1st gen 4runner post 3.4 swap symptom guidance request (1 Viewer)

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Hi all,

Done a ton of reading and hoping to narrow down the root cause and also prioritize my attempt to resolve this issue with some more expert advice:

Drove my '87 1500 miles with the check engine light on after purchase - no issues. Thought it was on just because of the 3.4 being installed. No problems. Recently, twice now, drive it and when I stop for something [turn off engine] it will not restart. I smell fuel when cranking, at this point assuming not fuel pump related. This last time I did notice that after clearing the check engine light previously mentioned that the light came back on when i was coming off the highway prior to turning engine off at my next errand. The thing is though, both times after sitting stuck for 1.5-2 hours it started up without even fidgeting any connections or hoses etc. Checked the code and it was because there is not catalytic converter. Check engine light is cleared now.

I've read a lot about all the different sensors. another member suggested that it is the MAF sensor causing this. But I previously cleaned this [between the 2 incidents].

I've also read that the crankshaft position sensor will not throw a code. But wouldn't that not allow it to start after waiting the 2 hours?

Another avenue could be check valve in fuel pump failing to hold pressure in fuel rail?

Anyone know for certain what the issue is? or other suggestions? or even what to attempt first?

Thank you as always,

Aaron
 
Heat related issues are common to bad sensor or high resistance issues. Recently diagnosed a 300zx with a bad ECT causing similar symptoms.
Electrical diagnostic can be tough from this end not knowing which route they used when wiring.

When you are in no start, is the CEL on at KOEO?

Do you have a scan tool to read data?
 
We build alot of custom 3.4 harness for swaps .. and in turn diagnosis our fair share of issues .. fuel smell and no start could be a injector stuck open . a code would be helpful even if one was o2 sensor . crank and ignitor and coils will not set a code .. most common irrational 3.4 issues are a chipped crank gear .
 
Heat related issues are common to bad sensor or high resistance issues. Recently diagnosed a 300zx with a bad ECT causing similar symptoms.
Electrical diagnostic can be tough from this end not knowing which route they used when wiring.

When you are in no start, is the CEL on at KOEO?

Do you have a scan tool to read data?

Good point - check engine light was still on during no start. a friend has a scan tool and found the catalytic converter code [truck has no cat]. he cleared it and had no issues starting it.

leaving us at - how do i prevent the CEL from coming on when there is no cat?
 
We build alot of custom 3.4 harness for swaps .. and in turn diagnosis our fair share of issues .. fuel smell and no start could be a injector stuck open . a code would be helpful even if one was o2 sensor . crank and ignitor and coils will not set a code .. most common irrational 3.4 issues are a chipped crank gear .

thank you for another avenue, >> chipped crank gear.
 
URD racing has some o2 eliminators/simulators that could work . .. just puting the cat back on is the best option
 
a 3.4 swap will always perform at its best if all of the components are installed it allows the ecu to take full control over fuel at a range of temperatures and altitudes .making a happier owner .
 
a 3.4 swap will always perform at its best if all of the components are installed it allows the ecu to take full control over fuel at a range of temperatures and altitudes .making a happier owner .

I definitely was not a happy owner Saturday night between 10pm and 1130pm, after purposely overeating mexican food, and waiting for the cool down period searching diagnostics on my cell phone with 20% battery needing gps with an increasingly angry lady in the passenger seat.
 
two avenues , for fuel smell ,,,first a stuck open injector dumps raw fuel and wont start as it gets hot the injector fails electrically and continues to stay open until it cools down . .. second it is not sparking the spark bolts ,but still firing the injectors ,not as common , as the same signal to fire the injectors is used to spark the plugs .
 
when it is hot and you are able to duplicate the problem , see if it has spark to the drivers side spark plug wires , this will separate , a spark problem from a injector issue
 
I definitely was a happy owner Saturday night between 10pm and 1130pm, after purposely overeating mexican food.

Fixed it for you :flipoff2:

The rest of the post is just details...
 
sounds like a hot soak issue. I'm going with injector(s) sticking open also. the 3.4 is known for cooking #3 and #6(the 2 in the back on both sides) I have personally seen 2 different 3.4s with bad injectors. Most recent one would start after being turned off but it would take a lot of cranking and then missfire for a while before clearing up. could smell the fuel. would always start right up when cold/sitting. replaced 3&6 fixed it. unlike yours though, they were throwing missfire codes
just google "3.4 hot soak issue" or "3.4 fuel injector replacement". it's a semi-common occurrence on an otherwise great motor
 
Last edited:
just an update today: been slowly working through this, trying to find time to fit it in, etc. but cleared code, cat installed. drove fine all wekeend with a 26mile road trip, some dirt road messing around, some errands, a 70mile roundtrip commute, and jockeying positions in the driveway. all good over 4 days. today woke up to CEL on first start. good news so far is it started twice [with CEL]. wont be able to read new code until monday. probabl spend some time trying to track down if this was originally a automatic [5 speed now].

will update again after some baby steps.
 
Check your charcoal canister - they're crack ALL the time.

I had that code pop up and I threw some JB weld on mine and called it good. They're stupidly expensive to replace too. You'll probably need a smoke machine or a good cigar to determine where your leak is.

I prefer the cigar route. 😎
 

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