Hi Everyone,
I am having fuel pump problems. I am on my second new AC Delco. I don't seem to notice any mileage issues or performance issues, but the noise is getting worse. It's the same problem with every pump, so something else is at play.
Last year they replaced my pump with 130K on it because it was getting noisy. I mostly noticed when towing in hotter weather. The new AC Delco last 30 days and started making the same noise. This time, (since the fuel filter was a year old), I had them replace the fuel filter too.
Fast forward almost one year later, and I have the same frickin' issue again. I only hear the noise when I prime the pump. Once in a blue moon, you can hear it as the truck shuts off. I can only describe the noise the pump makes as a "warbly" noise or a like a half dead muted turkey. It almost sounds like something boiling over. As soon as the pump is primed it stops. At one point, I could have sworn I heard the regular fuel pump priming sound, behind the noise-but I can't say for sure.
Winter was fine. Spring was fine. No noise until it started getting really hot. I first noticed after towing on an 85 plus temps days. I also noticed the noise after 30 minutes of driving in 95 plus temps.
I should also note, other when when the pump primes, I don't hear the noise or notice any performance/mileage issues. However, the longer I drive, the louder it gets (after I shut down the vehicle, then turn the key to prime the pump).
So with the awesome videos from May03LT, I went ahead and tested the relay for voltage measurements. Per another post, I also swapped relays to see if noise went away.
relay tests
battery supply volts 12.5
ground -12.5 volts
pcm control 11.5 volts (I had radio and ac on)
to pump-good since pump gets power.
Next, I bought a fuel pressure guage.
fuel guage pressure check before travel at idle: 56psi
After driving for an hour, I pulled into the gas station. I was beginning to hear the noise (I turned the key to prime the pump after filling up).
I pulled in the driveway later that day and checked the PSI at idle.
56psi (but needle was vibrating like crazy between 54-58 PSI, averagin 55-57psi, if that means anything--before travel the needle was was rock steady)
At this time I decided I was going to take a stethoscope and listen to the gas tank...what's weird is as soon as I did this, the dang noise stopped as soon as it started! I've never had that before...usually I have to wait for the truck to cool down before it stops making the noise.
Well, since May03LT doesn't have part 2 out, I'm hoping he can maybe chime in.
--though I have a feeling anything left would involve dropping the tank.
What's left to check? What other part of the fuel system is causing all three pumps to make this same noise after extended driving in the heat? I've towed over two hours at the beginning of spring when it was in the 70's and never heard anything.
What's a vent valve? Do gases escape from it? Is this what I hear? Could a faulty fuel pressure regulator be the problem? Whatever the issue, it's spanned across 3 pumps and seems to progressivly get worse, but again, I've never noticed mileage or power issues....just sometimes when you shut it down, you hear that boiling noise from the tank or when you prime it. Everything I've checked so far seems in spec.
Warranty runs out at the end of August. If the tank has to be dropped to check the rest of these components, I think for the $280, 4 hours of labor, the dealer should be able to replace the pump and check all of these components and replace the filter? The last time they charged $50 bucks to replace the filter (but labor for replacing the new AC delco was free, since it was in 30 days). I look now and I can't believe how easy it would be; especially on a lift and with fuel pressure already relieved. If I can't check any of the rest of this myself, is this asking too much? Is it fair?
Would the shaky need on the second "after" reading signify anything? It was still in normal range.
Any ideas, theories, things I can try or tell the repair shop is MUCH appreciated.
Please restore my faith in this truck!
Thanks everyone,
gunrock
(and sorry for the long post)
I am having fuel pump problems. I am on my second new AC Delco. I don't seem to notice any mileage issues or performance issues, but the noise is getting worse. It's the same problem with every pump, so something else is at play.
Last year they replaced my pump with 130K on it because it was getting noisy. I mostly noticed when towing in hotter weather. The new AC Delco last 30 days and started making the same noise. This time, (since the fuel filter was a year old), I had them replace the fuel filter too.
Fast forward almost one year later, and I have the same frickin' issue again. I only hear the noise when I prime the pump. Once in a blue moon, you can hear it as the truck shuts off. I can only describe the noise the pump makes as a "warbly" noise or a like a half dead muted turkey. It almost sounds like something boiling over. As soon as the pump is primed it stops. At one point, I could have sworn I heard the regular fuel pump priming sound, behind the noise-but I can't say for sure.
Winter was fine. Spring was fine. No noise until it started getting really hot. I first noticed after towing on an 85 plus temps days. I also noticed the noise after 30 minutes of driving in 95 plus temps.
I should also note, other when when the pump primes, I don't hear the noise or notice any performance/mileage issues. However, the longer I drive, the louder it gets (after I shut down the vehicle, then turn the key to prime the pump).
So with the awesome videos from May03LT, I went ahead and tested the relay for voltage measurements. Per another post, I also swapped relays to see if noise went away.
relay tests
battery supply volts 12.5
ground -12.5 volts
pcm control 11.5 volts (I had radio and ac on)
to pump-good since pump gets power.
Next, I bought a fuel pressure guage.
fuel guage pressure check before travel at idle: 56psi
After driving for an hour, I pulled into the gas station. I was beginning to hear the noise (I turned the key to prime the pump after filling up).
I pulled in the driveway later that day and checked the PSI at idle.
56psi (but needle was vibrating like crazy between 54-58 PSI, averagin 55-57psi, if that means anything--before travel the needle was was rock steady)
At this time I decided I was going to take a stethoscope and listen to the gas tank...what's weird is as soon as I did this, the dang noise stopped as soon as it started! I've never had that before...usually I have to wait for the truck to cool down before it stops making the noise.
Well, since May03LT doesn't have part 2 out, I'm hoping he can maybe chime in.
--though I have a feeling anything left would involve dropping the tank. What's left to check? What other part of the fuel system is causing all three pumps to make this same noise after extended driving in the heat? I've towed over two hours at the beginning of spring when it was in the 70's and never heard anything.
What's a vent valve? Do gases escape from it? Is this what I hear? Could a faulty fuel pressure regulator be the problem? Whatever the issue, it's spanned across 3 pumps and seems to progressivly get worse, but again, I've never noticed mileage or power issues....just sometimes when you shut it down, you hear that boiling noise from the tank or when you prime it. Everything I've checked so far seems in spec.
Warranty runs out at the end of August. If the tank has to be dropped to check the rest of these components, I think for the $280, 4 hours of labor, the dealer should be able to replace the pump and check all of these components and replace the filter? The last time they charged $50 bucks to replace the filter (but labor for replacing the new AC delco was free, since it was in 30 days). I look now and I can't believe how easy it would be; especially on a lift and with fuel pressure already relieved. If I can't check any of the rest of this myself, is this asking too much? Is it fair?
Would the shaky need on the second "after" reading signify anything? It was still in normal range.
Any ideas, theories, things I can try or tell the repair shop is MUCH appreciated.
Please restore my faith in this truck!
Thanks everyone,
gunrock
(and sorry for the long post)
