Air in Fuel System -- How do you check? - Defender Source
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Old September 5th, 2016, 02:17 PM
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Air in Fuel System -- How do you check?

I have a very tired 2.5 NA with low compression in cyl #1 @40%; all others @ 80%. I have not had time to change the motor back to the 300 tdi that's sitting in my garage. I am going to put that, a new tranny and a new xfr case in, but I won't have time to do that until the holidays. I still want to drive it 5 min to work down hill; then back 10 min up hill;-), but the long cranks are discouraging and I don't want to damage my new starter, or get stranded.

The motor takes a while to start -- about 20 seconds of cranking. Even when I stop momentarily and then try to start it again, it takes a while (engine at normal operating temp). Not 20 seconds, but about 10-15. I assumed it was because of the low compression, which may is probably a contributing factor, but it runs fairly well when warm.

I'm suspecting air is seeping into the lines when I cut the engine off. I replaced the fuel lines when I installed the motor, so I think they're leak free. Now I think it might be the lift pump (condition is suspect) is allowing air in the system. I could replace that cheaply enough ($27 on ebay), but is there some type of test I can conduct to confirm? Heard you could temporarily use clear tubing to see the diesel retreat back into the tank?

Thanks
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Old September 5th, 2016, 02:42 PM
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When did you last check your lift pump and sedimenter?
It cannot hurt to replace the filter.
Don't let it run low on fuel.

http://www.defendersource.com/forum/...ons-46387.html
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Old September 5th, 2016, 05:01 PM
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You can disconnect the feed line at the tank and plug it on the tank side.
Then connect a 12V fuel pump with the inlet in a fresh can of diesel and the output the source line from the tank.
Any air leak will become a fuel leak when the 12V pump is on.
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Old September 6th, 2016, 11:31 PM
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Ed
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Quote:
Originally Posted by Rocky View Post
When did you last check your lift pump and sedimenter?
It cannot hurt to replace the filter.
Don't let it run low on fuel.

http://www.defendersource.com/forum/...ons-46387.html
So, I don't have a sedimenter, I let it run low on fuel and I don't know how to check the fuel pump. Guess that's three strikes...

The good news is that it runs the same before and after the low fuel incident -- poorly.
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Old September 7th, 2016, 12:03 AM
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It's been a while since I had a 2.5NA in my truck but the procedure is to open the banjo bolt on the fuel filter and prime the lift pump manually with the little lever on the bottom or have a friend crank the starter to do the same.

I would put my money on a bad lift pump. Second thing would be a leak at the fuel filter housing.

Here's a video of Brian Hall bleeding my fuel system on my three hundy at the fuel filter banjo bolt as I cranked the starter. My air problems turned out to be a leak at the sedimenter and a faulty lift pump. Replaced sedimenter with one of Robert Davis's and replaced the lift pump and re-bled and all was well.

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Old September 7th, 2016, 07:33 AM
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Chris:
Glad your 300TDI is running fine.

Ed:
The 2.5 N/A has fuel routing that prohibit the type of easy start up the 300TDI can have.
On the 2.5 N/A the return line is routed back into the fuel filter which recirculates trapped air and prevents the engine from starting and after it does prevents it from running properly.
In our shop we get rid of the sandwich filter and install the following:
Tank -> sedimenter -> 12V fuel pump (without any filter - some of them come with a small filter) -> engine lift pump -> spin-on fuel filter (replaces the sandwich filter) -> IP -> return line joins with the spill over line and goes directly back to the -> tank.
Result is a self bleeding fuel system that will deliver enough fuel for that 2.5 to almost get out of its own way!

Good Luck...
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Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)

"What's with this death wobble, Uncle Douglas, I can't keep it in 1 lane?"
UD: "Just Power through it man!"
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Old October 2nd, 2016, 07:37 PM
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Selfishly reviving this thread. I think I found the culprit to my delayed/non starting issue. A rodent has chewed up one of my spillover lines (2.8 TGV). Any recommendations on sourcing one piece vs the entire assembly? I think it's 8mm ID. Thank you
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