Infamous Warm Start Issue- Can we end it?

well there is a big difference in two crankings and two revolutions.

my 4 banger goes yan-yan-yan-vroom so that's 3-4 revolutions to start each time.

when I hear someone say 2 crankings to me that means yan-yan-yan-pause then yan-yan-yan-vroom so 2 crankings usually means there is some issue while 3-4 revolutions to start is just the engine priming itself before starting and perfectly normal in my mind. all my old engines acted that way and until I got something brand new with todays engines I never had anything start on the very first revolution.

 

Maybe that's why slander said that he thought my problem is "normal", he was thinking revolutions and not cranking. I am talking about the cranking with the pause in between- the one you said indicates a problem. If I used the wrong terminology someone let me know.

 

I Mis understood you the first time when you said rotations of the crankshaft- I was referring to cranking with an actual pause in the middle - because I agree when it comes to 2-3-4 even 5 rotations being normal.

 

For what it's worth. I had a Suzuki Samurai that I converted to fuel injection. Had the same condition. Start-up just fine when cold, stop go into the store 10-15 minutes. Damn thing was hard to start. Found that the fuel pressure regulator was culprit. Replace with a new regulator never had another starting issue. Good Luck.

 

Everyone glanced over it, but I think tan4x4 nailed it on the head.

I noticed when I set the key to run, I don't hear the fuel pump prime. Mine does the yan-yan-yan-vroom. My 95 Jeep Grand Cherokee however, when switched to run for a few seconds to let the pump prime, will start 3/4's of the way through it's first revolution.

 

Def sounds to be true, but would this explain why my truck when warm takes two to three complete cranks? I mean na-na-na-na-na (nothing) attempt 2: Na na na vroom. Wouldn't the pump already be primed by this time? I would think the pump not turning on until the starter is one would cause a problem on the initial cold start.

 

Hi OP, don't know where you are at with this problem, as I didn't read every post. But skimmed through and saw that you said you did your injectors? Like another poster on this thread, our long battle (5 months!) was from injectors dripping, even though they were passing on injector testing machines. Our mechanic borescoped the cylinders to video the dripping after the truck was turned off from being up to full temp. Drip, drip, drip. He was kind enough to put his own known good injectors in and let us drive it for a bit to be 100% this was the fix to the hard warm starts before committing the large pile of cash a set of new injectors requires. We are on day 4 of driving it with the known good's in there, and every start has been consistently normal. Life is good again, and finally we get to purchase the RIGHT part to fix our problem!

FWIW - just thought if you haven't replaced with new injectors (not rebuilt) yet, perhaps you could have the same problem. Check out our thread about it if you are interested: https://www.tacomaworld.com/threads...p-3-4l-5vzfe-v6.354399/page-153#post-10234158

Best of luck to you, I feel your pain battling this mystery problem! We went through hell and back about 10 times before getting ours resolved!!

PS: I quoted Mod's post because I wanted to point out that I am that crazy cookie lady he's referring too! : )

 

lovemytacolots is well versed in troubleshooting this problem and she has more troubleshooting hours invested then some dealership mechanics so she know what she is talking about.

 

Aw, thanks Keakar! Might be overstating my knowledge just a tad (I can talk about it all day but have never held a wrench!), but I'll still take the compliment! : )

 

I feel confident letting you troubleshoot any problem I would ever have on my taco.

reading and understanding what you read is the most important part of being a mechanic. any monkey can turn a wrench but it takes a brain to solve problems and you got the skills to be a great mechanic if you don't mind being elbow deep in grease and grime

 

Thank you for the reply! Perhaps my replacement with re manufactured injectors is the issue and I would need the real "new" ones. I just need to find a friend to let me barrow his bec I agree- what a price to pay for those things.

I also recently wrapped the fuel line and rail with heat-shield in case vapor lock was the issue. Didn't work... Of course.

If anyone has ideas I'll leave this thing open! Again: hard to crank after being warm. By crank I mean having to turn the key at least two times for it to start.

 

yep, you need to bore scope it and see if the injectors are leaking, that's what solved Jen's problem and what can confirm if you have the same problem.

 

Mine was a bad fuel pump on my 2.7. It has been several month now, when hot or cold its nananavrooom.

 

I had a similar problem after my cylinder head rebuilt. I installed some rebuilt injectors and it did exactly what your was doing. I needed to crank 2 times in order for it to start. After it started my truck was running/idling rough. So I re-installed the old ones back in and it started right up on the first crank and there after.

 

Sounds like I need to get my boroscope on.... Thank you guys/ I'll come back when it's done.

 

Well what happened still no answer?

 

If ya spend much time here you’ll find a lot of posters take the info and run without finishing up the thread, I used to get irritated now I just appreciate the ones that come back and tell everyone what did or didn’t work.

 

during cranking the PCM should send a signal to the IAC to modulate the opening of the IAC according to temperature of the motor. This is a Pulse width modulated signal (PWM) and unless you have a scope the only other tests that a driveway tech can preform are for voltage and resistance.

To eliminate/confirm/deny the IAC as a reason for hard starting cold/hot is to crack the throttle slightly when cranking. If she fires right, she needs more air if the problem persisits continue to look elsewhere.

If this is a hot start issue and you suspect your injectors are leaking down, turn the key to the on position, push the accelrator pedal to the floor and crank it over. 99% of fuel injected vehicles out there have a "clear flood mode". The injectors are shut off during this procedure. Stop cranking, take your foot off the throttle and turn the key off then restart.

 

Can someone (this is an old thread) clarify what this "clear flood mode" does to help troubleshoot, and if it applies to the 5vz engine? I suspect my rebuilt injectors are leaking or bad, giving starting symptoms I never had before.

 

Unfortunately I have not been successful getting the clear flood to work on my Tacomas. I dont think my Tacomas have this strategy in the PCM. In vehicles that do have this strategy available the injectors are not allowed to inject fuel and with a wide open throttle and enough cranking the flooded engine clears and starts. If there is a suspected leak from the injector(s) this is a quick way to test.