Cummins ISL hiccup

[sofar-sogood]

Ours is an 03 Cummins ISL with 20K miles. Just serviced with new filters before a trip form Fla to Utah. It ran perfectly until the 4th day when it started to develop a very brief sudden loss of power when climbing small grades. The best that I can describe it is that the engine seems to stop for about 1/2 a second and then picks back up. It happens in all gears and any speed range. It will also occur during moderate acceleration and the event often times has multiple consecutive hiccups several time a minute. It idles fine and runs great on flat grades. I couldnt find and trouble codes on the Allison and I dont get the "check engine light", but Im not sure that I have a check engine light as I dont see one when the ignition is first turned on. Were in Moab and there are no diesel shops here that deal with Cummins. The closest is in Grand Junction. I have checked for loose battery connections, water in fuel, etc. I really dont want to make the trip over to GJ if I dont have to since I have dogs and cats to deal with. If anybody has some trouble shooting ideas it would be greatly appreciated.

[wolfe10]

sofar-sogood wrote:
Finally figured it out, the primary is a 2 micron and then the secondary is a water separating 10 micron. I took off the 2 micron and dumped the fuel from it and it was clear. I then cut the filter open and found it to be fouled with a black very fine looking power like material. Changed both filters and cleaned the Winn filter and ran it 250 miles with no issues. Picked up some extra filters just in case it happens again. Now Im wondering about the generator filter?

Actually, I hope you have your terminology incorrect, as the filters would be backward if installed as you state.

The PRIMARY fuel filter is the first one the fuel gets to from the tank. It is also the water separator and has the course micron rating (10-30 is fine). Next, the fuel goes to the lift pump.

The SECONDARY fuel filter is after the lift pump and is the fine filter (2 micron in your case).

I have seen them installed incorrectly, that is the reason for the post.

[sofar-sogood]

Finally figured it out, the primary is a 2 micron and then the secondary is a water separating 10 micron. I took off the 2 micron and dumped the fuel from it and it was clear. I then cut the filter open and found it to be fouled with a black very fine looking power like material. Changed both filters and cleaned the Winn filter and ran it 250 miles with no issues. Picked up some extra filters just in case it happens again. Now Im wondering about the generator filter?

[sofar-sogood]

My primary filter is a 10 micron, the secondary is a 2 micron. They are what is the book says they should be.

[hershey]

stillthinking99 wrote:
Hershey, my local shop had my motor home for three days to install a fuel pump. It was $90 per hour and the rebuilt pump was discounted to $1,800 (working from memory here) you got a fuel pump for $540......I want a do over! I know, they didn't work on it all three days I was waiting my turn.

Putting my diesel mechanic hat on here......thats scarry.
After my ordeal I learned the following:
1. My Cummins has two fuel pumps. The primary (the one I had replaced) and a secondary pump which they called the injector pump, I think.
The primary is a small unit mounted to the side of the motor and is only $178.00. It supplies up to 150 gallons an hour...who can afford that.
The secondary pump is located somewhere else and the cost for that puppy is $2000.00 I was told.
So I got lucky, it was only the primary pump.
Also learned:
When the primary pump quits working, the secondary pump will continue to suck diesel thru the pump and let the engine to continue to run, but poorly and without power. If that is allowed to continue, it will indeed cause the secondary pump to fail and of course that will cause a complete shut down.
Sounds like the fuel pump you had replaced was the secondary pump or injector pump.

[farmingdad]

mind done same thing , an what it was is i had the wrong micron filter on the primary, it come out with racor 10 micron filter on the primary an 2 micron on the secondary, an i got some filters at carquest an was wrong micron ,it is not getting enough fuel check that 1st

[stillthinking99]

Hershey, my local shop had my motor home for three days to install a fuel pump. It was $90 per hour and the rebuilt pump was discounted to $1,800 (working from memory here) you got a fuel pump for $540......I want a do over! I know, they didn't work on it all three days I was waiting my turn.

[barlow46]

If not the gasket/O ring sucking air, you might be dealing with plugged filters from algae in the fuel. You have a 2003 coach with 20,000 miles on it which means it has been sitting a lot. If you end up taking the filter off, trying dumping it into a clear container or cut in half and see if it is clogged with algae. If so, post back and get recommendations on "polishing" the fuel and/or cleaning the tank. Hope it is a gasket/o-ring not seated....a lot less headache. Good luck.

[sofar-sogood]

I did open the thumb valve on the bottom of the primary filter and only got about a 1/4 oz of clean clear diesel out of it. I thought that there would be more fuel than that? I did that with the key off. I turned on the key and a pump near the filters ran for 20 sec or so and then I had lots of clean fuel coming out, the pump must have refilled the filter? Also I have a small switch panel with 2 push button switches, 1 says "Air purge", the other is "H2O purge". There is a green pilot light on this panel that comes on with the ignition. I pressed both switches and nothing happened with the H2O but the Air purge light came on yellow. I assume that the primary filter drains back towards the tank when not running? I guess the next step is to remove the secondary filter. I tried the belt method but it just slipped.

[DSDP_Don]

sofar-sogood.....If you're comfortable with it, the filters should just spinoff with your hand if they were recently installed. If not, you can wrap an old leather belt around the filter, pinch the belt as tight as you can with pliers or vise-grip and lean the pliers in the direction you need to turn.

Both filters have a large rubber o-ring, just a little larger than the o-ring you find in the end of a garden hose. Two things may have occurred, either one of them was left off, or there are two on one filter. Remove the filter and check the end of the filter and up into the filter housing.

If the O-rings are in place, pour the fuel out into a bowl and check for excess water or other visible contaminants. If the filter is clean, refill it with clean diesel fuel (buy small gas can). Put your thumb into the center hole, blocking it off and pour the clean diesel into the filter around the outer edges.

The ISL is suppose to be able to start with empty filters by turning on the ignition several times for 10-20 seconds to fill the filters, but I've found this to not work well.

[hipower]

Had similar symptoms with my 2003 ISC Cummins. Problem came and went for a lot of miles and new filters, algae treatment, etc. seemed to fix the problem for a short time.

End result we found a faulty fuel transfer pump. Replaced it and all is well again. On my DS the job had to be done from under the bed and upside down since the pump is mounted on the bellhousing area of the engine.

Good luck.

[Ivylog]

I had the same indications and after replacing the primay filter with the water drain I had the same problem. I replaced the seconda one in the engine compartment and that solved the problem. I would drain fuel from the one with the drain valve and see what yout get. I would also take off the secondary filter and poor the fuel into a clear container to see if it really needs changing. It would be worth trying to tighten them and you should be able get both hands on them which is usually enough to take them off or tighten. Park with the back of the MH up high so fuel does not run out while you are checking. Turn the key on for 30 seconds several times to prime the system before trying to start. Cleaner made from orange peals helps on getting the diesel smell off our hands and arms.:W

[The_Texan]

Now that is interesting....the town grows and gets more diesel traffic, but the several diesel mechanics that were there have vacated the premises. good information.

[hershey]

Sorry Texan....but believe me I didn't leave any rock unturned when I was down and out there last Thursday. Yes there is one if you google and the place from the outside looks promising but when you walk in its like an episode from the Horders. What a junk heap. He did sell me a filter and installed it for me for $70 which didn't fix the problem. I begged to get the name of anyone who might work on diesels...he referred me to the wrecker service. Claimed they might do some work. I did and they too told me that the only diesel service would be in Grand Junction.

[The_Texan]

Actually there are several diesel shops in Moab, on the south end about a mile from town. We used one on the west side of 191 a few years back and the mechanic was very knowledgeable and reasonable. Just ask the locals and you would be amazed at what you can find.