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Topic: Starting Issue When Cold 1995 U320 Cummins M11 (Read 1936 times) previous topic - next topic

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #25 –
If air is entering the fuel system, it will be on the suction side of the system-- i.e. before the lift pump.  If there was a leaking connection after that, it would be leaking fuel OUT, not air in.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #26 –
Quote from: wolfe10 –
If air is entering the fuel system, it will be on the suction side of the system-- i.e. before the lift pump.  If there was a leaking connection after that, it would be leaking fuel OUT, not air in.

Got it. I guess I just assumed we were all thinking of the fuel lines, fittings and filters between the tank and the pump, and possibly the pump itself, and not the pressurized side after the pump.

Does anyone have a good description/graphic/schematic of the 1995 U320 M11 fuel system (ahead of the pump)? I have all of the replacement filters, and I think I have a good idea of the system, but I don't recall seeing details of the overall system.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #27 –
With your engine serial number in hand,  Cummins QuickServe Online  will serve you better than any person here can with regards to fuel system drawings. 
Robert
Build # 5304
1998 34' U270 Cummins 6CTA8.3

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #28 –
Just another comment on the original Winn system. My coach would run fine but occasionally die at idle. I replaced the Winn and no problems since. Good luck.
jor
93 225
95 300
97 270
99 320

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #29 –
Yes, I believe it is common knowledge that Parker/Racor has a complete replacement for the Winn system because of all the failures.

The Winn system has a lot more leak-prone areas.  Yes, one can keep them working, but for most, replacement with a more reliable system is indicated.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #30 –
Quote from: rsihnhold –
With your engine serial number in hand,  Cummins QuickServe Online  will serve you better than any person here can with regards to fuel system drawings. 

I have a QuickServe account, and it's a most valuable resource for the engine, and the M11 fuel system. However, I've found nothing there regarding the overall fuel system on my 1995 U320. Therefore, I'm wondering if anyone has that information available.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #31 –
Use a ViceGrip, welding clamp or other clamp on the feed hose at the tank or other convenient spot and then use a MityVac  ( Mityvac Vacuum Pump - Save on Mityvac Pumps at Harbor Freight! ) starting at the first connection closest to the tank and work toward the discharge side of the engine lift pump. As soon as you start to lose vacuum, you have found the leak. About an hour of work should find any leak. Don't go crazy with the teflon tape putting the fittings back together. I like a little teflon compound on the male side, never on the female side.  Rule is that if it's pipe threads on both sides, you can use teflon compound to seal it but just a little. Some fittings are designed to seal themselves and don't use anything.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #32 –
I am (almost) positive that you have a fuel return check valve and a fuel strainer.
The fuel check valve is forward on the ECM fuel cooler plate (fastened to the block) and is in the 90 degree fitting that connects to the primary fuel filter hose behind the ECM wiring bundle (all forward of the ECM.)
(Be ginger moving the ECM wire bundle out of the way when removing the 90 degree fitting.)
The fuel strainer is at the forward end of the fuel pump, under the (large) button style +screw.  pc

S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #33 –
Quote from: pocketchange –
I am (almost) positive that you have a fuel return check valve and a fuel strainer.

How do you think this could be related to the cold-weather starting issues I described? Does that strainer filter the fuel returned to the tank?
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Starting Issue When Cold 1995 U320 Cummins M11

Reply #34 –
The check valve stops fuel from syphoning back to the tank and the little strainer keeps debris from going through the pump.
If the check valve is stuck open, fuel will drain back to the tank.  pc

S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..