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If there is air in the fuel system it will eventually work its way back to the tank via a fuel return line. Do you hear the pump turn on for a few seconds when you turn the key to on, but not start yet? Without a gauge, there really is no way to tell what the fuel pressure is.
Its moving fuel to the bowl, Im just not sure if its able to keep up with the demand while trying to crank.
Im waiting on a helper to go torque the drive bolt down, then Im gonna play with the IPR Valve. Ive narrowed it down to one of these 3 things. Although I guess it could be a bad HPOP? I mean Joey is supposed to test it right? IDK
I have been told by a reliable source that HPOP's rarely go bad, often get blamed.
Well its a rebuilt one, so IDK. Im in the process of removing the fuel pump. Also planning to replace the IPR valve, both are probably stock and could use replaced, although if they are still good I wouldnt mind having extra parts anyhow. We will see what I can do tomorrow. I did get the drive bolt torqued down, and I tried to start it with the IPR unplugged which I read should allow it to start if that part is bad, still no luck so I really think Its the fuel pump. Got both my batteries charged up to about 80% so they should be fine. Ive got power, Ive got air, last possible thing is fuel related right?
It's the ICP sensor, on the drivers side head towards the front of the engine that needs to be unplugged, i think you are either confusing the two, or their names.
Have you tried unhooking the fuel line on the inlet into the fuel pump on the frame rail and running a line to a jug of diesel instead? This would help eliminate clogged screens in the tank as being the problem?
It's the ICP sensor, on the drivers side head towards the front of the engine that needs to be unplugged, i think you are either confusing the two, or their names.
Have you tried unhooking the fuel line on the inlet into the fuel pump on the frame rail and running a line to a jug of diesel instead? This would help eliminate clogged screens in the tank as being the problem?
Which one is the possible issue? Would I need to pull the line off of the fuel tank?
The ICP sensor (Injector Control Pressure), on the drivers side head, would allow you to unplug it and still start the truck. If this sensor fails the PCM can compensate for it by running the truck off a stored set of values.
The IPR (injector Pressure Regulator), center of the engine behind the HPOP, should not allow the truck the run if disconnected. This controls the amount / pressure of the oil to operate the injectors.
As for the fuel line, just disconnect the inlet (rear) fuel line going to the pump (stuff something in the end of it to stop any debris getting in there) then run a new line to the fuel jug with diesel in it. This is a temporary arrangement just to eliminate any fuel delivery / flow issues between the tank and the fuel pump. If the truck does fire up with this arrangement, you have a fuel restriction somewhere (usually the tank pickup screens) and a hitch and harpoon mod is best performed to prevent this from reoccurring in the future.
Do one at a time (ICP sensor first, as it is by far the easiest) so you can determine which one alleviated the issues the truck is having.
The loose bolt on the HPOP was likely your problem all along, and you've remedied that. The truck should start with everything hooked up correctly if it ran before the HPOP replacement. I've had the misadventure of a jammed IPR shortly after introducing air in the oil rails (swapped injectors), but cleaning it got me going.
The injector Control Pressure sensor tells the PCM what the HPO pressure is, and the PCM sends a signal to the Injector Pressure Regulator to raise or lower the ICP based on that feedback. No IPR, no High Pressure Oil, no start.
The rebuilt HPOP he has is a T500, and they have a solid reputation from what I recall. Did you check for oil in the rails on the heads? You can start replacing sensors if you like because they are aging, but you are just throwing parts at it at this point.
I would do the following if I were you.
1. Check oil rails for oil on both heads
2. Check the fuel pump operation
3. Unplug ICP
4. Check for IPR tin nut
5. Replace IPR
Or, get a scan tool of some sort and post up some numbers for the boys to look at and see what is going on. If you want to swap the parts out anyway and have spares, by all means do that. I plan to do the same thing, and have already started with HPOP lines from RiffRaff, etc...
The loose bolt on the HPOP was likely your problem all along, and you've remedied that. The truck should start with everything hooked up correctly if it ran before the HPOP replacement. I've had the misadventure of a jammed IPR shortly after introducing air in the oil rails (swapped injectors), but cleaning it got me going.
The injector Control Pressure sensor tells the PCM what the HPO pressure is, and the PCM sends a signal to the Injector Pressure Regulator to raise or lower the ICP based on that feedback. No IPR, no High Pressure Oil, no start.
Thanks for helping clarify which sensors are which everyone. . . not sure how I got em that mixed up buy anyhow. Tugly are you saying I need to clean my IPR valve?
Originally Posted by Sous
The rebuilt HPOP he has is a T500, and they have a solid reputation from what I recall. Did you check for oil in the rails on the heads? You can start replacing sensors if you like because they are aging, but you are just throwing parts at it at this point.
I would do the following if I were you.
1. Check oil rails for oil on both heads
2. Check the fuel pump operation
3. Unplug ICP
4. Check for IPR tin nut
5. Replace IPR
Or, get a scan tool of some sort and post up some numbers for the boys to look at and see what is going on. If you want to swap the parts out anyway and have spares, by all means do that. I plan to do the same thing, and have already started with HPOP lines from RiffRaff, etc...
Correct I put a T500 in. I will go through that list and check those parts thanks. I have a scan tool but Im still learning how to use it. What data do you guys need? I can see if itll grab that for you guys, its a DiabloSport flash tuner, diagnostics tool, and does some monitoring, but its a handheld unit.
Ive got 2 of the bolts off from the fuel pump as well having the electrical disconnected, still have the fuel lines connected. Would it work for me to test what you guys are saying with the pump not bolted on all the way or do I need to put those other 2 back on? Im still not sure about the pump tho, that sound it was making was pretty weird.
Bolt the pump back up to the frame, and re-install the wiring for it. Previously it was suggested to check the operation of the fuel pump you could remove the link going to the rear of the vehicle (into the tank) off the rear of the pump and plumb it into a clean bucket with some diesel fuel. If you still hear the strange noise, then your pump may be going out. If your pump operates properly, then you may have to drop the tank in order to perform the Hutch mod.
It can happen, but the chances of your fuel pump going out at exactly the same time you changed the HPOP are slim.
Got the fuel pump back on, tried to start it again, no luck. Heard fluid draining, was like, "Great blew some seal." Yeah I left the drain open on the back of the fuel bowl *facepalm* burned up mosta my battery power. I did try to start it again after I built pressure in the fuel bowl, feels like Im getting a lot closer, my RPMs went up to about 500 Vs the 132 I read off of the scanner while starting. I pulled that sensor out and found the seal to be a bit deformed, is that from overheating?
Charging the batteries again Ima go try it in about 45 minutes again and see what I get, I will try your method @knottyrope. Also did not hear the gurgling/groaning sound from the fuel pump, maybe it wasnt getting good electrical connection? IDK, as long as it starts I dont really care xD.
