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Butter Ball · 06-09-2015, 03:13 PM

Hello All,

I have the ISC 350 in my '01 Windsor. On my last trip from Redding to Central Oregon, after 50 or so miles I began ascending grades, and shortly after my engine began hesitating and stuttering losing power at and over about 1,700/1,800 RMP - higher RMP were more stuttering/hesitation. If I slowed and downshifted to keep the RPM under this range the engine performed fine.

The transmission was shifting well, the fluids were correctly filled, the turbo boost seems fine, all temps and oil pressure were as they should be, and so long as I'm under the 1,700/1,800 mark there is no issue in any of my six transmission gears; over 1,700/1,800, however, and in any gear the engine stutters hesitates...RMS drop then in a split second recovering, dropping and rebounding, etc. as the engine loses power and the coach speed. The problem seemed to become more intense as my trip went on. I was running with a 3/4 full diesel tank.

My last trip was from Phoenix to Redding over the Tehachapi pass with no 2,500# toad, no issues whatsoever and no indication of this problem. Since the last trip, all I have done is add fuel and check fluids. I weighed in before this trip at 32,400# with my toad, well under the 42K# GVWR and load distribution between axles was fine.

I'm in rural Central Oregon now (45-miles South of Bend) until July 9, and at least that far from a qualified mechanic. I'm trying to determine if a) it's a minor problem I can diagnose/address, b) if I can muddle my way to a mechanic under my own power or c) do I need to be towed/obtain mobile service.

I would appreciate hearing from anyone with thoughts, ideas, similar experiences or suggestions.

Thanks a lot,

Chris

PS 125K engine/coach miles

William Willard · 06-09-2015, 03:26 PM

How long has it been since you changed the fuel filters ? I would change them regardless of how long it`s been -- That`s the less expensive place to start -- Bill Willard

Mr_D · 06-09-2015, 03:39 PM

Quote:

Originally Posted by William Willard

How long has it been since you changed the fuel filters ? I would change them regardless of how long it`s been -- That`s the less expensive place to start -- Bill Willard

Agreed, with symptoms like that the first thing to change is filters.

REV40C · 06-09-2015, 07:48 PM

I was having the same problem this past weekend. I read a lot on here and desided to change the fuel filter today. I have a 350 cummins and that fixed the problem. Filtrer was a little less than $30 and $31 In fuel to Make sure it was working.

Stretch · 06-09-2015, 08:39 PM

I agree with other folks. Clean fuel, clean air, and good compression, the engine is going to run run. Fuel filter first. Then air filter.

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TMan59 · 06-09-2015, 09:31 PM

That would be my first thought also.
A slightly bad fuel filter restricting the amount of fuel allowed to pass through at the higher rpm.

Butter Ball · 06-10-2015, 10:25 AM

Thanks for all the advice! My research seems to indicate, and these comments validate: check the fuel filter(s), injector pump screen, lift pump, injector pump - in that order. Could water in the fuel cause this type of symptom only at high RPM?

traveler999 · 06-15-2015, 04:07 PM

I had a problem with fuel starvation and changing fuel filters would help for a short time, but it would always come back. I finally found a check valve between the tank and the first filter that had become clogged with what looked like black gunk that was probably algae. You have to remove the check valve and look in the back or input to the valve. I would do that as step 2 before looking at the pumps.