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Cat Fire!

So here it is, I bought a 1991 Ford F-250 with 100k miles on it. It has the big block 460 with an E4OD transmission. I drove it from Idaho all the way to Amarillo with no problems. I filled up in Amarillo and when I started the truck again I noticed it took longer to start and when it did finally start it idled very rough. I drove it and it ran smoothly under a load so I continued towards Houston. Around Dallas it started to surge and hesitate at 65mph. But I was close to home so I continued. Near Houston I heard the power steering pump begin to whine from being low on fluid so I stopped to fill it up (had some power steering fluid on me) and left the truck idling b/c I wasn’t sure it would start back up. While idling it began to idle really roughly! I then noticed smoke coming from the mid part of the truck and looked under and to my surprise I saw the catalytic converter on fire!!! I shut the truck off and the fire went out in about 15 seconds. I towed it home and haven’t looked at it yet. Is this a fuel injector problem possibly? Any help would be greatly appreciated!!

No…it’s a catalytic converter problem. The cat has started to come apart inside and is blocking your exhaust. When this happens the converter gets so hot it will start to burn. This is actually a common problem. A new catalytic converter will make your truck run great again.

Might be a problem too with the engine running overly rich or having an occasional miss or poor ignition on a cylinder or two—this will cause unburnt gas to load up in the catalytic converter and burn there, causing it to overheat.

This truck should be a TFI ignition model version and it could be that the ignition module is failing. The symptoms for this are many and varied and anytime an engine performance problem exists the module is always suspect.

Maybe the poor running caused by the module is overheating the converter. One of the symptoms of a failing module may be rich running.

Do a net search about the Ford and the TFI-IV module problems and you will see what I mean.

I failed to mention that the check engine light is not on and had not come on during all this. It comes on when the key is turned on but goes off when the truck is started.

Another thing that can cause this is a leaking fuel pressure regulator. If the diaphram in regulator has a leak, gas can be pulled into the intake via the vacuum hose. The excess fuel that isn’t burned off goes out the exhaust into cat where it lights off and burns.

The Check Engine light won’t come in your vehicle if there’s a problem with the cat. Your vehicle has the OBDI engine management system. And OBDI doesn’t monitor cat performance.

Tester

Thanks for the info!