Today I discovered the solenoid valve on the carb bowl vent line was hot - too hot to touch for more than a couple of seconds.
This was after only about 2 minutes running.
I disconnected the power to it but I'm wondering if the fault is likely to be in the solenoid itself or with the system operating it? This is all EEC-III.

A couple of questions - how does this valve operate in conjunction with the purge valve (also electric) & check valve?
And now that it's disconnected, what state is the whole system at - ie venting to the canister but not sucking back? Or sucking from the canister but not venting to it etc?

Thanks for any help

 

Solenoid coils usually overheat when the metal core inside is stuck and does not slide up inside the coils when voltage is applied.

Most of these bowel vent valves are closed with the engine running, and open with the engine off, to vent fuel vapor from the carb bowel to the canister. I have had problems disconnecting these before(you know the old "want to get rid of emissions stuff" syndrome). I found if I took a short piece of hose with a bolt in it to block the vent off on the carb, it would be hard to start in hot summer weather. It looks like they still have a vent inside the air cleaner still, but apparently that's not good enough. So then I took the hose off and left the nipple on the carb open. That worked fine until you hit the brakes hard, and sometimes fuel would slosh out the port.

 

Thanks Dave

I'll run without it operating short-term & see if there are any problems as a result. I don't think there should be as long as it stuck open. The check valve should still let the purge valve vent the canister OK.

If there are problems, I'll get a replacement solenoid, they're not cheap - about $60.

Eventually it's all going to go, for a few different reasons.

 

I was ordering a few other parts for the truck, so I got a new solenoid too - $47 at RockAuto. I fitted it yesterday but it's operating at the same high temp as the original.

Now I'm wondering if this is normal? Or, if not, what voltage the solenoid should be getting supplied?

Thanks anyone

 

Should be 12v. I don't have any first hand experience on how hot they are when operating.

 

Some of those solenoid's will run hot, have burnt many fingers touching them! As long as you can hear a clunk from it when power is switched and the solenoid doesn't appear to be burnt up looking, its probly normal operation.

You can try installing a ignition ballast resistor in line with the solenoid to lower the current levels and make the solenoid run cooler, but make sure the ECU don't mind the extra resistance you installed. It could set codes depending on application.

 

Thanks Dave, Eddie

I'll check the voltage & go from there - maybe there's not any problem

 

Well, the power supply to this solenoid (& all the other emissions solenoids - thermactor,egr etc) is at 14.3v.
Does this seem right? I haven't been able to find any sure specs on what it should be.

 

The 14.3 volts is the voltage output of the ALT, so I would say that would be the only choice for voltage unless the EEC has its own voltage regulator.

The real question is how hot is too hot??
Will it burn it self up or shorten the life, that is the really question. Look on the bright side, you can use the old one for a spare part if it fails.