All fuel returning back to tank when off? or air leak?
Hey guys, this is my first post. I have a 1994 7.3 IDI and recently had alot of fuel issues. Well now after being out of the shop multiple times, im having a huge starting issue. if i leave it off for 2 hours or more it takes about 45 sec to turn over. after i get it to turn on, it sputters unless i hit the gas to get fuel flowing through the lines again. my dad thinks its an air leak into my fuel but that would mean that diesel would be coming out of that leak too right? i think that when i shut it off and let it sit, all my fuel in lines is returning back into my tanks.
thanks, wes
Air is smaller than diesel, you can have an air leak that diesel does not flow out of. The most common location is the return cap o-rings. You do not have all the fuel returning from the tanks just enough to create a bubble that will cause an airlock that causes missing and of shutting off. You can plump in a electric pump and bypass the mechanical lift pump that allows you to prime the system after filter changes.
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Alvin Mitchell
Pablo Montana
1983 F250 4X4 4.10 gears 4 speed dana 50 center/44 outers Dana 70 rear
Not trying to hijack this, but I'm hoping for a little more information on this same topic. My 91 does the same thing as the OP. Even after putting on a new return line kit, if I let it sit for a day, it doesn't like to start. You mentioned that failed return lines are the most common reason, but I'd like to know what some of the other common reasons for this are. I'm at the point where I'm seriously thinking of putting in an electric pump because I can't find the real problem.
Thanks, Don
All fuel returning back to tank when off? or air leak?
One common mistake when installing new O rings and caps is not using any or enough lubrication when pressing the caps into place, and nicking or splitting the O rings. Another leak point is the fuel supply line from the filter header to the IP. There are olive seals at each end that are only heightened enough to maintain a seal. They could be loose or over tightened causing air intrusion.
there's other seals too. there's "olive" seals on the hard line that feeds the IP. My IP has an O-ring behind the fitting that the hard line attaches to.
Also there's various fittings on the filter head. There's the filter seal itself. There's the fuel heater connector on top of the filter head.
Air can enter the system pretty much anywhere you would imagine.
There's really not much to the system. Selector valve in the middle, has two lines forward and four back. It switches supply, return, and level sender wiring at the same time. two lines forward, one is the return to the valve from behind the motor. the other goes to the lift pump. lift pump pushes to the filter head. filter head pushes to the IP. IP pushes to the fuel injectors. injectors waste to the return. return also ties back into the filter head.
Air can enter the system pretty much anywhere in the active supply and return lines, or at the selector valve itself.
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1992 F250 XLT 4x4 Super Cab 7.3 IDI E40D 3.55 ATS 088 4"R.C 360k
1982 MBZ 300SD W126 California model w/Sunroof, no EGR
The seals are cheap I'm breaking down buying all the olives and putting them in I already bought a viton oring kit from Harbor freight an have installed them I'm also replacing to return line that runs from back of motor where the lines from both banks meet
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1990 f250 4x4 e4od 7.3l idi
Turbo ip turned down tq screw
315/75r16
3in lift
K&n air filter and home made ram air
5in stack straight pipes
165,xxx mi (I think/hope)
Large tranny cooler
16-18mpg
Soon to be turbo'd with nice cold air and wraped exhauste be for turbo
The seals are cheap I'm breaking down buying all the olives and putting them in I already bought a viton oring kit from Harbor freight an have installed them I'm also replacing to return line that runs from back of motor where the lines from both banks meet
Got any pictures? and what about your homemade ram air kit?
new question. my truck seems to idle low when its warmed up, rattles everything when it just sits at an idle. anyway to turn up my idle (timing, screw, anything!).
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1994 Ford F-350
5-speed manual, 4x4, 7.3L IDI
K&N air filter
3.5" straight pipe exhaust
285 Maxxis Buckshot M/T's
All fuel returning back to tank when off? or air leak?
The idle is adjustable at the IP where the throttle cable attaches. There should be a set screw that the plate rests against. What RPM is the engine running at idle when fully warmed up?
Got any pictures? and what about your homemade ram air kit?
My ram air won't really work on your truck but here's the link DIY ugly ram air
As far as the other pics if I remember to take them when I'm out working on it I will
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1990 f250 4x4 e4od 7.3l idi
Turbo ip turned down tq screw
315/75r16
3in lift
K&n air filter and home made ram air
5in stack straight pipes
165,xxx mi (I think/hope)
Large tranny cooler
16-18mpg
Soon to be turbo'd with nice cold air and wraped exhauste be for turbo
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