Lift Pump appears to be bad
05-09-2009, 11:50 PM
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Lift Pump appears to be bad
After obsessing on the rubber (plastic) fuel lines being the cause of not getting fuel to the engine, they looked OK. Then, I noticed that the lift pump leaks fuel from under the rubber end cap when it is manually operated to bring the fuel up to fill the fuel filter.
That strikes me as an obvious place for the fuel to lose its prime. Anyone in agreement or think otherwise?
Assuming that is the problem, are there any online sources for a replacement lift pump?
The local Dodge or Cummins service / parts outfits are unlikely to be anything other than demanding ransom for one, if they have it.
That strikes me as an obvious place for the fuel to lose its prime. Anyone in agreement or think otherwise?
Assuming that is the problem, are there any online sources for a replacement lift pump?
The local Dodge or Cummins service / parts outfits are unlikely to be anything other than demanding ransom for one, if they have it.
05-10-2009, 12:31 PM
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That strikes me as an obvious place for the fuel to lose its prime. Anyone in agreement or think otherwise?
You can't really tell by just looking if the rubber fuel lines are leaking.
They almost always suck air without leaking fuel.
Best way to find a delivery system leak is to pressurize the fuel tank with compressed air, 10 psi max, then go hunting.
05-10-2009, 01:19 PM
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Thx infidel for your feedback.
The O-ring should be the problem causing the leak. I'll get right on it.
By "obsessing on the rubber hoses" I mean that I've just removed both of the rubber hose sections (supply and return) that run down the backside of the engine ( the ones you need to be a 10' snake to get to) and found them to be in good condition with no cracking or hardening of the material. They were not the cause of the loss of fuel prime.I have replaced the return section before when it was very badly cracked and leaking air.
If the O-ring fix does not cure the loss of prime problem I'll definitely do the fuel system pressurization and leak search, which brings up a question:
Is there a better way than installing a one way valve on an after market fuel cap to pressurize the tank?
The O-ring should be the problem causing the leak. I'll get right on it.
By "obsessing on the rubber hoses" I mean that I've just removed both of the rubber hose sections (supply and return) that run down the backside of the engine ( the ones you need to be a 10' snake to get to) and found them to be in good condition with no cracking or hardening of the material. They were not the cause of the loss of fuel prime.I have replaced the return section before when it was very badly cracked and leaking air.
If the O-ring fix does not cure the loss of prime problem I'll definitely do the fuel system pressurization and leak search, which brings up a question:
Is there a better way than installing a one way valve on an after market fuel cap to pressurize the tank?
05-10-2009, 06:11 PM
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I use a stock fuel cap that a friend gave me when he went with a locking one, drilled and tapped a 1/4" port in it and installed a Schrader (tire) valve.
Another way if you have two people is to just wrap a blow gun with a rag and stick it in the fill hole.
It's worth it to have the cap with port just for filling and bleeding the filter after a change. Takes about 15 seconds to fill and bleed with the bleed screw open. Heck with the primer button, I haven't used mine in 15 years.
Beware if the tank is real full, if you remove the blow gun or cap while the tank is still pressurized fuel will come flying out all over you.
Don't ask how I know that...
Another way if you have two people is to just wrap a blow gun with a rag and stick it in the fill hole.
It's worth it to have the cap with port just for filling and bleeding the filter after a change. Takes about 15 seconds to fill and bleed with the bleed screw open. Heck with the primer button, I haven't used mine in 15 years.
Beware if the tank is real full, if you remove the blow gun or cap while the tank is still pressurized fuel will come flying out all over you.
Don't ask how I know that...
05-23-2009, 12:36 AM
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OK, Sorry it has taken so long to get back on this. But, I've been away from an i-net connection.
The problem is now fixed.
It did require a new fuel transfer pump to fix the problem ($100.01 from the local Cummins service center).
The manual priming pump is made of plastic parts, even on the new redesigned replacement pump too.
The whole plunger shaft with it's o- and other ring was not sealing against the "cylinder".
The fuel leakage through the priming pump was allowing air to enter the fuel supply line when the engine was running, even worse when it was shut down, allowing the supply line to drain back into the tank in a very short time.
I also replaced the fuel heater element. It has never worked all the time I've owned the truck. Technically it still doesn't because I haven't hooked the electrical connection. There were metal shavings in its strainer bowl. Cummins people said they were probably from the lift pump. I question this because the fuel heater is upstream from the lift pump. But then, they may have been drawn there when the fuel drained back into the tank. Who knows.
Total bite for parts, gaskets and all = a $200 bill. (cough, choke)
Didn't need to pressurize the tank, but will keep that info on tap for when it becomes necessary.
I also installed the starter I bought last fall and installed the over sized solenoid contacts in. I was holding off for better weather to crawl under the truck.
Between the new (rebuilt?) started and the transfer pump, it starts and runs the best it has in a long time.
I'M READY FOR SUMMER!
The problem is now fixed.
It did require a new fuel transfer pump to fix the problem ($100.01 from the local Cummins service center).
The manual priming pump is made of plastic parts, even on the new redesigned replacement pump too.
The whole plunger shaft with it's o- and other ring was not sealing against the "cylinder".
The fuel leakage through the priming pump was allowing air to enter the fuel supply line when the engine was running, even worse when it was shut down, allowing the supply line to drain back into the tank in a very short time.
I also replaced the fuel heater element. It has never worked all the time I've owned the truck. Technically it still doesn't because I haven't hooked the electrical connection. There were metal shavings in its strainer bowl. Cummins people said they were probably from the lift pump. I question this because the fuel heater is upstream from the lift pump. But then, they may have been drawn there when the fuel drained back into the tank. Who knows.
Total bite for parts, gaskets and all = a $200 bill. (cough, choke)
Didn't need to pressurize the tank, but will keep that info on tap for when it becomes necessary.
I also installed the starter I bought last fall and installed the over sized solenoid contacts in. I was holding off for better weather to crawl under the truck.
Between the new (rebuilt?) started and the transfer pump, it starts and runs the best it has in a long time.
I'M READY FOR SUMMER!
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