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Topic: Need to prime fuel to start (Read 1123 times) previous topic - next topic

Need to prime fuel to start

Have not started coach in about a month. Needed to prime fuel to start. Is this normal? Replaced all fuel lines last February. No fuel leaks on blacktop. Needed to prime last time started too. What's up with this? Where is fuel going and why losing prime?
2001 4010 U320
Build 5875

Re: Need to prime fuel to start

Reply #1 –
Quote from: Spiderhitch –
Have not started coach in about a month. Needed to prime fuel to start. Is this normal? Replaced all fuel lines last February. No fuel leaks on blacktop. Needed to prime last time started too. What's up with this? Where is fuel going and why losing prime?

You don't have to have a fuel leak to have to prime engine.  Sucking air in one of your lines for sure!  I'm sure others will chime in here for help!
Joe & Dottie Allen
Sold!  December 2023.      2000 U320; build # 5645
Our coach " Maxine"
Motorcade #  15922;  Escapee 150950; FMCA F330833; Boondockers Welcome;  Harvest Hosts;  Thousand Trails
'98 U320 from 2000-'06
USAF '62-'66

"Do not spoil what you have by desiring what you have not; remember that what you now have was once among the things you only hoped for." ―Epicurus

Re: Need to prime fuel to start

Reply #2 –
At least you can disregard condition of the fuel lines from the tank back but I would re check tightness on the fittings. Then I would put a wrench on every connection where fuel passes thru ie injector lines and so forth. This won't cost you anything because you can do it. This is starting with the easiest and see if any improvement before moving to replacing parts. Mine lost prime a couple months back and it was the lift pump but I did all the above before moving on to possible parts failure. Mine is a mechanical 8.3 but everything has to be tight for any diesel to hold prime. Hope it's that simple and many times it is.
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #3 –
Could it be o- rings on pre filter? I'm going to replace all. Do they go bad frequently?I have read numerous times on forum that the system is not well regarded. I have almost 100  of each size.
2001 4010 U320
Build 5875

Re: Need to prime fuel to start

Reply #4 –
No harm in changing.
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #5 –
Looking for such as this is where a 150.00 per hour shop can tear a wallet up. The things I listed and may have missed you can do and avoid that.
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #6 –
If you have compressed air you could go to the fuel tank and make a seal with a shop rag and put a bit of pressure in the tank and have help stand at the engine and look with a flash light. Not a lot of pressure and if the tank is full be careful when you take lift the rag or it will wet you with fuel.like Joe said you can still be getting air in without leaking fuel out so all the tightening I mentioned still applies.
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #7 –
I had a primary filter with the water drain leaking air in at the drain. Pain to find

Re: Need to prime fuel to start

Reply #8 –
If your pre-filter fuel level is 1/4 or less after sitting then you should remove the pre-filter and put in new O-rings (4).  Clean the pre-filter while it is out and reinstall.  If the plastic ends are distorted it will leak fuel or air.  I carry a new spare pre-filter just because. And 2 each of the other fuel filters.

Run the air purge a couple of times, start the engine and run on the first high idle for three minutes.  (Cruise control on and press the set button.)

Clean everything up around the top and bottom of the pre-filter and fittings. It may be dirt dirty but it shouldn't be fuel dirty.  It is always easier to check for leaks when is clean to start with.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Need to prime fuel to start

Reply #9 –
Thanks. Have a spare and plenty of o-rings. Will clean up the one I take off and keep as spare. It is only year old. I have algae in tank and am planning on trip to FT in spring and plan on getting fuel scrubbed. I'll start checking fittings tomorrow. Leaving for short trip to Orlando next week wasn't planning on this. Lots to do
2001 4010 U320
Build 5875

Re: Need to prime fuel to start

Reply #10 –
Is it typical for a M11 to have a pre filter water separator with 4 O rings in it?
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #12 –
Quote from: Spiderhitch –
Thanks. Have a spare and plenty of o-rings. Will clean up the one I take off and keep as spare. It is only year old. I have algae in tank and am planning on trip to FT in spring and plan on getting fuel scrubbed. I'll start checking fittings tomorrow. Leaving for short trip to Orlando next week wasn't planning on this. Lots to do
If you have algae in the tank, your filters will take care of it plus, use the HWH to lean the coach over and with a LED, check to see what is on the bottom of the tank. Use suction to remove any algae, water, etc.

Polishing fuel is a huge waste of money as a clean tank is only clean until the next fillup where you have no idea what's in their tank.

Use an additive to kill the algae so it does not get worse.

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

Re: Need to prime fuel to start

Reply #13 –
Might have found fuel line leak. Severely misshapen inlet/ outlet ports on Winn pre filter.
2001 4010 U320
Build 5875

Re: Need to prime fuel to start

Reply #14 –
Racor 300200
U320 fuel screen
[300200]Racor 300200 Prefilter W/ O-Ring - 200 Mic
Realized I never posted o-ring part numbers.
Scott
Takes two each of the o-rings on each end

Item ID:  O-ring AS568-114
AS568-114 - O-ring

AS568-114 - O-ring


Standard Dash Size AS568 -114 B70 (NBR) Buna O-rings 50 Count Orings Bulk | eBay

----------------------------------------------------
Item ID:  O-ring AS568-208
AS568-208 - O-ring
EAI AS568 O'RING Seal #208 (20PCS) ID 5/8" CS 1/8" NBR Oring 5/8"x7/8"x1...[/url
AS568-208 - O-ring

Re: Need to prime fuel to start

Reply #15 –
 The plastic pre filters can crack the bowel very easily and the crack is hard to see.  Runs poorly that way .

Re: Need to prime fuel to start

Reply #16 –
On a related topic I've attached a photo of my Winn pre-filter while the engine is idling.  Does this look normal to those of you who are familiar with this filter set up?  The fuel stream is flowing in at virtually the same rate that it is flowing out and there is usually little or no fuel accumulated in the reservoir.  When the engine is off the fuel level is usually about half.  I have no engine problems at all and it runs strong without acting like it's starving for fuel.  It just seems like that filter should be full.  Any guidance on this is appreciated.
George Mann
2002 U320 #5934
2017 Rubicon
2013 BMW GS
Waterford MI

Re: Need to prime fuel to start

Reply #17 –
I have had 2 coaches with the Winn filter and both worked like yours.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Need to prime fuel to start

Reply #18 –
I think Racor makes a water/ contaminate filter similar to that and when it is full indicates it needs changed as in contaminated.
Dub McBride 1996 270

Re: Need to prime fuel to start

Reply #19 –
The distorted end will cause both air leaks and fuel leaks.  When you reassemble it lube the rings with a bit of silicone plumbers grease or some fuel.  Be careful with alignment during reassembly.


George, yours looks about right. When you shut the engine off it will be 1/2 to 2/3 full.  I don't see any fuel/dirt at the top or bottom and the screen looks clean.  If you get black flakey stuff in there it is algae.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Need to prime fuel to start

Reply #20 –
As I have mentioned in other threads, the original Winn filter system on our 1995 U320 became problematic--particularly in colder weather. Despite my best efforts at maintaining it, I still had problems (due to fuel starvation) starting the engine in cold weather.

A few years ago I replaced the Winn system with the Parker 790R30 system and haven't had those issues again. I highly recommend it!

The Racor 700 Series Fuel Filter Water Separator is a two-stage filtration and re-priming system that's designed for use in heavy-duty diesel applications. The assembly comes equipped with a state-of-the-art integrated fuel pump, which allows for easy priming and simplified service by eliminating messy filter pre-filling and engine hard starting.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Need to prime fuel to start

Reply #21 –
George there is a Schroeder valve on mine at about the top left of your photo just out of view. I bleed the excess air out with the purge pump. Mine runs at about half full of fuel. Was low when I had air leaks in the system. David I originally thought I would go to the filter Racor 700 series but have since decided I want the benefits of the FASS  pump system because of the lift pump and positive air removal. I do know for a fact our main fuel pump runs and draws a vacuum while operating. My fuel minder indicator I added always shows half scale-goes higher if filter is plugged. Vacuum actuated. The 700 only has a purge pump.
Scott

Re: Need to prime fuel to start

Reply #23 –
I planning to put a Fass system in my coach soon. One of my concerns is the return
line as I have phoned Fass and they say it needs its own entrance back into the
tank. If I had of know about the Fass system when I did my fuel lines I would have
welded  a bung into the tank. They have a system where I could cut the fuel fill
neck and put it in there but I'm not sure I want to do that.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Need to prime fuel to start

Reply #24 –
Quote from: oldguy –
I planning to put a Fass system in my coach soon. One of my concerns is the return
line as I have phoned Fass and they say it needs its own entrance back into the
tank. If I had of know about the Fass system when I did my fuel lines I would have
welded  a bung into the tank. They have a system where I could cut the fuel fill
neck and put it in there but I'm not sure I want to do that.
Yes I agree about adding another bung. So in pondering about this for a month I think one could add the return in one of the other return fittings. Generator returns very little fuel. Generator line on my coach is 3/16 line and steps up to 3/8 return line at tank. Should be sufficient for return of air and generator return demands.
Scott