our 95 quit in front of our house. Bought it brand new in 95. I do all my own maintenance. I hear the fuel pump run, but i meaured the pressure anyway. 45 to 50 psi. won't start. it WILL run just fine on starter fluid. So i figured the CFI was bad again. replaced it today. Didnt start up right away...but after a while it started and ran perfect for about 2 minutes, then quit. won't start again without either. so what tells the CFI to fire? is there a crank position sensor or does the signal come from the distibutor? I haven't seen the " service eng soon" light so i haven't looked for codes. I guess i should? Any idease or suggestions would be appreciated. I'm trying NOT to tow it to the dealer. thanks Pat

 

Without a check engine light, it means the problem is not monitored by OBD, which lets out a ton of possibilities, crank sensor included, IF your engine has one. 1995 was a change-over year: 2 different systems, 2 different diagnosis procedures & specs. Do the spark plug wires attach to the distributor cap horizontal or vertical? In either case, fuel pressure is too low, that's why it won't start. What is the fuel pressure 10 minutes after the pump shuts off?

EDIT: Next step will be to modify the fuel pressure tester so it connects directly to the fuel filter outlet. This will require some "creative plumbing" on your part. All pressure and flow must end at the tester. Key ON, engine OFF, fuel pump running, what is the pressure? AND, what is the pressure 10 minutes after the pump shuts off?

 

Sorry to tell you sounds like a fuel pump I have the same setup and if my pump drops below 55 psi the poppets will just not open.

If you do all your own maintenance you can do the pump.
A helper would be great but I've done it three times myself.

Shocked that if this has been yours out of the box it lasted this long.

Make sure you get a delco replacment.

Theres how to's all over this forum and plenty of nice vid's on youtube.

It's more stress thinking about how bad it's going to be then just doing it.

I'm old and fat. Took me four hours the first time with cig's and beer.

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Just saw Cpts. post.
Follow his diagnostics.
He will get you to the exact problem, think he dreams about these fuel systems, nightmares maybe.

 

i would think fuel pump psi to low. it should be up around 60-65 psi or the injectors wont operate right. its running fine on starting fluid so that tells me its not a timing issue or anything like that but rather a fuel issue my guess is fuel pump. only run delco parts

 

ok first i'd like to thank you guys for trying to help me out with this. Now onto the problem!. I suspected fuel pump issues. the car quit last year far from home. the original fuel pump had stopped after 175k miles. so i figured the gas tank would be rusty too, so i bought a complete new gas tank with the fuel pump already in it. I got it from Rock auto. it was made in Canada- i don't know what fuel pump they had in it, but it ran perfectly for 6 months or more. When i measured the fuel pressure i bought a complete test kit- had tons of fittings in it, but i couldn't set it up so that it T'd in the line, so i had to jury rig it at the fuel filter . so it was at a DEAD END. the first time i hit the key it went to about 45 psi. the second time it went to 55. at this point i started thinking that i was making a mistake by dead ending the line at the gauge. I have several other EFI cars and they are all quite happy with 40 psi. I worried that by bypassing the fuel pressure regulator i was going to "screw something up". anyways i concluded that the fuel pump was doing it's job and the problem must be the CFI- so i bought a rebuilt one on rock auto for about $135. I installed that yesterday ( second one in this engine). The distributor wires come off the cap vertically- i changed the cap and rotor yesterday when i had the upper intake off- much easier to see what your doing without all that intake in the way. As a side note: the car had not been turned on for about two weeks- so i assumed the fuell pressure had returned the zero- when i pulled the line out of the CFI yesterday it was still under pressure and it sprayed gas all over! So what's next for me? thankspat

 

turned the key this morning and didn't hear the fuel pump! I'll check again later with an assitant to make sure i'm not imagining things...

 

yup its the fuel pump 1st time you turned the key and it was 45 way to low everytime after that it will build some pressure but its not enough to actually keep it going.

 

1992 1995 S10 Blazer Jimmy Sonoma ACDelco New Fuel Pump 1 Year Warranty | eBay

Listen I would still go through diagnostics on this. On the diy section there is a fuel system section.
One thing that has happened more then once is you put a new pump in and its still runs funky cause you got a bad ground.
Black wire 5 ohms or less.

Fuel pump relay is in glove box, when you turn the key on should click for two seconds you can test it by swaping the other relay thats in there.

When everything is correct the pressure at the filter should "snap" to at least 90 psi at the filter. Your reg on the new spyder is set to 60 psi.

 

You have an early production '95 4.3L engine with OBDI engine controls, (no crankshaft position sensor). We still don't know what leakdown is in the pump, but it doesn't matter, pressure at the pump is WAAAY to low. Fuel pressure at the service port (by the distributor) must be 55psi to 61psi, (key on, engine off, pump running) and must remain above 50psi for at least 10 minutes after the pump shuts off. The poppet valves don't function well below 55psi and will not open below ~40psi. Dead head pressure at the filter should instantly reach 73psi to 108psi and must remain above 50psi for at least 10 minutes after the pump shuts off. As spittbays mentioned, check the grey and the black wires at the pump module connector. Grey wire must show battery voltage for ~2 seconds when the ignition is initially turned to the run position. The black wire must show less than 5 ohms resistance to ground at all times. If the wires check OK, replace the pump with an AC Delco or Delphi pump. Don't waste your time or money on aftermarket pumps. As you found out, they don't last.

EDIT: With regard to holding pressure, theorhetically, in a perfect world, the fuel delivery system should hold pressure indefinitely when the pump shuts off. In reality, it needs to hold a minimum of 10 minutes.

 

ok well i guess i'll need to do some more diagnostic work before i pull the pump. So after i figure it all out i'll post again. might be a few days. i'll need some help getting the beast pushed into my barn where i have a lift to work under. it's outside on the grass now! thanks for all the advice and stay tuned! Pat