Trouble starting only when engine is hot...

D

dneu92

New member
Hello everyone,

I've searched this topic in the past to no avail. I have a 2000 limited 3.4L. It starts great in the morning and after a long day at work. Pretty much starts with no problem when the engine is cold. As soon as it gets up to normal temps, shut it off, come back within 20-50 minutes is when the problem begins. It cranks and cranks, then stumbles when trying to start. Once running (after giving it some rpms) though, its like nothing is wrong again. No idle jumping. No loss of power. I almost seems like it is flooded... I can't figure out what is causing the issue. Any help would be appreciated. Just threw a p0300 yesterday. Changed the plugs and wires recently as well. Throttle body has been cleaned too.

Thank you.
 
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Here's a few things to check:

1. Idle Air Controller, located on the underside of the throttle body. Often this will get dirty and clogged and won't open like it is supposed to. Will cause hot idle issues and hard starts.

2. Ground wires. When you add heat wiring can act up if there is damage or weak points. Mine would have trouble starting when hot because my battery ground was a bit damaged. Don't have that issue anymore since I fixed it.

3. Leaking injector is possible with the P0300 (multiple misfire), but not likely since it's not throwing a code from just one cylinder but multiple. Odds of having several injectors fail at once is very, very slim.
 
gamefreakgc said:
Here's a few things to check:

1. Idle Air Controller, located on the underside of the throttle body. Often this will get dirty and clogged and won't open like it is supposed to. Will cause hot idle issues and hard starts.

2. Ground wires. When you add heat wiring can act up if there is damage or weak points. Mine would have trouble starting when hot because my battery ground was a bit damaged. Don't have that issue anymore since I fixed it.

3. Leaking injector is possible with the P0300 (multiple misfire), but not likely since it's not throwing a code from just one cylinder but multiple. Odds of having several injectors fail at once is very, very slim.
Click to expand...

I appreciate your help. I will take a look at these things after work. Just a thought about the IAC. I am not having idling issues, jut issues getting it started when the engine is warm. Once I get it running after many tries, it runs as it should. No idling problems or stumbling. Could it still be the IAC with these symptoms? Most of the times I've had this problem it would never throw a CEL either.
 
My old Corolla had this issue. Research showed other yota models reported it too and most attributed it to IAC issues. I never did persue it on the Corolla, just lived with it.

My 4runner used to occasionally do this too, most often in stinking hot weather. I have pulled the tb and IAC and cleaned both on the bench. They needed it. I have not had it occur since but cannot say for certian it won't come back.

How did you clean your TB? If you did it on the truck is it possible you got crud down in the IAC? Might want to pull it.

Just my thoughts.
 
Kanoe said:
How did you clean your TB? If you did it on the truck is it possible you got crud down in the IAC? Might want to pull it.

Just my thoughts.
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You hit it right on the nail. I didn't want to say it but a lot of people clean out their throttle body, only to wash all that crud and junk in the hole at the bottom which then clogs the IAC. Then it's worse than if they had not cleaned it at all.
 
gamefreakgc said:
You hit it right on the nail. I didn't want to say it but a lot of people clean out their throttle body, only to wash all that crud and junk in the hole at the bottom which then clogs the IAC. Then it's worse than if they had not cleaned it at all.
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It was taken off during the cleaning. Looks like I will still end up pulling the IAC to clean and verify all is well with it. Have to do the least expensive options first. I am still quite puzzled with this issue. Been searching around for just under a year now trying to narrow possible culprits. Hopefully I can get it working 100% of the time soon enough.
 
cashmoney said:
I'd check fuel pressure also. I've seen fuel pumps that once the fuel gets hot it affects the pump operation.
Click to expand...
this was my first thought also.

get a pressure tester. test it in the morning when cold, then again after its been running. notice the pressure when its not starting. I expect that it will be low.
 
I recently had the same problem. Replaced the fuel injector and it solved my issue 100%. Hope you figure it out, it's a major pain in the ass.
 
I'm diagnosing this issue with mine also (plus a couple more symptoms).
I think it's the fuel pressure regulator on mine; it's leaking through the vacuum hose and actually depositing fuel in the air intake silencer baffle. It starts up just fine in the morning (after a long night of evaporating dry I assume), but when starting when warm, I think that the air intake is also sucking in gasoline fumes as well. I'll know in a few days when mine comes in the mail.

Check your air intake silencer. Just remove it and turn it at different angles and see if anything spills out.
 
AntleredRuin said:
I'm diagnosing this issue with mine also (plus a couple more symptoms).
I think it's the fuel pressure regulator on mine; it's leaking through the vacuum hose and actually depositing fuel in the air intake silencer baffle. It starts up just fine in the morning (after a long night of evaporating dry I assume), but when starting when warm, I think that the air intake is also sucking in gasoline fumes as well. I'll know in a few days when mine comes in the mail.

Check your air intake silencer. Just remove it and turn it at different angles and see if anything spills out.
Click to expand...

Now that you say that. A little while back I found some thick oily dark colored sludge that was coming from the main intake just above the intake silencer (it was very slowly running down toward the intake silencer). I'll have to look now to figure out exactly where from. Thought it was quite odd and not supposed to be happening, but didn't have the time or resources to dive into it at the time. Could this be related to the fuel pressure regulator as you describe it, even though its not exactly fuel? Wish I had more information to give you regarding this.

Thanks
 
Slow_T4R said:
I recently had the same problem. Replaced the fuel injector and it solved my issue 100%. Hope you figure it out, it's a major pain in the ass.
Click to expand...

Problem is, which injector is it. Are the cheaper $49 injectors even worth it from RockAuto?
 
dneu92 said:
Now that you say that. A little while back I found some thick oily dark colored sludge that was coming from the main intake just above the intake silencer (it was very slowly running down toward the intake silencer). I'll have to look now to figure out exactly where from. Thought it was quite odd and not supposed to be happening, but didn't have the time or resources to dive into it at the time. Could this be related to the fuel pressure regulator as you describe it, even though its not exactly fuel? Wish I had more information to give you regarding this.

Thanks
Click to expand...

Any thoughts on the sludge described above? It's coming out of a hose where the intake silencer and the throttle body connect. It isn't a ton, but I can post pics after I'm out of work.
 
I haven't had a non-supercharged engine on these 4Runners so I'm not exactly sure of the stock vacuum hose routing, where does the other end of the hose go? Is it the PCV valve that's on top of the passenger's side valve cover on the engine? If yes, time to get a new PCV valve, it's probably stuck open!
 
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