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Thread: 12 v fuel air leak?

  1. Top Of Page | #1
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    12 v fuel air leak?

    Hey all! First time posting here, thought maybe could gain some help with an issue I'm having.

    Chances are there is another thread on this, but I'm on my phone and in very limited service - I honestly don't know if I'll have the connection time to look up what I need - hence my plea for help.

    Here's what I have: 1997 Dodge Ram 2500 CTD, stock.

    About six months ago I hit the road (my lady and I are traveling the USA for the next year) and before that I replaced:

    Lift pump
    Fuel filter
    Feed/return lines at engine (with marine grade bio-compatible line)

    About three months ago, upon arriving in Arizona, and after a few REALLY hot days, I noticed our truck didn't want to stay running after starting. It would fire right up, then after a minute or two would grumble and die. I figured I had a leak somewhere in the fuel line and was losing my prime. This problem would happen intermittently, and stayed the same for about a month, until couple weeks ago.

    At this point the truck began to have this after-starting / loss of prime issue nearly every day. It used to take a day or two for this to happen, but now within 24 hours it would resurface.

    In desperation I researched and deduced I should buy a couple parts to replace. So, I then replaced:

    90° hose from lift pump to pre-filter
    Fuel-heater delete, new pre-filter screen
    Re-tightened all new feed/return hoses
    New overflow valve

    Problem solved, right? Nope...
    Now the truck doesn't seem to want to start at all without a little push on the pedal (never did this before) and when she fires up white smoke blows out the exhaust (air in fuel, right?)

    After a minute or two of running, same thing happens again - engine sputters and dies.

    If I catch the sputter in time and push the pedal down I can plow through the air leak and regain prime, at which point the truck *seems* to run fine.


    Where could this leak be? Or is it multiple leaks? Do I need to redo the hoses at the fuel tank? Please no...


    Please take into account that right now I'm traveling and living on the road. I have most tools I need for repairs, but I am not in a position to buy specialty items for a one-time job. I don't have access to a garage, and don't have much money to spend or throw at parts. If I have to I'll take her to a diesel mechanic, but I'd really hope to do the work myself.

    If you have any suggestions, I'm all ears and appreciate any help. Thank you!


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  3. Top Of Page | #2
    WE WILL STAND! IGOTACUMMINS's Avatar

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    @Polaraco any ideas?

    Ask us how to become a Lifetime Platinum Member today!

    "The grass is greener where you water it"


  4. Top Of Page | #3
    Old & Grumpy! Polaraco's Avatar

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    Quote Originally Posted by rystjohn View Post
    Hey all! First time posting here, thought maybe could gain some help with an issue I'm having.

    Chances are there is another thread on this, but I'm on my phone and in very limited service - I honestly don't know if I'll have the connection time to look up what I need - hence my plea for help.

    Here's what I have: 1997 Dodge Ram 2500 CTD, stock.

    About six months ago I hit the road (my lady and I are traveling the USA for the next year) and before that I replaced:

    Lift pump
    Fuel filter
    Feed/return lines at engine (with marine grade bio-compatible line)

    About three months ago, upon arriving in Arizona, and after a few REALLY hot days, I noticed our truck didn't want to stay running after starting. It would fire right up, then after a minute or two would grumble and die. I figured I had a leak somewhere in the fuel line and was losing my prime. This problem would happen intermittently, and stayed the same for about a month, until couple weeks ago.

    At this point the truck began to have this after-starting / loss of prime issue nearly every day. It used to take a day or two for this to happen, but now within 24 hours it would resurface.

    In desperation I researched and deduced I should buy a couple parts to replace. So, I then replaced:

    90° hose from lift pump to pre-filter
    Fuel-heater delete, new pre-filter screen
    Re-tightened all new feed/return hoses
    New overflow valve

    Problem solved, right? Nope...
    Now the truck doesn't seem to want to start at all without a little push on the pedal (never did this before) and when she fires up white smoke blows out the exhaust (air in fuel, right?)

    After a minute or two of running, same thing happens again - engine sputters and dies.

    If I catch the sputter in time and push the pedal down I can plow through the air leak and regain prime, at which point the truck *seems* to run fine.


    Where could this leak be? Or is it multiple leaks? Do I need to redo the hoses at the fuel tank? Please no...


    Please take into account that right now I'm traveling and living on the road. I have most tools I need for repairs, but I am not in a position to buy specialty items for a one-time job. I don't have access to a garage, and don't have much money to spend or throw at parts. If I have to I'll take her to a diesel mechanic, but I'd really hope to do the work myself.

    If you have any suggestions, I'm all ears and appreciate any help. Thank you!
    I hate it when the boss wakes me up.

    If memory serves me correctly, you have a mechanical fuel pump. I'm thinking the pump may not be up to par, like it has a sticky check valve or there is a piece of dirt in it moving around. The other posibility is the tank screen may be clogged. I didn't see the mileage. Lastly, but unlikely, the cam lobe may be worn.

    How does the truck run when you get going? Does it smoke? White, black, blue? Does it seem like it has plenty of power?

    You could try disconnecting the hose from the injector pump and spinning the engine. If you are getting good healthy squirts than we have to look elsewhere. If it's just dribbles, then start with the pump.

    You have to get that fixed. Low fuel supply can wear out the injector pump.

    I'll be back in a few hours @rystjohn.


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

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  6. Top Of Page | #4
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    Thanks for the response - I just replaced the fuel lift pump, I can't imagine it could be at fault. Especially since it took nearly four months after replacing it for this problem to surface.

    Would that cause a loss of prime anyway?

    When the engine gets past the initial (what I assume is a ) burp in the line it runs fine. Doesn't seem to have a loss of power or anything. Granted I'm at 7,000ft and it was a 0-2,000ft above sea level truck, so I do get some black smoke, but so do the other diesels I see.

    If I were to remove the hose to the injector, how would I go about turning the engine with limited tools? Just crank it?

    Thanks again and I'm all ears for recommendations. I might order. Fuel pressure gauge from LarryB's and see what it says. Hate to throw more money at it, but it would be peace of mind


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  8. Top Of Page | #5
    Old & Grumpy! Polaraco's Avatar

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    With no lift pump pressure it won't start. Just spin the starter for a couple of pump shots.

    With the way things are made today, it's possible. I just had a pump with only a few hours on it go bad. Yes it was a gas job, but a good example


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

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  10. Top Of Page | #6
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    Well I put some self-sealing silicone tape over the inlet fitting on the fuel heater (hard line after coming from tank side) and adjusted my idle speed up a bit as it had dropped.

    So far problem has been nonexistent....for two days. Let's keep our fingers crossed.


  11. Top Of Page | #7
    Old & Grumpy! Polaraco's Avatar

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    You didn't tell me that. . . . . idle dropping is injectors or injection pump.

    Wrapping the line did nothing. But the low idle speed can act like a bad lift pump too.


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

  12. Top Of Page | #8
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    Quote Originally Posted by Polaraco View Post
    You didn't tell me that. . . . . idle dropping is injectors or injection pump.

    Wrapping the line did nothing. But the low idle speed can act like a bad lift pump too.
    Idle had only dropped from set screw backing down. It happens on our truck every 5-6 months.

    I think wrapping the connection definitely did something. I adjusted the idle back to spec only after the truck stopped with the random burping and starting issue.


  13. Top Of Page | #9
    Old & Grumpy! Polaraco's Avatar

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    Quote Originally Posted by rystjohn View Post
    Idle had only dropped from set screw backing down. It happens on our truck every 5-6 months.

    I think wrapping the connection definitely did something. I adjusted the idle back to spec only after the truck stopped with the random burping and starting issue.
    Good to know on the idle. Allot of times we have to imagine. crystal-ball.jpg

    If that was a threaded fitting you wrapped, it makes sense. But wrapping a line doesn't. There should have been a fuel stain where it is leaking. It would be slight on the suction side.

    Sorry I was such a hard butt. Low on patience in my senior age


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

  14. Top Of Page | #10
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    It was a threaded fitting. I just found another forum that speaks of this being an issue that often causes lots of head scratching. It's a square cut o-ring that goes around the flared end of the hard line that comes from the tank (after the short hose section) and into the top of the fuel heater. It must be bad and wrapping it has stopped (or slowed) the leak.

    Makes sense too - that's why starting was easy at first but I'd hit a burp - anything behind the fuel filter was drained back into the tank.


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