Community Forums

goldcreekrd · 11-20-2018, 10:19 AM

Greetings,
Left Gulf Shores heading to Tallahassee RV Park.
Noticed a fuel leak dripping down over the starter.
After 30- 40 seconds the leak stopped, we drove all the way to Tallahassee , stopped at every rest stop to check for leakage- none.
Started the coach this morning, same results, leaks at first, then stops. Looks like the lift pump is leaking
Called Cummins at Midway , too busy to repair, however their service guy was very helpful and contacted a local diesel mechanic. He will call me tomorrow.
I crawled under the coach to assess the pump change out, looks like it needs to go to a repair shop for sure.
My question is , if it doesn't totally fail, is it alright to drive it to the Orlando facility for repairs.
Any comments?
Thanks!

Ray,IN · 11-20-2018, 08:43 PM

Sounds to me like loose bolts or fittiings on the pump, as when it enlarges a bit from heat the leak stops. However, there are many Cummins authorized service centers around, and even more HDT repair shops that have the capability to service the injector pump. Were this my issue, I would stop at one of them instead of gambling with a fuel leak starting a fire in the engine compartment.
FWIW, the majority of MH fires are with diesel pushers, the majority of those are related to fuel leaks in the engine compartment.

irishguy · 11-20-2018, 09:02 PM

If your ISC lift pump is like many ISL lift pumps then it only runs for 30 secs to feed the injection pump during start up. It then shuts off until you do another start up cycle.

That might explain why it only leaks for a short time. I don't know for sure if it is okay to drive though. You definitely don't want a fire or air in your fuel system.

Irishguy

jcussen · 11-20-2018, 09:21 PM

http://www.irv2.com/forums/f123/cumm...nt-280226.html

rag_ftw · 11-20-2018, 09:36 PM

As Ray said it could be a line leaking. I noticed a leak this summer and traced it to a loose fuel line. Put a wrench to it and no more problems the rest of the trip.
Tightening a line is a lot less expensive than a new pump!

FL420 · 11-20-2018, 09:37 PM

Quote:

Originally Posted by irishguy

If your ISC lift pump is like many ISL lift pumps then it only runs for 30 secs to feed the injection pump during start up. It then shuts off until you do another start up cycle.

That might explain why it only leaks for a short time. I don't know for sure if it is okay to drive though. You definitely don't want a fire or air in your fuel system.

Irishguy

It sounds that way to me also. I was talking to a Cummins tech a couple of weeks ago and asked him if it was necessary to prefill my new fuel filters to prime them. He explained that they always just turned the key on for 30 seconds, then off, then on for another 30 seconds, then off. He said it might take 4 or 5 times to fill the lines and filters. That was the only function of the lift pump. I have an ISC.

Dale70 · 11-23-2018, 11:53 AM

FL420 -- I do not think the only reason to have a "lift pump" is to charge empty fuel filters. If you had one go out you would find it very hard to start your engine.

thx Dale

FL420 · 11-23-2018, 12:11 PM

Quote:

Originally Posted by Dale70

FL420 -- I do not think the only reason to have a "lift pump" is to charge empty fuel filters. If you had one go out you would find it very hard to start your engine.

thx Dale

I may not have made it clear enough, Dale. That may be because there are probably significant gaps in my understanding of diesel pusher fuel systems.
I agree the lift pump does more than fill the fuel filters. I suspect that when the fuel system is sitting idle and not under pressure for awhile that some fuel may drain, perhaps through the fuel return line, to the tank leaving a small amount of air in the line(s.) Pausing with the ignition switch in the RUN position before turning it to START does a number of things like powering up the ECU, the intake heater or glow plugs and operating the lift pump for 30 seconds to push fuel back into the lines so the engine can suck (mods - may I use that word?) fuel through the lines without faltering due to loss of vacuum.
In my previous post I did say: "to fill the LINES and filters."
Are we good?[emoji846]

jacwjames · 11-24-2018, 05:59 AM

If you had a leaking fuel pump Cummins actually had a TSB out on the lift pump dated 2006. Initially they would replace the lift pump, then opted to replace just the gasket, then just ignored the problem and left it up to owners to fix & pay.

This is a common problem. You might try tightening the bolts to stop the leak.

I found a source for a gasket

Capital Volvo
Montgomery Al
334-262-8856

part number 4928511
Cost ~$7

I bought one to carry as spare in case of emergency, haven't had to use yet.

If that doesn't work then lift pump replacement is necessary.

If the pump is leaking while it is running (~30 seconds at startup), then there is a good chance it is sucking air when engine is running. This could cause a problem in the injection pump itself, which can cost ~$4K to replace so I would not do ignore the problem.

William Willard · 11-29-2018, 10:21 AM

Tighten the two 11mm bolts on top of the pump -- They are probably loose, causing your problem -- Bill Willard

Ray,IN · 11-30-2018, 10:43 PM

Cummins ISC, ISL and QSL bolt torque specifications and manuals:should help when re-tightening bolts.

jimmy braden · 03-03-2019, 03:46 PM

See update to http://www.irv2.com/forums/f123/isc-...ak-425055.html

Freightliner said it would leak when idling, so I guess the lift pump runs all the time..

FL420 · 03-04-2019, 11:34 AM

Quote:

Originally Posted by jimmy braden

See update to http://www.irv2.com/forums/f123/isc-...ak-425055.html

Freightliner said it would leak when idling, so I guess the lift pump runs all the time..

I would tend to believe an experienced tech, now service manager, for the manufacturer of the engine (Cummins) would have more accurate information on the operation of the lift pump than a person of unknown qualifications employed by the manufacturer of the chassis (Freightliner.)
The Freightliner employee's statement is accurate up to a point. The engine will be idling for the 30 seconds before it shuts down as designed.
JMHO [emoji41]

jimmy braden · 03-04-2019, 11:47 AM

Since the lift pump is integral to the fuel path, it's prob somewhat academic as to if it runs or not

The way the pump mounts, if the bolts are loose or the gasket torn/deteriorated, it will likely leak anyway...