Fuel System and air leaks

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kdaniels

Member
Steel Soldiers Supporter
192
10
18
Location
Dothan, Al
Quick and dirty...truck quit under acceleration. replaced fuel pump and filter. Primed both but I seem to have air bubbles in the clear hose going into my water bottle I have for a catch and a little foam/air bubbles in the fuel going into the bottle.

Can I hook a section of new fuel line to the pickup side of the pump and put it in a can of diesel to determine if the air leak is fore or aft of the pump ? I have read that the filter bases go bad and develop air leaks. is there any other area that are prone to suck air into the system?

If I developed an air leak from a bad line could it have caused the stoppage ? Trying to rule out the simple stuff before moving on.

THANKS !!

Semper Fi !

keith
 

cucvrus

Well-known member
8,595
1,268
113
Location
Jonestown Pennsylvania
Many places to develop leaks on such and old vehicle. Bad hoses at sections of the feed line. Rusted thru sweating fuel lines. Anywhere air can get in does not mean fuel must leak out. Best to close off the end of the fuel supply line and create a vacuum and see if it can hold a vacuum for a few minutes. If it is tight it should be able to do so. A mighty Vac pump works great for pushing and pulling pressure in a system. I use it for bleeding brakes alone and it saves the mess of fluid loss when doing it with no hose attached to the bleeder. Check all the rubber hoses and the metal lines. M1008's the steel line can rub thru above the cab at the cab rear crossmember. Good Luck. Be Safe.
 

kdaniels

Member
Steel Soldiers Supporter
192
10
18
Location
Dothan, Al
Many places to develop leaks on such and old vehicle. Bad hoses at sections of the feed line. Rusted thru sweating fuel lines. Anywhere air can get in does not mean fuel must leak out. Best to close off the end of the fuel supply line and create a vacuum and see if it can hold a vacuum for a few minutes. If it is tight it should be able to do so. A mighty Vac pump works great for pushing and pulling pressure in a system. I use it for bleeding brakes alone and it saves the mess of fluid loss when doing it with no hose attached to the bleeder. Check all the rubber hoses and the metal lines. M1008's the steel line can rub thru above the cab at the cab rear crossmember. Good Luck. Be Safe.

THANKS. !! I'm going to replace all the rubber fuel line in the engine compartment area and check for those wear points on the metal lines. great running M1009 till this mystery struck. It does have that crazy zig zaggy soft line on the fuel pump side.....don't know if that's a preformed or someone at GM did it that way.
 

cucvrus

Well-known member
8,595
1,268
113
Location
Jonestown Pennsylvania
That is a preformed factory fuel feed line. 3/8" hose can be made to fit. I use split loom to prevent it from kinking. It will be a bit longer but it will work. Also trim the end from each side of the hose and get some fresh bite on that hose clamp. I always noticed many of the factory clamps have been overtightened so badly they are stripped or sprung. Replace the clamps after you remove them. Check the return ;line on the frame and if you see any wetness of sweating replace the entire steel fuel line. I have done it on a few. Not a hard job but time consuming to get the attachments back on correctly. Do it right the first time. Good Luck.
 
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