Fuel issue here looking for help

[97blueyuk]

My 97 Yukon 5.7 vortex is not starting.

This all started after I fixed a cracked fuel line near the tank. The fuel pump is only about 3 years old and I can hear it running when key is turned on.

After I fixed the cracked line it was fine for a day or two. Then it started giving me issues starting and I had to use starting fluid. I though maybe the filter needed changed so I changed it. After changing it it would not start. I double checked the filter was going the correct way. I pulled the filter, had gas coming out of both fuel lines ( back from the motor and from the tank). It seems gas is getting to engine but not starting. Spark is fine. I was thinking pressure regulator/spider injector but would like some opinions before going through taking it all apart.


Thank you

 

[Mechanic421]

Fuel pressure tester they will not start till some were like 55psi. But will run on less pressure.

 

[97blueyuk]

I will get a fuel pressure tester today and test it and post results.

 

[97blueyuk]

Fuel pressure is 56-57 when trying to start the truck. It will start with starting fluid but dies shortly after

 

[east302]

It may be on the low end, factory specs are 60-66 psi with the ignition on (not cranking).

What is the pressure after you stop cranking? Let it sit for a few minutes, if it quickly drops to zero within a few seconds then it could be a bad regulator or leaking injector.

Is the instrument cluster passlock (security) light on?

Here are the diagnostics for a 1998 5.7L, maybe it will help...















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[97blueyuk]

So it's been awhile been very cold most days. I have been checking and testing today. I changed a kinked line. After cycling the IGN as stated in the above docs the pressure gets to 58. It will start at that point for a few seconds. While running the pressure drops to about 54. After turning off IGN very lil pressure drop shows on the guage maybe a pound or two after a few minutes. Also the rear of truck is in the air not sure if that matters. I am thinking weak fuel pump. Any opinions?

 

[iamdub]

I agree- weak pump. Is it a Delphi or AC Delco pump? The aftermarket replacement pumps for these are widely known to be hit-or-miss. Did this replacement pump come with the updated wire connector?

 

[97blueyuk]

It is Delphi. I believe the wiring was already done prior to me. New pump plugged right in.

 

[iamdub]

3 years is a short life for a quality pump. Have you verified the wiring and all was good- all connections clean and solid, etc.? I know this generation of GM had odd ground locations. For instance, my S10 had a ground at the very back on the left side frame rail that was for the taillights (makes sense) AND the fuel pump (dumb, in my opinion). That's a long way for a ground for a relatively high-amp device when there's plenty of closer options. This, and the wiring itself being small makes the power supply to the pump marginal even when the wiring and all is in tip top shape. Starving the pump for voltage, even if just a small amount, will make it pull more amps and run hotter, shortening it's life. Powering it off of a relay is cheap and easy and would eliminate any voltage drop concerns. If not new, I like to use the fan relays from mid-90s cars (usually Fords) at the salvage yards. They're good quality, have weather-tight sockets with heavy gauge wiring in them already and they're cheap. Power your fuel pump off of this and you may actually notice better engine performance.

 

[97blueyuk]

The wiring is pretty good. I replaced the ground when I put the pump in last time. I it just ran from pump to frame. It was thin and kind of short, i changed that

I read on a few diff places that people were getting short lives with them even the quality ones.

My thinking is same as yours with the shirt life but.....