Mhelvestine

Hello again, it's been about a year since I have had any problems with my 1997 4-runner which now has 422,000 miles on it. Problem now is when I go to start the truck in the morning I have no problems, fires right up, however when the temp hits operational and I shut the truck off, come back out and restart, it seems to take a lot longer to start, what I mean is it has to crank a few before it catches and even then I have to keep the start engaged a couple of seconds longer before it starts. Just changed out the fuel pump a couple of months ago and it too was original.

RAD4Runner

To eliminate doubt on temp sensors, clean all of them to bare metal, including mounting threads and where they mount.

Mhelvestine

Why would the temp sensor cause the hard starting issue?

RAD4Runner

Because "Hard starting after warmed up".
Meaning it is temp-dependent, meaning it could be caused by inaccurate feedback of temp to ECU.
Either spend time doubting the temp sensors or spend a little time making sure they're clean and well-connected.
I cleaned all my sensors down to bare, shiny metal after 30 years and it fixed my hard warm starts.
Sensors with only one wire going to them rely on contact with block for their ground. Therefore, threads should be cleaned to bare, shiny
metal.

RAD4Runner

Because "Hard starting after warmed up".
Meaning it is temp-dependent, meaning it could be caused by inaccurate feedback of temp to ECU.
Either spend time doubting the temp sensors or make sure they're clean and well-connected.
I cleaned all my sensors down to bare, shiny metal after 30 years and it fixed my hard warm starts.
Sensors with only one wire going to each rely on contact with block for their ground. Therefore, threads should be cleaned to bare, shiny
metal.

Mhelvestine

Thanks will give that a try in the morning, will let you know what I found. Mike

RAD4Runner

Also, if ur gen has Fuel Pressure Up vacuum switching valve, chek if it works. When ECU thinks it needs more fuel pressure (to prevent vapor -lock when fuel vaporizes in lines), it exposes pressure regulator to atmosphere, instead of vacuum fron m intake. It raises fuel pressure.
https://youtu.be/gHXTsgUTImU

RAD4Runner

Also, if ur gen has Fuel Pressure Up vacuum switching valve, chek if it works. When ECU thinks it needs more fuel pressure (to prevent vapor -lock when fuel vaporizes in lines when warm), it exposes pressure regulator to atmosphere, instead of vacuum from intake. It raises fuel pressure.
https://youtu.be/gHXTsgUTImU

bensyota

Mhelvestine

Nothing yet, still checking, I cleaned the sensors down to bare metal it made no difference, got to check fuel pump pressure today.

bensyota

Mhelvestine

Had something interesting happen yesterday, stopped for gas and cut the motor off, went to restart and it would crank but wouldn't start. Since there were several people lined up behind me waiting for gas I pushed the truck into the parking lot out of the way. Tried to start again and nothing. I turned off the key and was trying to figure out my next move, which was …. what tow company was I going to call. and after about 3-4 minutes I heard a click come from under the dash on the drivers side, like in the area of the fuel pump relay. Turned the key and it fired right off. If anyone has any idea let me know, I just don't want to start changing out parts, that can get costly, what I need to figure out is what circuit sends the signal to the relay to switch? besides the computer.

RAD4Runner

So did you take a look at what exactly clicked? Any obvious sign of problem? Bad or dirty contacts?
Best diagnostic tools are our senses; see, her, feel, smell what are going on,

Mhelvestine

Mhelvestine

Hello to all again, I have an update for this hard starting after warmed up. Friend of mine had the exact same issue, He went to a shop and they had changed out his crank position sensor. So I decided to take a look at mine....Took out the only bolt holding the sensor in and it fell off in 2 parts, however the other part was stuck in the bracket on the engine, So i dug to where I could get behind the part and gently push from the backside to remove it came out without a whole lot of problem. Upon further inspection of the cam shaft sensor I saw the wires were pinched and the shielding was broken, so since I was this far into it I would change it out as well. No problem with that one either except I wish I had smaller hands. Put it all back together... fired right up but now it kicking a PO300 code which is random misfire on cylinders . Went for a test drive hardly no power and lobing had a fast response on the throttle, got it up to speed 60 mph but it was struggling. Any Ideas? Mike

bensyota

Don’t you have to adjust these to spec? I remember messing with mine when I pulled my engine way back. Can’t remember specifics but I remember not being happy with the adjustment. It’s very picky. But I left it as good as I could get it

Mhelvestine

Thanks for the response it ended up being that it jumped time. So I had replaced the belt and both rollers and the problem was solved. just still dealing with a high idle.