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nicholst · 10-28-2012, 02:10 PM

I changed the fuel filters on a 275 cummins in a 2001 coachman motorhome. unit ran fine before changing now will not start. if i run a direct wire to pump unit will run. any help appreciated.

greystroke · 10-28-2012, 02:31 PM

Based on what you said you probably have air in the system. When yu changed the filters did you fill the filters with diesel first?

Did you change the small o ring? On the chassis filter there is a small o ring that could fall out while changing. There is also an oil ring on the Engine filter but it probably won't fall out, but should be changed.

Did you bleed the system?

wonderer1 · 10-28-2012, 02:36 PM

did you fill the filter with fuel before you installed it? you probably got air in the system that you are going to need to bleed off. if you didn't fill it take it back off and fill. then if it doesn't start bleed the injectors. mine is the mechanical injector so i don't know how to bleed your electrical injection. someone here will know, if not google bleeding the injectors cat _____ (engine moden #).

greystroke · 10-28-2012, 02:51 PM

Cummins gave me a procedure for bleeding the ISB.

After you filled your filters.

For the following you do not want the engine to run:

1 Turn key to ON position. Lift pump will run about 5 seconds.

2 Turn key to "bump" the starter and back off the key. Lift pump will run about 30 seconds.

3 Turn key "OFF"

4 Repeat Steps 1 thru 3 about 5 or 6 times.

Now try to start the Engine. It may smoke when starting but that is normal.

Skip426 · 10-28-2012, 03:33 PM

Quote:

Originally Posted by nicholst

I changed the fuel filters on a 275 cummins in a 2001 coachman motorhome. unit ran fine before changing now will not start. if i run a direct wire to pump unit will run. any help appreciated.

If it runs when powered up that way , did you check all the fuses in the ignition circuits ??
Can you post a picture of where you wired up to make it run?

v8dave · 10-28-2012, 04:51 PM

Quote:

Originally Posted by nicholst

I changed the fuel filters on a 275 cummins in a 2001 coachman motorhome. unit ran fine before changing now will not start. if i run a direct wire to pump unit will run. any help appreciated.

Please tell us what will not start. Does diesel engine turn over, but won't run?

Is the wire you are running to the lift pump?

What "unit will run" with the wire attached? The diesel engine will turn over but not run? Only the pump runs? The diesel motor starts and runs?

nicholst · 10-28-2012, 06:28 PM

The RV turns over but will not start, we ran a wire to the lift pump and then it fires up. Can keep it running hat way but when we remove the wire it shuts down.

v8dave · 10-28-2012, 08:00 PM

Skip previously asked about fuses. There is a chance that something contacted the line to the lift pump that has now been cleared. As Skip suggested check the fuses.

But there is some reason the fuse blew. You could follow the original wire going to the lift pump and see if it was squashed in the process of changing the filters. Sometimes a squashed wire will make a light contact to ground that will burn off at 'power on' while also blowing the fuse. Then with the fuse blown the circuit will not function. If this is the case repair the squashed point by re-insulating the wire or cut the wire at the squash and then crimp a butt splice to re-join the two wires. If you find a squashed wire you need the fix the reason it got squashed. Re-route the wire and/or get some plastic split flex tubing at an auto parts store and slip it over the wire for additional protection.

greystroke · 10-28-2012, 09:05 PM

Could also be one of the water in fuel senors or lines. If the computer thinks water is in the filter it will not start by not letting the lift pump turn on. Happened to me once. no light but I saw a water in fuel code thrown on my vmspc. Replaced he sensor and it started right up. It would be nice to know if your throwing any codes.

nicholst · 10-29-2012, 05:37 AM

Thank you for the information, I will be working on this tonight for my frirend and trying a few of the suggestions. Kind of weird that it ran previosly and now will not start. Know it is likely something simple.
Will keep you all posted as to what we find or if we need more help.
Have a great day all.

nicholst · 10-31-2012, 05:06 PM

Sorry for the delay in letting know the outcome. We ended up finding 3 fuses in the battery box that had blown. Replaced them and all works fine. Thank you for all the valuable input. Greatly appreciated.