I have run a jump wire from the ECU STA pin direct to the CO relay STA pin, bypassing the plug wire incase there is a short somewhere. but as soon as I connect the two I lose 12V.
Should I be maintaining 12V when the 2 (ECU & CO realy)are connected? when cranking the engige should it still be 12V?
it definatley seems like something is shorting out but not sure where to turn my search now.

 

Well, you would need to identify the source of the problem. So try testing resistance between the two points and to ground. Should have 0 ohms between the two points and infinite resistance to ground or any of the other CO relay connector pins. If that is OK, it may be a poor connection at the ECU or as noted earlier, maybe the ECU STA pin output is weak.

Fallback is to just put in the FP test jumper and forget the secondary STA winding in the CO relay. I ran my truck for years like that until my starting issue just mysteriously fixed itself.

 

Fallback is to just put in the FP test jumper and forget the secondary STA winding in the CO relay. I ran my truck for years like that until my starting issue just mysteriously fixed itself.[/quote]


it appears I have bigger issues then. I jump my fuel pump (FP test jumper) and truck still won't start. lots of spark & lots of fuel. my ECU still doesn't throw any codes. I guess I'll check compression but that seems unlikely as only about 50,000 on rebuild.
Coldstart injector? Air Flow Meter? or TPS? are these issues that could be related? wouldn't my ECU throw these codes though?

I really appreciate your help.......gotta beat this thing, get it running & really beat it

 

Well if you are getting fuel, then the fuel pump and CO relay are working (with the test jumper), so it is not that. Figure out what else is wrong, FSM has page after page of troubleshooting steps. And when testing things, assume every part you look at is bad until you prove to yourself it is OK. Try unplugging the TPS and see if the ECU throws a code. If there are somewhat normal readings from those sensors, ECU will not throw a code, only does it for open/short circuits in those lines. And try swapping ECUs if you have (or can find) a spare.

Just talked to one guy the other day who initially reported he had loss of power and yet everything (including TPS) tested OK. Then I ask it timing was set (yes) and did it change with test jumper install (no), then he reports back that he had "strange" readings when he tested the TPS (although he said it was OK in the initial e-mail) and when he replaced/readjusted it, now all was fine.

 

I un-plugged both TPS & AFM. had some codes thrown pertaining to both. I plugged them both back in & now getting code 6. Igniter/coil/distributor/ECU. will go through these tests & report back.

 

I have seen a bad TPS cause a truck not to start.

 

so i swapped in a different ECU & no codes now but it still won't start & I'm not hearing my CO relay click. I've got my FP tester in to bypass the relay & I'm going to change the TPS & AFM cause i have extra parts lying around. Any other suggestions?

even though i have good spark on all 4 plugs, should i consider changing cap/rotor/distributor?

 

Well, figure out why the CO relay is not clicking. It might just be quiet and not make a loud click, or there might be a power or ground issue preventing it from turning on.

 

it is/was a loud relay. i can make it click by running a jumper from battery-resistance checks out.

Anyway i have no signal from STA pin when cranking.

Does the 12V come from the ECU & go to the CO Relay or vise versa?
When the ECU is unplugged i read 12V at the ECU STA pin and CO relay STA pin is solid ground? is this correct or should relay STA provide power?
As soon as i plug the STA back into the ECU i loose the 12V

 

From the FSM:



You can see the aux. CO relay coil hard wired to ground on one side and powered by "ECU STA" signal on the other side. One would make the assumption that the ECU supplies 12 volt power to the CO relay coil to turn it on while starting. And with that hard ground connection, the aux. coil (STA-E1) should measure ~25 ohms, so by "solid ground" you mean well less than 25 ohms, then there must be a CO relay issue or a problem in the socket wiring:
- http://www.4crawler.com/4x4/CheapTri...ORelayLocation

 

4crawler,

i really appreciate your paitience. this electronic stuff is new to me.

alright let me wrap my head around this.....

The CO relay is measuring 20ohms between STA & E1

I get 12V from the ECU STA pin but as soon as i plug in the wire that connects to the CO relay STA terminal i loose voltage. where does the E1 wire go? should it be a ground?

if the fuel pump switch in the AFM was shot.....would that keep the truck from starting?

 

Well, then measure the resistance from the ECU STA connector pin to ground. If you see the same 20 ohms as the CO STA-E1 coil resistance, then the wiring is OK, but if you see less resistance there, you have a short someplace between the ECU connector and the CO relay socket.


Look at the diagram, see that thing below "E1", that is a ground connection.

If the STA-E1 winding does not pull in and turn on the relay, then it is up to the AFM Fc contact to do so (or else the FP test jumper). And if neither one work, then no CO relay and no power to the fuel pump.

 

hi im confussed i have 85 22re just redone the head and timming chain to specs. will spin over but wont run timing is right i have spark i have fuel to the rail pressure tested and have 38psi to the rail but no fuel to the cylinders ive checked fuses relays ecu unit all grounds are good i must be forgetting something please help confussed lol

 

Might check the injector wiring:

 

hi im confussed i have 85 22re just redone the head and timming chain to specs. will spin over but wont run timing is right i have spark i have fuel to the rail pressure tested and have 38psi to the rail but no fuel to the cylinders ive checked fuses relays ecu unit all grounds are good i must be forgetting something please help confussed lol

 

hi im confussed i have 85 22re just redone the head and timming chain to specs. will spin over but wont run timing is right i have spark i have fuel to the rail pressure tested and have 38psi to the rail but no fuel to the cylinders ive checked fuses relays ecu unit all grounds are good i must be forgetting something please help confussed lol

 

hey just put in a new ignition switch in the truck started went back out to start the truck will spin over and act like it wants to start but wont can anybody tell me which wires on the switch to check with a volt meter confussed again or just bypass the switch and put a push botton in HELP

 

I have a 1991 Toyota Pick up. Ran for three weeks after I bought it. Then got harder to start. I put a new fuel pump and filter in. Can poor fuel in the throttle body and runs until fuel runs out. Don't here the fuel pump. I got to looking around and found the 15 amp efi fuse blown and replace it. It is now blown again. After sitting a long while it did try to start on it's own for just a second and then went back to just turning over and over. Would like some help as well on why the fuse keeps blowing and what to do. Thanks and sure like the knowledge base on this site. I'm not a mechanic and need all the help I can get. JR

 

Common source or EFI fuse problems is a shorted O2 sensor wire, wire falls against hot exhaust, insulation melts, wires touch, fuse -> poof.

For fuel pump, see below:
- http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

 

to change a EFI to carb. i have to change the intake dist. fuel pump,is there anything else thanks fot the help