6 8th digit of vin is w. When I try to start it in the morning it will only turn over. I replaced the distributor cap, rotor button and coil and fuel filter. Then I discovered if I spray carb clear inside it will start up and run like a brand new one. Runs perfect after it starts. Once it is shut off and sets it will not start. Put on computer and has no codes to read. Fuel pressure is 55 psi. Is the fuel pump weak? Is there another ignition part that needs replaced?

[j cAT]

Originally Posted by ohpd03

I have a 95 S-10 Vortec V-6 8th digit of vin is w. When I try to start it in the morning it will only turn over. I replaced the distributor cap, rotor button and coil and fuel filter. Then I discovered if I spray carb clear inside it will start up and run like a brand new one. Runs perfect after it starts. Once it is shut off and sets it will not start. Put on computer and has no codes to read. Fuel pressure is 55 psi. Is the fuel pump weak? Is there another ignition part that needs replaced?

I believe vin=w is injectors the fuel regulator or vacuum line/s on the intake manifold check all for chafing. I just repaired a vacuum line on 94 s10 TBI which caused high idle slow start and because it went to the vacuum ball controlling the heat duct heat problem. measure fuel pressure with out starting if no or low pressure measure fuel pump voltage at tank, at fuel relay. seen relays needing replacement AT THIS AGE.may continue to run after spray because voltage is higher when engine starts. when cranking should have 9volts at battery when engine starts should be 14.5volts....................

[MT-2500]

Have you checked the fuel pressure on a cold start?
You need up around 60-61 lbs of fuel pressure on a cold start for the injectors to squirt cold.

If it will go ahead and start with a squirt of carb cleaner it is a fuel delivery problem.
MT

[old_master]

I agree, fuel pressure is too low, also check for leakdown. Must remain above 55psi for 3 to 5 minutes after the pump shuts off.

[ohpd03]

If it has low pressure or is leaking back is that a fuel pump problem? If so is it easier to take off the bed than to drop the tank?

[MT-2500]

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
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.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
The 95 or yours is 55/61 lbs 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 55/61 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

Remember a fuel pump pressure regulator controls the pressure and maintains a steady pressure depending on engine load and vacuum.
It has to be capable of producing higher pressure than the regulated pressure.

The fuel pressure regulator controls pressure and can leak off or bypass pressure.

[ohpd03]

I replaced the pressure regulator and still had to give it a quick spray to start. Still looking for a fuel pressue gague to check the pressure.

[ohpd03]

I have some pressure numbers. With the gauge on and turning on the key it goes to 55. After turning the switch on and off about 10 times it makes it to about 60 psi and when cranking it drops to 40 psi. Once spray is used and starts it never went above 60-62 psi while running. After I shut it down the pressure was about 45 and i could see the needle slowly drop from 45 to 40.

[MT-2500]

Block off return line and check pressure or check direct fuel pump pressure at fuel filter.
If the direct or full fuel pump pressure is not up around 75-85 lbs your fuel pump is weak.

[ohpd03]

Thanks for all your help.