snugent

Have a 1992 Toyota Pickup that I recently rebuilt the 22RE motor. Ran find after the rebuild but would be hard to start to after it warmed up. Found it was having losing gas pressure and taking time to rebuild it without the cold injector to help start it warm. So I dropped tank and replace fuel pump. Now it starts up fine and runs great with around 38 psi and hold pressure when off. But if I get in it with it running and simply step on the clutch pedal, not putting it in gear, my pressure drops to 20psi and less and it eventually chokes out. I am starting with the Clutch Start Switch, so it appears my actually Clutch Switch it causing issues somehow. Anybody seen this before?

wyoming9

iTrader: (1)

Are some of the wires being pulled apart or moved when you press the clutch pedal

Unless you have a major short dropping the voltage so low the circuit opening relay or the EFI relay drops out

The EFI relay might be loose in the socket which flexes when the clutch pedal is pushed

Might also be a loose fuse in the socket causing the issue

No telling what kind of wiring upgrades may have been done

The clutch safety switch will keep it from cranking !!

scope103

Stick your multimeter between B+ in the diagnostic connector to ground. With key-on, should be about 12v. Step on the Clutch. If the voltage drops more than 0.2 volts, you have a short somewhere.

Put the multimeter on FP, and start the truck. It should jump to about 12v with key to start, and stay there. Step on the Clutch. If the voltage drops more than 0.2 volts, you have a problem in the COR/VAF circuit, and most likely the COR is opening.

Now jumper FP to B+ (this bypasses the COR/VAF circuit, and forces the pump to run with key-on). If the problem clears up, this just confirms the prior test; the COR is probably opening.

snugent

Excellent stuff! B+ test tested okay and it never drops voltage. FP test drove me crazy until I understood why. It is not just the clutch pedal doing it. Started it up with meter in the window. Could not make it die. Let it warm up while I cleaned out my work truck. Every now and then I would climb in and pump the clutch...nothing, kept running with 13.95 vdc. Did that a few times until I was certain it was warmed up. Climbed in and when clutch wouldn't kill it, I hit the brake. Voltage went to zero and truck died, so thought I was mistaken about the clutch. Had to run an errand, came back and repeated test. This time neither the clutch nor brake pedal would kill it. So I tried the radio, nothing. Switched the fan on and lost voltage and trucked die. So I did the FP to B+ test and it started up and ran fine until I pulled the jumper. Got it restarted and decided to call it an evening, closed the hood with it running and that cause it to die. So clearly I have a short or loose connection in the COR/VAF circuit? Going to try to look up a wiring diagram but any ideas on where to start? And thanks so much for the help!

wyoming9

iTrader: (1)

You have a loose connection!!

If you had a short it would either open circuit protection.

Melt and burn wires till the circuit opened.

the fire department would come and water down what was left

snugent

Thanks to "Toyota 4Runner and Pickup: Cheap Tricks" by 4Crawler, I have determined that I have a loose ground. Initiating any kind of load from the cab (A/C fan, Clutch, Brake, etc...) causes me to loose ground at E1(at Diagnostic terminal). Since the secondary coil of the COR relay is held in by completing the ground, it drops out when the ground drops out and thus kills the fuel pump. Went thru all the ground cable twice before but will need to find the loose ground. Anybody know where E1 gets its ground?

wyoming9

iTrader: (1)

It is where the wires ground from the ECM if that is loose your engine will not even run.

If you put it back in the same location it should be on one of the intake bolts.3 brown wires together

damage something during the engine work??

rodents been chewing on the harness??

Run a jumper wire from E1 to the negative battery terminal see if that cures your problem

scope103

The ground point that most affects electronics (including E1 on the diagnostic connector) is ED, which is (relatively) easily accessible on the aft right cam bearing cap.

wyoming9

iTrader: (1)

The 22re is just a little different not having the two cams

snugent

Finally got back on it today and it appears I have a short as I suspected. Ran test with Fluke meter between E1 and battery ground, after I checked battery ground to frame and ground wire terminations. Ran test at E1 at Diagnostic port and COR with no differences. Here is what I got:
Motor Off/Key Off - 0.4 ohms and 0.000 vdc
Motor Off/Key On - 6.5 ohms and 0.006 vdc
Motor Off/Key On/Fan On High - 11.8 ohms and 0.012 vdc
Motor On/Fan Off - neg 14.8 ohms and neg 0.012 vdc
Motor On/Fan High - neg -0.027 vdc before COR drops out and motor dies.

Note: Voltages varies with fan speed and also get spike by pressing brake pedal. Easier to test using fan swtich/

I know the small dc voltage on my Fluke messes with my ohm readings, so it appears to me that I have something trying to short out/go to ground in my key/dash circuit. Any ideals?

snugent

Still chasing this problem. Went thru all connections and grounds. Checked everything and everywhere for a short or loose connection. Even added a ground to my grounds under the dash. Had battery and alternator tested and they tested good. Alternator was the original so went ahead and replaced it with a new one. So this is where I stand. Have my meter setup with one lead on battery + post. The other lead is the stud post of alternator. With truck running and everything else off, meter reads .12vdc. As I start adding a load in the form of lights, blinker, brake pedal, or especially the fan, voltage goes up above the .2 limit(read that in another post). When it gets up to .3 - .4, the secondary coil of the COR drops out, thus stopping fuel. Still not sure if I have loose connections or a short that only starts to appear with a load.