Fuel problem.

BAMF-Z71 · September 15, 2006

I bought a '99 Silverado Z71 w/ 4.8L about a month and a half ago. When I bought it, the dealership (a ford outlet lot) had just received it in on a trade and had only taken it for a short drive and barely had time to look over it. I bought it after they said they were going to replace the fuel pump in it as it acted like it was starving for fuel for the first, oh lets say 30 seconds or so, until it got warmed up. It worked fine for about a week and then it started acting up doing the same thing. I ran a "fuel system cleaner" through it and that worked for about 3 days. I crawled underneath the other day and looked and to me it looked like they didn't even replace the fuel filter. I've been busy with work and school and finally got a day off tonight and said to hell with procrastinating. So I put on a Wix fuel filter, changed the oil, started it up and it's doing the same damned thing. My father works at John Deere and is bringing home a fuel pressure tester tomorrow night but I'm going to be gone until late saturday evening to a firefighting class.

What other possibilities would there be other than the dealership didn't replace the pump? Also what would be the next step if the fuel pressure is fine? Anyone ever have similar problems?

Any help is very much appreciated. Thanks in advance.

BTW: My cardomain link for the truck is http://www.cardomain.com/ride/2440325 for those who want to see pictures.

BAMF-Z71 · September 15, 2006

Anyone got any ideas at all? Someone on pickuptruck.com forums mentioned that it could be injectors but I'm hoping it's not.

ChevyTech007 · September 16, 2006

First thing I would do is pull the vacuum hose off the fuel pressure regulator and check for fuel. If there is fuel replace the regulator.

BAMF-Z71 · September 17, 2006

Well, I was headed to a party last night and when I started the truck up my check engine light came on. I took it over to O'Reillys where a friend of mine works, we hooked up the code reader and it was throwing P0440. This code is an evaporative emissions malfunction. My friend kept trying to tell me it was the EGR valve and so did a guy my father knows, but after looking in the Chilton it's saying there is a solenoid under need the valve cover. Said that could be bad or the charcoal filter inside the EVAP by the gas tank.

Anyone know of some sure fire ways to check both?

GM-Tech · September 17, 2006

There's no solenoid of any kind under a valve cover. The most common cause of a P0440 on your vehicle is a bad/loose gas cap or leaking vent valve. You can probably see this valve by looking between the gap of the bed and the body on the drivers side. It's on top of the gas tank.

The only way to know for sure is with specialized equipment to test the system for leaks. Otherwise, you're just guessing.

BTW, this will not affect the way the vehicle runs.

BAMF-Z71 · September 17, 2006

So what do you suggest is making the truck run so s**tty?

BAMF-Z71 · September 20, 2006

Ok, well me and the old man figured the EGR valve was stuck open.. so the only way we could think of to test it out was to unhook the wires to the valve. The truck ran the same as before and didn't even throw a code when started with the wires unhooked, although after turning it off for a brief moment to feed the horses and then starting it up again, the code was then thrown. I'm sure it's the code for the EGR valve as we already cleared the P0440. A friend of my father's has a code reader and is going to check it tomorrow to make sure. He is also going to clear out all the codes.

What would be the next step, by ourselves, of diagnosing the problem.. or atleast a step in the right direction?

GM-Tech · September 20, 2006

Take the EGR off and attempt to blow through one of the holes. If you can't, it's not leaking and is not your problem. I highly doubt it's a stuck EGR because that wouldn't go away aft4er 30 seconds.

Whatever is causing the P0440 would not cause any sort of driveability problem, so you can ignore that for now.

Have you checked fuel pressure? That would be my next step. You need to do some valid diagosis, guessing will get you nowhere fast.

ChevyTech007 · September 20, 2006

If the EGR is stuck open, you need to pull the valve off. Unplugging the wires will do nothing. It is held open by carbon.

BAMF-Z71 · September 21, 2006

Well, we put a fuel pressure tester on it and it is normal for both started and key just turned on. This tells me that it's not a problem in the fuel line at all, correct?

What is the next step?

GM-Tech · September 21, 2006

Well, we put a fuel pressure tester on it and it is normal for both started and key just turned on. This tells me that it's not a problem in the fuel line at all, correct?

What was the pressure?

95Sierra2500 · September 21, 2006

Well, we put a fuel pressure tester on it and it is normal for both started and key just turned on. This tells me that it's not a problem in the fuel line at all, correct?

What was the pressure?

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X2. On these newer trucks, even being at the low end of the specs can spell bad news and cause misfires/no-starts due to not having enough fuel.

GM-Tech · September 21, 2006

X2. On these newer trucks, even being at the low end of the specs can spell bad news and cause misfires/no-starts due to not having enough fuel.

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Yep. Even a couple PSI can be a problem.