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Fuel contamination

Yes, if the oil pressure switch has failed, (it can still show pressure on the gauge and not be working correctly) it will not send power to the lift pump and cause what you are feeling as a drag. it's making the IP work harder. install a fuel pressure gauge on a tee between the FFM and the IP and monitor it. I wouldn't recommend having a live fuel line to a manual gauge running into the cab though others have done it for short periods of time. if it springs a leak and ignites... well be prepared to jump from a moving truck. best to use an electronic gauge with a sending unit mounted on the supply line to the IP.

there is a modification you can do with a couple of relays where it takes the amp draw off from the oil pressure sensor that the lift pump pulls. I made my own, but they do sell a kit for this that is much easier to install than a homemade one :)
 
@dbrannon79 Thank you..I got thinking about it cause one of the guys sent me one to have as a spare.. I got looking at it and wondered what exactly they do so I looked it up.. I'm thinking that if by chance it is the problem, then it must be a intermittent think as in it works when it wants to because the drag issue comes and goes...and usually if the truck is running great the problem starts after letting off the throttle. Which also means I most likely applied the brakes.. I've been chasing a brake problem because it feels like drag and usually happens after applying the brakes , like they didn't release all the way after applying them..(and it all started right after getting brakes worked on..) it never occurred to me that if I applied the brakes that also means I had taken my foot off the throttle..
The day the brake work got done while the truck was in the garage my buddy changed the fuel filter for me.. (I couldn't get it loose) he had trouble with it also but finally got it off.. he has extremely big hands so it's intirly possible that he damaged the ops in the process of damaged the wires to it ..
Like I said I would think that IF that's the problem then the ops is working when it wants to and not working when it doesn't want to. Or the wires to it are messed up.. just theory's
 
Definitely do diy- saves descent cash. And you can add the switch to make the LP come on without the engine running for things like what you have to do now, and for fuel filter changes.

Pretty sure people have already drawn up how to and what color wires to play with
 
I doubt he could have damaged the sensor when changing the filter. the sensor is threaded into the block way down below where the filter is in the valley
 
there are lots of ways to DIY the relay mod for the lift pump. I have mine so that it's also tied into the glow plug controller and will run the lift pump for a few seconds while the wait to start light is on. the main thing was to have the load off the sensor and make it last forever lol.

doing the diy depends on how comfortable you are with cutting factory wires and splicing them into a relay and such. it can be done with a single 5 pin relay and a fuse. there are three wires on the connector that goes on the oil pressure sensor, only one gets cut and spliced into the relay along with a hot from the battery and ground. the 5th pin on the relay would then be used to tie into the glow plug controller or a manual switch in the dash, or both if you choose.

I have a drawing on my home pc somewhere I can post if you are interested in trying it. others may also have better ways to install it.
 
Considering you just completely lost me, I think I better leave that to someone who knows this stuff.. I thought I could just unplug the lift pump and run a hot wire to it on a toggle switch
 
Stoney said:
Considering you just completely lost me, I think I better leave that to someone who knows this stuff.. I thought I could just unplug the lift pump and run a hot wire to it on a toggle switch
Click to expand...
you can do that too just for troubleshooting. but I wouldn't recommend leaving it that way because if there ever was a leak in front of the lift pump or you just forgot to turn the switch off when parking your truck at night you'd be in more trouble!
 
Or maybe not.. the ops only has 3 wires evidently judging by this plug... You were talking about the pump 5wires not the ops.. my fault
 

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no the relay you add to the mix will have 5 wires. the ops only has three. to add the relay you will only use one of the wires from the ops and run it to the relay by cutting it into two (one from the ops and one to the pump) bringing them to the relay you add. iirc its the brown wire.

to explain it better, the one wire you cut on the ops plug will make two, one going into the ops with the other side going to the pump in the harness. you would splice a long piece of wire to both ends you cut and run them over to where you decide to mount the relay.

the relay is like a switch but will only use the power from the ops sensor to turn on the relay.

the relay also receives a hot wire from the fuse box ( 3rd wire ) which when turned on by the ops, will send power from the fuse box down to the pump.

the relay also needs a ground for it to operate as a switch. that is you 4 wires.

the 5th is for extra function like the ability to manually turn on the pump or have it turn on and prime while the glow plugs are warming up.

I hope that makes better sense.
 
the ops plug has three wires. wire 1 is hot. wire 2 is going into the dash for the oil pressure gauge. wire three goes to the lift pump. internally in the ops sensor it does two things. it sends signal to the gauge to show pressure and it also sends power to the lift pump when oil pressure is above iirc 5 psi by a couple of very tiny contacts that tend to burn out and stop working.

I would have to look at the diagram in the book to see what colors each wire is.
 
dbrannon79 said:
Yes, if the oil pressure switch has failed, (it can still show pressure on the gauge and not be working correctly) it will not send power to the lift pump and cause what you are feeling as a drag. it's making the IP work harder. install a fuel pressure gauge on a tee between the FFM and the IP and monitor it. I wouldn't recommend having a live fuel line to a manual gauge running into the cab though others have done it for short periods of time. if it springs a leak and ignites... well be prepared to jump from a moving truck. best to use an electronic gauge with a sending unit mounted on the supply line to the IP.

there is a modification you can do with a couple of relays where it takes the amp draw off from the oil pressure sensor that the lift pump pulls. I made my own, but they do sell a kit for this that is much easier to install than a homemade one :)
Click to expand...
I think I posted the connectors needed to make the kit plug and play - no cutting and splicing.

Just as easy to buy Leroy's
 
Will L. said:
Definitely do diy- saves descent cash. And you can add the switch to make the LP come on without the engine running for things like what you have to do now, and for fuel filter changes.

Pretty sure people have already drawn up how to and what color wires to play with
Click to expand...
I thought Leroy added an on off switch to his?

I prefer mountable relay sockets to mountable relays.
 
From what I saw online. I've got to remove the ffm to get to it.. which I have in order to do the fuel lines anyhow... I'm going to go buy long black fuel rubber hose. Not the metal . That way it's plug and play.. so when I have the ffm off I'll change the ops. And put in the one sent to me.. don't know if this is actually the problem or not but worth a shot. Unless the wires got damaged.. that would be harder to figure out
 
Stoney said:
From what I saw online. I've got to remove the ffm to get to it.. which I have in order to do the fuel lines anyhow... I'm going to go buy long black fuel rubber hose. Not the metal . That way it's plug and play.. so when I have the ffm off I'll change the ops. And put in the one sent to me.. don't know if this is actually the problem or not but worth a shot. Unless the wires got damaged.. that would be harder to figure out
Click to expand...
Is the truck runable?

If so with the truck running check for voltage at the lift pump plug with both a volt meter and a test light.
Sometimes an OPS/Oil Pressure Switch will show voltage but not carry enough juice to run the lift pump. It will sometimes carry enough juice to trigger a relay, but not enough to run a lift pump.

If the plug at the lift pump will light a test light with the truck running. The OPS might not be your problem
 
@jrsavoie I agree but the problem comes and goes.. it will run great one minute and then like shit the next.. that do testing it might show fine at that moment but 10 seconds later it's shitty again.. I can turn the key on and get under the truck and feel the lift pump running. And most of the time I can hear it from in the cab before I start the truck. Because it runs for 8 or 10 seconds while the glow plugs are warming up. .. honestly at this point it's seriously a matter of addition firing the parts cannon at it constantly until I happen to get it right
 
If your going to replace the steel lines with rubber going from the FFM back to the lift pump be sure to get diesel rated hose and make sure they are secured along the inside of the frame like the steel lines are. Keep them away from heat sources like the exhaust pipe and manifold too. You might need to get some heat resistant covering for it up near the engine. That will help greatly for heat and for rubbing in vibration areas.

Replacing any of the hoses from the FFM to the ip will require you to remove the intake. I would suggest re-routing them over the intake. The one supply line under there that feeds the ip is a preformed hose and trying to use regular fuel line will cause kinks where it bends.

The drain hose to the tee will need to remain under the intake so it’s lower than the filter and will drain properly
 
HVAC rated copper tubing from the hardware store? just thinking outside the box here, but it's easy to bend and shape, resists heat, and will hold the pressure from the LP easily. won't rust out ether. others may chime in on this, but I think considering the cost of a 25' roll of diesel rated fuel hose it's probably about the same price and will last longer! you'll only need hose and clamps at the connections. keep a short piece of the factory steel line that has the fitting on it to connect to the lift pump connecting it with a short section of hose and clamps!
 
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