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Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 13661
Experience:  Jeep Certified Master Tech
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1990 Jeep Cherokee: 4WD, 4.0 litre, 6 cyl..It turns and cranks

Resolved Question:

I own a 1990 Jeep Cherokee, 4WD, 4.0 Litre, 6 Cyl.. A week ago I began experiencing a problem when starting the car. It turns and cranks but does not start for 15-20 seconds. It used to start instantly. Once it does start, if I turn it off and try it again immediately, it will start right away. If it sits a while, forget it, same problem.
Shortly after this issue, the car experienced a marked loss of power. Giving it gas had no effect. It drives and gradually will build power and speed, but if I try to accelerate I have to push the pedal to the floor and it kind of "nosedives" It's like it wants to go but it can't?
$$$$$$ later this is the list of items my mechanic changed on the car: Air filter, pressure regulator, fuel filter, idle air control valve, fuel lines cleaned out, new spark plugs, timing chain guide (he said a guide was off so they fixed that and adjusted the timing) He said the timing chain was okay.
They did NOT change cap and rotor OR fuel pump. Drove it home and all problems remain? My mechanic said bring it back to him. Can you help?
Submitted: 6 years ago.
Category: Jeep
Expert:  Chris replied 6 years ago.

Hello and welcome to just answer. The problem is a leaking check valve in the fuel pump. I have seen this before on these Jeeps. If the vehicle sits for a while then the fuel in the fuel rail and lines drains back into the fuel tank because of this leaking check valve. Then the long crank happens because now the fuel lines have to be primed with fuel again. Replacing the fuel pump will solve your problem.

I hope this information helps, and please let me know if you need more assistance with this.



Customer: replied 6 years ago. did not address the power issue? Will the new fuel pump fix that too? Cecelia
Expert:  Chris replied 6 years ago.
Probably. But there may be something else happening. The way you are describing the lack of power makes me lean towards the pump. If the pump's volume is inadequate, then the fuel mixture will lean out too much when you depress on the throttle which will cause this loss of power. You need to change the pump for the hard starting problem, so get that done. I really think it will solve your power problem.
Customer: replied 6 years ago.

Chris....I appreciate the suggestion to replace the fuel pump. I will have that done and hope it takes care of the power issue as well. (And I will check Accept Answer, no problem.)

However, you mention the power issue. Could you possible direct me as to what you mean by ".......but there may be something else happening." (A suggestion, in the event I need one, would be helpful.

Thank you Cecelia

p.s. Would you like to know the outcome when I have one?

Expert:  Chris replied 6 years ago.

Well what I mean is maybe a failing crankshaft position sensor, but usually when that happens the engine will not start at all. Another thing it could be is a lazy oxygen sensor so keep that in mind.



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