Fuel pressure question.

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09-20-2014, 05:32 AM

#31

frantic29

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Year: 1996

Model: Cherokee

Engine: 4.0

Well you guys stayed busy last night. Looked under this morning. No return line. Only lines I have is pump to the real then evap lines.

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09-20-2014, 08:13 AM

#32

cruiser54

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Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Sounds as if your fuel pump check valve is bad.

You can live with it by doing the "poor man's prime" in order to verify this, or forever if you like.

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09-20-2014, 09:22 AM

#33

frantic29

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Year: 1996

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Engine: 4.0

Poor man's prime works after abut 5 cycles. Is the fuel pump the only check valve?

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09-20-2014, 09:30 AM

#34

cruiser54

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Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by frantic29

Poor man's prime works after abut 5 cycles. Is the fuel pump the only check valve?

Not sure on that.

According to someone else, shouldn't need it...........

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09-20-2014, 11:00 AM

#35

frantic29

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Year: 1996

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Quote:

Originally Posted by cruiser54

Not sure on that.

According to someone else, shouldn't need it...........

If it didn't need it it wouldn't have it. Manufacturers don't spend money if they don't need to.

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09-20-2014, 03:55 PM

#36

DFlintstone

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Year: 90,84

Model: Cherokee

Engine: 4.0,2.5

Quote:

Originally Posted by frantic29

Poor man's prime works after abut 5 cycles.

Just for giggles, try leaving the fuel cap loose overnight and see. Maybe something to do with the Evap line is causing an unusual vacuum. Easy enough to try.

Bleed-down that eventually reaches zero has got to be normal. I suppose a good check valve will leave it still primed, where a bad check valve or some other factor may result in air, a loss of prime.