3.4L hard to start when sitting for 1-3 hrs

[trd04taco]

I've got an '04 Tacoma with the 5VZ-FE and 50K mi. It always starts right up when cold or hot. The problem is when it has been sitting for 1-3 hours and is luke-warm, often it cranks for about 30 sec before it fires up. It idles rough for about 3 sec and then it's just fine. The battery and starter are good.
I've cleaned the MAF sensor and played with the Idle Air Adjusting unit and put in all new NGK plugs with no results. It's been doing this since about 10K mi, but more frequently now. It definitely seems like it's getting enough fuel.
Is there maybe a check valve that could be letting fuel drain out of the fuel rails once in a while or something? If so, where is it and how could I check it? Any other ideas?
Yes, I searched and read quite a few threads on this topic first and couldn't find any answers.
Thanks in advance!

[jvergos]

I'm having the same problem. It's going in for inspection this week to the dealer, I'll keep ya posted on what they tell.

[Philfab]

This might help:

http://ttora.com/forum/showthread.ph...ight=hot+start
http://forum.ih8mud.com/showthread.php?t=102573

[mudferret]

I had this problem with my '03 Tacoma when I first got it; I asked my cousin who was a Toyota engineer at the time about it, and he said it was a fuel rail pressure problem, concurs with the links Philfab posted.

No signs of it on my '98 Runner, and no idea if the Tacoma still does it as it was sold a couple of years ago.

[trd04taco]

Thanks for the links. I checked them out and will be checking the fuel pump wires asap, even thought that seems like an unlikely cause to me. Keep the ideas coming. I'll post what I find after I take a look at the wiring.

[trd04taco]

I inspected the wires and they all look fine and the problem is getting worse. Any other ideas?

[BlownToy]

Originally Posted by trd04taco

I've got an '04 Tacoma with the 5VZ-FE and 50K mi. It always starts right up when cold or hot. The problem is when it has been sitting for 1-3 hours and is luke-warm, often it cranks for about 30 sec before it fires up. It idles rough for about 3 sec and then it's just fine. The battery and starter are good.
I've cleaned the MAF sensor and played with the Idle Air Adjusting unit and put in all new NGK plugs with no results. It's been doing this since about 10K mi, but more frequently now. It definitely seems like it's getting enough fuel.
Is there maybe a check valve that could be letting fuel drain out of the fuel rails once in a while or something? If so, where is it and how could I check it? Any other ideas?
Yes, I searched and read quite a few threads on this topic first and couldn't find any answers.
Thanks in advance!

This could be a residual fuel pressure problem;

Fuel pressure seems to drops when the engine is off. You need to hook up a fuel pressure gauge to the rail to confirm pressure drop. Start engine then stop it and watch the gauge for the next 10 minutes. It should not go lower than 20 psi.

possible causes:

check valve inside fuel pump; (replace the pump)
fuel pressure regulator
injectors leaking


if it drops; you need to isolate between the 3 just mentioned.


pinch the fuel return line; if the pressure is kept, the leak has to be one of the three.

to check the fuel pump check valve you need to take fuel pressure before it gets to the fuel rails.

it kinda hard to do without the right tools but you get the picture.

[trd04taco]

Thanks for the advice, I'll be looking at it as soon as I can.