Fuel Pump Question
My 88 F150 has two fuel pumps. How likely is it that both would fail at the same time? When I turn on the key I hear the fuel pump relay click, but that's all. I don't hear any pump sound. There's no fuel pressure at the rail. The truck hasn't been driven in a year. Could old fuel have caused both pumps to fail?
Do both fuel pumps make a sound, or just the one in the tank? I'm pretty sure the low pressure pump in the tank is not working. Could the high pressure pump be running and not making a sound if it's not getting fuel? I measure 12 volts at the high pressure pump. I haven't checked at the tank because the connector is not accessible unless I lower the tank. |
Originally Posted by forum
(Post 6078581)
My 88 F150 has two fuel pumps.
https://www.supermotors.net/getfile/...oorsticker.jpg (phone app link)
Originally Posted by forum
(Post 6078581)
How likely is it that both would fail at the same time?
Originally Posted by forum
(Post 6078581)
There's no fuel pressure at the rail.
https://www.supermotors.net/getfile/...ssuregauge.jpg (phone app link) https://www.supermotors.net/getfile/...itchesopen.jpg (phone app link)
Originally Posted by forum
(Post 6078581)
The truck hasn't been driven in a year. Could old fuel have caused both pumps to fail?
Originally Posted by forum
(Post 6078581)
Do both fuel pumps make a sound...?
Originally Posted by forum
(Post 6078581)
Could the high pressure pump be running and not making a sound if it's not getting fuel?
Originally Posted by forum
(Post 6078581)
I measure 12 volts at the high pressure pump.
Originally Posted by forum
(Post 6078581)
I haven't checked at the tank because the connector is not accessible...
https://www.supermotors.net/getfile/...connectors.jpg (phone app link) https://www.supermotors.net/getfile/...rs22172dmm.jpg (phone app link) |
Steve.
Thank you for the detailed response. You obviously put a lot of time and thought into it. Really appreciate! My truck has one fuel tank. It's a 1988 F150 302v8 auto. Maybe I can get a photo of the spec sticker later. The truck is not here at my house. I checked fuel pressure at the fuel injector supply rail (schrader(?) valve) with a gauge. I checked high pressure pump voltage at the pump connector. I unplugged the connector and attached volt meter to two pins inside the harness connector. To test the pumps I grounded the fuel pump test pin on the VIP(?) connector. The fp relay clicks and the volt meter shows 12V at the high press pump connector. It's going to take me a little while to go through all the valuable info in your response. Thanks again! |
A pic of the VC label isn't useful - YOU putting all its information into your signature is.
Follow the HP pump wiring down to the pump body, slide the rubber boots up, and inspect the terminals there. Make sure they're tight & not overheated. Check voltage there, with everything connected normally, and the DLC (VIP) jumpered: https://www.supermotors.net/getfile/.../dlcjumper.jpg (phone app link) |
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