After the issues I had with my intake manifold at the bash I thought it might be a good idea to take the carb off and clean it - which I did.

I put the carb back on and as soon as I started it up, the high temp engine light came on. The temp light is faint - not full brightness and it seems to flicker just a little. The engine does seem to be running a little hot - that could be just me. I also noticed the radiator fans did not kick on. I'm afraid to drive it for fear of causing damage.

Here's what I've done so far:
1) Checked coolant and oil level - they are fine
2) Checked electrical connections to engine temp sensor
3) Triple checked hoses coming in and out of carb
4) Checked to see that there was coolant flowing into and out of the carb bypass to the engine temp sensor

I've tried everything I can think of - any suggestions?

Man... This has to be a problem with the sensor or the connections. I believe (I may be wrong) that it's a ground activated sensor. Have you traced that wire to see if it's making a ground somewhere along the way to the sensor and that's tripping your temp light?

I would wire the fans so they will come on when the ignition is on, most 250 have to idle a while and burp. I would get a meat thermometer and put in the rad where the cap goes, let it idle and see how high it gets

Thanks for the suggestions guys - I'll dig a little deeper in the electronics to make sure I didn't loosen a connection when I was working on the carb. I'll also see if I can sneak the meat thermometer out of the kitchen without the wife knowing

If it comes on right when you started it, it's most likely in the electrical connections. When I installed the 32mm pumper carb, I had to change the wiring around and everytime I had it wrong, that damn sensor would go off.

I'll work on it tonight - I hate electrical problems!

The thing that gets me, if the senor is saying the engine is hot, why aren't the fans kicking on?

Chuck and Eric, is there any downside to having the fans run all the time? Could they drain the battery?

Those are two different sensors, at least on my machine. The one that triggers the fans is located on the radiator. The sensor that triggers the dash is in a different location, I believe near the carb or water pump. Does yours have a buzzer? Mine does and it's annoying as he77.

They are two different sending units on my buggy. One down by the radiator that actually triggers the fans and one up by the head that triggers the warning light. That's why I'd look at the sensor first... It's improbably that the motor is getting hot right right away and for both sensors to pinch a loaf at the same time.

I'm sure there isn't much down side to running the fans all the time other than wear and tear... I'm new to this but my fan only kicks on every once in a while and doesn't stay on long.

So with two sensor one on radiator that would control the fans and one on the head that is tied to the dash sensor, something must be going on in the cooling system to trigger the sensor on the head. Like I said, the engine seems to be getting very hot, very quickly.

I wonder if I have something mechanically or electrically going on with the coolant to the engine? Water pump?

If there isn't coolant flowing to the engine that would explain a few things.

check the wire harnes for shorts, we had a couple in the shop that the buzzer and nlight would come on as soon as the key was turned.

we fould a couple of wires in the harnes has been rubbing and rubbed al the insulation off.

Have you drained and refilled your cooling system just before this happened? The last time I drained and refilled some coolant from the system, I introduced air in the system which resulted in an 'air lock'. This caused my engine temp light and buzzer to go off very quickly. To fix it, you will need to run your engine for a little while with the radiator cap off to 'burp' the cooling system. You should notice after a while the coolant level in the radiator drop somewhat, then you just top it up to full and you should be good to go. All this is, of course, assuming that an air lock is your problem.

If you problem is electrical, it sounds to me that you may have a short to ground on your temp sensor wire (the one that is in your thermostat housing straight off the head) or the sensor itself has shorted out. Your overtemp light usually will turn on when the resistance of the sensor gets low enough (as it gets hotter) to make an electrical circuit to ground thus bringing on the light and/or buzzer. Remove the wire on the sensor, and check for any short to ground. Also, while you have the sensor disconnected, check for a short to ground from the terminal on the sensor. You shouldn't have any unless your engine IS really hot.

If I'm reading your post right, your temp warning light is coming on right away... like immediately. It is simply impossible for the engine to heat up this fast, even if you had no coolant in the system. Even if you had no oil in it, no coolant and it was 100 degrees outside, it is not possible to have the motor heat up that quickly. You'd have to be on the surface of the sun. Now, if you are starting it up and it comes on in a minute or so, then I'd did into the coolant flow. Plus, that would trigger your fan sensor and they would fire up.

The way this is being described, its something in your temp sensor. Like I said before, that is where you should be looking. If you take the wire off your sensor and ran a ground to it, it would make your temp light come on. That tells me that you have an ground to that wire some where along the wiring or your sensor itself is junk.

Start with your fans, if you like. Take the two wires off the sensor in your radiator, turn the ignition on and touch the two wire together. If you're fan(s) kicks on, you are golden there. It takes 30 seconds and you can feel good knowing that the fan is operational. Then, trace your wire for you temp sensor and see if you can find any pinches, nicks, etc...

Something in that sensor isn't right. Let us know what you find out.

Update:

I checked the electrical connections all the way into the electrical box, took the engine temp sensor out (coolant flowed out) and I made sure there was coolant flowing out of the engine discharge hose. Everything seemed to be working as it should so I took it for short spin on Saturday.

The engine temp light was very dim when I started in the shop, almost invisible when I got into the sunlight.

Everything was working fine, no weird noises, performance was normal. At this point I'm thinking the light was defective. Then about 10 minutes into the drive, a couple hundred feet from the house, the engine temp light came on full brightness and the audible temp alarm went off so I nursed it back to the shop.

I parked it and haven't worked on it since. When the weather cools off later this week I'll give it another once over. I could use some cooling off time too. This stuff can drive you crazy,and for me that's a short drive.

Thanks for all the suggestions guys - I'll keep at it.

Disconnect the wire from the sensor on the engine. If the alarm goes away, measure the resistance of the sensor contact to ground. Unless your engine is hot and overheating, this measurement should be showing open. If it does not, the temp sensor failed.

If the alarm is still sounding with the sensor wire disconnected, you have a short in your wiring and will have have to follow the wires back to the console to find the problem.

If you give up, load that buggy up and bring it to Seattle (less than 2000 miles from KC). Take a vacation with your family and I will have it fixed for you before you leave.

I understand completely. My little bro bought the same buggy I did. He had a problem where the lights were dimming when he gave it throttle. We ran through the wiring. Come to find out, it was a tiny, tiny, tiny split in the wiring back at the tail light and it was messing up the works. It's nerve racking for sure. And... if all else fails, Seattle is a beautiful town

We drove through Ogden on the 2nd and 3rd, but rain and thunder storms discouraged us from staying longer. I almost thought I made a wrong turn and was in Miami - Lack of good Cuban food made me realize we were going the right direction.

Thanks Peter - you may be 2000 miles away but you gave me a few ideas and some needed motivation to look at the buggy again - but I still may take you upon on the invitation to visit (the wife worked near Moses Lake a few years back and really liked it).

Anyway back to the buggy -
Took the buggy out again, for about 10 minutes. Temp here is 80 deg with about 70% humidity (thick). Again all was well, fans were running on radiator - then the engine temp alarm went off. Took off the wire for the engine sensor and the alarm stopped.

At this point I noticed steam coming from around the radiator cap - so the engine is genuinely overheating.

Sooooooo, the issue is most likely not electrical. But if I have coolant going in and out of the engine and the engine is still overheating - hmmm. Could there be a valve somewhere that is stuck?

I did take the jet from a 132.5 to a 130 when I had the carb off - that wouldn't cause the engine to overheat would it?

And nothing else has been done to the buggy other than carb work, right? It was running fine prior to that? That amount of difference in the jetting should not make a a motor heat up to that extreme. These things run hot before the fans kick on. The fans don't stay on that long to cool it down....

Maybe something in the thermostate housing blocking the coolant flow? Did you pull the spark plug? How does it look? Can you tell if it's running lean? Still shouldn't make the motor heat up like that. It has to be something in manifold area if carb work was done. I'd pull the sensor and the thermostat housing. Make sure it's clear. Drain an refill with coolant... I think you need to go back to basics. Sounds like no coolant flow. Only so many places it could get a block...

Bomoco - see attached for picture of the spark plug.

Buggy was running fine at the bash a few weeks ago. I did have trouble with the rubber intake manifold from carb cracking so I replaced that. But otherwise I haven't done any work to it.

I think the next step will be to drain the cooling system and see if I can flush it - maybe dislodge any possible obstruction.

Make sure the impeller in the pump is really moving coolant. I'm having a hard time believing the engine can get so hot in 10 minutes...