MLJBikes

I have a '99 4Runnner 3.4 V6 that over the last six months or so has become more and more difficult to re-start when it is at full-operating temp. A specific example, if I drive 20 mintues or so (say at fwy speed, although it doesn't seem to matter), stop to run an errand, and the car sits for 20-30 minutes, when I attempt to restart, it will not unless I use the gas pedal to get it to go (keeping in mind with EFI, no pressing of gas pedal should be necessary). If I don't slightly depress the gas pedal, the car will not start (again, only when it's hot)

Once running, it runs great. No issues with cold starting.

Today, after a similar example, except the car only sat for about ten minutes, it was difficult to re-start, even when giving it gas to start, on one try, I revved to about 1500, then released the pedal, it immediately stalled (wouldn't idle). I was able re-started by giving gas on next try, stayed idling (smooth, no rough idling).

Plugs are clean/gray, MAF sensor clean, PCV rattles, no "check engine" light.

Any suggestions of source or ideas would be welcomed.

Mike (first time poster)

mike_d

how 'bout something as simple as cleaining the throttle body? my friend had an '88 22re that was really hard to start cold. other than that everything was perfect. we cleaned out the throttle body and it runs like new. don't know if it would affect hot starts, but it's a 5 minute investment of your time.

MLJBikes

It was on my list for this weekend to do, as I read on some other posts others having issues, but most were when cold not hot.

TPS was another thought, again, I just wasn't sure of it's impact when the engine is hot.

It acts as though it's not getting enough gas or a relay to allow it to idle isn't working.

Thank you for the reply.

MTL_4runner

Couple things to do:

1) clean throttle body
2) replace plugs
3) replace the air filter
4) change your fuel fliter
5) add some Techtron injector cleaner

Post back if you still have problems after doing all those.

MLJBikes

It's getting to be a narrower list, as all the items you listed have been done, except for the throttle body cleaning.

Since it doesn't appear to be a major undertaking, I'll try tonight then post.

I guess I should mention the following mods:

removed elbow from air box
AMSOIL 2 stage (lates version)

Nothing else changed

Mike

MLJBikes

I cleaned the throttle body, thoroughly
The plugs have less than 5K miles onthem, looked good and clean
Air cleaner is new
Still need to change fuel filter

The problem still exists.

I'll get to the filter this weekend, then post final results, and hopefully will resolve.

GoudyMan

filter wont fix it.... hot starts..... ehh??

also, why are you giving it gas to start?? its an EFI and so gassing it wont do a thing!!

what about your battery/ alternator??

GoudyMan

my bad, you are turning over, you just die!! could be ur fuel pump!

and PLEASE tell me you checked your oil!

MLJBikes

The reason I posted the question is the fact (which you point out) that with EFI, I shouldn't have to give it gas, hot or cold. But, it will not re-start (or immediately stall) unless I give it gas, this issue only occurs when it's hot (Sat for hour or less after reacing full operating temp), which is the problem I'm inquiring about.

It's not an electrical issue as it turns over fine (battery is less than six months old anyway), plus there's never an issue with starting cold.

Once it's going (starts and idles) it runs smooth, no hesitations in acceleration, etc.

The only other thing I can think of might be a vacuum leak somewhere, but where do I start with that?

Fuel filter was suggested in a prior post.

Memphis4X4

One or more of your injectors are cracking open due to heat soak from the hot engine temperature. This is bleeding your fuel system and the long start is required for the fuel pump to re-pressurize the fuel system.

I had this happen on my truck. I ended up having Toyota replace all 6 injectors in order to fix it. It was not easy to get them to do it.

David

MLJBikes

Now that makes some sense to me, albeit the more expensive answer.

Is there anyway to tell which one (or more) may be the problem, such as anything on the plugs or through the computer diagnosis?

What's happened more of late, I can give it gas, it will rev as you would expect, then immediately stall. Next crank, fires up. Sure seems to me to be an issue with proper gas flow.

Thanks for review, and I welcome any suggestions.

Mike

Memphis4X4

Yes, at +$200 per injector it is very expensive, Toyota balked and said that this was normal operation. I didn't accept this answer.....but enough about my old situation.

As far as your situation, troubleshooting down to which injector is not something that I was able to figure out how to do. One cheaper option instead of replacing all injectors is to have all of yours pulled and ultra-sound cleaned and checked. The spring in them is what needs to be checked because they weaken and thus the heat causes the injector to crack open. I don't want to get your hopes up though because Toyota actually had this done to my original injectors and this did not fix the problem. We put a fuel pressure gauge on the fuel system and watched the system bleed down when hot but were not able to pin point which specific injector......thus I was able, after much arm twisting, i.e., BBB arbitration, to get 6 new injectors, which have worked great for 130,000 miles.

Good luck,
David

MLJBikes

To GoudyMan, I'm a nut about oil being changed and clean....I spend the extra bucks on AMSOIL. Full and clean (changed less than 500 miles ago).

Mike

MTL_4runner

That part about needing to give it gas was a good hint.......I should have picked up on that. That means that there was an excessive amount of fuel built up in the engine (ie flooded) and it needed lots of air to start. It is for sure coming from a leaky injector (can't be a fuel pump cause that would not explain the need to "give it gas" but check fuel pressure just to be sure). One option is to replace all the injectors with a higher performance version rather than just replacing all the injectors with factory OEM, I would suggest to use these from URD or you can get a set of injectors from a late model Supra or you can send yours out to be flowenched which will surely find the leaky injector in no time. I would tend to go the first route because it is an upgrade and for $380 you get high performance injectors and you are on your way if you ever want a S/C in the future. The flowbench should be about $200 plus if you have a leaky injector you will be paying $200 each for a replacement. Totally your call.

Mike Murrell

Some european cars have a check valve back by the fuel pump to help deal with heat soak or "vapor lock" as some call it.

I wonder if the Toyota in question has a comparable device?

Might be cheaper than new injectors and solve the problem?