Its a 1997 chev 5.7l 1500. It was running fine, went to town and started sputtering, finally died and got it towed. Changed fuel, not it, then got the codes of, told me it was front oxygen sensors, changed them, not it. Now I'm thinking fuel pump or strainer because it takes a bit to start but idles and run fine for about 1/4 throttle then starts to hesitate and backfire if you put your foot into it anymore, and the fuel pump is stuttering, instead of get that higher sounding whine. So is it fuel pump or just the strainer or is it somthing else??
Marshall, Before going to the expense of replacing the fuel pump, I would recomend a fuel pressure check. If you do not have the equipment, take it to your favorite mechanic and ask them to check. The pumps and strainers run between $180 to $400 depending if reconditioned, new and brand.
Let me know.
Regards,
Marshall, EQUIPMENT NEEDED: 1) fuel pressure Gage. 2) needle nose pliers ( fuse pull )..
There is a fuel pressure access valve located on the fuel injector rail. The access port or "shraider" valve has a usually black screw on cap. Remove the cap and you will see the valve. CAUTION: The fuel rail is under pressure....before installing the pressure gauge, relieve pressure by starting the engine and removing the fuel pump fuse from the under hood fuse box......
Once the engine quits, turn the key to the off position and safely install the pressure gauge. Put a rag around or under the access valve to catch any drizzling fuel. I always prefer to do this when the engine is cool.
install the pressure gauge, start the engine, check for leaks and read pressure output at idle, record pressure reading.
Also, it should be checked under load but you will need another person to help.
Let me know.
Regards.
Mar, The fuel bleed off is a good observation. However it is bad for the pump. There are a few reasons why this is bleeding down. 1) A dirty injector is sticking and fuel is leaking into the cylinder.2) Pressure regulator on the rail is defective or 3) The fuel pump check valve is leaking back at the pump.
Engine off: To start eliminating components, gently pinch off the fuel return hose after the regulator, be careful not to damage the hose,start the engine, read pressure and shut the engine off. See if the fuel bleeds off. If it does, the regulator is not the problem, although check to make sure there is no fuel in the vacuum hose to the regulator (often over looked).
NEXT: You will need an extra person for this. You are going to pinch off the pressure line hose during a "key on" ( don't start engine} while the fuel pump is running. When the fuel pump stops after a couple of seconds, watch the pressure. It should hold or not leak down as fast as you observed in you original test. If the pressure holds steady, you have a fuel pump check valve leaking.
There are fuel pump volume tests that can be done. You need fuel volume along with pressure. Pump volume problems will caused hesitations, poor acceleration performance (sluggish).
I know there is a lot to do here, but worth the time when your looking at changing an expensive component.
Good luck and let me know.
Regards,
Marshal, This will indicate you have an injector or injectors that are sticking open. With the fuel injector rail pressurized and the pump pressure line pinched off, the injectors should hold line pressure.
The injector or injectors are probably "gummed" up and not sealing properly and causing the problem.
You can remove the fuel rail and injectors, take it to a local GM dealer or favorite repair shop and they should have a fuel injector cleaning machine. They will attach the rail to a machine that will pump cleaning solvent through the rail, pulsate the injectors and clean the varnish out of the injectors. The only other solution will be to replace the injectors.
I don't know how many miles you have on your truck but anything over 150K should have the pump considered for change.
Good luck, let me know.
regards,
Marshall, YOU ARE ABSOLUTLY CORRECT THE FUEL PUMP IS THE PROBLEM. I miss read your description, my fault.
The check valve located in the pump assembly has failed.
Also, the 93 pump will not work in a 97 truck. The 93 has a lower pressure pump and will not keep up with 97 port injection.
Good luck and let me know how it goes.
Best regards,
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Thanks I had the same advice already, just thought I'd check with u guys, What kind of equipment do I need to do that?? Just a gauge or what?
Thanks I know exactly where you mean, I'll let you know, thanks again!!
Thanks I know exactly where you mean, I'll let you know, thanks again!!
Ok I checked the pressure key on engine off and it was about 35 psi, but bled down by itself right away after the pump quit. I got the truck started and it went up to about 50 psi and again when I shut the truck off it bled down by itself and theres no leaks, under load it was fluctuating 50 and 55 and when i hit the point where it didn't want to run it actually went up to about 60psi, what does this mean please help??!!
This should do it, looks like I should be able to eliminate the problem with these great tips, somebody else thought regulator too, but i be sure to follow your steps, THANKS VERY MUCH!!!
Ok finally got time to check the lines and it still bleeds down with the return line pinched off and doesn't with the main fuel pinched off. But just to clarify that means a new fuel pump right??
Hey thanks for the help but please clarify that bleed down if fuel line is pinched means a new pump, oh and also would the pump from a 93 GMC work or are they different from 96 up??
Hey I finally had time to do the fuel pump and it was definitley that. Thanks for all your help and sticking with me through it all, thanks very much
chev s 10 4.3 have to prime to start after it starts works fine for 4 to 5 miles then dosnt seem to get fuel turn off and restart then it runs fine for another 4to 5 miles ???
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