Hard start when hot

My 1996, 2.7, on occasion, will just keep turning over when it is hot. It doesn't happen when the motor is cold. It will fire right up. but if I'm running errands and making multi stops it happens. And only when the outside temps are above 75 degrees. Of course living in GA that happens alot.

When it is hard to start, I can wait a while for it to cool off. Then it will start after a little trouble. And is burns rich and my fuel economy goes out the window.

I've done the usual, full tune up, fuel filter, cleaned the MAF sensor. I've also changed the exhaust maifold (due to a crack). and TPS (it was throwing a code and I can't seem to get it set right to turn the code off).

 

First step is to check the fuel pressure. You will need a gauge. If low, fuel pump. If normal, coils, crank position sensor, ECM, temp sensor, something along those lines that is weak when hot. Process of elimination if no codes.

 

Air filter dirty? Bad engine ground. Defective pick-up coil in distributor. Clogged fuel tank vent line?.

 

Agree that a fuel pressure check should be performed but what was the code ?

 

This guy hit the nail on the head. Check all the above, however, prime suspects in previous hard start cases under heat soaked conditions have typically led me to the fuel pump being the failure or the engine coolant temp sensor. Shortly followed by the crank sensor. Coil is not too far outside the realm of possibility either.

Like I said, spot on advice.

 

Thanks! I will definitely start with a pressure check. And I haven't gotten any codes at all. It's been happening for years. Sometimes I can wait 10 minutes. Sometimes an hour if it's really hot outside.

 

Could definitely be the VSV for fuel pressure control. The valve switches vacuum to the fuel pressure regulator during warm start-up if the computer detects high coolant temps. Think it's on firewall.Might check vac lines. When you take gas cap off does it hiss at you?

 

Yes. I get a hiss. And if it's hard starting and I stop for fuel. It's starts up just fine.

 

Fuel rollover,fuel cut-off valve,vsv.

 

Fuel control issue for sure. The new cooler fuel cools failing part back down enough to the point where it makes it qork again. Though without a chance to physically check it myself that's the most advice I can offer you. Good luck bud!

 

Thanks! I'll get it checked out.

I stopped by a mechanic, and he has never seen the issue before. He is really interested in it. So we will see. BTW, he is going to adjust the TPS on the truck also. It's throwing the CEL.

 

There is a lot on this issue if you search around. I had it last year - solved it by cleaning my throttle body and IAC valve. Others found the problem to be one of the engine temp sensors. Those seemed to be the two most common causes from the dozens of threads I read on hot hard starts.

A temporary fix just to get the truck to start is to unplug the air temp sensor on the side of the airbox. This will allow the truck to start in "limp home" mode - which saved me some trouble a few times when I didn't have time to wait the problem out.

 

Thanks everyone. I am listing these items to start and troubleshoot them. Cleaning the MAF helped last year for a little while. I'm hoping to find out the issue and correct it soon!

 

I had a verysimilar problem amd tuned out to be the fuelpump. You just have to remeber to be diligent with the test. Test it hot test it cold and watch for bleed down as well. This was a bugger of a problem to solve for me.

 

Update:

I had the new TPS set at the mechanic. Huge difference! I'm getting better fuel mileage and it's running smoother. Also the hard to start seems to have gone for now. But I will keep my eye on it. And if it comes back up, I'll know what the fuel is doing. Thanks to everyone for the input!

 

your problem may be related to the temperature sensor like this guy found out: http://www.tacomaworld.com/forum/1st-gen-tacomas/350987-2-7l-will-only-start-if-you-catch-gear.html

 

Hello! I know that this post is, now, several years old, and I'm not sure if you're even going to get this message, however, I wanted to know how this ended up for you. I just bought a '97 Tacoma, and am having a similar problem starting it when it's hot. Tuned it up yesterday, and my initial thoughts beyond that were changing the fuel pump (I got lucky and mine isn't tucked up near the fuel tank), and also maybe swapping out the TPS because it's such a simple fix.

Just wondering how your truck fared down the road with the starting issue!!!

 

i know this is an old thread, but did the op ever find the issue?