Accessing lift pump behind ECM on ISB 300 Cummins?
Hi, glad found this valuable site.
ECM is on curbside of engine and mounted on rubber dampers. Removed 2 lower ones, but appears to be another one at top of ecm? Ecm needs to move away from engine more to R and R the lift pump which is behind it?
Hoping to leave ecm connected to wire plugs as appears to be room to but how do I access upper dampener bolt for access to lift pump?
TIA ,Greg
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It will help other members immensely if you fill in your signature with the make,model, and year of your motorhome; otherwise we are guessing at what you are talking about.
First, if your lift pump is leaking tighten the 3 bolts on the top of the pump. If that fails: A replacement gasket is available from Capitol Volvo 1815 W. Blvd. Montgomery, AL 334-261-8856. I think they are less than $10. The Cummins OEM gasket is unavailable, this is an aftermarket gasket.
FWIW there are several threads in the Cummins forum discussing the Cummins lift pump, with solutions and aftermarket mods.
__________________ 2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
Thanks Ray, pump isnt leaking it doesnt run despite confirming power to it. New pump runs with key on and just need to figure out how to move ecm out of the way to R and R the old pump?
Feels like theres another bushing mount at top of ecm, but hard to see up in there
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2004 Holiday Rambler 34PDD Neptune with ISB 300 Cummins and 5 speed Allison
I believe what you have is the first or second year of the ISB lift pump being mounted behind the ECM , and your post is the first I've seen about a member replacing one .
I have a picture of the 2007 ISB and a diagram of the lift pump mount on an ISC , that looks like removing the ECM from the motor is required .
I'll do a search to see if there is a U Tube video or better diagram of the mounting for your year of the ISB.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Ok an online search turned up this diagram , showing the top ( Third ) mount bolt recess ; this may be covered by a rubber plug in the face of the ECM.
EDIT : If this diagram doesn't help ; please post a photo of your ECM .
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Thanks Skip. While my 04 isb300 has ecm located closer to the rear of the coach on the engine, I see the 3rd dampener you're talking about and likely the same on my ecm.
Hope can get to it. Will have to use mirror to see up in there.
Any other tricks to R and R lift pump much appreciated!
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2004 Holiday Rambler 34PDD Neptune with ISB 300 Cummins and 5 speed Allison
Thanks Skip. While my 04 isb300 has ecm located closer to the rear of the coach on the engine, I see the 3rd dampener you're talking about and likely the same on my ecm.
Hope can get to it. Will have to use mirror to see up in there.
Any other tricks to R and R lift pump much appreciated!
Unfortunately , my experience is on the Dodge P/U version of the ISB of that vintage , and there are a lot of differences .
On the Dodge version the lift pump was on the back of a fuel filter on the side of the engine and was only a 20 min. job to replace.
I'll track this post , so just chime in if you hit a snag.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Ok an online search turned up this diagram , showing the top ( Third ) mount bolt recess ; this may be covered by a rubber plug in the face of the ECM.
EDIT : If this diagram doesn't help ; please post a photo of your ECM .
Will try to post my ECM pic. Thanks
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2004 Holiday Rambler 34PDD Neptune with ISB 300 Cummins and 5 speed Allison
OK , the ECM , is mounted to the cooling plate ( yellow arrows , there'll be two more on the top ; at least that's my thought ) then the cooling plate has the three rubber mount to the block. The two red arrows , the third mount bolt won't be visible till the ECM is off the cooling plate .
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Thanks much for all the help Skip and others! Got her done and shes running great again .
Good test drive with no more stumbling. Was able to wrangle the pump out without removing the ECM and took a bit but got new one in as well.
Would have had to loosen the AC compressor bracket to get upper ecm bolt out and was able to pull ecm away from block just enough to swap the pumps. Was a bear but after priming she fired right up! Thanks again!
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2004 Holiday Rambler 34PDD Neptune with ISB 300 Cummins and 5 speed Allison
It will help other members immensely if you fill in your signature with the make,model, and year of your motorhome; otherwise we are guessing at what you are talking about. 
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