2.7l Will not start when hot - ANY ideas?

I know this is an older thread, but I also have a 96 that has had this issue during the summer. It did it again yesterday so I got the resistor and did this last night. To verify the issue since it's cooler at night I took my heat gun to the IAT to simulate the issue and it would not start. After switch install, I did the heat gun treatment until it would not start, hit the switch, and magic! Started right up. Thank you so much as this has aggravated me for the past 5 summers.

 

Try a new thermostat...that'll do it!

 

Well it came back haha. Its not one of the sensors for me.

 

Edit: my issue was a start then stall. It was the main efi relay

 

Edit: my issue was a start then stall. It was the main efi relay

 

I know this is an old thread but everyone has to keep in mind that these newer vehicles are crap. No matter who makes them. The reason is because computers control everything. Therefore, especially on the very new vehicles it helps tremendously to click you're ignition on, let all the beeping come to an end and THEN start it. I have 2004 3RZ and I wait until the five beeps are done before I try to start the engine. I don't have to on a 2004 but I do anyway. It gives the stupid computer time to figure out what it wants to do! Then, when I get to my arrival point I wait a minute or so before I shut it off. That gives the stupid computer time to figure out that I'm idling and not going anywhere soon. That's with a 2004. Those with the older computerized junk are just suffering because you were the guinea pigs. This really new junk such as 2010 and later? You better wait for the beeps to stop before you start your engines and let it idle for a minute or so before you shut it off. I'm not a mechanic but have to deal with this computerized junk every day.

Keep in mind. The "smart" is the new DUMB!

 

Heres you guys tacoma fix . Put a normally open descending unit on the engine that will work with the oil pressure. Wire the air temperature sensor wire to pass through it .When you shut it off hot and 5 mins later come back the oil pressure falls off opening the circuit . So when you spin it over it will crank and as the oil pressure comes up it closes the circuit to the air temp sensor . Thus making a complete citcuit.And ecm will read it and adjust .Ok , good luck !

 

its called vapor lock caused by your return fuel lines to tank check they may be colapsing when hot all so replace your gas cap it may not be venting under pressure causing the return fuel not coming back to tank 27 years as toyota tech

 

My truck is a 1996 tacoma with 2.7 , with 240,000 miles .I pulled my ambient temperature sensor out of my air box . Added about 3 1/2 feet of wire . Taped up the plugin and wires . I heat shrinked the connectors with sleeves to keep water out . I then plugged the hole in the air box with a cork . On the right fender their is a hole and i slid the sensor down in the fender toward the rear bottom of the right fender . It gets it away from the heat in the hood compartment. When the ambient temperature and the water temp gets within 15 degrees of each other it will cause the computer to cut off milliamperes to injectors . So if the water is like 197 and spikes to 216 during shut off . And the ambient temp under the hood rises to 201 then it wont crank . The 2 conflicting temps have to cool down and get the 15 degree gap so computer can reenergize injectors. Im going to eventually put this sensor in a small bottle and silicone it up and slide it back down the fender so water wont get on it . Once your weather cools off , you can simply stick it back in the original filter hole. This is just a summer time option .

 

I agree with you. This is quite common on motorcycles. The gas cap should be venting. When this no start issue happens again, loosen your gas cap. If you hear a big whoosh!, then the cap is bad, causing a vapor lock and must be replaced.

 

Curious if anyone has anything new on this? Like every other thread on the subject, no hard solution but the active posters on the thread usually disappear with a part in their hand ready to try…

I’m able to recreate the issue by warming my IAT probe (anything about 15-20 degrees F above ambient temperature), and immediately solve the problem by cooling my IAT to the actual ambient or below. Seems like the IAT heat soaks up to about 30-40deg F above ambient in the airbox with the engine shut off warm.

96 2.7 here.

Mike

 

The only thing that seemed to work was to clean the maf sensor wires, carefully using the proper spray.

 

Not for me… just did it again and no change.

I’m getting data on ECT and IAT temps to try and figure out a coorelation, but it just seems like if both are high (200+ on ECT and 120+ on IAT), the problem arises. Cool either one down and the issue is gone… still need more data points though.

Mike