Fuel Delivery Problem? - JeepForum.com
 
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post #1 of 10 Old 07-20-2011, 12:01 AM Thread Starter
peanutfarmer101
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Fuel Delivery Problem?

First off, 78' CJ 7 w/ 304 aftermarket edelbrock intake and carb...No return on the fuel filter. I have searched and am stumped..

Everything has been fine for last 3 years until about a month ago. After about 20-30 minutes of driving, it starts to hesitate and "bog" like its running out of fuel then it sputters and dies.

It happened today when riding around checking my crops. I looked at the fuel filter and it was bone dry. It would not crank immediately, so I let it sit for about 5 minutes. It then cranked(with a little hesitation) and the filter immediately began to fill with fuel and it ran fine all the way home.

I have noticed the filter going almost dry when it idles for a while(even though it never dies) It eventually catches the filter back up. It does this even with the fuel cap off, so I don't think it is vapor lock.

I pulled the fuel line from the carb and directed it to a quart jar today.It pumped about a pint in 30 seconds.

Any ideas where to go next? Could the fuel pump be going out?

Thanks in advance...


Peanutfarmer101

'78 CJ-7..304 T400.. 30 up front, locked 20 in back(1 piece axles)..Quadratrac w/ parttime conversion..4" lift w/Currie greasable shackles..33" AT's on 15x12 alum wheels
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post #2 of 10 Old 07-20-2011, 12:41 AM
scottymac62
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"I pulled the fuel line from the carb and directed it to a quart jar today.It pumped about a pint in 30 seconds"

It sounds like your fuel pump is failing or you have a partially blocked fuel line between your fuel pump and tank. Take the supply fuel line off of your fuel pump and blow down the line, there should be very little or no resistance. A pint of fuel in 30 seconds sounds mighty low.

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post #3 of 10 Old 07-20-2011, 02:06 AM
BagusJeep
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What kind of pump have you got?
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post #4 of 10 Old 07-20-2011, 02:07 AM
BagusJeep
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And it would work better with the 3 way filter and the tank return connected. Not sure this is your immediate problem though.
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post #5 of 10 Old 07-20-2011, 07:03 AM
JeepHammer
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V-8 didn't have a return line lots of times,

I agree, it sounds like the fuel pump is giving up.
Pint in 30 seconds isn't much.

Do you have a fuel pressure gauge?
That would be the tell of the tale if you did.
Pressure drops when volume of fuel drops it would be one of three things,

1. Fuel Pump giving up,
2. Sock filter or something else in the tank blocking the fuel pickup tube,
3. Old rubber fuel lines collapsing under suction.

I've had all three problems before...

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post #6 of 10 Old 07-20-2011, 12:18 PM Thread Starter
peanutfarmer101
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Bagus..it is a mechanical pump..

I have traced the steel fuel line from the engine compartment back and have nt from any kind of leak..the only lines I havent checked are on top of the tank(where most of the problems are!)

JeepHammer..I am going to see if I can find my fuel pressure guage that I had from my old mud racing days.

This just seems crazy. I have never noticed a fuel pump not pumping, then when it shuts down and you restart the engine it goes back to pumping.I guess I should have got a transparent fuel filter long ago..

I have not run it long enough after a restart to see if it repeats its self. Most of the time I am too aggrevated to remember to leave it running so I can check it.

Thanks guys!
I appreciate all the help I can get!

Peanutfarmer101

'78 CJ-7..304 T400.. 30 up front, locked 20 in back(1 piece axles)..Quadratrac w/ parttime conversion..4" lift w/Currie greasable shackles..33" AT's on 15x12 alum wheels
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post #7 of 10 Old 07-21-2011, 11:11 AM Thread Starter
peanutfarmer101
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I was unable to locate my fuel pressure guage..so I think I am just going to replace the fuel pump and see where it goes from there...

Peanutfarmer101

'78 CJ-7..304 T400.. 30 up front, locked 20 in back(1 piece axles)..Quadratrac w/ parttime conversion..4" lift w/Currie greasable shackles..33" AT's on 15x12 alum wheels
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post #8 of 10 Old 07-28-2011, 09:47 PM Thread Starter
peanutfarmer101
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....I replaced the fuel line from the frame to the fuel pump, the fuel pump itself and the inline filter before the carb ....drastic improvement in volume of fuel.. so either the pump was on its way out or the rubber line before the pump was collapsing

Also, I later found that the metal line from the pump to the carb was collapsed in the bend above the pump..so it was replaced

I am starting to think it was a combination of all of these things...

Thanks again!

Peanutfarmer101

'78 CJ-7..304 T400.. 30 up front, locked 20 in back(1 piece axles)..Quadratrac w/ parttime conversion..4" lift w/Currie greasable shackles..33" AT's on 15x12 alum wheels
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post #9 of 10 Old 07-28-2011, 10:53 PM
BagusJeep
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You can get bits of old rubber in the filters.

Good to hear it worked out.

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post #10 of 10 Old 07-29-2011, 02:29 AM
John Strenk
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Well just a collapsing fuel line before the pump could do all that.

The suction from the pump collapses the walls. cut's off fuel delivery. Wait a bit and the suction is gone so you can start it back up and drive a little then it collapses again and so on.

You probably were probably going to need a new fuel pump anyway so you didn't waste any money.


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