hesitation unknown

Apr 25, 2004 5 Replies
J

Good morning. Well, I posted here a few weeks ago with an unknown issue that I thought might be the transmission. It was diagnosed by those here and a tranny shop as other issues. At the recommendation of the shop, I replaced cap/rotor, I had just done plugs and wires and skipped those for now. At the advice of this group, I replaced the fuel filter, that seemed to have done the trick. Now my problem is back.



I'll describe it as I did before, at highway speeds only, I get a hesitation. It feels like all the power just drops out of the engine. I get no spike up or down in oil pressure, voltage, rpm or temp. I have no check engine lights flashing or staying on and no other idiot lights showing. What I feel is something like pulling a trailer with electric brakes that all of a sudden start pulsing. It only happens at highway speeds and typically only after 20-30 minutes of driving.



Any thoughts?? I did check the ground strap and see no rust/decay/fraying.



Thanks.


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M

A plugged up air filter on the gas tank vent will cause symptoms like that.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"JeffD." wrote:

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J

OK, that kind of makes some sense. Another issue, not described makes this seem even more likely. When I remove the cap to fill the tank, I often get a lengthy vapor pressure discharge. Where is the air filter for the vent hose?

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M

It is under the hood and is on the bottom of the charcoal canister. The canister looks like a coffee can with tubes out the top. It is a $2.00 filter and is a real pain to change. The canister doesn't come apart so the filter has to be dug out. The second one is easy though...

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's
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J

Must bang head against brick wall! Forgot to mention it's a 92 XJ, 4.0 FI HO. It appears that the evap canister is a single molded plastic unit, not the coffee can style. Next thoughts?

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M

I guess they didn't like it that we could just change the two buck filter eh.

I would be taking the tube off that goes from the canister to the air filter box and be seeing if I could blow or suck through it with the gas cap open.

On mine I check the filter by driving with the gas cap loose. If the hesitation goes away, bingo. Mine doesn't have a check engine light to go off though.

Mike

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