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Losing Fuel Prime

Hi all, let’s try out this new forum!  Thanks again to Steve!

My coach occasionally loses fuel prime and is very difficult to start when it does.  I have finally figured out that there is an air leak at the fittings coming out of the fuel tank.  I can reach the fittings after removing the back wall of the front passenger side storage compartment, although I may have to lower the tank a bit to complete the task.  I will need to disconnect the compression fittings that connect the plastic(?) fuel line.  My question is, what kind of fittings are holding the fuel line?  Will I run into problems when I disconnect them?  Should I have spare parts on hand?

Thanks in advance for any information.

Dale Collier
05 Inspire 53477
Dale Collier
05 Inspire 53477

Re: Losing Fuel Prime

Reply #1 –
I had a problem with fuel prime and ended up replacing a fuel check valve on the back of the engine. I have a Detroit Series 60 and the fuel check valve is located on the back of the head where the fuel exits to return back to the tank. I had to remove the bed and engine access panel in the bedroom. Changing the valve was the easy part.

Best,
David
98 CC Concept Alpha 40'

Re: Losing Fuel Prime

Reply #2 –
Does not sound like much fun:)! So is the DD60 in a Prevost Based coach? Smooth sailing for you for awhile:)!
Best,
Smitty
04 Allure 31017
04 Allure Sold to a nice new owner! Now enjoying a 07 Magna Rembrandt 45' ISX600 #6775
"We're ONDROAD for THEJRNY!" (Toad and Coach license plates, say Hi if you see us!)

Re: Losing Fuel Prime

Reply #3 –
Thank you David. 

This being a Cat C9 it has a HEUI fuel system there are not any check valves shown on the schematics or that I can find by visually inspecting.  There is a fuel pressure regulator valve on the back of the block which I hav already addressed a leak at the fuel return to the tank line.  When trying to get the engine started following loss of fuel prime I noticed the fittings, on top of the tank, for both the fuel supply and return lines were leaking significantly with very minimal air pressure on the tank.  I am going fix the fitting leaks, install a check valve, or two, and an electric lift pump in the fuel supply line.  I'm hoping the electric lift pump it will care any future loss of prime issues.  As soon as the current cold front goes away, I'll go to work on it.  Was hoping for fitting information so I could purchase in advance, but will just dive in to see what I find.

We really love our coach and haven't had any problems other than well known issues, and the fuel supply lines.  It seems kind of strange to me that this isn't an issue for others.  We've had problems with loss of prime since we first purchased the coach.  I fix problems as they come up, this now make a total of 5 problems with the chassis fuel supply system.  After repair of the tank fitting every chassis fuel line connection wil be addressed.  Hopefully we'll be done!

Thanks again,
Dale
Dale Collier
05 Inspire 53477

Re: Losing Fuel Prime

Reply #4 –
For board information, I finally figured out that the air leak was at the fittings on the top of the fuel tank.  They were not properly tightened during new assembly.  That being the case, it is likely a one off missed step during the build.  The, remove, clean, apply sealant and, tighten fix was not easy.
Dale Collier
05 Inspire 53477