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Agreed, and I have read threads where that was the cause of a no start, but that won’t stop the bowl from filling, just stop the flow from bowl to heads.
You’re right. I forgot the standpipe valve stops flow out of the bowl.
Did a dead head test with 80+ psi measured from the supply line at the fuel bowl.
Found the totally busted regulator. Replaced with dorman, it failed to, so i bought a whole new bowl.
With the dorman regulator, the truck started and ran for a few minutes. Fuel pressure pre filter was 95 psi. Another possible failure but fuel was coming into the bowl. Pressure only built to about 20 psi beforeni cranked it.
I switched to a dorman drain valve, and it failed too. The stock one failed. Internal seals were blown.
Swapped the bowl, now fuel wont make it to the bowl very well. Some fuel makes it, but not much. I know the bowl should fill with the cap off in a few seconds, and it does not. I had the fuel pressure gauge on and it was zero from the pre filter (mechanical gauge, not the glowshift). Bowl was about half full.
I think the next step is to bypass the tank switch manifold thing and see if that changes anything. Its a big variable, and there could be some intermittent failure happening. Im betting it will. I swap the reutrn to so i can see that working.
I go back to the truck tomorrow. Ill bring a gerry can.
The truck WILL run by sunday lol. I have the whole day with it on sunday, even if it means running all new fuel lines and ditching this alternative fuel system.
Maybe i missed a plug or something in the bowl? Fuel does spill out of the supply port of the fuel bowl. New filter is clear. Ill do another dead head with the tank system bypassed.
Gotta eliminate this fuel system at this point. There isnt much else to look at.
Did you check the supply port from outside of the bowl to the interior to see if there is casting flash blocking it? Have you tested the tubes that go from the bottom of the engine up to where they feed the bowl to see if those flow freely?
Did a dead head test with 80+ psi measured from the supply line at the fuel bowl.
Found the totally busted regulator. Replaced with dorman, it failed to, so i bought a whole new bowl.
With the dorman regulator, the truck started and ran for a few minutes. Fuel pressure pre filter was 95 psi. Another possible failure but fuel was coming into the bowl. Pressure only built to about 20 psi beforeni cranked it.
The fuel pump should be on a relay system controlled by the PCM and has a 20 second power supply before it cuts out if the motor isn’t started or cranked over.
I switched to a dorman drain valve, and it failed too. The stock one failed. Internal seals were blown.
Swapped the bowl, now fuel wont make it to the bowl very well. Some fuel makes it, but not much. I know the bowl should fill with the cap off in a few seconds, and it does not. I had the fuel pressure gauge on and it was zero from the pre filter (mechanical gauge, not the glowshift). Bowl was about half full.
I think the next step is to bypass the tank switch manifold thing and see if that changes anything. Its a big variable, and there could be some intermittent failure happening. Im betting it will. I swap the reutrn to so i can see that working.
I go back to the truck tomorrow. Ill bring a gerry can.
This will eliminate the entire aftermarket/ alternative fuel system.
The truck WILL run by sunday lol. I have the whole day with it on sunday, even if it means running all new fuel lines and ditching this alternative fuel system.
Maybe i missed a plug or something in the bowl? Fuel does spill out of the supply port of the fuel bowl. New filter is clear. Ill do another dead head with the tank system bypassed.
This is not a good thing. Can you snap a picture of where the fuel is spilling out.
Gotta eliminate this fuel system at this point. There isnt much else to look at.
This is the location of the factory plug for the fuel pump circuit. It’s a red with dashed black line.
Drivers side just above the sway bar link.
Curious if your aftermarket fuel system pump is fed off this circuit. 20 psi at koeo to 95 psi when cranking is peculiar.
This is the location of the factory plug for the fuel pump circuit. It’s a red with dashed black line.
Drivers side just above the sway bar link.
Curious if your aftermarket fuel system pump is fed off this circuit. 20 psi at koeo to 95 psi when cranking is peculiar.
The pump is fed from the factory wiring. If there was a partial restriction, i feel like it would cause this. It is a black and red wire. I dont remeber if there were dashes on the red. Ill double check polarity just in case though it did run. The beast pump has an aftermarket relay thing going on, but its disconnected. The pump has power and is making pump noises.
The system is controlled by a switch and a couple of relays and terminals under the dash. The wiring ill probably disconnect and leave it. It has power for sure and seems to check out electricly.
If the bowl isn’t filling something downstream is jacked, pump, switching valve, fuel line or tank.
Gutting the standpipe only helps for the upstream which is heads and injectors.
Assuming the tank selector valve is controlled by a 12v switch have you confirmed circuit continuity, good voltage and is the valve fully opening to the selected tank.
What’s the current temperature where you are? Could it be fuel gelling?
On the weekend you had 80psi and now it won’t fill the bowl. I’m like IDK…WTF… nothing but spitballing from here.
Like you said earlier you could try to bypass the selector switch, but before you go there run the fuel pump feed line into a jerrycan and see what happens.
Temps hover around freezing here currently and its recent diesel so should be a winter blend. Its not gelling. Seen plenty of fuel to know that.
Did you check the supply port from outside of the bowl to the interior to see if there is casting flash blocking it? Have you tested the tubes that go from the bottom of the engine up to where they feed the bowl to see if those flow freely?
I pulled the supply line off and fuel did come out. I dont remember seeing anything. When i pull the supply line off to do the dead head test, ill poke something through to verify.
It is something with the manifold. This whole system is coming out.
55psi of pressure pre filter with key off engine off and with engine on.
I just bypassed the manifold on the supply, and somehow, its pissing fuel out from the supply hole which is reutrn fuel probably. Only the return is still connected. Maybe there are internal leaks, and its trying to suck fuel from the return line? I wonder how long its been like that.
Im going to patch it up ans rip and tear at home. I have some fuel line ordered, and i want my garage. Truck is going home tonight.
Bypassing the supply.
That nipple is the supply to the pump. Fuel is pouring out of this, but i dont think it should. The tank is hooked right to the fuel pump.
Im going to get the return hooked up, and then make arrangements to get the rig home.
I think this system is plumbed wrong. I dont see a return to the after market tank. I think it may need to come out at the farm. There is what seems should be a reutrn on the tank, but its plugged. I dont think this thing ever had a return on the aftermarket tank. It looks like when the purge was hit, the reutrn would go into the supply, which makes no sense.
Regardless, im not sure i can drive this home right now.
So that line that crosses over i think should goto the return on the aftermarket tank. Im not 100% on that. I know there is a purge that would switch the returns so any alternative fuel would return to the rright tank while feeding diesel. I dont think that is what this did.
It will no longer cause issues though....i know that!
Ok. I think its patch worked enough to drive it home.
I took the plug out (it was a bolt lol )of the suspected return hose from the aftermarket tank and ran the reutrn to it. It...ummm....it doesnt sound like there is any piping and the return just pours into the tank from the top (instead of piping running the return fuel to near the bottom of the tank, i wonder if this is why it was plumbed weird)....hopefully i dont foam up too bad....This is note worthy as the sound was very audible while pressure was bleeding off while the truck was off, and i have never heard this sound before (further confirming there was never a return). At the very least, the bowl return was either dead headed or sent back to the supply. Might explain why the truck ran for 5 years. Good news is the aftermarket tank is far from full so it will be easy to remove. Just needs to drive like 15 miles. "Come on baby...."
Im going to leave the mechanical fuel pressure gauge on just to see what the fuel pressure does while driving. Never did get the glowshift in (sensor is in the bowl though).
Im really interested to see if it runs any differently, especially under heavy throttle.
Batteries are dead so i gotta boost it. They did well considering.
But hopefully she makes it home straight into the garage, and get er done...with heat and all my tools and a smooth floor. I got all new rubber fuel line and matching injector clamps.
I may plumb one of the pre filters back. I like the idea of a pre filter.
Im sick of being covered in diesel....
Last edited by Hellraiser456; Jan 11, 2026 at 03:44 PM.
I’m going to guess that the fuel system was regulated at the pump and the return looped behind the pump and back into the supply. This is just based on some other flow dynamics that I’m familiar with on unrelated pump systems. Maybe the FPR was gutted to send all pressure back to the pump which was then regulated and dumped into the supply side?
Glad you got it home. I was gonna say, I would have purchased enough fuel line to run it back to the house with them plumbed into a jug in the bed. It’s no fun working away from home/tools/shelter/heat.
)of the suspected return hose from the aftermarket tank and ran the reutrn to it. It...ummm....it doesnt sound like there is any piping and the return just pours into the tank from the top (instead of piping running the return fuel to near the bottom of the tank, i wonder if this is why it was plumbed weird)....hopefully i dont foam up too bad....This is note worthy as the sound was very audible while pressure was bleeding off while the truck was off, and i have never heard this sound before (further confirming there was never a return). At the very least, the bowl return was either dead headed or sent back to the supply. Might explain why the truck ran for 5 years. Good news is the aftermarket tank is far from full so it will be easy to remove. Just needs to drive like 15 miles. "Come on baby...."
