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JC2 · 10-17-2012, 07:29 PM

Wife and I took off early today for a 3-4 day getaway in Branson for our 30th anniversary. About 1-2 hrs before arriving, noticed that the Cummins 8.9L, (370hp) was starting to have some loss of power issues on the hills and would occassionally feel a miss or jerk. On level hwys, it seems to be running ok but this stuff today is a first. I'm optimistically thinking maybe fuel filter even thought it is a combo fuel/water separator) and was supposedly changed before we bought it 8-9000 miles ago. What does everyone think?

Mr_D · 10-17-2012, 07:38 PM

Fuel filters are cheap, I always carry a couple just in case. Naturally, since I have them onboard, I've never needed them. Won't hurt to try it as it's about the cheapest thing you can do and relatively easy too.

dennis45 · 10-17-2012, 07:39 PM

Quote:

Originally Posted by JC2

Wife and I took off early today for a 3-4 day getaway in Branson for our 30th anniversary. About 1-2 hrs before arriving, noticed that the Cummins 8.9L, (370hp) was starting to have some loss of power issues on the hills and would occassionally feel a miss or jerk. On level hwys, it seems to be running ok but this stuff today is a first. I'm optimistically thinking maybe fuel filter even thought it is a combo fuel/water separator) and was supposedly changed before we bought it 8-9000 miles ago. What does everyone think?

Locate the Fuel Filter (on my 03 it is under the Battery Box) and open the water drain on the bottom of the filter. I check mine once in a while and have found nothing so the next step would be to replace the filter. From there, anything is possible. 8-9K is not unusual to change the fuel filter......

JC2 · 10-17-2012, 09:36 PM

Thanks Mr_D and dennis45 for the replies. I fortunately carry (2) xtras with me and will do a changeout tomorrow. I believe I read that no pressure bleed off is needed, just spin off the old, then spin on the new and cycle the ignition key 4-6 times to prime the filter. Correct me if my info is wrong.

siggyd · 10-17-2012, 10:02 PM

When I had an oil and filter change done last time on my 400ISL,the pros
were pre-filling the filters with CLEAN diesel via the outer holes of the filter.
This way you don't put extra air into the lines.
I also carry extra fuel filters and a small clean 2 gal. can of clean diesel fuel.
Everyone is entitled to my opinion!
Siggy

"007" · 10-18-2012, 04:48 AM

Your in a good area "Branson" to check out hills and acceleration problems.
Have a safe trip and happy anniversary.

JC2 · 10-18-2012, 05:28 PM

Replaced the old Napa #3422 fuel/water separator filter today and fuel didn't look to bad, no slime/discoloration noted. For some reason the old filter didn't have the rubber O-ring on the threaded shaft but the new Wix filter did, which I replaced. I still have (1) new Napa filter left and it also has a rubber O-ring included. Maybe they forgot to install one on the old filter. Turned the ignition on/off 3-4 times to prime and she fired right up and seemed to idle fine. Hopefully it won't hiccup on the way home Sat and beebop right on down the road. Will have Cummins-Onan check it out next week and let everyone know the final outcome.

JC2 · 10-21-2012, 06:50 PM

Just to let everyone know that the mh fired right up on saturday and seemed to run out smooth without any repeats of the problems coming down. Will have Cummins-Onan check it out and make sure the pump is performing as required and no other causes were responsible. My thanks for everyones help, and yes 007, those hills are indeed a true test for ones rig.

Mr_D · 10-21-2012, 07:01 PM

On the ISC and ISL you don't need to prime the filter, just turn the key on and let the pump cycle four or five times (but don't try to start it). The unit is self purging and you won't get air into the system, no need to prefill the filter as some seem to think.

"007" · 10-22-2012, 05:49 AM

Glad to see every thing checks out OK maybe those missing O rings were causing your problems.

Clayobx · 10-22-2012, 06:07 AM

Changing the water fuel separator probably will solve the problem! You may have "air" in the system because of no o-ring, this would cause a loss of power under load. Also, do you have a secondary primary fuel filter? This should also be changed out?

JC2 · 10-22-2012, 06:43 AM

Quote:

Originally Posted by Clayobx

Changing the water fuel separator probably will solve the problem! You may have "air" in the system because of no o-ring, this would cause a loss of power under load. Also, do you have a secondary primary fuel filter? This should also be changed out?

Can't remember exactly, but I called Spartan and Newmar after I bought the the unit and they told me that I supposedly have just the (1) filter which is apparently a combo fuel/water separator that Cummins reportedly switched to for several years back when the unit was born. It would be embarrassing to find out if I indeed had (2) but will have Cummins-Onan check when I take it in for them to look at.

JC2 · 11-20-2012, 07:44 AM

A follow up on the lack of power issue. Took the beast to the Cummins-Onan/Spartan in the KC metro area and the code 329 showed. The lift pump was also leaking and had obvious signs of black slime inside the inlet screen. After a new lift pump and the addition of a second filter like it should have had, picked it up yesterday and she drove like a champ on the way home. I had put a biocide in the tank before taking it in and will probably treat again. Hopefully any remaining gunk in the tank will be minimal but will keep some extra filters on hand. Thanks to all of you that offered help/suggestions in the beginning. Just for grins and giggles, I'll be calling Spartan to find out why they went to the (1) filter setup back in the time frame when our coach was built.