Hey all,
I have a 1989 4 runner that has developed a hard start and rough idle. It will not stay running and presents like it has no timing control without feathering the throttle. Little history on this rig. This is a 89 4 runner rock crawler build with tube doors so it's open to the elements. We had a storm here the other day so the ECU got wet and the fuse box on the driver side door panel got wet. I have removed the ECU and dried it out. replaced and still have the rough idle and start issue. The main engine fuse supplies 12v to the cluster gauges. I have half the gauges working but no oil pressure or engine temp.
Lookin over the Elec schematics the main EFI relay to the ECU will put it in closed loop EFI control ?
Will the truck start with a faulty ECU? or will it just not have timing adv/ret control. Seems like if the ECU was fried I wouldn't be able to start the truck.
So I'm leaning on moisture still somewhere in the EFI main relay / fuse box keeping the ECU from being able to perform its job on smoothing out the timing and or supplied enough fuel pulsation to keep the truck running.

I think I'm on the correct track just wondering if others have had issues with moisture on either side of the kick panels and issues with starting, fuel delivery, timing control.

The truck started and ran fine about 1 week earlier never left the drive way and wasn't worked on up until I tired to start it the other day.

Ive spent some time reading on others issues and pointing to the co2 sensor, afm, tps, none of this was worked on or the vehicle driven so it may still be a cause but not the most likely case.

Any sugestions will be appreciated.
Thanks,

 

I figured it out. After the ECU was removed for some reason it didn't like the timing when it was put back in. I had to retard my timing a couple degrees. Also I think the AFM flap was stuck or not in the absolute closed position upon starting as I heard it snap back when adjusting the timing....weird. Onto the next adventure.

 

Well, I guess I didn't figure it out. Started giving me issues again. It's like it has no timing control then with no rhyme or reason, or time it will start timing control and run great after babying it to keep it running for 5-10 min.I can hear a mechanical click or valve opening and it will start running great. Some things I need to run through.
Jump fuel pump and try to start.
Check my main distributor cable that runs up over the plenum.
IAC getting stuck,
EGR?
COR

 

Thought I'd come ack and update since we don't often see that on this forum. If I had any advice for those who still use this forum, Read the post's and then read again. Wealth of knowledge and information on here.
So, as stated in pots #1 I had an issue suddenly pop up acting like random timing. Ran through all the suggested trouble shooting and what was mentioned on the threads.

My issue ended up being two fold. This build is a rock crawler / trail build. Tube doors and a leaky front window. Water ingress took out the ECU but only the timing portion of it. Had no spark with my inductive pick up on my timing light out of the coil. Replaced the ECU and had spark again. I WILL NEED TO RELOCATE this ECU once the truck is back from getting its cage. 2nd issue was fuel delivery. Pulled the fuel pump and boy was it terrible. The pick up filter was non existent. and had nasty growth on all of the metal surfaces. Replaced all of the fuel pump parts. Truck is now running. I assume I will find more issues once I get the truck back but now the shop can move it around as needed. Thanks for those who messaged me and to those who posted their issues on the forum.

 

UPDATE to all the necessary and unnecessary work done above. After trouble shooting and the replacement of a couple items. The issue would mask itself but then return after a while. After getting completely sick of the issue I tore into this thing with a vengeance and went at the fuel system. The final issue was the cold start injector was stuck open. I went to remove the air intake tube to remove the TB and re-clean it and the tube was full of fuel. Took awhile to find a replacement cold start but now it starts right up. Though id share and save some of y'all the frustration if you experience the same conditions.