Engine overheated , now lights stay on when ignition switched off

[wiggs]

I came back from a 200 mile burn then got caught for 40 mins stationary / walking pace on my 87 fj in traffic in texas heat .I knew it was running hot so switched the motor off when I could, when I got home it was seriously overheating, opened the gas tank and gas almost bubbling. Switched off with key ignition , nothing ,  so had to use the kill switch. Engine shut down but headlight remained on . Thinking a relay / ignition barrel connector fused , shorted maybe with the heat - any ideas from members or similar occurrence

[Pat Conlon]

Crossing the Mojave my FJ has gotten so hot that the steel tank would scald my legs. I had to ride it like a bitch having a pelvic exam.

I never cooked an ignition switch but I can see it happening.  I can see the ignition coil cases cracking from heat. Tremendous heat build up under the tank.

Good news is that it sounds like your engine is still running. Check your valve clearances, then check the compression or better yet, do a leak down, make sure your valves and seats are not cooked.
Keep an eye out for oil smoke on start up, you may have cooked a valve stem seal or two or three...
FYI...RPM's Viton valve stem seals are superior to the oem seals: http://rpmracingca.com/proddetail.asp?prod=Head%3AVSS

Take the tank and fairing off...check everything for heat damage, wires, connectors, coils, fuel/vacuum lines, etc, etc.  

I've been known to slowly ride on the shoulder and split lanes, just to keep air flow moving across the engine.  I have no problem justifying it to a LEO.

Good luck, let us know what you find.  

Pat

[ribbert]

The most common cause of a carburettor engine running on when switched off after severe overheating is dieselling. Worth checking by starting and stopping the engine again once it's cooled, before you embark on a complete dismantle and rebuild. The headlight would normally stay on if you turned it off at the kill switch.

Noel

Pat, I know that feeling of the tank being hot enough to melt the skin off the inside of your thighs, makes you wonder why they don't spontaneously combust.

[wiggs]

Crossing the Mojave my FJ has gotten so hot that the steel tank would scald my legs. I had to ride it like a bitch having a pelvic exam.

I never cooked an ignition switch but I can see it happening.  I can see the ignition coil cases cracking from heat. Tremendous heat build up under the tank.

Good news is that it sounds like your engine is still running. Check your valve clearances, then check the compression or better yet, do a leak down, make sure your valves and seats are not cooked.
Keep an eye out for oil smoke on start up, you may have cooked a valve stem seal or two or three...
FYI...RPM's Viton valve stem seals are superior to the oem seals: http://rpmracingca.com/proddetail.asp?prod=Head%3AVSS

Take the tank and fairing off...check everything for heat damage, wires, connectors, coils, fuel/vacuum lines, etc, etc.  

I've been known to slowly ride on the shoulder and split lanes, just to keep air flow moving across the engine.  I have no problem justifying it to a LEO.

Good luck, let us know what you find.  

Pat

Thanks Pat, fortunately engine all good, valves , compression etc, I did notice my fuel cap not venting so removed the little flaps. Next job is removing the carbs and sending to rpm as I know I have idle jets blocked if balancing them does not help. Will then work on the mystery headlight , ignition switch and try tracing all wiring to see why It comes on as soon as I hook up the battery

[wiggs]

The most common cause of a carburettor engine running on when switched off after severe overheating is dieselling. Worth checking by starting and stopping the engine again once it's cooled, before you embark on a complete dismantle and rebuild. The headlight would normally stay on if you turned it off at the kill switch.

Noel

Pat, I know that feeling of the tank being hot enough to melt the skin off the inside of your thighs, makes you wonder why they don't spontaneously combust.

Thanks Noel, not actually engine run on , I just now have a defective ignition switch , it will not turn off the motor now so use the kill switch, but the headlight stays on so thinking wires or contacts fried somewhere?

[Pat Conlon]

.... so thinking wires or contacts fried somewhere?

Yep, you could try to disassemble and clean/repair your 30 year old switch or just spend $40 and get a new one

RPM has a couple of flavors, both plug and play with your '87:

Flat key:

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3Aflatkeyswitch

Tube key:

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3Aroundkeyswitch

[Alf]

Tube key:

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3Aroundkeyswitch
[/quote]

It would be fantastic the complete 3 lock set, ignition, seat & tank

[wiggs]

.... so thinking wires or contacts fried somewhere?

Yep, you could try to disassemble and clean/repair your 30 year old switch or just spend $40 and get a new one

RPM has a couple of flavors, both plug and play with your '87:

Brilliant - thank you

Flat key:

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3Aflatkeyswitch

Tube key:

http://rpmracingca.com/proddetail.asp?prod=M%2FC%3Aroundkeyswitch

[Pat Conlon]

I'm partial to the flat key switch. I like the dust shield, something that is missing on the tube key switch.

I've been meaning to take Randy's flat switch down to my locksmith and see if he can change the tumblers to match my tank and seat key.

It's on my list....