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Discussion Starter #1
Hey everyone,

Very helpful forum, just signed up to get some help!
I checked through several threads here and elsewhere and can't pin down this issue.

My father in-law has a 1996 4Runner 4wd 3.4 Auto he purchased new.
Well maintained, he was always good about his service maintenance, but it is old. Vehicle has 324k, original drivetrain.

When it's cold, or hasn't been started in an hour or so, it fires up just fine. When it's been driven recently, it won't start.
It cranks all day long but won't fire, unless you jump start it or it hasn't been driven in an hour or so. If you jump it, it'll fire up. Seems like it has to be cold, or get extra juice, and the battery is above the recommended CCA (and brand new, it's cranking it over all day long, I replaced it yesterday because the old one wasn't holding a charge).

I replaced the fuel pump/strainer/filter a month ago and double checked it this weekend. I replaced the battery (it was old) and starter yesterday. Alt is testing good and putting out steady voltage. It will crank all day long with no lag or drop in power, but it won't fire unless those above conditions are met. No check engine light pops on, I've had a basic scanner on it and nothing shows up.

I'm not a mechanic but I've always done my own maintenance and am comfortable doing basic diagnostic work but I'm at a loss with this one. Any help at all is greatly appreciated.

I should note the key occasionally gets stuck, not often at all, and bumping it from Park to Neutral and back to Park lets it come out every time.
 

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Welcome to the forums! :)

When was the last time it got a tune up? Spark plugs, wires, PCV valve, throttle body and idle air control (IAC) valve cleaning, MAF cleaning, and COP boot inspection/replacement. ;)
 

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Hmmm, so of you jump it, it will fire up every time?

Sent from my SM-J320V using Tapatalk
 

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Discussion Starter #4
Thank you both for the input!!

BamZipBow - I tuned it up about 2 years ago. That's only been about 2300 miles, the vehicle is rarely driven but I've needed it recently. It runs great when it wants to start but I can go clean the MAF/TB/IAC. Good suggestions!

Vibe - Yep, that's the weird thing. Alt is putting out steady voltage, I'm thinking maybe a grounding issue that only manifests when it's hot (been driven recently), and for some reason jumping it overcomes that? I'm pulling at straws here but I'm going to clean every ground and probably replace the negative battery cable, after looking at it yesterday it's got some exposed wire right at the battery and I assume elsewhere.

I really appreciate you both replying!
 

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The one ground that many seem to overlook is the brown ground wires near the Diagnostic connector on the air plenum. These are the grounds fer the injectors. If they are bad, the injectors will not work correctly since it's a ground triggered system. It should take a 10mm socket to remove the bolt and you can check the condition of the connector and contact surfaces. ;)

Is the ground from the firewall (passenger side) to the engine still connected? I'm not sure what systems would be affected if that wasn't connected. ;)
 

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Discussion Starter #6
The one ground that many seem to overlook is the brown ground wires near the Diagnostic connector on the air plenum. These are the grounds fer the injectors. If they are bad, the injectors will not work correctly since it's a ground triggered system. It should take a 10mm socket to remove the bolt and you can check the condition of the connector and contact surfaces. ;)

Is the ground from the firewall (passenger side) to the engine still connected? I'm not sure what systems would be affected if that wasn't connected. ;)
I'll take a look at those today, thank you very much!

So it did pop a code last night, P0335 and P0340. Crank sensor, but I'm hesitant to replace it right away since I'm not sure if they only came on because of the repeated cranking attempts. I'll pull a testing procedure, and go through all the grounds. Thank you for mentioning those 2, very helpful!
 

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Check the wiring and connector to the crank sensor. The connector should be attached at on the timing belt cover. If it's loose and bouncing around, there's a good chance that one of the accessory belts might nick the harness enough to cause some issues. ;)
 
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