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Fuel Filter Change Concern

October 29, 2012, 11:30:52 am

We have owned our 2001 U270 for 10 years. It had 13,000 miles on it when we bought it and has 170,000 on it now. I have changed the fuel filters myself, usually at about 14,000 miles but many extra times the first year we owned it and when we got a really bad tank of fuel. I always followed the procedure in the Cummins manual. The last time I changed them I got an air lock between the fuel tank and the prime button located right before the water separator.

My questions are: How did this happen? and What can I do to keep it from happening again?

More details follow:

Last June we were camped in the Seward AK city campground with the airbags lowered as far as they go. After four days we needed to dump but the engine would not start. I knew that the fuel filters were due for changing and had planned to have it done in Anchorage the following week as we were having the front tires replaced and they said they would do it in their shop.

I called CoachNet and they said they would not send someone to replace filters so I changed them myself. This was really not a good day as I am 78 years old and it's hard enough changing them on my concrete drive with the airbags raised. I filled the water separator filter with diesel and left the main filter dry as I have done in the past following the recommended procedure in the Cummins manual. I lost the prime between the fuel tank and the water separator. There is a manual push button primer next to the fuel separator which I have always used to reestablish prime. After multiple tries engine still would not start.  (You could feel there was still no prime.)

 It was Sunday and we needed to catch a flight from Soldotna to Lake Clark the next day so I called CoachNet again and was told that they could send help from Anchorage but not before Monday! Well, I got lucky. A large tow truck pulled up to change a flat tire on a tow vehicle parked nearby. The truck and driver were from Seward and he said they had three trucks but only one was working on Sunday.

He spent about two hours diagnosing and fixing the problem. From inside the engine bay, he unscrewed the fuel filter enough to fill it with diesel. It still would not start so he went to the auto parts store and got a can of ether. He removed a sensor from the air input pipe just before the turbocharger and squirted ether in the hole and the engine started after many misfires and plenty of anxiety.

The driver suggested I get it looked at by the Anchorage Cummins dealer. I neglected this advice as we had friends with us for only a couple weeks and a tight schedule and lots of prepaid reservations. As we didn't experience any further problems, I decided to continue our trip without the Cummins visit. We made it home to Texas in September without further fuel feed problems.

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Re: Fuel Filter Change Concern

Reply #1 – October 29, 2012, 12:10:38 pm

Rob,

If the level of the primary fuel filter base is ABOVE the level of fuel in the fuel tank, when you remove the filter, fuel can drain all the way back from the filter base to the fuel tank.

Best solution is to install a "diesel approved" ball valve on the inlet of the primary fuel filter.  Close it before removing the filter.

Brett

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Re: Fuel Filter Change Concern

Reply #2 – October 29, 2012, 02:08:49 pm

I replaced the Winn fuel filter, water seperator, purge pump unit with a similar Racor unit when the Winn pump failed. Diesel drained back to the tank. Both of these units have shrader valves to let the air escape. I attached an old quick release valve stem connector from a tire hand pump to a clear hose. I drilled two holes in the cap of a small pop bottle. One hole was sized to tightly fit this clear hose. The other hole was sized to fit a short hose which was connected to a hand vacuum pump. Now I can connect to the scrader valve and suck the air out of the fuel line with the hand vacuum pump. Any diesel stays in the pop bottle. Once the purge pump is full of diesel, it can push out by the remaining air.

This could be done in an emergency by removing the core of the scrader valve, attaching a clear hose, suck with your mouth watching the clear hose for diesel. When diesel appears clamp the clear hose with vise grips. Later, after filling the tank, the clear hose can be removed and the core of the scrader replaced. 

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Re: Fuel Filter Change Concern

Reply #3 – October 29, 2012, 03:16:05 pm

For DIY'ers, check the link below. Tom Hall designed an excellent solution to getting ALL the air out after changing filters, hoses, etc.

Tom Hall

U300 Detroits come with the same check valve. Ours was cracked so I did a little searching and found one for $31. Much higher at NAPA so you have to call around. Electric pump in parts list is 24V so a 12V model would need to be found.

Good way to save starter repair and lots of headaches.

Pierce

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Re: Fuel Filter Change Concern

Reply #4 – October 29, 2012, 03:35:50 pm

Yes, those check valves are great, buying one from DD, they sold for over $45.00 each ten years ago, so I bought a dozen from Univeral Coach Parts (MCI), for $3.70 each.
Great little units that work.
Dave M

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Re: Fuel Filter Change Concern

Reply #5 – October 29, 2012, 04:40:47 pm

Many thanks to all of you for your great ideas. I think that Brett nailed it. I always fill my tank just before I park the rig. Then I change the filters when I get around to it. We checked our records and we took on 70 gallons of diesel at Girdwood so the 150 gallon tank was probably around half full. Now that I think about it, I normally get leakage when changing the water separator. I think I like the ball valve idea best as it should solve both problems.

Robert

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