Mixture control solenoid

[Project86]

Any ideas as to what would cause my mixture control solenoid to get hot enough to catch fire? When I unplugged it there was gas in the connector, not sure if the gas was what caused the fire or the fire caused the gas to leak in. This is the OEM carb from my 86 C10. I feel like I got pretty lucky that it stopped smoldering when I shut the truck off and I was only a few feet from my house!

[bd]

Only a guess - poor connection between the internal winding and terminal or more likely a shorted winding.  I wonder if enriched fuel attacked the enamel on the wire. 

You are lucky!  The liquid fuel probably cooled it as it evaporated.  Any hotter and it might have ignited.  Interesting that it didn't blow the ECM fuse....

[454Man]

Ethanol! Jjk X2 loose connection. Or bad a solenoid

What's under the hood??? If you have to ask maybe we shouldn't race!

[rich weyand]

Normally for a coil to burn up, part of the coil has to be shorted.  If the coil is shorted, for example, so that only half of the coil is across the leads, it will draw twice the current, which is four times the heat.  If the coil is shorted so only one quarter of the coil is in circuit, it will draw four times the current, which is sixteen time the heat.

Why did it short?  The coil wires are typically insulated with varnish, which ages and gets brittle.  Heat cycling and vibration do the rest.  Is this coil original?  That would make it 27-28 years old. 

[Project86]

  Is this coil original? 

The carb has been rebuilt, was done by someone else, so I assumed that the solenoid had been replaced at that time but I don't know that for a fact. I've installed a different carb, I just want to make sure I don't have something going on that would cause this issue to happen again but it sounds like the issue was most likely with the old carb itself.

Thanks for the info and thoughts.

[VileZambonie]

Do you need to run this carburetor or do you have required visual emissions inspections? If not I would throw that thing in the garbage can. Which model carburetor is it? Looks like the dual capacity pump solenoid.

http://forum.73-87chevytrucks.com/smforum/index.php?topic=11916.0

[Project86]

Unfortunately I do have to meet a visual emissions inspection. It's the M4MED. Any thoughts as to a suitable replacement?

[VileZambonie]

http://www.carburetion.com/CarbNumber.asp?Number=17087125

[mcintyrederek]

I have the same exact carb on my '85 Monte Carlo and it did the same thing.  The plug that goes into this has a green boot on it, but if someone washed the engine and got water into it, it probably turned into a green/blue corroded connection. 

I agree with the former post, disconnect the wiring altogether and replace it with the same Qjet, just one that doesn't have electric mixture controls.  Running that carb with no wiring hooked to it will cause it to run fully rich.