Intermittent power loss 91 landcruiser

[Alleycats]

Any pressure release when you open the gas cap (venting)?

 

[Flylow 72]

Yes there is, but no more or less than one would expect

 

[SUMMIT CRUISERS]

I may have missed it but did you replace the fuel pump sock/strainer?

 

[bass 1]

What about battery terminals? I had a 4Runner that would act up and stall (with ANY electrical load.... ex: brake lights). Turned out to be an awful battery-to-ground connection. Its free, so might as well clean your battery terminals and tighten them down to see if it helps. Also maybe the ground straps are in a similar condition as your fusible link.

 

[Flylow 72]

I may have missed it but did you replace the fuel pump sock/strainer?

Yep did that and the inline filter.

 

[Flylow 72]

What about battery terminals? I had a 4Runner that would act up and stall (with ANY electrical load.... ex: brake lights). Turned out to be an awful battery-to-ground connection. Its free, so might as well clean your battery terminals and tighten them down to see if it helps. Also maybe the ground straps are in a similar condition as your fusible link.

Terminals both look good, haven't looked specifically at ground straps. At this point I'm open to any suggestions.

 

[Flylow 72]

Don't pull your hair out. You're chasing down an intermittent problem which is the most difficult to troubleshoot. We will all hold your hand and wipe away your tears while you go through this and you will be better off in the end.

Any thoughts on what to do next?

 

[Flylow 72]

Well, it wasn't a bad Throttle Position Sensor, as I just replaced it today. Back to the drawing board. Again any ideas, happy to listen.

 

[SUMMIT CRUISERS]

Well, it wasn't a bad Throttle Position Sensor, as I just replaced it today. Back to the drawing board. Again any ideas, happy to listen.

In your original post you mentioned you replaced the inline fuel filter and found water on the pump side. Have you drained the bottoms off the tank via threaded plug? If you had water originally going into the filter, that could happen again unless the tank had the bottoms (water) drained off. You may also need to change the filter again. If no codes are showing up, then a fuel delivery issue is more likely the problem.

 

[jonheld]

This keeps circling around in my head to an electrical issue. You said that when the problem occurs, the truck will idle regardless of throttle position. That's telling me that the ECU is not "seeing" the throttle position or being fooled somehow. However it is not throwing codes to indicate a sensor issue.
The 3 sensors in play here are the TPS, ISC, and AFM. They all work together to give the ECU the correct information so it can fire the injectors properly. The O2 sensors then trim fuel delivery, but IMO they're secondary to this issue.

 

[Tally FJ80]

It may or may not help yours but it did fix mine. I have a 91 same symptoms. Just finished a desmog on it and so far smooth as glass idle, no power loss and better torque and acceleration. I did the full desmog not the bb trick. Although both may work the same. Good luck.

 

[Flylow 72]

In your original post you mentioned you replaced the inline fuel filter and found water on the pump side. Have you drained the bottoms off the tank via threaded plug? If you had water originally going into the filter, that could happen again unless the tank had the bottoms (water) drained off. You may also need to change the filter again. If no codes are showing up, then a fuel delivery issue is more likely the problem.

I thought about the water in the fuel filter and have gone back and disconnected the pump side of the line leading to the filter. I sort of hoped that I would drain some more water but the fuel I collected was clean. I have not drained any fuel out of the tank but I am going to do that next.

 

[Flylow 72]

It may or may not help yours but it did fix mine. I have a 91 same symptoms. Just finished a desmog on it and so far smooth as glass idle, no power loss and better torque and acceleration. I did the full desmog not the bb trick. Although both may work the same. Good luck.

I would absolutely de smog this vehicle as there is no emission to pass here. That being said, dealing with my current issue has overshadowed any additional work I would consider doing to this truck. By the way I drove it yesterday and manually shifted it as to keep the RPM's in a higher range, and no problems. Which may or may not be complete coincidence. When it's running it runs great. Ha-ha.