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88 f250 5.8 fi dual tanks
seem to be low pressure at rail
Got a loaner pressure test gauge but it doesn't seem to work
I pushed it on my tire and got a reading just to test it
if i depress valve on rail fuel does come out a little spray not super high
truck will run on fluids sprayed into intake
I changed fuel filter, was able to blow through it easily.
I unhooked plug to dual tank switch ran a jumper from battery can hear both fuel pumps running in the tanks.
Tried starting truck with jumper to each pump and nothing.
Checked fuel rail regulator with vac line off and pumps energized no fuel coming out, replaced 25k ago.
Thinking high pressure pump?
Truck had been stumbling under a load been going on for awhile but i was only using front tank rear has a leak.
I know i need to get a reading at the rail, going to swap loaner gauge.
But any other ideas are appreciated
Until you get a working pressure gauge you are guessing, but given the symptoms it looks like low pressure at the rail. You can jumper Pins 2 & 6 on the data link connector (where plug in a code reader) then cycle the key to the Run position to keep the fuel pump relay energized. Much easier than doing what you tried before.
You can jumper Pins 2 & 6 on the data link connector (where plug in a code reader) then cycle the key to the Run position to keep the fuel pump relay energized. Much easier than doing what you tried before.
Thanks for the picture and diagram, electrical not my best and i didn't know where the port was.
so i bought a fuel pressure gauge and both pumps are reading zero pounds pressure at the rail, i pressed the release button on gauge and fuel did flow slowly so i know its getting to the gauge. Im still running the pumps from the tank selector switch on dash if thats a problem.
I did buy a high pressure external pump
Last edited by basdog; May 25, 2022 at 02:55 PM.
Reason: Ok
Im getting about 1/2 # pressure at the rail. I pumped about a cup of gas through the pressure gauge release button took awhile.
dont know what to do next. Inerta switch good
I bought the high pressure pump hoping that would be it due to ease. Its still in box and dont have a ride to parts store 15 miles away
Im going to replace front pump and fuel tank because i plan on keeping for a long time, but now i see 2 tank sizes 16 and 19 gallon anyway to tell the difference? Mine xlt ext. Cab
I replaced front tank 19 gal. And fuel pump.
this got me 8 # pressure at the rail. up from a half #
I replaced high pressure fuel pump and still 8# pressure.
There are 2 relays in front of test plug drivers side under hood they attach to the backside of overflow, windshield wiper juice tank not sure what they are for yet
when I check parts stores and search for a fuel pump relay
They all show one a 5 pin
Last edited by basdog; Jun 7, 2022 at 09:06 PM.
Reason: Ok
If any of the fuel pumps are activating I see no need to install a new relay. 8 PSI fuel pressure is an indication the high pressure pump is not getting power or the ground is compromised. The low pressure in-tank pumps are rated at ~ 8-12 PSI I believe. Do you hear the high pressure pump energize for 1-2 seconds when you cycle the key from Off to Run? To keep the fuel pump relay energized all the time with the key in Run position jumper pins 2 & 6 on the data link connector as suggested earlier. That will make troubleshooting this circuit easier.
Don't forget this year model has the dual-tank reservoir that feeds the filter and the high pressure pump on the frame. This is the valve that switches which tank feeds the rest of the system and which tank the overflow fuel goes back to. It frequently fails in several fashions, so it could be blocking fuel from going to the high pressure pump.
Only real test is to disconnect its output hose and see if there's plenty of fuel coming out with the key on.
Don't forget this year model has the dual-tank reservoir that feeds the filter and the high pressure pump on the frame. This is the valve that switches which tank feeds the rest of the system and which tank the overflow fuel goes back to. It frequently fails in several fashions, so it could be blocking fuel from going to the high pressure pump.
Only real test is to disconnect its output hose and see if there's plenty of fuel coming out with the key on.
My truck had been sitting for ~ 9 years. It was stuck on the front tank. I would think that it would not be stuck somewhere in between the front and rear positions. Even if it was, according to what rla said that pressure is correct for the in-tank pumps. I would say the that DFR is functioning.
I hooked an external ground to high pressure pump
and jumped sockets 2 and 6 at the test ecc? Port and nothing happens, no power to pumps.
If i supply power to connector that plugs into dual tank switch on dash i can hear internal pumps running.
i dont think high pressure has run yet, working by myself so cant lay under there to listen.
when you jump 2 to 6 would that make high pressure run continuously? Same with in tank pumps?
I wonder if relay is in between test port and dash switch.
Im getting a relay
when you jump 2 to 6 would that make high pressure run continuously? Same with in tank pumps?
It will when you cycle the key to the Run position.
If that does not work try jumpering Pin 6 to ground instead of going to Pin 2. Pin 2 is Signal Return which is another path to ground, but sometimes that path is broken.
