Cummins El Paso

smlranger wrote:

wolfe10 wrote:
When you changed the fuel filters-- what did you find?

Fuel poured out of any of my filters has looked absolutely fine. I have not cut any filter open yet. I always store the coach with a full fuel tank and I have been treating the fuel with BioBor (just in case) for the past year.

My issue this trip started after getting 50 gallons of fuel at a very busy Pilot and after driving over some really rough road in LA. That led me to suspect something stirred up in the tank.

I talked to my local Cummins shop in VA and they told me that some folks had reported similar issues and had switched their secondary filter to a 10 micron filter and the problem went away. My secondary fuel filter head has 7/8" stud and I have not yet located any 10 micron filters that will fit that head. My Fleetguard FF5636 is 2 micron. My primary filter is 10 micron. A friend with an ISC read a Cummins tech bulletin about fuel starvation on ISC's with 2 micron filters and recommended changing to 10 micron. He has done that and his similar issue went away.

I do not have any issue with oil consumption. I have never had to add oil between annual service except last year when I had a leaking valve cover and gear cover. That was fixed at Cummins.

When I had the coach at my local Cummins shop last year for the oil leaks, they were aware of the previous issue I had with low fuel pressure. They said they checked over everything and found no obvious issues. They ran the coach on their dyno for 3 hours and it ran fine.

I have never had any overheating issues. My coolant temp runs 186-188 until hard pulls when it may reach 195 for brief periods.

No chips. This is a bone stock 425ISL clean diesel (DPF).

In that case, forget the engine contaminating the fuel system, (our problems are not the same)
The 2 micron filters clog very easy. 2 micron is .0.00007874015748031496 inches. that is 98% of the particles bigger than that will be trapped. Many have gone to a 10 micron, and have no problems.

wolfe10 wrote:
When you changed the fuel filters-- what did you find?

Fuel poured out of any of my filters has looked absolutely fine. I have not cut any filter open yet. I always store the coach with a full fuel tank and I have been treating the fuel with BioBor (just in case) for the past year.

My issue this trip started after getting 50 gallons of fuel at a very busy Pilot and after driving over some really rough road in LA. That led me to suspect something stirred up in the tank.

I talked to my local Cummins shop in VA and they told me that some folks had reported similar issues and had switched their secondary filter to a 10 micron filter and the problem went away. My secondary fuel filter head has 7/8" stud and I have not yet located any 10 micron filters that will fit that head. My Fleetguard FF5636 is 2 micron. My primary filter is 10 micron. A friend with an ISC read a Cummins tech bulletin about fuel starvation on ISC's with 2 micron filters and recommended changing to 10 micron. He has done that and his similar issue went away.

I do not have any issue with oil consumption. I have never had to add oil between annual service except last year when I had a leaking valve cover and gear cover. That was fixed at Cummins.

When I had the coach at my local Cummins shop last year for the oil leaks, they were aware of the previous issue I had with low fuel pressure. They said they checked over everything and found no obvious issues. They ran the coach on their dyno for 3 hours and it ran fine.

I have never had any overheating issues. My coolant temp runs 186-188 until hard pulls when it may reach 195 for brief periods.

No chips. This is a bone stock 425ISL clean diesel (DPF).

lc0338 wrote:
Might be a weak lift pump. Be careful if so because you can knock out the injector pump if pressure gets too low. I would want to put a gauge on pressure to see what it runs over time.

He has common rail system, it can not be a weak lift pump. it turns off after 3 minutes.

When you changed the fuel filters-- what did you find?

Might be a weak lift pump. Be careful if so because you can knock out the injector pump if pressure gets too low. I would want to put a gauge on pressure to see what it runs over time.

Do you have a programer/chip on your 425 ISL?

You maybe running too hard, over heating the fuel in the head as the return fuel is returning to the tank, this will cause Asphalting, and clog filters.

Does you oil quantity go down as you drive. If so, you can have a leaking "O" ring that separates the oil from the return fuel in the head.
Have your shop call Cummins technical get them involved, they will tutor the shop thru the repair process.

Do not allow the shop start throwing parts at this problem, none of cummins injection pumps can cause this, and they are huge expensive.

You either picked up a load of bad fuel, or have oil or combustion products getting into the return fuel.
Have you ever seen any black jelly like substance in the filter cans when you change filters? (that would be algae )
A loose injector will allow combustion products to enter the return fuel when combustion occurs. IT simply by-passes the copper gasket at the bottom of the injector, enters the return fuel.
A leaking injector "O" ring will allow oil to enter the return fuel, but usually shows as high oil usage.
Both will eventually clog a filter. quickly at first. -- ( that, I still don't understand)
PM me for all we have done to cure our problem.

Is the fuel in your filters black?
read my old post, I've been fighting this for several years, my cummins is now having all the injectors removed checked for cracks, tested, re-sealed.
my filters will clog at 10k miles (+-) but the first few times they would clog almost every day while traveling. it took 5 sets of filters to nurse it home from Tenn. in 2010.

Algae must have water and sun light to grow, it is very rare that Algae will grow in a motorhome tank, but it can be pumped in.