YJ cutting out

Hey, I know this is just a Jeep problem and not the anguished cry of a sick mind(or 3), but if I don't get it fixed, it might turn into one. :-(

'94 YJ, 4.0/5sp

Just started last weekend. After driving 40 or 50 miles all of a sudden engine refuses to rev above about 1500-2000rpm without cutting out. Idles fine, restarts no problem, and if you're in downtown traffic you never know there's a problem. Just running out on the open road. Last night it started acting up on our way to a concert, didn't have time to mess with it, so called one of my kids who lives on our route and switched out cars. Later on, when I picked the Jeep back up(4 hours later, maybe)it ran fine most of the way home...until it hit about 45 miles from startup. No check engine light, plugs/wires/cap/rotor/air and fuel filters changed about 2 months ago(maintenance, not chasing any problems at that time). I changed the fuel filter again last weekend when this cropped up, because it sorta felt like low fuel pressure. Went out this morning and cleaned/inspected connectors for the crank sensor, cam sensor, IAC, and TPS. Haven't driven it the required mileage yet, so I won't know if it's fixed yet, but was fishing for any ideas I might have missed. I'm thinking maybe fuel pump(maybe 3-4 years old), or coil(OEM, I'm sure). Don't have my fuel pressure gauge at home, but I'm planning in checking that probably Monday night. Coil ohmed out good this morning, but then again it's not acting up right now.

-- Old Crow '82 FLTC(P) 'Mistress Pearl' '87 FLTC 'Crosseyed Mary' '61 F-100 BS#133, SENS, TOMKAT, SLOB#13, MAMBM

Reply to
Old Crow
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thinking maybe fuel pump(maybe 3-4 years old), or

A weak coil can definatly do what your describing. Go grab one of these and check out how much spark it's throwing. Fairly cheap and they save a lot of head scratching.

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If you have a low-side R-12 gauge, they will fit the pressure port on the fuel rail. (If you have a port on the rail that is)

Reply to
DougW

A blocked gas tank vent air filter will cause symptoms like that. Easy test, just crack open the gas cap and see what happens.

I even had an air filter cause that when the PCV system decided to mess up and a mess of oil puked into the air filter blocking the flow. The

4.0 CCV can have fits and do this too because of a blocked back grommet or plastic pipe.

Mike

2000 Cherokee Sport 86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail > Hey, I know this is just a Jeep problem and not the anguished cry of a
Reply to
Mike Romain

Since you haven't mentioned it, have you checked the MAP sensor? The "runs fine the next day" and "acts up after 40 miles" would be typical of one starting to go, but the other symptoms are usually different.

Reply to
J. Clarke

Yup, got the a/c gauge...in the same drawer in the tool box at work as the fuel pressure gauge. Spark tester's a few drawers up :-( Drove it 45 miles today, but with several stops, one of which was a couple of hours. Didn't miss a lick, so I'm sayin' I probably didn't drive it far enough.

Reply to
Old Crow

Checked the vac line to it, and cleaned the connections, just forgot to list it

Reply to
Old Crow

I'll remember that for the next time it acts up. Had it happen several times on the bike over the years, you'd think I'd have thought of it.

All the vac plumbing is in good shape, but I didn't check it for blockage. I pulled the air filter out and blew it out...no sign of blow-by in the air box.

Reply to
Old Crow

My MJ started that crap one night. I basically got home at just above idle - finally. It pulled fine at idle to about 1100 RPM then did just what you describe. After testing everything else, I finally noticed that the CPS cable was sitting awfully close to the exhaust. Sure enough, I had forgotten to tie it back and it had melted thru against the exhaust and was shorting to the manifold. Gave new meaning to "limp home mode".

Reply to
Will Honea

Hmm, I took the connector apart and cleaned it, didn't think to check the wire below the intake. Thanks.

Reply to
Old Crow

that sounds like a fuel pump problem?. I had the same problem with a zj I had.

did you check the pump filter? there might be a lot of crap in your tank that gets sucked against the filter and that can cause the pressure to drop (and ruin your pump)

I drove around with a hesitating fuel pump. After a while it started 'failing' and not run at all. When I 'whacked' the fueltank with a rubber hammer a few times the problem went away for a short while.

When you have that pressure problem again give the gas tank a good 'whack' and see if the problem (temporarily) goes away. If that's the case you might have a pump that's failing. (Usually fuel pumps work or don't , but sometimes they slowly fail). The computer in that zj I had didn't register the failing pump either.

Reply to
csdude

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