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Thread: Cummins PT Fuel Injection Pump

  1. #1
    chips2002 is offline Rookie
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    Default Cummins PT Fuel Injection Pump

    Hello,

    I have a '92 Cummins L10 engine with a PT fuel injection pump. The engine is running kind of rough when I give it some throttle. I am leaning toward the fuel system as the problem.

    I am thinking that air is somehow getting into the fuel system or the injector(s) maybe bad. I looked from the suction side of the fuel pump to the fuel tank and didn't see any visible fuel leaks. Also, I found that this engine isn't like the smaller Cummins 5.9 engines. All the injectors are inside the cylinder head assembly on this engine. There is a pressure fuel line that goes from the fuel pump to the head and a return fuel line that goes back to the fuel tank.

    Here are some questions I am having and would like to hear your opinions.

    1) What is a good way of checking that air is getting into the fuel system?

    2) I have read that air maybe getting through the aneroid. I was wondering if this engine has an aneroid. If so, where is it located.

    3) Is their a test I can perform to determine which injector is the potential problem?

    4) Also, what is a good way to remove carbon build up from the injectors without removing the injectors? I was reading a Cummins manual and it mentioned about reverse flushing. Here is what it said:

    ** Loosen all injector adjusting screws one turn from the bottom or one and one-eighth turns from the set position. Lock with the jam nut after completing the required turns.

    ** Start the engine and accelerate with maximum throttle from idling to high-10 to 15 times.

    ** Readjust the injectors to their standard setting.

    5) But I don't know where the injector adjusting screws are located. Do I have to remove the valve cover and get to the head assembly to get to these screws? The manual didn't have a diagram of where the screws are located.

    Sorry about the long post. I have been trying to troubleshoot this problem and couldn't find a probable cause. I am posting this message as a last resort before I take it to a qualified diesel mechanic.

    Thanks for your time and hope to hear from you soon.

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  3. #2
    Windwalker's Avatar
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    "You ain't gonna believe this......

    I have a mechanic that would suggest you check your connections to the battery. Especially the ground connections. He's found a number of them that run rough and even won't rev up. Nothing to do with the fuel.

    If the connections where the ECM gets it's power (or ground) from are corroded, your connection is "intermittant", and without power, the injectors will not inject.

    One of the simplist things you can try would be to clean all the connections to the batteries, and there should be a ground connection to the frame near-by as well. Make sure every connection is good and clean, try the engine, and if that does not cure it, go back to the fuel. But I have seen him cure three different trucks by working on the battery connections, including mine.

    As to checking which injector might be giving you a problem... A computer hooked to the jack would tell in a very short time. But you can also use an infra-red temperature meter. When my injector went bad, the block was 100 degrees warmer at that cylinder than the rest of the engine. Good luck.
    Destroy the cities...
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    Destroy the farms...
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    Destroy the economy of the blue-collar worker...
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    Windwalker's Avatar
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    Well, did I do you any good????
    Destroy the cities...
    and they will rebuild them.
    Destroy the farms...
    and grass will grow in the streets of the cities.

    Destroy the economy of the blue-collar worker...
    and grass will grow in the executive offices.

    The bill has come due.
    ( R E T I R E D , and glad of it)


  5. #4
    chips2002 is offline Rookie
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    Default Battery Connections

    Thanks for your reply Windwalker. I appreciate your help.

    I loosened up the battery connections today and cleaned out the terminals on the battery as you advised. Both the positive and negative connections from the battery led up to the starter motor. I couldn't find a ground wire directly mounted to the frame of the truck.

    The battery connections had some corrosion but wasn't too bad. I put some baking soda and water and cleaned it up. After, I started the truck and let it idle a bit. Then, I gave it some gas.

    The roughness has drastically decreased. But it just doesn't run like before. I can't really tell the roughness in the higher rpms near the limiter but in the lower rpms I could feel the engine running unbalanced. It sounds as if their is a leak in the exhaust.

    I guess I will try driving it around and see how she runs. Also, I can't find a jack or an ECM on my truck. Where are these usually located?

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    Windwalker's Avatar
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    ECM should be a "box" mounted to the left side of the engine... behind, and below the injector pump...

    '92 may be before electronic engines. I didn't even think of that.

    If you like, I'll PM you a phone number. Call him and see what he says about it. But, an L10 should be electronic... Unless you have a "BIG CAM 3" or something like that. He knows about them too.
    Destroy the cities...
    and they will rebuild them.
    Destroy the farms...
    and grass will grow in the streets of the cities.

    Destroy the economy of the blue-collar worker...
    and grass will grow in the executive offices.

    The bill has come due.
    ( R E T I R E D , and glad of it)


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    chips2002 is offline Rookie
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    I got your message. Will try and give him a buzz tomorrow. As for the ECM, I can't find one near the injector pump area. I guess this one is none electric. Again thanks for your quick replies and help.

  8. #7
    chips2002 is offline Rookie
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    Hey,

    I called your mechanic today. He was a really nice guy. He told me that the injectors on the truck might be bad. He said to warm up the engine and feel the cylinders on the engine and see if any of them is cold. Also, to put a clear tubing on the suction side of the fuel pump and see if any air is being sucked into the pump. I guess I will try this week see what happens.

    Thanks

  9. #8
    GREASER is offline Rookie
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    I was reading one of your posts back in March about a L10 you had that Idled fine but would run rough when you gave it fuel. I am having the same problem what did it turn out to be in the end?

  10. #9
    bowslap is offline Rookie
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    Huh.......

    Before I started driving, Worked on these darned things for 8 years. The last place was for Cummins Mid-States in Indy........

    Definitely check the fuel lines to the pump, and coming off the pump to the head. I had a few come in that were cracked due to vibration.

    Does this engine have a "live" throttle, or electronic?
    Take pride in your ride......

  11. #10
    bob h's Avatar
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    Quote Originally Posted by bowslap
    Huh.......

    Before I started driving, Worked on these darned things for 8 years. The last place was for Cummins Mid-States in Indy........

    Definitely check the fuel lines to the pump, and coming off the pump to the head. I had a few come in that were cracked due to vibration.

    Does this engine have a "live" throttle, or electronic?
    He already told you, it's a PT... what do you think?
    Bob H

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    Quote Originally Posted by Windwalker
    ECM should be a "box" mounted to the left side of the engine... behind, and below the injector pump...

    '92 may be before electronic engines. I didn't even think of that.

    If you like, I'll PM you a phone number. Call him and see what he says about it. But, an L10 should be electronic... Unless you have a "BIG CAM 3" or something like that. He knows about them too.

    Big Cam is 855... not L10.
    Bob H

  13. #12
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    PT means Pain in The a*s

    A PT fuel system is a mechanical pain in the a*s
    If you can't shift it smoothly, you shouldn't be driving it.

  14. #13
    bowslap is offline Rookie
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    I have seen L10's with electronic pumps that were "PT" pumps.......weird, but true.........no need to be rude, hand.
    Take pride in your ride......

  15. #14
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    Quote Originally Posted by bowslap
    I have seen L10's with electronic pumps that were "PT" pumps.......weird, but true.........no need to be rude, hand.
    I'm not trying to be rude... I'm trying to ask a question ;0) don't be so defensive!

    PT pacer engines are electronically controlled, but they still have a throttle cable. I figured that since you had spent 8 years working in a shop you might be teaching me something I didn't already know...
    Bob H

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    bowslap is offline Rookie
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    Those systems were rarely seen in the shop when I worked there.......think I laid eyeballs on 2 of them. 99% of my experience is with the Celect and Celect+ M and N-series engines, with a few old-scholl NT's thrown in for good measure. The ISX-series engines were still relatively new, and saw few of them in the shop.

    If someone has a question, and I feel I may be of some assistance, I'll post. I'm not above learning something myself......'slap....
    Take pride in your ride......

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    bob h's Avatar
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    Quote Originally Posted by bowslap
    Those systems were rarely seen in the shop when I worked there.......think I laid eyeballs on 2 of them. 99% of my experience is with the Celect and Celect+ M and N-series engines, with a few old-scholl NT's thrown in for good measure. The ISX-series engines were still relatively new, and saw few of them in the shop.

    If someone has a question, and I feel I may be of some assistance, I'll post. I'm not above learning something myself......'slap....
    I have one; we know why the N14s are fretting the block, why are the M11s fretting?
    Bob H

  18. #17
    bob h's Avatar
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    Quote Originally Posted by bob h
    Quote Originally Posted by bowslap
    Those systems were rarely seen in the shop when I worked there.......think I laid eyeballs on 2 of them. 99% of my experience is with the Celect and Celect+ M and N-series engines, with a few old-scholl NT's thrown in for good measure. The ISX-series engines were still relatively new, and saw few of them in the shop.

    If someone has a question, and I feel I may be of some assistance, I'll post. I'm not above learning something myself......'slap....
    I have one; we know why the N14s are fretting the block, why are the M11s fretting?
    no take on that question? well, I have another; why do celect injectors sometimes have a plunger stick down after adjusting the injector... is it possible to free them up?
    Bob H

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    chips2002 is offline Rookie
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    It's been awhile since I have been on here. The problem ended up being an injector. I still haven't fixed it and am driving it the way it was before. I think the engine oil is getting diluted with diesel, and it is starting to blow white smoke. I am going to get rid of this truck soon. It has about 1,018,000 miles and don't want to spend money on it.

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