code 26 and stalls

[semlin]

the vehicle has three noteworthy events i can think of that might be relevant

1. as per the below old thread link, the po "fixed" high rpm start up by adding a relay into the efi circuit in the main fuse block so that the ecu would have no power when ignition was off and would reset. i removed it and spliced the wires back to normal. i have looked very carefully at the repair i did and it seems sound.

https://forum.ih8mud.com/80-series-tech/531956-interesting-high-start-up-idle-fix.html

2. the main ground cable is too short. it was shortened a few months before this happened by the shop that switched my battery. they had to change the lug for the new terminal and i guess they cut all the slack out of it. the thing is now quite tight so i replaced it with a completely new ground cable even though it shows good continuity. then i realized that i needed the branch lines from the old one so i connected the old one as well at both ends. i can position the battery so there is no strain on the old cable for test purposes. it makes no difference.

3. the vehicle has a gentle front ender a few weeks before this happened. it damaged the bumper and valence. i can't see anywhere wire might be affected.

 

[TrickyT]

bump

so this thing has been sitting in my yard for months. i initially fixed this by putting my other 8o on the road. then i fixed it by buying a hundy.

now i am actually trying to fix it. i am using my working 1993 80 to borrow parts from and to compare reactions

so far

-swapped fusible links from my working 80
-added a second engine ground cable between the same points
-confirmed all ground cables have continuity
-checked all the connections and harness points i can near to the battery
-swapped out every ignition related fuse
-checked the dizzy looks ok
-confirmed i have spark at the #6 plug
-confirmed #6 plug is bone dry after mucho cranking
-inspected the harness under the egr (looks good)
-sprayed carb cleaner into the intake and got it to stumble

other than that, it stumbled when i first cranked it (after months) but then not at all. no repeat of the total ignition failure so far.

i tried hot wiring the fuel pump by jumping b+ and fp. this did nothing discernible. people have mentioned hearing the pump but in both 80s i can hear nothing when i jump those two points with ignition off. i can hear a whirring noise inside the cab when i turn the ignition on, but i can hear that whether or not the jumper is. one difference i noted was that the jumper wire got very hot in my working 80 but had no temperature change in the broke 80.

There may be two problems at play here. The primary problem sounds like a fuel delivery problem. I'll get to the possible second problem later.

Jumping B+ to FP should definitely make the fuel pump run when the ignition switch is on. First, make sure you are getting 12v at the B+ terminal with ignition on by using a multimeter. If no 12v, then either the EFI main relay is not getting energized, or the EFI main fuse or fusible links or relay itself are bad. If the fuse and fusible links and relay are all ok but still no 12v at the B+ terminal, then either the ECU is not getting power or is bad.

If you get 12v at B+ but no fuel delivery, then you'll need to do more troubleshooting because Toyota forgot to indicate where the FP terminal connects to in my EWD. The easiest way to test the fuel pump circuit is by accessing the fuel pump relay (bolted to the DS inner front fender). Unbolt it from the fender and disconnect the relay from its socket. Locate terminal #3 in the relay socket. If you are looking down at the socket and holding it so that there's a row of three terminals on top and a second row with only one terminal in the middle position on the bottom, then terminal #3 is the rightmost position in the top row. If you measure with an ohm meter from #3 to ground you should get between 0.5 - 1 ohm resistance. You can also connect a wire from terminal #3 to +12v on the battery. This should cause the fuel pump to run and you should easily be able to hear fuel running through the fuel rail.

If you can't hear fuel running in the fuel rail, or just aren't sure about it, disconnect the fuel return hose from the fuel pressure regulator. Whenever the fuel pump runs, fuel should pour out the regulator. (No smoking. )

If you're not getting fuel when you jump terminal #3 to 12v, then either it's a bad fuel pump or the fuel pump wiring.

The second issue you may have is the one where you say "everything went dead" -- also where you said you turned the key but the starter didn't engage for a couple of seconds. There's only a few things that would cause this: bad fusible links, bad AM1 fuse, bad ignition switch, or bad wiring or connector (assumes a healthy battery). Since this situation is easy to detect, I'd focus on the fuel delivery issue first.

Keep us posted!

 

[TrickyT]

I spent 5 minutes with my multimeter this morning and found out there is no connector inside the FP position of the underhood diagnostic connector, at least not on my 1997 fzj80. I'm not sure what year this change occurred. But it could be that the difference you saw between your '93 and '94 is because of this change. You need to verify that there is actually a metallic contact for the FP test point on your '94.

 

[semlin]

many thanks tom!

-i will check the fp terminal for power
-if negative i will jump it at the fuel pump relay
-if i still can't hear anything i will pop the fpr return line to check for fuel
-at that point i will head for the fuel pump and check for power

actually i think i will pull that ds kick panel first and look for trouble. i just remembered the "hot" lead for the po's efi relay bodge was taken from an ignition wire in there that i had to fix and iirc the factory alarm is wired in there somehow also.

 

[semlin]

ok,

fp has metal contacts
b+ gets 12 volts when ignition is on
i pulled the fpr return line and there is no fuel flow when b+ is jumped to fp
i also jumped 12v directly to the third terminal on the fuel pump relay plug -- no fuel flow but there was a clicking from the main fuse box.
-remembered that the toyota mechanic switched out the fuel pump relay for a known good relay
-checked and the efi main relay gets power on one terminal with power off, and two terminals with ignition on, same as the good 80. this confirms my old splice repairs work.
i cannot see anything amiss in the driver's kick panel

-next stop is directly testing the fuel pump.

 

[TrickyT]

OK, you are definitely zeroing in on the problem!

...
i also jumped 12v directly to the third terminal on the fuel pump relay plug -- no fuel flow but there was a clicking from the main fuse box...

Hmm. Something is unusual about that. Maybe you still had the jumper in between B+ and FP? If so you were probably backfeeding the main EFI relay when you jumpered terminal 3 to +12v.

Did you measure resistance between terminal #3 and ground? It should be about 1 ohm. If it's not, either the fuel pump is bad or the wiring between the relay and the pump is bad.

 

[semlin]

OK, you are definitely zeroing in on the problem!



Hmm. Something is unusual about that. Maybe you still had the jumper in between B+ and FP? If so you were probably backfeeding the main EFI relay when you jumpered terminal 3 to +12v.

Did you measure resistance between terminal #3 and ground? It should be about 1 ohm. If it's not, either the fuel pump is bad or the wiring between the relay and the pump is bad.

just double checked and i had it upside down and powered the #1 terminal. when i put power to #3 nothing at all happens. no fuel or click

resistance to ground at the battery is .63 ohms on #3

 

[TrickyT]

Fuel pump should definitely run when +12v is applied to terminal #3. Time to remove the 2nd row seats and open up the access panel to the fuel pump.

 

[TrickyT]

Once you get the access panel for the fuel pump removed you can unplug the connector between the fuel pump and wiring harness. The fuel pump side of the connector should have male pins, and pins #3 and #6 connect to the pump. A good pump should measure about 1 ohm resistance between these pins.

 

[semlin]

ok

-fuel pump works with 12 volts at the terminals. i get gas in the return line at the pressure regulator.

-but resistance from terminals 5 to 6 on the fp side fails the fsm test. i get 0.02 or 0.01 ohms on the 20 ohm multimeter scale, when i should get .2-3.0 ohms. fsm says replace fuel pump in that situation.

-the first time i measured resistance from the fuel pump relay socket terminal #3 to the positive terminal at the fuel pump i started at 9 ohms and it climbed steadily up to 12+ ohms when i stopped (20 ohm scale)

-according to the fsm fuel pump relay #3 also goes to the "fp" terminal in the dlc. so i measured resistance between those points and got 0.0

-then i measured from fp at the dlc to the fuel pump and got "1". this appeared to defy the laws of electiricity

-so i went back to repeat the fuel pump relay #3 to fuel pump #6 and again got 1. i tried several times and could not get any continuity.

from this i deduce i have an intermittent short between the fuel pump relay socket power and fuel pump that may have burned out my fuel pump.

there is no sign of damage near the fuel pump harness connectors so i am going to start hunting underneath for a damaged harness hunt. any suggestions on how this is routed are appreciated

i also could switch in the fuel pump from the other 80 but i suspect that if i did this and it worked it would then gradually burn out.

 

[TrickyT]

ok

-fuel pump works with 12 volts at the terminals. i get gas in the return line at the pressure regulator.

-but resistance from terminals 5 to 6 on the fp side fails the fsm test. i get 0.02 or 0.01 ohms on the 20 ohm multimeter scale, when i should get .2-3.0 ohms. fsm says replace fuel pump in that situation.

-the first time i measured resistance from the fuel pump relay socket terminal #3 to the positive terminal at the fuel pump i started at 9 ohms and it climbed steadily up to 12+ ohms when i stopped (20 ohm scale)

-according to the fsm fuel pump relay #3 also goes to the "fp" terminal in the dlc. so i measured resistance between those points and got 0.0

-then i measured from fp at the dlc to the fuel pump and got "1". this appeared to defy the laws of electiricity

-so i went back to repeat the fuel pump relay #3 to fuel pump #6 and again got 1. i tried several times and could not get any continuity.

from this i deduce i have an intermittent short between the fuel pump relay socket power and fuel pump that may have burned out my fuel pump.

there is no sign of damage near the fuel pump harness connectors so i am going to start hunting underneath for a damaged harness hunt. any suggestions on how this is routed are appreciated

i also could switch in the fuel pump from the other 80 but i suspect that if i did this and it worked it would then gradually burn out.

OK, lot of data here. First off, unless there's a short inside the fuel pump itself that would cause it to draw more current than it's rated for, a short in the wiring to the pump can't "burn out" the pump. Also, you said "fuel pump works with 12 volts at the terminals." So your fuel pump is fine.

From the different resistance readings you're getting, it sounds like you have an open connection or high resistance connection (not a "short") somewhere between the fuel pump relay and the pump. My (1997) FSM shows two connectors between those two points: ID2 and BO1. If you look in the "G" section in front part of your FSM it will show you where those connectors are. ID2 in inside the DS kick panel and BO1 is somewhere near the rear of the DS passenger door, although I can't tell if it's inside the vehicle or underneath the body. Either way you should start by examining both of those connectors for signs of damage or overheating (= high resistance).

The other possibility is that the wiring harness between the fuel pump relay and pump is damaged. That's less likely, but of course possible if it was physically abused somehow.

At least from the way I'm reading your post, I don't think there is any point to swapping the fuel pump from your good 80, since it sounds like the pump itself is OK.

Let me know if something I've written doesn't make sense to you, because it's possible I misinterpreted something you wrote in your post.

 

[TrickyT]

Oh, one more thing. First, unless you have a good quality multimeter like a Fluke 115 or equivalent, you can't put too much faith in resistance readings of ~3 ohms or less. For example, your meter may read 2 ohms and the real resistance is more like 0.5 ohms. Or your meter may read 0.5 and the real resistance is 2. It takes high quality meter components to accurately measure small resistances, and most inexpensive DVMs don't do it well. So I'm not sure the resistance you're getting between terminals 5 to 6 on the fuel pump connectors indicates a failed pump unit. More telling is that the pump works when 12v is applied to it. So that and the changing resistance values between relay terminal #3 and the connector at the pump is what's pointing to a bad connector or damaged harness somewhere in between those two points. Lastly, make sure you inspect the terminals in the relay socket and connectors at the fuel pump, since the problem could be there too.

 

[semlin]

thanks tom

i thought a voltage drop to a motor caused by high resistance could burn a motor out. in any event, my plan was to fix the wires and see how the pump did. do not want to switch.

i was just coming back to report only 0.1 ohms on the fuel pump resistor which fails the fsm. however, the working 80- has the same resistance. based on your comments i will not worry too much about that. i am using two multimeters one of which is "decent" but not a fluke by any stretch.

and i have just been trying to trace bo-1 and id2. bo-1 is in the "luggage" and id2 is near the "instrument panel area" according to my fsm. i will try your alternate locations. i have the centre console mostly off since it is the location of the fuel pump ground and i can see a harness coming out of the back of the centre console from underneath the truck heading back for parts unknown so i suspect that may be the "luggage"

 

[TrickyT]

...i thought a voltage drop to a motor caused by high resistance could burn a motor out...

That can happen, especially with AC motors under high load. Like a refrigerator compressor trying to run during a brownout situation. But since your pump runs when connected to 12v and pumps gas to the fuel rail, I think yours is fine.

 

[semlin]

found id2 in the ds kick panel. disconnected it and tested in either direction

from wire 15 on the cowl side to fuel pump relay and to fp in the dlc i get 0.0. that matches the fsm. and indicates the problem is the other direction.

from wire 15 on the floor side of id2 to fuel pump terminal #6 i get 1.0 this is a thick red/green wire with silver blotches. this wire matches the fsm for colour and location as correctt does not work.

from wire 18 on the floor side to fuel pump terminal #6 i get 0.0 this is a normal yellow/red wire with silver blotches

i have tripled checked how they line up and the fsm diagram.

 

[semlin]

meanwhile i cannot find bo1. it's not under the central console. i traced the wires from id2 towards the rear ds quarter panel and pulled that off. no sign of it.

i think it may be the harness plug at the fuel pump itself. that is a grey 6 pin plug but with one plug vacant. i thought the fsm did not list terminal plugs but maybe it does.

 

[TrickyT]

...
from wire 15 on the floor side of id2 to fuel pump terminal #6 i get 1.0 this is a thick red/green wire with silver blotches. this wire matches the fsm for colour and location as correctt does not work...

I take it 1.0 on your meter means infinite resistance (i.e. an open circuit)?

meanwhile i cannot find bo1. it's not under the central console. i traced the wires from id2 towards the rear ds quarter panel and pulled that off. no sign of it.

i think it may be the harness plug at the fuel pump itself. that is a grey 6 pin plug but with one plug vacant. i thought the fsm did not list terminal plugs but maybe it does.

My FSM doesn't show BO1 to be right at the fuel pump. Rather it's "close to" the DS rear tire and then there's a length of harness that goes to the fp. So I think ya gotta keep looking.

 

[TrickyT]

Can you find the "thick red/green wire with silver blotches" in the harness back by the DS passenger door? One possible option would then be to run a new wire from there to the FP connector, bypassing BO1 altogether.

I think you're getting real close to finding the fault though.

 

[semlin]

foubd bo1 and found the problem. it is under the sill under the read ds door tucked into the rocker panel and as you can see it needs a little werk.

 

[semlin]

the power line is severed and very corroded and two other lines are nicely scorched. not sure if a critter got it or it just rotted.