my 90 4runner stalled out on me yesterday and now it wont start.
my first reaction was to hammer on the fuel tank while turning it over, no luck. next i removed the fuel pump and hardwired power to it, it works.
so somewhere between my ignition switch and my fuel pump i am losing power.
any suggestions of where to look? hidden relays? anything?
this is day 2 of pissing around trying to figure this thing out in -30C and i am getting pretty choked.

 

Circuit Opening Relay?

 

i have been reading other threads about similar problems. i recently added a cold air intake to my truck, is it possible that the MAF has shut down the COR and fuel pump?

 

the ignition (key) switch should turn the COR on when cranking and then the AFM keeps it on once the engine starts (overly simplified, but overall what happens)

 

ok, so i bypassed the COR with a jumper wire and it still wont start. it just turns and turns but nothing. i can hear the MAF clicking likes its opening or shutting. i dont know what else it could be....

 

How do you know that it's a fuel pump issue? Does the rotor in the distributor go round when you crank it? Does a timing light show the ignition to be in time when you crank? Does the engine have compression?

 

If you jumper "B" and "FP" in the diagnostic connector the fuel pump should run.

You should be able to start the truck if the fuel pump not running is your problem.

 

the fuel pump wont turn on with out the jumper wire and i am getting spark. so that leads me to believe that it is an electrical component in the ignition/EFI system. i tested the main EFI relay today and found that it is faulty. but i cant get a replacement til tuesday. anyone know of a way to safely bypass it to test the rest of the circuit without the risk of damage to the ECU?

 

Power goes from the battery through the IGN fuse to the EFI relay. Then from the EFI relay to the COR relay. Your COR relay gets held on by the AFM and while cranking. Pull the passenger kick pannel and pull the glove box out. You will see the COR bolted to the wall. While cranking you should feel and hear it clicking. If not then your EFI relay is not working (or relay NFG). It is under the hood up with the fuses.

YOu can check for bad wires by pulling the carpet up on the passenger side a bit and right under the passenger seat there is a plug. Check voltage at the plug wires White/black stripe and Blue/(red dots or just blue). This will tell you if you have bad wires from there back.

I have had problems with my COR relay before. I just unplugged it and plugged it back in and it worked.


I just red your last bit. You can jump the EFI relay by jumping from the Green wire under the relay to the one opposite it (can't remember the color.

 

so looking at the schematic would that be the wire coming from the battery to the EFI fuse?

 

my EFI relay is out and non functional, so wouldnt i need to jumper the ign to ground as well?

 

so i tried jumping the EFI main relay and my truck still wont start.
doing that it should have activated the COR and turned on the fuel pump?
and by jumping power to the fuel pump it should bypass the COR and the AFM?
so by doing either of these two things my truck should start?

nope!

 

check all you wires going to the fuel pump mabe there is a short somwhere

 

but the pump turns on when i jumper it in the diagnosis box. that should mean the wiring works from that point on right?

 

While cranking, do you get fuel to the injector rail? Test this by cracking open the cold start injector line, and turning it over. Fuel should come spraying out. If it does, you know A. your fuel pump is working like it should and B. you are getting fuel TO the injectors, but not likely PAST the injectors.

 

yea what he said sounds like mabe a cloged line somwhere

 

ok, tested the CSI and have fuel to the injector rail. so my injectors must be clogged?
should i just try to add some injector cleaner and keep cranking it over? or do i need to tear the intake manifold out and really get into it?

thanks for all the help and advice guys!

 

you need to verify the injectors are getting the signal to open from the ECU using an appropriate test light

 

how would i do that?

 

can i check it out at the ECM if so which terminals?
here is a link to the ECM terminals in the service manual
http://personal.utulsa.edu/~nathan-b...e/102engin.pdf