Oil and fuel mixing in ppump - Page 4 - Dodge Cummins Diesel Forum
94-98 Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect...NO ADVERTISING

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post #37 of 49 (permalink) Old 07-17-2019, 11:08 PM Thread Starter
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This doesn't make a lot of sense to me. My stock OFV ran at 10psi and the truck started/ drove fine with none of the issues you're seeing (the only benefit I saw replacing the OFV and setting it at 28psi is a possible increase in power, but that may be just in my head idk). Also if it was a suction restriction like a clogged draw tube, wouldn't the issue be more present at high RPM / under heavy load when fuel demand is higher, not at idle and 1100 RPM like you're seeing?
I think if you have positive pressure to the injection pump (which you do) and no air leaks (which you've verified with the clear hose) that your low pressure fuel system is not the cause and start looking other places.
Yeah I was thinking about and it and came to the same conclusion. I ended up bleeding the lines to the injectors some more to see if it did anything and now the fuel pressure rises with rpm. It still drops after a second a second or two of staying at a certain rpm but it seems to be a lot closer to the correct pressure range. The truck still runs the same though.

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post #38 of 49 (permalink) Old 07-18-2019, 08:51 AM
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I ended up bleeding the lines to the injectors some more...........
You lost me. What did you bleed them of? Any small amount of air in the injector lines is pushed out less than 30 seconds after starting the engine.

There is a good possibility that the gauge was ruined by not installing the needle valve in the beginning. A good lift pump with a functioning OFV should give you more than 20 psi of pressure.

I suggest you drop the tank and check the module for damage and crud build up.

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post #39 of 49 (permalink) Old 07-19-2019, 03:16 PM Thread Starter
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You lost me. What did you bleed them of? Any small amount of air in the injector lines is pushed out less than 30 seconds after starting the engine.

There is a good possibility that the gauge was ruined by not installing the needle valve in the beginning. A good lift pump with a functioning OFV should give you more than 20 psi of pressure.

I suggest you drop the tank and check the module for damage and crud build up.
Hmm I guess I'll put a new gauge on there and see if it changes. For whatever reason though the fuel pressure started rising with rpm after I cracked the injectors a few times. Ive been meaning to get a diesel can and length of fuel hose so I can bypass the fuel tank and see if it gets rid of the issue so I'll try to do that this weekend.
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post #40 of 49 (permalink) Old 07-19-2019, 03:20 PM
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Hmm I guess I'll put a new gauge on there and see if it changes. For whatever reason though the fuel pressure started rising with rpm after I cracked the injectors a few times. Ive been meaning to get a diesel can and length of fuel hose so I can bypass the fuel tank and see if it gets rid of the issue so I'll try to do that this weekend.
If you think your sucking air into the fuel system the easiest thing to do is to crack open the filters bleeder after the engine has sat for about a hour. Then manually pump the LP and watch for air bubbles coming out of the bleeder, if there is air bubbles then you have a bad fuel line of fuel tank module.

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post #41 of 49 (permalink) Old 07-24-2019, 09:06 PM Thread Starter
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If you think your sucking air into the fuel system the easiest thing to do is to crack open the filters bleeder after the engine has sat for about a hour. Then manually pump the LP and watch for air bubbles coming out of the bleeder, if there is air bubbles then you have a bad fuel line of fuel tank module.
Thanks but already eliminated the possibilty of air before the injection pump with the clear hose test
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post #42 of 49 (permalink) Old 07-24-2019, 09:24 PM Thread Starter
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So I finally made some progress on diagnosing the issue. Put a new fuel pressure gauge on and saw it was reading about 27 psi at idle so I know the fuel pressure is good. Decided to turn up the fuel pressure with the tork tek ofv and see if the issue got better. Turned it in all the way and the pressure only rose to about 30 psi at idle but the issue got a lot worse. Random misfire out of the exhaust and lots of white/light blue smoke. Since it was doing it constantly I was able to narrow the issue down to cylinder 1 by cracking the injector lines. When I cracked number 1 the smoke almost completely dissapeared and when I tightened it again it came back. Since I just changed the injectors and the issue remained the same im now looking at the injection pump. Im thinking either a sticking delivery valve or warped barrel. One thing to note is when I free rev the engine the fuel pressure will rise but then drop 5-10 psi after a second and then rise again. What do you guys think, throw in some delivery valves or remove the pump and send it to a shop?
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post #43 of 49 (permalink) Old 07-24-2019, 09:35 PM Thread Starter
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Actually I think I might just get the delivery valve socket and pull out the dv to see if I can notice anything visibly wrong with it first. Im really hoping its a dv problem though cause I really cant afford to have the pump rebuilt right now.
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post #44 of 49 (permalink) Old 07-25-2019, 07:38 PM Thread Starter
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Well got the socket and removed the #1 delivery valve. Nothing appeared to be wrong with it except some light rust. Barrel seemed to be fine no scoring or anything. I removed the #2 delivery valve and switched it with #1 but the issue still remained with cylinder 1. So im thinking it has to be something further in the pump but before I spend the money on a rebuilt one is there anything else it could be?
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post #45 of 49 (permalink) Old 07-25-2019, 08:01 PM
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Nothing wrong except rust? Rust! Really? So, just wondering, did the #2 have rust in it too?

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post #46 of 49 (permalink) Old 07-25-2019, 08:20 PM
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You might want to have that pump rebuilt... Jus sayin

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post #47 of 49 (permalink) Old 07-25-2019, 10:37 PM Thread Starter
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Nothing wrong except rust? Rust! Really? So, just wondering, did the #2 have rust in it too?
Yeah #2 looked exactly the same. No rust on the contacting surfaces or in the barrel but some light rust in the corners of the piece that sits inside the dv piston.
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post #48 of 49 (permalink) Old 07-25-2019, 10:42 PM Thread Starter
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You might want to have that pump rebuilt... Jus sayin
Would have it rebuilt but its a 94 175 pump so I'll probably end up buying a used or rebuilt 215 pump. I just want to be 100% sure its the pump since a rebuilt one is $1500-$2000.
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