I have gotten so much out of this forum, so thanks to all that contribute! Im not great at diagnosing and troubleshooting, but i think i got it figured out. So my fuel pump wasnt kicking on and the Runner was just cranking over and over with no start. I jumped the test connector to turn on the fuel pump, i heard it turn on, but still no start (so i know the fuel pump isnt the problem). I then removed the jumper and blocked open the AFM and could hear the pump turn on and the truck started right up. According to the service manual there is a circuit that is completed in the AFM to turn on the fuel pump...so my question is...

have i figured out the problem? am i correct to assume that the AFM is bad since it starts right up just fine when the flapper is blocked open?

thanks in advance!

 

Yep. Sounds like that is your issue. You can search "AFM relay circuit" and get lots of stuff to check out.

 

if the tube to the afm to the intake has a hole in it or if its not connected it stops the pump. also check the cold start injector, it will make the motor turn over without starting

 

okay so new AFM did not remedy the problem. Just like the old one, i can shove that flapper all the way open and i hear the fuel pump kick on and it starts right up...without blocking it open (even with the new AFM) it wont start, just turns over and over and over. i dont see any cracks or gaps or anything within the intake tubing.

any other ideas? does the cold start injector affect the fuel pump?

 

See below:
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

The AFM does not operate the fuel pump during starting.

 

So I could leave the jumper permanently plugged in the test connection to bypass the afm? and it would start up fine each time then right? The old afm tested fine within the ranges when i tested the ohms from the chart you posted, but i figured id try a new afm and return it if it wasnt needed.

if the pump comes on with the jumper plugged in doesnt that mean the COR is fine?

 

I ran mine with a jumper installed for a few years until the ECU-STA issue fixed itself. I removed the jumper and wired in a switch in case it ever acts up again:



If the AFM tests out fine, then it is OK.


Yes, the jumper makes the COR turn on and if the pump is running with the jumper in place then the COR is fine as it is what supplies power to the pump. The problem the jumper bypasses is that the ECU-STA signal is not turning on the COR when the key is in the start position. Either that signal is weak, or the secondary COR coil is weak or there is a wiring issue in that circuit. Mine went out on me once, left the jumper in for a few years. Then I thought that might make a neat anti-theft feature, so I wired in the switch to test things out. Lo and behold, the darn thing has worked perfectly since then without the test jumper. I left the switch there in case it ever acts up again.

 

Okay so i put on the old AFM (which test good, within the ohms) and placed the jumper to the test connection of the fuel pump...still just rolls over. But yet if i keep the AFM forced open it cranks up just fine. COR is good cuz fuel pump comes on, AFM is good. Ive checked the hoses coming from the afm and no cracks or gaps...any other ideas? i guess im back to square one. Could it be the actual plug leading to the AFM (the connector?)

 

maybe the yota knows im trying to sell it. :-/

 

Im sure you've either got your problem fixed by now or sold the truck, but mine is doing the same thing. I have to open the AFM vane with a screwdriver until it warms up, then i can reinstall the air tube and itll fire up on its own. My problem is the cold start injector time switch is shorted. Just thought id let you know.