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 T444E creating air in fuel bowl or lines. Help!!
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New Member

United States
3 Posts

Posted - 11/02/2012 :  09:04:45 AM  Show Profile  Visit DrAlign's Homepage  Reply with Quote
Hello, I have 2001 IH 3800 bus T444E low fuel pressure worse when cold, Intermittent imagine that!! I checked the fuel vent, opened the fill cap and ran engine, tested the fuel pressure still low, test port has air sperting at times when bleeding. Cleaned rock catcher, cleaned fuel regulator screen, no dirt in filter bowl, filter ok. Thought it was a week fuel pump & replaced. still creating air after bleeding system. Going to bypass old fuel inlet line with new line from seperate 5gal fuel container. Help me out here, could i also install a clear fuel hose before i get to the fuel filter bowl? would that tell me if i have a hole in the delivery line or pluged stainer pickup in the tank? Also when at idle it will build pressure slow but after you rev rpm it goes down and runs rough.. Any help would be great... Thanks.

Not sure why the fuel pressure doesn't stay stable, using a digitel fuel gauge it moves from 60 @times to 20psi using a new fuel line with no holes or restrictions. What should the boost pressure be @ idle then wot reading?
I also checked the fpr valve and cleaned. alot of blue smoke.
any help??

Ok update, Installed new Fuel line to tank no restrictions... I also installed a short (CLEAR) line after the fuel pump regulator in frt of the fuel bowl and its showing air bubbles all the time! Dosn't that meen i'm sucking air or is this coming from compression or from injector o ring.. What other test do i need to be doing to find the problem? Thanks again for any help.

Update again Installed a vacuum gauge right after rock catcher going to the pump "reading is jumping 0 to 5 all the time. Dosn't smooth out. ANY HELP??

Update, Found the problem!!! Removed the pump again. I was going to replace the rubber fuel sealing gaskets again the second time just to be sure. I spotted a wear hole (small pin hole) on one of the three steel lines coming off the frt of the pump right at the 90" bend from the harness bracket holding them together for the route up. The one sucking air was for the top of the fuel lift pump it also is the one from the incoming fuel line. This pump has two incoming lines one from the fuel bowl other from the main fuel line.. Thanks.

Edited by - DrAlign on 11/07/2012 12:41:33 PM

Advanced Member

United States
247 Posts

Posted - 11/06/2012 :  07:45:50 AM  Show Profile  Visit willism's Homepage  Reply with Quote
A thought check the fuel lines coming off the lift pump ive seen the clamp that holds the 3 lines together rub a hole in one of the metal lines. Also those rubber connecting hoses after a lift pump change a flap inside the rubber pealed off and was restricting flow one that came back from the dealer a few yrs back. Are your pressures the same with the bus hooked back up to original if so your tank and lines are probably ruled out. Let us know what you find :)
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