rear end hissing

Roll-over · May 15, 2005

I'm having some fun w/ this one... The jeep is a '90 xj 4.0 5-speed 4x4. The problem is when i start the engine there it a loud hiss coming from the rear end. It sounds just like a leaking air hose or punctured tire. the jeep is basically stock with about 3-4 inches of lift, so there's no OBA or vacuum back there. Has anyone dealt with this before?

Rev Den · May 15, 2005

Exhaust restriction?

Rev

Yucca-Man · May 15, 2005

Fuel pump? If you turn the key to 'on' but not 'start' you should hear the fuel pump pressurize the lines. Once you do that, start the engine and see if the noise still occurs.

Roll-over · May 15, 2005

that's possible as the muffler is dented, but the hiss i slightly louder on the driver's side.

Roll-over · May 15, 2005

Yucca-Man said:
Fuel pump?

When I turn the key to "run" I can hear the pump wind up but it's more of a whir, not a hiss... Though it does lead me to wonder if once the rail heats up, that pressurizes the tank and I have a pinhole somewhere. Would that be possible?

Matthew Currie · May 16, 2005

Roll-over said:
When I turn the key to "run" I can hear the pump wind up but it's more of a whir, not a hiss... Though it does lead me to wonder if once the rail heats up, that pressurizes the tank and I have a pinhole somewhere. Would that be possible?

Quite possible, also possible though rare that a clogged charcoal canister is preventing it from venting. Easy to check: just take the gas cap off and see if it goes away.

luvdaxj · May 16, 2005

Do you have the stock air filter? I have a Rock It Air Tube with K&N Air filter and it makes a hiss.

JaysXJ · May 16, 2005

luvdaxj said:
Do you have the stock air filter? I have a Rock It Air Tube with K&N Air filter and it makes a hiss.

Your air filter is in your rear end. Funny, mines in the engine bay, up front...

What Rd · May 16, 2005

My fuel pump has hissed ever since it was new. People regularly ask me if I have a leak or something, but it's just the fuel pump. Hasn't posed a problem in 237,000 miles.

xjrugger · May 16, 2005

my fuel pump on my 88 does the same exact thing you are describing, again, hasn't given a problem.

Kreutz · May 16, 2005

My new fuel pump does the same thing. My old one wasn't quite loud as the new is, but it did hiss.

rear end hissing

Roll-over

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Rev Den

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Yucca-Man

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Roll-over

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Roll-over

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Matthew Currie

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luvdaxj

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JaysXJ

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What Rd

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Kreutz

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