1992 Truck 3.0 not firing when hot.

I have an old 1992 4x4 truck, 3.0. My problem, I drive around for 15 minutes, park the truck, come back out in 35 to 40 minutes and it will crank but not fire. Now, I let it sit for an hour and it will fire right up. No problems when the engine is cool. I have changed the fuel pump and filter and the EIF relay (fuse). It has 270-K miles. I can’t keep throwing parts at this truck it is in excellent condition. The Toytoa dealer suggested replacing the COR (circuit opening relay). Any ideas out there? Naturally, if I drive the car to a dealer or mechanic, it will start just fine. I made a test; took a good themometer and placed it under the hood. Drove around for 15-20 minutes, pulled into my garage, open the hood and it was 112 degrees. I waited 35 minutes then went out, truck would crank and not fire again, opened the hood, and now it was 132 degrees. I had no idea it would get that hot sitting after being driven.
Paul, Green Valley, AZ

 

This seems to be a common thing with Toyota V6 engines. My 3.4 will do similar things. It will start but if it sits after running for a while it will either be an extended crank or it won't turn over on the first try. Have you checked the coolant temp sensor? Or the crank shaft postition senor? That was what was suggested to me. As for getting hot after not being driven: there isn't any air flow anymore with the truck not moving and the fan doing nothing as well. Add to that your coolant no longer flowing and you get a hotter under hood temp when it sits for the first while.

 

Fuel injectors are leaking. Creating a flooded combustion chamber.

 

That would explain all the symptoms. Didn't even think of that.

 

Yep, the flooded engine condition evaporates over night, so the truck starts normal.

 

Actually, the truck will start in about an hour. I have on a few occasions got a CE Light with code 12. That might be related. So, what is the Fuel Injector fix?
Paul, Green Valley, AZ

 

Replace the injectors is about all you can do.

 

Koditten..did you mean, all six comubustions chambers are flooded? Wouldn’t I get a check engine light code 26 or 27?

 

The only real way to tell us to snake a bore scope down the intake and examine the injectors while truck is hot, but turned off.

I would guess that more than 1 is leaking, but can't tell you any more than that.

 

Might also want to check out the water temp sensor and the air intake temp sensor circuits. The water temp sensor is in difficult to reach spot on the back of the engine and get pretty fragile when they are old. I will send some diagnostic info from the repair manual later.

 

Dug out my 92 repair manual. I can scan and send you a few pages in the morning.

 

Attached are a some trouble shooting guidelines. One pages 1 and 2 there is a difficult to start hot line and suggestions on trouble shooting. Let me know if you want other pages.

 

Thanks very much! I just printed them. I’m getting the Mass Airflow Sensor replaced on Monday, played hell finding one. I bought an Engine Temp Sensor. Looks like it would be best to pull the engine to replace it. NOTHING is easy to work on with the 3.0

 

Pulling the engine would make replacing temp sensor easier, but not if that is the only reason you are pulling the engine. The top of the sensor was so old and brittle that it broke off when I was trying to remove the connector. I also had to buy a replacement connector.

 

Okay...just had the “Mass Airflow Sensor” replaced. The truck seems to be starting okay. Could the sensor have anythning to do with a firing problem when hot?

 

It turned out to be the distributor (which was as after market). I had a code 12, put the old Toyota factory distributor back in, no problem now. Not one mechanic felt it was fuel injectors. They ALL said, if were injectors, the truck would be running like crap.

 

The problem turned out to be the distributor. It was an after market and was giving me a code 12. I put the original one back in.