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PostPosted: Sat Sep 27, 2014 3:21 pm 
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Javelin

Joined: Sat Apr 06, 2013 10:51 am
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Location: Oshkosh, Wis.
Its the stock fuel pump from the donar jeep a 93 zj....i figure the pump check valve is leaking but it works fine otherwise. I do have the fuel filter in the engine bay tho i am sure that dont help any.

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1976 hornet sedan 258 with 4.0 fuel injection
1985 eagle sedan 4.0 with fuel injection
jeep 1997 grand cherokee

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PostPosted: Sat Sep 27, 2014 5:49 pm 
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Hornet
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Location: North Seattle sort of
ZJs are all electric pumps

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PostPosted: Sun Sep 28, 2014 5:27 am 
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Javelin

Joined: Sat Apr 06, 2013 10:51 am
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Location: Oshkosh, Wis.
Yes but i thought they still had a anti drain back valve on them. Or is the fuel just not supposed to be able to do that, cause it is.

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1976 hornet sedan 258 with 4.0 fuel injection
1985 eagle sedan 4.0 with fuel injection
jeep 1997 grand cherokee

http://s12.photobucket.com/user/amchornet/profile/


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PostPosted: Sun Sep 28, 2014 7:31 am 
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Hornet
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Location: North Seattle sort of
Sounds like the pick up line has a hole in it. That or you didn't set up the 3 second priming time like the factory did. It may be relying on the oil light to go out to make the ground go to the pump relay.

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PostPosted: Wed Feb 18, 2015 4:00 am 
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Javelin

Joined: Sat Apr 06, 2013 10:51 am
Posts: 240
Location: Oshkosh, Wis.
the pickup line is the steel tube pickup on the stock gas tank sendor. The fuel pump is running for the three seconds when I turn the key on. I put my fuel presh. gauge on it. When cold it primes and starts fine. Its when hot the pump still runs the 3 seconds but wont prime (charge) the line. It must have too much vapor pressure in the line for the pump to overcome in the 3 seconds. It also is running while cranking the engine over. What I have discovered is that when its hot I have to run the pump on my jumper switch a long time before it builds pressure. I mean like 15 seconds or so long. I believe its cause of the vapour lock condition under the hood with the fuel filter there. No fuel injection car I know of has the fuel filter under the hood,probably for that reason...maybe. Any ways it has no issues when starting cold so that leads me to the vapour lock thing. I have checked all the fuel lines over and haven’t found any wetness or leaks anywhere. I am sure there are other problems I havent found like the fuel pressure regulator. The pressure is correct when running but that doesnt mean its not bad and letting the gas leak back down. My priming switch is working great for now and she is running great so I will get to it...sometime. Once I get some $$$ I will buy some high presh. fuel line and mount the filter in a different place.

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1976 hornet sedan 258 with 4.0 fuel injection
1985 eagle sedan 4.0 with fuel injection
jeep 1997 grand cherokee

http://s12.photobucket.com/user/amchornet/profile/


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PostPosted: Wed Feb 18, 2015 3:44 pm 
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Hornet
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Location: North Seattle sort of
Do you have a return line to the tank? If you have the later system with no return, they have that problem in some Jeeps too when the fuel has a lot of alcohol. They are trying to pull the RFS (renewable fuel standard) to stop corn being turned into fuel and causing these kinds of issues. It lowers vapor lock temp to where even hot days can cause it.

If you have a return line, maybe you could just add a purge solenoid that drop the line pressure so fresh fuel flows in.

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