An Introduction and Request for Assistance with Diagnostics

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eth

Joined
May 23, 2026
Threads
1
Messages
2
Location
Pacific Northwest
Hello IH8MUD community! I'd finally like to introduce myself after lurking on the forums for the past couple of months. My name is Ethan and in July of 2025, I decided to purchase an 1985 FJ60 with it’s original desmogged 2F engine that I aptly named “TWUCKY” while on its 3000-mile maiden voyage to the Grand Canyon. Thankfully I ran into no issues during my trip until the last 40-miles when I discovered that some of the drive train bolts had wiggled themselves out. It was a quick fix and I ended up having no issues for a while.

But sometime around the middle of March, I started to run into an idling issue that began after driving about 70-miles on a highway. I was driving TWUCKY at around 2800-3000 RPM going 60-65 MPH and when I finally reached my exit and stopped at a light, the engine immediately died. I was able to start the engine again when I stepped on the gas pedal as I turned it over. I ended up revving my engine the entire drive to my girlfriend's apartment where I parked for the night. A chalked it up to be a weird thing until I was promptly informed the next morning when I had to step on the gas pedal to start the engine again.

After making my way home with a weird sensation of always having to press the gas pedal, even when not in motion, I noticed that my clear fuel filter that's installed before the carburetor appeared to be filled with rust. Assuming that this was the issue, I purchased a 40-micron fuel filter and installed it… to no avail. At this point and before I replaced the fuel filter, when I would start the engine cold, it would idle at around 500-700 RPM and over the course of 30 seconds slowly die.

After taking a quick two week break from TWUCKY to deal with schoolwork and other life obligations I finally started the engine back up again. And this time it idled with no issues at around 500 RPM. When I drove it down the street and stopped, the engine didn’t die and idled a little higher at around 700-800 RPM. I was ecstatic and glad I could finally drive my favorite vehicle to work and the grocery store again.

Until the following day when on my way home from work, the engine died when I came to a stop and let off the gas. The only major difference I could notice between the idling and non-idling day was that on the non-idling day, when I was at lower speeds of around 20-30 MPH, there was a delay and reluctance in increasing my speed when I pressed on the gas pedal. Both days I kept my cruising speed around 2200-2400 RPM with a max speed of 55 MPH other than my non-idling where I decided to push the engine a little harder going 2600-2800 RPM going 60 MPH for about 15 seconds.

I am at a complete loss when it comes to diagnosing and addressing this idling issue. From the searches I have done on this forum and the internet in general, I believe the cause could be:
  1. An idling issue with the carburetor that would require a rebuild and tune up related to the rust found in my old fuel filter.
  2. An idling issue caused by a vacuum leak that would require further assessment.
  3. A bad idle solenoid.
  4. The EGR valve not working appropriately.
  5. Vapor lock.
  6. An evil curse placed upon me by ancient demons who look to find ways to anguish the common man.
My main question is how do I diagnose and address this idling issue? Is there a common practice to diagnosing car issues in general?
Is the first thing I should do buying a vacuum gauge and seeing if I have a leak as it’s the easiest thing to start with?

When I have a chance, I'll record a video of it idling and post a link here.

Please note that while I do understand some basic concepts of how an internal combustion engine functions and turns gears that eventually move a vehicle forward, I am by no means a professional or even a novice at that. The most extensive mechanical work I have done is changing the brakes on my previous vehicle and replacing the u-joints on my drive-train. I have almost no experience with working on an engine other than replacing the oil. However, a major reason I bought TWUCKY was because I wanted to learn how to properly maintain and work on cars as it’s one of the largest purchases I’ll make in my lifetime and an important piece of equipment in the function of my life. The other reasons are because Land Cruisers are awesome and I think that this could be the last car I'll ever own if I maintain and treat it well.

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However, a major reason I bought TWUCKY was because I wanted to learn how to properly maintain and work on cars
You have a Golden Opportunity to get your feet wet here. I think what you need to start with is a simple, thorough tune-up. You'll adjust your valve clearance, change your plugs, maybe wires. Your carb may or may not need a rebuild, try just adjusting it first. You'll check other things, like the idle solenoid as you go. Hopefully rule some things out. It's probably not vapor lock.
You will need some new tools(!), a vacuum gauge is very handy, and a timing light with a tach.
It really is a simple engine, you've got a good-looking engine bay. There's probably a FSM on line here somewhere, find the FAQs and read up on the valve adjustment, it might be confusing the first time.
And welcome. :flipoff2:
 
there was a delay and reluctance in increasing my speed when I pressed on the gas pedal. Both days I kept my cruising speed around 2200-2400 RPM with a max speed of 55 MPH other than my non-idling where I decided to push the engine a little harder going 2600-2800 RPM going 60 MPH for about 15 seconds.
Does that sound like a leaky secondary vacuum diaphragm? Search "Paper Clip Test"
 
Looking at your engine compartment, it appears the PO has completed a desmog and replaced the charcoal canister. There is also a hose missing from the front of the air intake, not a huge deal but something to think about adding in the future. Depending on how well they performed this desmog exorcism, it can be a blessing or a curse. As others have stated really well above, start with baselining the engine (valve adjustment, distributor rotor and cap, fresh plugs and wires and an oil change). Spark plug wires are NLA from the dealer but NGK makes a good aftermarket set if I'm not mistaken. Once you have that completed, then the vacuum gauge will provide a lot of information, along with a compression test. Also, I always encourage folks in this situation to pull the spark plugs and take a picture of them and post here, indicating which cylinders they come from. This provides a great window into how the engine is running and can get you some good information without spending a lot of money.

Good luck and keep asking questions, this forum has a fantastic collective of folks and information to help get your truck sorted.

Cheers, James
 
Thank you all for the encouragement and education!
I have a 1981-1987 2F Engine Repair Manual I purchased a while ago and I'll go through the engine tune-up section:
  1. Drive belt
  2. Battery
  3. Engine oil
  4. Cooling system
  5. Air cleaner
  6. Hot air intake
  7. Spark plugs
  8. High tension cord
  9. Distributor
  10. Ignition timing
  11. Valve clearance
  12. Carburetor
  13. Idle speed adjustment
  14. Fast Idle speed
  15. Throttle positioner
  16. Compression pressure
I am currently waiting for my next paycheck so I can purchase a vacuum gauge, timing light with tachometer, feeler gauges, spark plugs, engine oil.
I'll send an update when I start moving through the list
 
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