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Old 02-07-2017, 12:48 AM
Kman911 Kman911 is offline
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Default Air in fuel lines... at my wit's end!

1985 Ranger 4cy 2.3 gas.

Okay so here we go. . . The long and short curly end of it I have air in my fuel lines. There is a section of line that is see-through right before the canister fuel pump. I can see both the return and the one it sucks from. Or I think it's the one. One is blue and one is whit/clear/yellowed. On the other end of the canister moving towards the motor, the blue line enters fuel pump then from there up to fuel rail. Then the return part of the rail is connected to the white/yellowed line that goes back into the canister filter housing. I'm not sure what happens in ther. If they combine or what. It should reunite the return with the tank right?

But back to the bubbles, i can see in the lines and see space where air is and sometimes no fuel moving, in both lines in different times and at same times.

Things I've done.... to fuel system : it had a bad sputter and loss of power under normal driving. So I've replaced the filter, pump and pressure reg valve. No love tho.... I've dropped the tank to see if a connections were loose. I've taken off and re-attached connections (I can kink fuel hose after pump and it builds preassure in a second flat, also pumped gas into a bucket with no hesitation very quickly) so I'm saying connections up to pump are A+

So someplace I'm catching air and it's getting in the lines right? Also I have zero gas leaks, I check every morning and when I get home from work, looking for wet spots under and up inside. So idk what the hell to do next.

One thing I can think of is after changing the filter I didn't re fill the canister, that may cause a big air bubble? But i pumped like a half gallon into a bucket no problem. So I don't think that could be it!

Also idk if it makes a difference. . . The kid that neglected this truck so bad before me wired up the fuel pump to a switch so it's manually turned off and on. It's just stlraight 12v from battery. Whould anyone know is constant power mess with the pumps performance. I plan to wire it back eventually

Any feed back is appreciated Thank you!

Last edited by Kman911; 02-07-2017 at 12:51 AM.
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Old 02-07-2017, 12:34 PM
tomw0 tomw0 is offline
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Join Date: Aug 2015
Posts: 954
Default Re: Air in fuel lines... at my wit's end!

You may have 2 pumps in your system. The first EFI models have a lift pump in the tank that fills the reservoir that houses the fuel filter. The housing mounted to the frame rail will have 4 connections, and contain the fuel filter element. It also has check valves. The lift pump fills the reservoir with low pressure (12psi?). The reservoir is also used for buffering demand, providing a 'chunk' of fuel to feed the high pressure pump mounted further forward on the frame rail, just about under the drivers seat.
If the fuel pickup in the tank is not sealed, you will get bubbles sent on to the reservoir. If the check valve in the reservoir assembly leaks, it will empty back into the tank over night or however long it takes. That leaves the reservoir empty, or full of air, depending. If the 'return' check valve leaks, the reservoir will fill with air. I think the return check valve needs a few psi to open, which would be provided by the high pressure pump sending excess fuel back to the tank via the return line.
The reservoir assembly is available on the web from some dealers. I think. There is a post on ford-trucks by numberdummy that has a link to a PDF file of all versions of the canister. Some come with filter installed, (1985 does, I think, as I cannot find another filter anywhere), some come as empty chambers.
When you really step on the gas, the high speed pump can demand more than the lift pump can deliver, supposedly, and the canister housing provides a 'ready supply of fuel so the pump does not run 'dry' when it first has a heavy demand. At least that is the story told.
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Old 02-07-2017, 10:21 PM
Kman911 Kman911 is offline
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Default Re: Air in fuel lines... at my wit's end!

Well thank you, this all makes sense. No where has anyone mentioned anything about a second pump. But I've seen the top of the tank and it does have a good size harness that plugs in.
So this is a good place to continue my investigation.. I will definitely look into finding out if there is a pump in ther.

I think I failed to put this in the OG post but the truck was running good after I had done my work on it, then I went and put gas in it and let the nossel click to stop. Then on the drive home it all started.

Would topping it off effect that pump in there? Maybe since it old and worn. . . Regardless I'm pulling tank once again and investigating.

And what do you (or anyone) think about running the fuel pump and purging the little Preston valve used to check fuel pressure? So see if I can get all the air out of the system. I was thinking since I had so many hoses off and on maybe I just, without knowing, filled the whole system with air.
But wouldn't it go back into tank and rise and vent?

Thanks for response, you gave me new direction
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air, fuel, gas, line, ranger

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