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I have an 88 f150. It has the 302 EFI. It has a humming noise coming from the high pressure fuel pump. Which was just replaced in January I think it was replaced with a Delphi. But it only happens when I switch tanks. If I switch front to rear it’ll do it mainly on that tank. Or it’ll change its mind and if I switch it rear to front it’ll mainly do it on the front tank. The issue just developed today when I drove a few miles on the rear tank which I usually don’t do as it fills the front tank when it’s parked. I’m thinking it’s the selector valve on the frame that isn’t fully switching making the pump not get enough fuel from the low pressure part of the system? I’m thinking the selector valve was the problem with the cross fill. Since fuel pressure didn’t change between tanks when I checked the pressure awhile ago. But the engine doesn’t sound any different when it makes this noise. I put a stethoscope to each tank and the high pressure pump. The pumps in the tank sound like they’re working great.
The frame pump is sucking air for a few seconds when you switch tanks?
The Bosch frame pumps do get noisy when ready to fail
Get a spare to keep in the truck for when it does fail
Might be years from now
The frame pump is sucking air for a few seconds when you switch tanks?
The Bosch frame pumps do get noisy when ready to fail
Get a spare to keep in the truck for when it does fail
Might be years from now
Yea just when I switch tanks it makes the noise which I assume is it sucking air. But I’m wondering since I have the cross fill issue, is that the selector valve on the frame getting worse? I’m gonna take the supply lines off this weekend and see if the in tank pumps work. I do have the old pump still. It worked just didn’t hold pressure overnight. Still doesn’t fully hold pressure now but the issue was helped by the new pump.
The in tank pumps work, or partially work, or it would not run
Maybe look for one of the old recall one way valves for the fuel transfer or keep replacing pumps
I found one of these for a 2004 I previously owned, I used to have a bunch of them
If both in tank pumps work, it is not as big a deal to have the fuel transfer
I’m not worried about the fuel transfer since it’s not overflowing. But I just don’t like that it randomly started making noise. It is what it is I guess. If you guys say it’s fine and I talked to someone else and they said it’s fine so I’m not gonna worry about it I guess.
