Ok it's been a while since I posted and I'm still dealing with the same issue as before bucking and bogging and narrowed it down to the fuel pump. Swapped tank with a known good one from brothers truck as the old one was contaminated. Anyway this is the 3rd fuel pump in the truck now. Delphi replacement upgrade from cheap AutoZone one and it only lasted as long as the previous 2 pumps before. It works for maybe a 100 miles or so and then it has gots weak and won't hold pressure during acceleration. What would cause this truck to eat fuel pumps so quickly? Wiring? Ground issue? I'm sick of swapping pumps and only want to do this one more time lol. I'll be going with the vortex pump next time.
Fuel pump
- Thread starter short1500
- Start date
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I won't replace a working fuel pump without verifying the power supply and ground. It's more than just a "pump", there's an electric motor in there, too.
ABSOLUTE MINIMUM:
1. Verify supply voltage with the pump RUNNING, as close to the pump as practical--which is generally the three-wire connector in the harness just before the harness goes up and over the tank. If the alternator is putting out 14+ volts, the pump better be getting 12 volts. More is better.
2. Verify voltage on the ground wire with the pump RUNNING, as close to the pump as practical. Less is better, anything over 1 volt is a problem.
3. Airtex says most repeat failures are due to debris in the tank that wasn't properly cleaned-out. I don't know how accurate that is, but that's their story.
4. Install a new filter sock on the bottom of the pump, and assure that the main fuel filter isn't restricted. With the pump removed, assure that none of the supply or return plumbing is restricted--no pinched hoses, or crushed metal tubes.
5. Install a new in-tank wire harness if the original has ANY sign of distress, such as corroded terminals on the wires, or swollen insulation. See photo.
Replacement harnesses are generally longer, to fit as many vehicles as possible.
6. Verify fuel pressure and volume after the pump is installed. High fuel pressure can be a regulator problem...or restricted return plumbing.
Optional, but strongly recommended if you have the tools to do it:
7. Verify amperage draw of the fuel pump, with the pump RUNNING. Typically about 6 amps, can vary depending on application. Amperage can be tested anywhere in the supply wire to the pump, or even at the ground wire for the pump, but you're already at that rearmost connector to check voltage.
8. Use a graphing multimeter or a digital oscilloscope, and a low-amperage probe to GRAPH the amperage draw of EACH INDIVIDUAL MOTOR ARMATURE BAR. The resulting graph is like a fingerprint--they all look the same to the janitor, they all look different to the detective. Each armature bar will have it's characteristic pattern on the graph, but they should all be reasonably similar. Once you figure out how many armature bars there are, you can also calculate the RPM of the electric motor.
ABSOLUTE MINIMUM:
1. Verify supply voltage with the pump RUNNING, as close to the pump as practical--which is generally the three-wire connector in the harness just before the harness goes up and over the tank. If the alternator is putting out 14+ volts, the pump better be getting 12 volts. More is better.
2. Verify voltage on the ground wire with the pump RUNNING, as close to the pump as practical. Less is better, anything over 1 volt is a problem.
3. Airtex says most repeat failures are due to debris in the tank that wasn't properly cleaned-out. I don't know how accurate that is, but that's their story.
4. Install a new filter sock on the bottom of the pump, and assure that the main fuel filter isn't restricted. With the pump removed, assure that none of the supply or return plumbing is restricted--no pinched hoses, or crushed metal tubes.
5. Install a new in-tank wire harness if the original has ANY sign of distress, such as corroded terminals on the wires, or swollen insulation. See photo.
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Replacement harnesses are generally longer, to fit as many vehicles as possible.
You must be registered for see images attach
6. Verify fuel pressure and volume after the pump is installed. High fuel pressure can be a regulator problem...or restricted return plumbing.
Optional, but strongly recommended if you have the tools to do it:
7. Verify amperage draw of the fuel pump, with the pump RUNNING. Typically about 6 amps, can vary depending on application. Amperage can be tested anywhere in the supply wire to the pump, or even at the ground wire for the pump, but you're already at that rearmost connector to check voltage.
8. Use a graphing multimeter or a digital oscilloscope, and a low-amperage probe to GRAPH the amperage draw of EACH INDIVIDUAL MOTOR ARMATURE BAR. The resulting graph is like a fingerprint--they all look the same to the janitor, they all look different to the detective. Each armature bar will have it's characteristic pattern on the graph, but they should all be reasonably similar. Once you figure out how many armature bars there are, you can also calculate the RPM of the electric motor.
When last pump replaced I changed fuel tank to a clean good used on from brothers truck and also new fuel filter with new sending unit and sock. So entire whole new pump assembly. Tbi was gone through recently with all new gaskets and seals. Never checked the return line for blockage. This last time also gas gauge was bouncing around and never done that. I will check voltage and see what I get. Also I will check lines for blockage.
So if I get under voltage will this cause motor to burn out? Also how do I check the ground for voltage? Positive voltmeter wire to pump ground and the ground the negative wire on voltmeter to frame?
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Thanks. I was wondering how to check for voltage on ground side. As Shcurkey stated this.
Verify voltage on the ground wire with the pump RUNNING, as close to the pump as practical. Less is better, anything over 1 volt is a problem.
At minimum, the pump runs slow and produces poor pressure and volume.
Low enough and motor damage is possible.
Positive probe on ground wire close to the pump, negative probe connected to alternator case (engine running, alternator charging) or negative battery post (engine not running.) Use a clean non-corroded jumper wire as needed to extend the multimeter lead to reach the battery or alternator. 18-gauge wire is fine, bigger is OK. Mine is 16-gauge wire with small alligator clips on each end.
