2nd generation tundra 4.0 lt V6. HARD START NO CODES

I am needing some help here i been doing the matinence on my 2010 TUNDRA 4.0 lt.V6 sometimes these codes are so vague.I been dealing with a hard start almost every time I crank it up it has this issue but sometimes it will crank like it should.I put in a new fuelpump,plugs the best $ can buy,up stream & downstream H0 sensors,MAS. Sensor ,Battery, starter,coil packs,gas cap and last but not least evap solinoid (gas cap& evap purge solinoid) were last to be put on it has eliminated past codes and no new ones to date but the hard start condition is still there.But for a week now (Check engine) has not re-appeared! So any advice the truck i have had since brand new and currently has 250000 miles runs like a brand new truck no issues gas mileage is not like it should be but besides the hard starting issue this truck is the best investment i have ever made.

 

I don’t have any answers to your questions, but I have the same year and engine as you.

I go to tacomaworld.com to get info on the 4.0l motor as it is more prevalent in tacomas.

Hope you figure out the issues soon.

 

Have you confirmed voltage of new battery?
I had a coil pack go bad on my 4.0L Tacoma, it was a PITA to diagnose.
Only happened intermittently at low idle. Only threw a code after weeks of ongoing issues.
Did you replace all coil packs?

 

Yes i did voltage on battery is perfect

 

Can you elaborate what you mean by hard start? Is it cranking slow? Does run super rough after starting like its flooded? Does it do it when its cold?
These 4.0L head gaskets like to blow at cylinder 6. You will definitely notice it in the morning when its cold. The parts shrink after cooling off and that causes a coolant to seep into the cylinder overnight. Trying to push/burn all that coolant out in the morning will cause a hard and rough start

 

No it dosent lag or start slow it cranks normal but takes a long time to start.It runs perfect dosent seem to me mis firing and idels at 800rpm.It does not seem to have this hard starting problem after its warm.i am maybe thinking fuel preasure regulator.Not sure how to test the preasure there is no port. To connect the preasure gauge to...

 

It's kind of difficult to help diagnose without hearing it... how's your coolant level? You could have a coolant temp sensor issue maybe? In theory your fuel pressure should be good if you did your fuel pump correctly.

 

If you want to test fuel pressure, it's likely that you'll need something like this:
https://www.toolots.com/wd-0001b.ht...Uo3ODfg-IbXsJEWykM-7xPpq64bMXsdgaAsk4EALw_wcB
I don't remember if the 1GR-FE has banjo bolts, but I believe that's the correct kit for the 4.6/5.7. Maybe toss up some photos of the fuel system and we can have a look. Fuel pressure will often manifest as a sluggish vehicle.

The bigger problem here is that you started with a problem and you've just been throwing parts at it. Hopefully you bought all OEM parts when you replaced things, otherwise you may have made more issues.

What you'd really want to do is to look at some live data when the car isn't starting to see if something is missing. I would imagine either the crank or cam positioning isn't reading properly, but you need to see which one is being flaky. If you're trying to start the car and both of those waveforms look good, then you'd want to check for spark. If there's spark and you still have hard starting, then you'd want to look for injector pulses. If you have injector pulses, then you'd move on to fuel pressure. In my opinion, it is that far down the list.

I just went through this with my neighbor and a junkyard Sebring he bought that wouldn't start. He threw a ton of parts at it and I threw the service manual at him, which suggested the valve timing was off (it was). He also found that a brand new sensor he put on made it run really rough, so he had to dig in his trash can to look for the old OE sensor.

 

I would suspect dirty injectors, especially with 250K miles on your rig. Did this issue just happen or has it been creeping up slowly to its present condition? What brand of fuel do you use?

 

Dirty injectors would show as significant positive fuel trim with a scan tool, which is certainly worth looking at.

 

I chased a very similar problem on my first gen 4.7 with random hard starts. cheap fuel pressure gauge showed me it wasn't holding pressure at shut down. Changed the regulator with oem one, still bad. Put in an aftermarket one and that fixed the fuel pressure issue. But it didn't solve the problem! Ended up being a damaged wire to the crank position sensor.

Through the few months of fighting with the hard starting it rarely threw codes.

I ended up throwing a few parts at it, but in my defense it really presented itself as a fuel issue. Not until I stumbled upon the damaged crank wire (buried out of sight, barely touched the fan belt) did I learn it was something easy.

So you should check your crank position sensor wire, connection and test the sensor itself. Test every other sensor and connection you can think of as well. Don't be that idiot who replaces the fuel pump when it's not the problem (I am that idiot).

Good luck!

 

^^^^^ here's my thread from my hard start journey. Obviously different trucks and engines, but you might find it helpful. If nothing else learn from my mistakes.

https://www.tundras.com/threads/05-4-7-hard-starting.73283/

 

The aftermarket fuel pump in my truck and perfectly good factory one in my garage storage says that I'm still the idiot... Haha.

 

I just did a coolant flush about 3 months ago.I sure hope i put the pump in correctly lotts of youtube teachers i aint going to lie by no means a mechanic but i cant afford to hire one so i do my best.I get by with a little help from my friends you can say.Apreciate ya!

 

Does it restart quickly after just previously running? Hard start only when it's been off overnight?

Try cycling the key to the ON position, wait 3 seconds, turn OFF, repeat 5 times, then turn to START and see if that helps.

 

It does start up normally after its been running but in time it will hard start after say 30 minutes

 

With this bit of info it seems that you are loosing fuel line pressure. So it could be an injector/injectors leaking down, so when it does not start try the key on off on a few times to see if the pressure will build up enough to get it started.