Rjjk45

Hello --

Hope we can solve this problem.

I have a 1989 Jeep Laredo...6 cyl, 4.0 liter. Old but I love it.

Recently, have had trouble starting after I take it out to store and then come back to drive it again.

On 2 occassions, the car was running at 40MPH and completley shut down...no RPM

Last time it happened, it back fired and flames came out of exhaust pipe.

When I got to side of the road, there was a fire under the car...above muffler...burning the under coating and hot enough to get carpet to smolder. Fire went out. Ever heard that hppen before?

Cat converter is relativley new...20K

Local mechnic tested the O2 sensor and said it is suppose to range 0.1 to 1.0 volts but was reading 2.5 volts and I was told that sensor was calling for more fuel. Does that make sense given that high reading?

Does this car have an Check Engine Alert when something like O2 sensor fails and/or it gets hot like that.

Was lucky this didn't go up in flames, I guess.

Any input from the forum welcomed.....rich (Coloado)

BigBear

I was going to say maybe EGR but then you lost me with the fire happening.

Off subject, how have you been on since 2009 but only have three posts? LOL

Do you post once a year?

ktmracer419

High exhaust temps usually mean its running lean. I had my header and downpipe glow red after long hills, wheeling, driving under a load, or high rpms. My carpet would smolder above the cat and muffler. Never had flames make it through the entire exhaust system, nor a backfire or stall however but if thats your issue any number of things could cause this. My particular instance was a weak spark caused by a weak coil.

cruiser54

Are the guts of the old converter clogging the muffler? Here's a test for clogged exhaust:

CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.