RomeoReject

Howdy everyone. Was wondering if anyone could make an educated guess in to how much trouble I'm in after a small engine fire, financially speaking.

My 1991 K2500 (TBI 454) had a very slight engine fire earlier this week. It was already at the side of the road with the hood popped (The MAP had been giving me trouble already, as it was puking black out the tail pipes). I had parts on order, but was still hoping to have it run in the mean time. Anyways, after a few tries with it dead on the side of the road, I noticed a small flicker inside my K&N (Thank god I had that on, or I'd have never noticed). I immediately rushed out and started unbolting the filter (In my defense, it was expensive). After doing that, I ran inside, nabbed a fire extinguisher, and shot the TBI.

It was the only thing that had been on fire, and the heat wasn't enough to melt any wires around the TBI, nor melt the vacuum lines attatched to the TBI. Heck, even the filter that had the flames lashing directly at it is completely undamaged (The element, anyways; The steel cage underneath has a blue tinge in the one spot). However, I know that pistons can melt from just being leaned out - let alone from having them suck in fire (As the engine was running when it first happen). There's also the fact that the system had been dumping in gratuitous amounts of fuel before - which would be inside, past where I could get with a fire entinguisher (Although the fire never restarted, which one would expect if there was a fire burning in a cylinder with the intake valve open, or if the intake manifold had a fire within).

Anyways, I have a brand new TBI here (And before anyone says it - I would love to switch it over to a carb, but regulations here forbid that, and they're very strict about it). Beyond that, none of the other sensors appear to have been damaged (Such as the MAP, despite it's proximity to the flame). However, would anyone know how much damage such a situation could wreak on internals? It's a fairly old motor (350000KM), but was a great little runner. I'd hate to let it go, but if the rotating assembly is likely damaged, I'll just get rid of the truck, rather than waste time ripping it apart.

Any help would be greatly appreciated, thanks!

OLD WRENCH

Dont worry about fire doing any damage internally. Just think when a piston fires there is way more fire and heat than could be done by an external fire. I have done fire jobs where all the wiring and hoses were burned off,and no damage was done inside.

RomeoReject

Oh good, thank you! That is a relief to hear. I had thought that too, but then again, I thought if might also be comparable to a pre-ignition situation (As the flame is being pulled in, then compressed). Glad to hear it should be salvagable though.

Thanks again!

RomeoReject

Ok, not to keep pestering you, but I have the TBI installed, and now a new issue (Or two) have sprung up:

For one, the vehicle wont maintain an idle. Keeping it at part throttle causes it to run as normal, although a slight "popping" can be heard, almost as if it's predetonating, but not severely enough to cause knock.

The second issue is that it appears to be shooting white smoke out the pipe now, which is usually indicative of a head gasket failure. However, given that there's coolant passages through the intake manifold, and there was presumably fire damage within the intake manifold, I was wondering if that's a more likely option.



Again, sorry to keep leeching information, but I appreciate the help!

OLD WRENCH

I beleive you are thinking right. White smoke is an indicater of coolant leaking in to the comb chamber. Bad idleing can be caused by a vac leak (among other things). Can you get it scanned for error codes?

kevinkpk

Sounds like head gasket to me, can you do a compression check?

RomeoReject

I'm still on an apprentice's budget, don't have the cash for a compression checker. As for an update, the white smoke seems to be gone (I suppose some could've spilled in to the intake when I took the first TBI off?). But the truck still idles poorly enough that it occasionally stalls, still hesitates with more and more throttle applied and these symptoms get worse the longer the vehicle has been driven (As in, the vehicle will hesitate less after two minutes, than with ten).

I had almost thought perhaps the fuel pump was getting ready to pack it in, but then it would have no problem at idle, as it isn't really a big demand for fuel. Vacuum leaks would explain the idle, but then would have less, if any, effect under load. Same goes for a faulty IAC, or maladjusted idle set screw.

Gah... Help! lol

kevinkpk

Ok, white smoke has "gone away", but going from there. If you suspect vacuum leak, I'd suggest with WD-40 "hit" (slight spray) vacuum connections, if the engine speeds up, you got a leak. If you have access to a vacuum guage check what it is at idle, 454 700.... rpms, minimum 20-21 inches mg. The white smoke leads me to think, what else was done prior to your problem.

RomeoReject

Well, the truck is out at the moment, but when it gets back, I'll shoot it with some WD-40. I know that there's one port for the EVAP canister I have wrapped and taped, so perhaps that isn't tight enough. There also some port on the front of the throttle body which I have still never figured out what it does, but also doesn't seem to draw any vacuum...

Sorry to ramble, will let you know when the truck gets back.

1993318

Sounds to me like the Idle Air Control motor, or the Throttle Position Sensor if its running erratically, stumbling, or hesitating. They are a couple sensors close to the proximity of the fire as well!