Have a 1994 single cab Toyota 22RE 5 speed 4x4. Soon as it cranks up, it dies 5 seconds or so. You can crank it however many times and it still does it. I jumped the Fp and B+ in port and the truck will stay running. Something is telling the fuel pump to shut off and I need some help troubleshooting

 

Welcome to YotaTech. Good job on your initial troubleshooting. You almost certainly have a problem in the VAF circuit (though it could be in the COR). Start by pulling the jumper, and with key-on Engine-off open the VAF vane with your finger. It's supposed to run the fuel pump (you can hear it); if not, you're getting closer.
http://web.archive.org/web/201209071...33volumeai.pdf

Nothing is telling the fuel pump "to shut off," what you're missing is the VAF (and COR) telling the fuel pump "to keep running."

 

Ohmed the air flow meter out everything is in specs from the chart you gave me. The COR is clicking when the key is turned to crank it

 

With KOEO, does the fuel pump start when you move the vane with your finger?

 

Sorry forgot to mention that, no it does not. I took the intake tube from meter to throttle off and opened it all the way and worked it back and forth and it does not come on.

 

Since the VAF ohmed out correctly, but it doesn't cause the fuel pump to run, it sounds like it could be the COR, or a broken wire. Just because the COR clicks, doesn't mean the contacts you need to make are actually making.

Having said that, since the fuel pump runs when the Fp-B+ connectors are jumped, I believe the wiring from the COR to the fuel pump is good. That also tests the COR RUN side. When the Fp-B+ connector is jumped, the COR RUN side relay is energized, operating the fuel pump.

SO, IMO, for what it's worth, you need to check continuity between the COD and the VAF. OR verify there is power from the EFI relay to the COR.

Good luck!
Pat☺

 

No. The jumper completely bypasses the COR; the relay does not operate with the jumper.

The FSM tests don't completely test the FC ("Fuel Control") circuit, because there's no test calling for holding the vane open. So go back and test for continuity from FC to E1 with the vane open (it should go from open to shorted when the vane is opened). I'm guessing it stays at "open," which won't operate the COR. While you're at it, on the harness side short FC to E1 with KOEO. You should hear the fuel pump start (you may also hear the COR, but mine's pretty quiet).

I think TicTac understands this, but let's review the operation of the fuel pump to make sure we're all on the same page. The COR (Circuit Opening Relay) has two windings and one armature. When you turn the key all the way to start, one set of windings is powered, the relay closes, and the pump runs. Once the engine starts sucking air enough to move the vane in the VAF, the FC contacts close, activating the second coil in the COR. The COR remains closed (and fuel pump running) even when the key returns from start to run. Why? If you get in an accident that breaks a fuel line, you want the fuel pump to shut off right away. Once the engine stops sucking air, the FC contacts open, the COR opens, and the fuel pump stops.

 

Ok when I jump the harness side fuel pump kicks on

 

When I ohm the meter out and open and close the flap it stays at OL

 

On most meters, OL means infinite ohms, as long as you're on the resistance scale. Sounds like you've got enough together that your measurement is correct, and you've "found" the problem.

Now what? The factory part is about 8 bills. https://parts.lakelandtoyota.com/p/T...225035050.html The part shows up all over the place out of salvage vehicles in the $200 range (part number 22250-35050). (Seems everybody and his brother calls it a mass air flow sensor. It isn't; a Volume Air Flow sensor is different technology. Just call it an AFM (Air Flow Meter) and you'll always be right.)

In theory you can remove the black cap and repair it. Others on this forum have done more dramatic surgery, so I'm sure you could do it. If your other choice is visiting a salvage yard, why not try?

 

Just as an aside, a Toyota Racing Development white paper i had in the early 90s showed how to remove the cap and adjust the AFM to richen or lean the mixture. It also showed how to disable EGR with a BB or ball bearing.

 

Ok thanks for all the help I will look into taking this apart and seeing about getting another one.

 

Alright. Took the top black cover off the flow meter, found that the contacts wasn’t making contact where needed. Fixed that. Between fc and e1. Truck cranks and stays running. Now I noticed the alternator is not charging. Got to figure that one out now