'97 C1500 5.7 V8 Odd problem

[DocBernard]

I went on here and found manuals for the 98......will those work for the 97? Were there any major or significant differences? I could not find any links for the 97 model.

Appreciate the advice, GoToGuy, I found it helpful.

 

[DocBernard]

Similar, yet different:

- KOEO, check pressure (as stated above)
- If pressure remains after pump shuts off, pull fuel fuse
- Crank engine, see if pressure drops (indicative of injectors firing)
- Reinstall fuse
- Crank engine again, check pressure is present and w/in spec (OP may have done this already)

And/ or:

- Pull fuse to disable injectors (see attached schematic)
- Crank engine, check fuel pressure (injectors disabled)
- Install fuse
- Crank engine, check fuel pressure (injectors enabled, pressure should be same or nearly 1st reading)

Ok, one more thing checked off with no luck finding issue. I have voltage to both sides of ECM1 fuse, so not that. I guess I'm going to have to go buy a fuel pressure gauge. Is there anything on the spider block plug I could check without specialty tools?

Thank you for the diagram, 1998_K1500_Sub

 

[spf1268]

Ok, one more thing checked off with no luck finding issue. I have voltage to both sides of ECM1 fuse, so not that. I guess I'm going to have to go buy a fuel pressure gauge. Is there anything on the spider block plug I could check without specialty tools?

Thank you for the diagram, 1998_K1500_Sub

Go to your local Oreilly auto parts or similar and borrow/rent the fuel pressure gauge.

Fuel Pressure Gauge Rental

 

[DocBernard]

Quick info update.....this is a 1998 (Sticker said 10/97), GMT-400 K1500 (Cab is badged Silverado, bed says Z71). Air cleaner says "VORTEC" and vin decodes as a 5.7.

Sorry for the confusion.

spf1268, fuel pressure gauge on the way......wife was out and about so I sent her over to get it.

 

[DocBernard]

Wife got home with the fuel pressure tester and I attached it to the Schrader on the supply line near the throttle body.

First off.....allow me to admit that I was wrong. I over-complicated things with assumptions. Lots of fuel spray, etc. does not mean adequate pressure. I make a horrible diagnostician. If this is the problem, I went way too deep into things.

Fuel pressure was 15 psi. and well below the 55-60 minimum. I need a fuel pump, and had one that I took back to pay for the MAS.... Once replaced, I will update y'all if that fixed it.

I admit I am an idiot who probably shouldn't drive fire engines anymore.

 

[Teddygraham]

Wife got home with the fuel pressure tester and I attached it to the Schrader on the supply line near the throttle body.

First off.....allow me to admit that I was wrong. I over-complicated things with assumptions. Lots of fuel spray, etc. does not mean adequate pressure. I make a horrible diagnostician. If this is the problem, I went way too deep into things.

Fuel pressure was 15 psi. and well below the 55-60 minimum. I need a fuel pump, and had one that I took back to pay for the MAS.... Once replaced, I will update y'all if that fixed it.

I admit I am an idiot who probably shouldn't drive fire engines anymore.

Dude happens to the best of us. Never ever assume, never ever believe what someone else says unless you see it yourself lol. That was my take away from ten years at a dealer

 

[SUBURBAN5]

Wife got home with the fuel pressure tester and I attached it to the Schrader on the supply line near the throttle body.

First off.....allow me to admit that I was wrong. I over-complicated things with assumptions. Lots of fuel spray, etc. does not mean adequate pressure. I make a horrible diagnostician. If this is the problem, I went way too deep into things.

Fuel pressure was 15 psi. and well below the 55-60 minimum. I need a fuel pump, and had one that I took back to pay for the MAS.... Once replaced, I will update y'all if that fixed it.

I admit I am an idiot who probably shouldn't drive fire engines anymore.

It's ok at 15psi I'm sure you found the problem. After 478k miles I'll have to admit if lm not sure about an issue I shoot the parts cannon and tell my wife it needs replacing anyways. Never a good financial strategy to do it that way. Nowadays I'm really trying to test what I replace so i don't throw away good parts. Now since you got a pick up I would look into the process of changing a fuel pump so you dont go busting wires, fittings, or hoses. Plus you most likely have fuel in the tank. Look up videos and get a game plan. At least that's what I would do

 

[DocBernard]

Already had the game plan when first thought fuel pump. Had the pump and a buddy coming over to help drop the tank. All bolts already been sprayed with break-free. And had back up plan with dimensions to cut through bed if needed.

 

[spf1268]

Tilting the bed OR removing the rear tires and sliding the bed back is much easier than dropping the tank.
Please do not cut a hole in the bed unless it is a rusty POS.
Here is a video on tilting the bed for fuel pump access on a GMT400:

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Be safe..