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Fuel Filter Change/ Hard to Start?

May 03, 2012, 01:09:58 am

Whenever I change my fuel filters it is hard to start afterwards. It is a 96 U320 with a Cummings M11 Engine, It has a Donaldson P551000 fuel filter/ water separator filter and Foretravel added a Baldwin/Dahl water separtor filter200 in line. I here there is a electric primer that goes in line to prime the system.  Thanks Art

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Re: Fuel Filter Change/ Hard to Start?

Reply #1 – May 03, 2012, 01:32:48 am

I have no idea if this applies to your coach, but......did you fill the filter with diesel or put the filter on empty?  On the coach without a modified filter, the M11 is said to require that the filter be put on without filling it with diesel.  A senior technician at MOT told me it had to do with some internal working of the filter versus how customers at home handled it and often had trouble so they recommended not filling the filter.  My manual says that it the procedure.  It may have no bearing on a 1996 or the system you now have.  I mention it more for you to consider than a real solution.  Wish I had better information on your particular problem.  Mike

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Re: Fuel Filter Change/ Hard to Start?

Reply #2 – May 03, 2012, 06:03:23 am

I believe it has more to do with air trapped in the fuel lines, it only takes a little bit of air to create a hard/no start. When you remove the filters to some extent it allows fuel to drain back to the tank (40+ feet of fuel line), so it takes a bit for the line to be purged of air. Generaly speaking all of the fuel filters are on the suction side of the lift/fuel pump(s) that doesn't help as well.  I have for years always pre-filled the filters, but most of the time I still end up with a start, run a few min, stall the first time I start it after service.

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Re: Fuel Filter Change/ Hard to Start?

Reply #3 – May 03, 2012, 11:04:00 am

I fill the new filters most of the way, screw them down until they have a couple of turns left before the gasket contacts the mating surface and then use the hand pump until diesel runs down the sides of the new filters. Then I tighten them and continue with the pump for another 30 seconds or so.

No big deal on a Detroit but Cummins are picky about air in the system.

Would think that recommendations otherwise would have to do with liability issues for diesel spill, contact with the skin or possible use of contaminated fuel.

If you don't have an OEM hand pump mounted, an electric pump would not be that hard to install. A couple of articles on how to do it are on bus forums.

Pierce

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Re: Fuel Filter Change/ Hard to Start?

Reply #4 – May 03, 2012, 09:35:04 pm

Art,

Do you have the priming instructions for your system?  On mine you turn the ignition switch on, but do not crack.  Remove the cap on the Schraeder valve(looks like a tire valve), push in the center pin, hold the priming pump button in until fuel just starts to flow out of the valve.  Then release the center pin, re-install the cap, and proceed to crank engine until it starts.  Run at fast idle for three minutes.  It will run rough for about 30 seconds, then smooth out.

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Re: Fuel Filter Change/ Hard to Start?

Reply #5 – May 04, 2012, 09:55:39 pm

I don't have a primmer on mine, Roger said he has a Racor Filter with a electric pump to prime the system.

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Re: Fuel Filter Change/ Hard to Start?

Reply #6 – May 05, 2012, 09:45:59 am

Art,

I bet someone removed your primer system.  FT replaced mine when the pump died.

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Re: Fuel Filter Change/ Hard to Start?

Reply #7 – May 05, 2012, 12:39:31 pm

Check the 03 320 at MOT C1541,look at the photo of the engine bay and you can see what appears to be a new fuel primer and filter,Caterpillar has a primer called a prime time pump.

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