86 TOYOTA VAN NO START WHEN COLD/WET

Some comments and questions before ideas:

Please turn off caps lock and observe netiquette

How many miles is "quite a few?"

When you say replaced "usual tune up parts" what exactly was replaced and how many miles ago?

What brand tune-up parts did you use?

How did you check the fuel?

When it is rainy or cold and the engine cranks but won't start, is it hard starting whether the engine is warmed up or cold?

There are several things that can cause the difficult starting but the answers to those questions will help narrow down the possibilities.

Well Ray..has 112,000 miles..replaced plugs (ngk) cap and rotor, fuel filter,air filter,(aftermarket)checked fuel at cold start injector fitting for pressure,starts easily and runs fine when dry or warm. when cold or rainy..cranks and ocassionally will fire but not run. Had problem before parts were replaced.Just started doing this one day!I have introduced fuel through pcv hose..and checked spark with old plug with increased gap and looks good. I am a mechanic so I am not guessing.I feel it is electrical? Thanks!

Change out the plug wires with a new set of Toyota OEMs.

I drove a 88 work truck that always ran and started fine unless it rained over night. If it rained then the next morning it would never start. The problem it had was the moisture at distributor wiring connector. By just unplugging it and plugging it back in the truck would then start right up after that. I drove it for at least a year like that.

Maybe if your lucky jiggling the wiring when its refusing to start will turn up something like that as well.

GL Dan

Since the problem only occurs in wet conditions, I'd guess an electrical problem as well.

I have seen some aftermarket distributor caps cause running problems in wet conditions, you can check it out by pulling the cap and seeing if there is any moisture in there and making sure the O-ring seals well. In those cases where there were drivability or starting problems, there was still spark.

Also check the electrical connections for the cold start injector and coolant temp sender to make sure there is no moisture in there.

Different subject, the bolt that holds the lower crankshaft pulley used to work loose on some of those vans, so next time you're underneath, you might want to check it out.

Usual tune-up parts? Please specify. Consider a bad coil arcing in humidity. Your symptoms indicate an ignition problem.