code 26 and stalls

[semlin]

hi folks

i am looking for suggestions here. picked up my 1994 80 to drive home from spokane just now and it stalled and died as i was taking an exit 5 minutes out from the airport.

it has a code 26. symptoms are -- it cranks fine but does not fire. after about 5 minutes it fired and ran for about 60 seconds then died again, this time it just lost power under acceleration like it as running out of gas.

i tried a replacement efi main fuse since i have a spare. it made no difference. checked the ground connections, fusible link and all seems good. removed the gas cap and it made no difference (thinking vapour lock?)

i am in a larry miller toyota now and fast approaching an overnight stay in spokane. any suggestions welcomed

 

[Timpanogos Slim]

26 is "air fuel mixture rich"

but diagnosis #2 in the FSM says:

(2) When the engine speed varies by more than 15 rpm over the preceding crank angle period during a period of 30 seconds during idling with the intake air, temp. 0C (32F) or above.

Which is a sciencey way of saying "this code can be thrown by idling rough"

Which means it may have nothing to do with running rich.

The points to check in the fsm are:

Engine ground bolt loose
Open in E 1 circuit
Injector circuit
Injector
Fuel line pressure
ECT sensor
Compression pressure
ECM

Try swapping the EFI relay with the horn relay?

 

[elhombre]

I would check the fuel pump relay for a fuel problem. Big tear in the air tube?

 

[Timpanogos Slim]

https://forum.ih8mud.com/80-series-...es-faq-item-recommend-keeping-copy-truck.html

 

[semlin]

thanks folks. i got home ok with some help from larry miller toyota in spokane. excellent guys. they started it instantly by spraying carb cleaner into the throttle body and then could not get it to stall out again. it just drove 150 miles home without an issue.

from slim's list
-i swapped in a spare efi relay i keep in the truck and it made no difference
-i inspected all the battery and ground connections and could see nothing amiss. the fusible links are good.
-the dealer tech swapped out relays with working spares and looked for trouble but could not find it.

since it won't start and also stalls out i am thinking bad intermittent wiring, fuel filter, or fuel pump.

thanks to the link to romer's troubleshooting guide. i had not seen that before. good stuff.

 

[semlin]

ok, not realtime anymore but the problem is back.

tuesday night i did 300 km with no issues
wednesday i commuted 4 miles to work and it would not start that night
tonight it started and got halfway home. it acted just like it was running out of gas.

but then the odd thing. i was cranking it trying to start and all of a sudden the ignition went completely dead. no dash lights and no crank. it did this 3 or 4 times then returned to cranking but not starting.

hopefully i can get it to run tomorrow long enough to get it home and in the garage.

i am thinking now this has to be an ignition problem. where could i have a failure that kills power to the fuel pump but lets the starter crank but also can kill all power to the ignition and the dash lights? i am thinking the main fuse in the engine bay, the ignition itself and maybe the fusible links. going to look at my ewd.

 

[Timpanogos Slim]

intermittent issues are sometimes caused by melted wiring harness near the EGR plumbing - passenger side firewall.

 

[semlin]

intermittent issues are sometimes caused by melted wiring harness near the EGR plumbing - passenger side firewall.

thanks. it is on my list to check when i get it home but i don't think that could account for the total ignition failure.

 

[jwilber]

that happened to me and it was the fusible links. couldnt tell by just looking at them had to load test them to figure it out

 

[Brentbba]

O2 sensor? 94's are notorious for eating these for lunch. Any idea how long it's been since they were changed? Both of them are an easy swap. Be sure to PB Blaster the nuts a day or two in advance of the work. You can also check the inboard wiring harness to that sensor as it does run fairly close to the EGR down tube.

 

[semlin]

O2 sensor? 94's are notorious for eating these for lunch. Any idea how long it's been since they were changed? Both of them are an easy swap. Be sure to PB Blaster the nuts a day or two in advance of the work. You can also check the inboard wiring harness to that sensor as it does run fairly close to the EGR down tube.

i looked at the o2 sensors early on. they look fine visually from the outside. i did not unclip the harness as i was not at home and have had the experience of a harness disintegrating.

at this stage i do not think a bad o2 sensor could cause all the symptoms which are:

-cranking strongly but not firing
-stalling while underway as if was running out of gas
-intermittently not turning over at all with dash trouble lights not coming on when trying to turn it over

i think the main problem is something is cutting off fuel supply. when it dies while underway it first loses power and then dies (there is no rough idle, it just becomes less powerful then stalls). also, the toyota tech was able to get it to fire by shooting carb cleaner into a port in the throttle body (although i have not been able to do this since)

whatever that problem is has now progressed to cutting off all power at the ignition, which seems like a relay problem. on reflection, last night there was also a momentary delay a couple of times when i tried to crank it before it cranked.

and i am going to check the egr wiring harness issue as one of the first spots once i get it home.

 

[semlin]

that happened to me and it was the fusible links. couldnt tell by just looking at them had to load test them to figure it out

this is intriguing. i have another 80. maybe i should switch them out.

 

[Dave 2000]

I have seen this a number of times when the battery is not bolted down secure, the battery moves and pulls on the wiring to the fusible link. The problem is the insulation hides the cable damage, get someone to sit in the car and hold the key over to crank, taking usual precautions keeping important parts of your body clear, give the cables a good push and pull and see if it makes any difference.

regards

Dave

 

[cruiserdan]

I would also look at the wiring attached to the alternator.

Look through this old thread. See if anything matches what you are experiencing.

https://forum.ih8mud.com/80-series-tech/193157-real-time-help.html

 

[semlin]

thanks dan. tricky t potentially to the rescue again. i do not know if i had headlights when it progressed to the point of having a totally dead ignition with no dash lights, but a bad connection at or near the alternator now makes the most sense. not ruling out the fusible links either.

 

[Timpanogos Slim]

O2 sensor? 94's are notorious for eating these for lunch. Any idea how long it's been since they were changed? Both of them are an easy swap. Be sure to PB Blaster the nuts a day or two in advance of the work. You can also check the inboard wiring harness to that sensor as it does run fairly close to the EGR down tube.

o2 sensors won't cause a stall.

26 sounds like an o2 sensor fault at first blush but combined with rough idle or stalling the o2 sensor is effectively ruled out by the FSM - which says straight out that code 26 can be caused by rough idle.

Also by the fact that the worst case scenario with o2 sensor failure is that your ecu runs it's 'safe' program and gets poor mpg / fails emissions.

 

[TrickyT]

I don't normally suggest replacing something unless you know it's bad, but given the symptoms and the low cost of the part, I'd say go ahead and replace the fusible links. A new one costs only $10-15, the symptoms you describe are similar to those caused by bad ones, and even if the new one doesn't fix the problem you then have the old one to keep in the glove box as a spare. And while you're under the hood you can check the white lead to the "B" terminal of the alternator as Dan suggests. If the insulation is cracked and/or exposed wires look like the copper is badly oxidized, then you need to splice in some new wiring.

 

[Brentbba]

o2 sensors won't cause a stall.

26 sounds like an o2 sensor fault at first blush but combined with rough idle or stalling the o2 sensor is effectively ruled out by the FSM - which says straight out that code 26 can be caused by rough idle.

Also by the fact that the worst case scenario with o2 sensor failure is that your ecu runs it's 'safe' program and gets poor mpg / fails emissions.

don't disagree with this at all. Usually I'll get a code and the truck is still drivable, tho a little rough. One time and one time only, was driving it to have it looked at and it died on the way there and wouldn't restart.

 

[semlin]

going to go wiggle wires and see if I can coax it home one mile.

 

[semlin]

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.