I have an 87 b2600and I just replaced the ignition switch, fuel filter, fuel pump, and starter. The truck sat for 3-4 months after running well. I went to start it after replacing the starter and the engine reved and died abruptly. One fuel filter and ignition switch later it still won't start. I chased the fuel line to the carb (brand new) and it's got plenty of gas coming out. the exact symptom is that I turn the key, it revs as long as I have the key turned, then dies abruptly. No amount of starter spray or anything will keep the engine running after the key is turned back. Help Please

 

 

Mazda did not have an engine ready for that truck so they bought the engine/etc from Mitsubishi. They bought alot of them back and crushed them. Except for the engine and controls it was a sound truck but the carb was junk. Plastic carb bowl and so many switchs and controls to set it made you dizzy. Not many techs nowadays will tackle those carbs they sucked so bad.
That said it sounds like a classic ignition switch problem but you can turn the key to on and check for 12 volts at the coil to be sure. If you have 12 volts in the on position try spraying carb spray into the carb and see if it starts. The carb may be gummed up and not delivering fuel to the intake. A jet may have plugged with varnish. If you can get it going it may come out of it if so. I think i would recheck the ignition switch anyway especially if you had a starter problem after you replaced it. It could have damaged it. Check those things and see what happens.

 

Oh yea. If your truck still has it take the resistor off the coil and chunk it. Just hook that wire straight back to the coil that the resistor was on. They go bad. Its just a noise suppressor.

 

It seemed to me to be an ignition switch problem too, but then, just last night, I replaced the whole assembly. Maybe we're talking about 2 different things, I mean the wires coming from under the dash, in a bundle, and coming in on the other side of where the key goes in. Those wires and the insert into the housing where the key is is all new. and what is the resister off the coil? Thanx for your help

 

In the top left corner of the wiring diagram there is a resistor between the ignition switch and coil. It is located at the coil, just chunk it and hook that wire straight to the coil.

 

How do I unplug or ungum the carborator and jets?

 

Did it start with carb spray down the throat of the carb? There is no surefire way to unclog jets but sometimes you can get it running with carb spray and it will dislodge. Otherwise it will require disasembly.

 

It seems like the pistons are getting fuel because when I crank it, it revs. It's feels and sounds like there is no problem but then it dies as soon as the key is in on.

 

Do you have a 12 volt test light? Check for 12 volts at the coil with the key on. Also did you find the resistor?