ranchodelux

I have a 2004 Silverado 4x4 extended cab with a 8.1 engine that has 75,000 miles. It began to occasionally loose power when the gas gauge fell below one quarter. It acted just like an old time, classic case of a plugged fuel filter. Chugging on hills or with a loaded horse trailer. Then the problem began to show up when the tank was fuller or the load was less. Outside temperature doesn't seem to matter. The problem used to go away entirely when you fill the tank above one fourth. When this problem occurs the engine won't rap above about 1,000 RPM. If the fuel filter is a lifetime filter, does this mean it can't get plugged up? I took it to the Chevy garage and they couldn't get the problem to occur when they were trying to diagnose it. They did not seem to subscribe to the plugged filter theory. Last night the tank was below a fourth, pulling a trailer with one horse on rolling hills and it finally quit altogether for the first time. I was able to restart it but not get above about 750 RPM. We towed it home and when the load was off the engine it ran ok again. Is this a plugged filter or something else?

RonH

If it is a fuel problem, it's most likely a failing fuel pump.

ranchodelux

Thanks, RonH. If it is a pump or a filter, apparently the fix is the same as I understand the filter is integrated into the pump and stashed away into the tank. But consider: This truck has a governor that cuts the engine out if it raps in excess of about 3,000 rpm (auto trans in park or neutral). When it starts the sputtering and chugging with the low fuel level, the engine sounds similar to when the governor kicks in, causing it to sputter. Based on these symptoms, do you believe it is a fuel supply issue or a computer/electronic issue? That is, I'm asking if you think it is more likely a fuel supply issue or something else.

kcb37

I would say it is a fuel issue. And while you have a strainer in the tank on the bottom of the fuel pump, you should have an inline fuel filter. If you get under your truck it should be on the inside of the drivers side framerail around the back of the cab and front of the box. I would change the filter, but it does sound like it could bea pump. If you bought your truck new and haven't changed the filter yet you need too. When you take it off see if you can blow threw it. If you can't it was really bad.

RonH

From the Service Manual for the 2004 Silverado 4wd:


This Product Information Update is to advise you of an error in the 2004 Owners Manual Section 6, Normal Maintenance Replacement Parts. This section list the fuel filter as a replaceable part; this is incorrect as gas powered V-8 engines have a lifetime filter built into the fuel sender inside the tank and thus is not serviceable separately.

ranchodelux

We live in a very rural area and feel good about even having a chevy garage in town. The next one is about 80 miles away. Having said that, my confidence in their powers of diagnosis is limited. I'm told the experiment to replace the fuel pump/filter will cost $500.00. I'm wondering if based on the symptoms described, I should direct that this work be done in spite of resistance from the service department (the tech was not keen on the fuel filter theory) or is there is any other way to check if the fuel system is the problem? A fuel pressure reading? Does anyone have any thoughts on why these symptoms are related to fuel levels below 1/4 of a tank? Isnt there a better way to diagnose a failing pump than to just replace it and see if that was the problem? Thanks again.

RonH

Yes, there is a schrader valve on the fuel railunder thesight cover on top of the enginefor hooking up a fuel pressure gauge. That test should be done. The reason the fuel level can make a difference is because the more fuel that's in the tank (the deeper the pump pickup is) means a difference in the effort required to pump the fuel out. The fuel pump has to deliver fuel to the pressure regulator at a certain pressure.

The fuel pump is not the only component that can cause problems. There's the pressure regulator and some sensors that can fail. The gas cap can be a problem if it won't hold pressure in the tank. As you say, throwing parts at a problem til you get the right oneis not the most economical or efficient way to fix it. On the other hand, the fuel pump/sender/filter/sensor is a component item that replaces most of the critical parts at once. Test the other components first.

ranchodelux

Thanks for your help. Your analysis makes perfect sense. What doesnt make sense is why Chevrolet would make it so expensive to change this part. By contrast, when my son's 87 Subaru's fuel pump went out it took one wrench and about 10 minutes to change it. Im going to print out this thread and take it back to the Chevy garage to show the tech. If anything interesting develops I'll keep you posted.

RonH

You might try looking online -- google and ebay -- and see if you can find a fuel pump kit. They sell them for some models so you can remove the entire component, take it apart,and replace just the pump. The dealer and auto parts stores don't sell them, but they are available online for at least some models. Good luck.

ranchodelux

Thanks again. Ill check it out tonight.