98 4runner will not start first try

98 toyota 4runner v6 4X4

when you get in the truck and hit the key it will spin over no spark no fuel pump operation when you let go of the key back to accessory mode and try and start it again fuel pump comes on and it will fire right up or sometimes buck the starter

same thing every time you turn the key off

i have tried ignition switch checked all the power and grounds engine computer showed sign of water damage so got a reman unit from a auto computer dealer we use regularly only thing i can think of is maybe ignition module has a problem

i put the lab scope on the cam and crank signals and they are present at all time while spinning the engine and no codes

 

That's a new one. I'd love to know the solution if you find it. My gut tells me it's a fuel pump circuit issue. Which may be the ECM not closing the COR relay properly so the fuel pump runs. You might want to try jumping that COR relay and seeing if things work better. That might point you towards a bad COR or ECM. The 2002 schematic is fairly simple for the fuel pump. The only other thing I see is the ignition switch which controls power to the ECM and COR. But if that was bad, I'd think it would do different things. Odd that it's so consistent in its failure though.

 

yeah the pcm ground the cor aka fuel pump relay when spinning the motor I tried bypassing the ecm and just straight grounding the relay were the pump runs when the key is on regardless and no change

 

Did you try completely bypassing the COR for now? Energize the pump directly?

Grounding the ECM line to the COR seems to make me think the ECM isn't the issue. I would look at the COR and the ignition switch now.

 

Actually, here is the 2002 diagram. There is potentially the EFI relay to look at\bypass.

 

Any chance you have a simar diagram for the transfer case you could put up in this thread?
https://www.4runners.com/threads/1999-4runner-limited-4x4-dash-light-flashing.48444/

 

https://drive.google.com/file/d/0B4...en&pli=1&resourcekey=0-AeWhnlEHWNLpTf_ZldgUAw

Scroll to around page 2000 for schematics. If you don't have it, save it locally. It's not my google drive.

 

yeah EFI relay isn't a problem because the COR has power and so do the coils, if you spin it over from the off position it will not ground the fuel pump relay or have spark but after the second crank it will fire up just fine. i just put a ignition module in it and it still does the same thing I'm at a loss luckily it is a dealership that owns it and not someone personal car so they are being patient. this morning i tried it and it ran but actual had check engine light but its out now with nothing in history

 

okay well after much digging found the customer put a crank sensor on the engine and even though i was getting good signal on the lab scope the computer did not like something about it the customer cut the O-ring to make it fit in the hole easier so it was not mounted correctly, put a new crank shaft sensor lubed the O-ring so it would slide in and mount securely and the engine fires right up every time

 

Good to know. Thanks for posting the solution. That is crazy. Why people pull stupid stuff like that is beyond me.