2F Hesitation/stumbling at various RPMs (2 Viewers)

[Yankee]

Hello all, I'm having a weird and frustrating issue with my 1985 2F FJ60 that I was hoping I could get assistance for.

A couple of weeks ago it was running fine and dandy, then one night on my return home from Taco Tuesday it started to pull and hesitate from 1500-2000 RPM intermittently. I first thought it was a fuel issue as it was acting like it was starving for fuel at these random moments, so I replaced the fuel pump with a new OEM one from @ToyotaMatt.

Well, I took the 'ole girl out for a ride around the block today as the weather has finally started to clear, and the issue still persists. I'm unsure as to how to proceed now as this has left me stumped and frustrated. I just want to be able to drive the 60 around with some peace of mind that it's running right.

What are some of the other items to check replace to diagnose this issue? Cracked/faulty intake manifold? Bad fuel filter? Carburetor? Vacuum leaks? The engine bay is mostly desmogged besides the carb and dizzy, so the EGR and air pump are gone. I also mention the intake/exhaust manifold because there's a loud squeak/chirp that seemingly comes from the manifolds at medium RPM/load.

Any and all help would be greatly appreciated!

 

[g-man]

Most common issue with hesitation is the fuel cut solenoid not working or not having an electrical connection. Check the green plug at the carb for a good connection and follow the wires and make sure they are all connected. check to make sure you hear the "click" inside the carb when you turn the key to the "on" or ACC position (the one before it actually cranks the motor) Usually it is a bad electrical connection that causes the failure. Also common with the FCS issue is backfiring, starting and stalling, and the hesitation while trying to hold the accelerator pedal in that range.

 

[OSS]

Stumbling, bucking and hesitation at higher rpms when trying to drive are all classic symptoms of fuel starvation. Not a vacuum leak.
Vacuum leak issues are most noticeable at idle.

Likely your carburetor has never been overhauled, and the odds are high that it’s not functioning properly.
At some point things start malfunctioning.
Maybe there was a bit of junk floating around in the carburetor float bowl — and one day it blocked the jet. Nothing you did or could have done would have prevented it.

My guess?
Carburetor.

 

[k91]

When was the last time you changed the fuel filter?

 

[Yankee]

Thanks for the suggestions y'all! I'm not sure when the fuel filter was last replaced as I only got the 60 back last September @k91.

I pulled the carb today to get it off and ready for inspection. I took the top off and pulled all the various jets and cleaned around with carb clean and compressed air. Going to look at it again tomorrow and possibly reinstall to see if that helps. If not, then I'll probably send it off to be repaired.

 

[Chris1989landy]

replace your points and condenser in the dissy, thank me later

 

[Bama4door]

60 dizzy’s don’t have points. They changed to electronic ignition around Sept of 1977 on the fj40.

 

[cruisermatt]

replace your points and condenser in the dissy, thank me later

Your Australian 60 would have points, but the OP's U.S. vehicle does not.

 

[Yankee]

Ok, so I took the intake and exhaust manifolds off and got them resurfaced at a local machine shop while messing with the carb. I'm having an issue with these two bolts that connect the I take and exhaust manifolds together

The bolt holes stripped on the intake side and I cant find the size of the bolts in order to fix the holes/get new bolts. They're neither M10 (too small) or M12 (too big), so are they standard? Any help would be appreciated

 

[HemiAlex]

I had a very very similar issue.

If you haven't done the green wire mod..

DO it now! I am not a great mechanic by any means and it shows. I did a lot of work to my truck based on what I have read here and asking some questions. I desmogged my truck a month ago, and it would not idle for the life of me, until the other day. I even disconnected the idle selenoid and...

forum.ih8mud.com

The stumble and misfire is back. After a round of frantic diagnosing and parts replacing, it’s driving terribly.

-checked for vaccum leaks. Couldn’t find any.
-inspected all vaccum lines. No cracks.
-replaced the city racer with a factory aisan. No change
-inspected and replaced the distributor cab, rotor and plugs. No fouling or issues there.
-replaced the fuel filter. Looked better since I’ve replaced the fuel tank.

Valves were adjusted about 15,000 miles ago in January, distributor was rebuilt by JimC last year, intake gasket was replaced before Xmas, fuel tank done a few months ago...and we just got done with a trouble free trip of 3,000 miles stopping at every gas station we saw.

It was idling poorly the other day, and stalling at idle. I played with the carb and it got better. The following day it went away. Now it’s bucking under any load, not accelerating past 2000 rpm, it will buck back after a shift and has a ton of hesitation.

If it is a tank of bad fuel, I’ve topped off 12 gallons somewhere that i trust, added iso HEET Incase there is water in the fuel and I’m trying to burn out most of this tank of fuel so I can drain the tank completely.

It just figures that I start playing with our 40 and this truck throws a fit.

I’m out of ideas.

Each one has its own solenoid. Same issues with both. It was completely fine until that 15 min mark.

Hot vacuum is 18. Not bad for the 690 idle on a really tired engine.

It was across all cylinders. I unplugged a plug wire, and that really sounded like a dead cylinder. This is completely uniform across it all. A true general misfire.

You can hear small pops at idle, but most notably at a 2000 rpm with load or no load, the the break up starts.


I replied to all of this for sake of completeness, but we are 99% sure we figured it out. I want to put this down as a record so nobody else has to fight what I went through.

I was honestly ready to pop my spare distributor in. It was getting bad. I had thoughts of pulling the 2F out if that didn't work.

Then, I messaged an land cruiser guru who works for a builder that a friend recently purchased a truck from. I explain the situation and he responds with something completely out of left field.

"Have you tried unplugging the tach wire to the coil? There are two separate connectors that go into the ignitor, one supplies the tach and I've seen this cause an odd stumble before. It's either a malfunction in the tach or perhaps the amplifier for the AC is going bad. The most recent one I dealt with bypassed the AC amplifier and had a separate switch to power the AC Clutch. He didn't care that the tach didn't work..."


My mind was blown. I unplugged the first wire and the truck wouldn't fire up. Plugged that one in, unplugged the next one and saw my tach was dead and the compressor wouldn't kick on. I drove around til the truck got to 187* and then I started flogging it for the next 30 mins. No issues. The truck ran flawlessly. It would have started messing up by now. I've driven it the last two days for at least an hour every day with no issues.

I can live with a known issue. I purchased a used AC amplifier and I'm going to try that next. I think since that is the only complex board on the truck, its not unreasonable for that to be causing interference, or maybe messing with the load of the ac compressor to cause this misfire. Once I swap my newer one in, I'm going to de-solder the RPM sensing portion of my old amplifier and try that. I never start the truck with the compressor on anyway, so it isn't a big deal. I really doubt that the tach is what's causing an issue, but I'm willing to throw another used one on for the sake of testing. It really felt like it had a soft touch rev limiter in place. The only thing that's smart enough to break and try to act like that is the AC Amp.

If anyone has to deal with this kind of strange issue....I'll document it as best I can. I never in a million years would have gone down this route if I hadn't reached out for help.

 

[g-man]

partsouq shows these Toyota bolts as substitutes for the manifold joint:

 

[scottcb]

Post in thread 'Stumbling Issue PLEASE HELP!!!'
Stumbling Issue PLEASE HELP!!! - https://forum.ih8mud.com/threads/stumbling-issue-please-help.550766/post-7273491

 

[Yankee]

Ok everyone I'm back with some updates! I got the manifolds put back onto the engine with new gaskets and got it all bolted up with the exhaust downpipe and the carburetor.

I fired it up, and well, there is an awful high-pitched whistling and the truck is backfiring and sounds like it is down 2 cylinders. Could I have installed the manifold gasket incorrectly? Is too much air being sucked into the motor through the manifolds and it's causing these issues? Do I need to pull the manifolds off again and re-inspect? Here are some photos of the manifolds in place with the new gasket:

I'm also wondering if the gap between the exhaust and intake manifold is too big as seen in the 2nd image?

 

[Yankee]

Well I took everything back apart again to somehow figure out what the issue is. Got the manifolds back off and back on the workbench.

Not really sure what's wrong at this point and am seriously considering taking it into a shop and paying them to figure it out and fix it at this point.

One thing I did notice was this piece here on the far right side of the exhaust manifold

It seems bent on not fully forming to the manifold and had two gaskets between it and the manifold, but it still looked like it wasn't forming a proper seal. Maybe this was causing the issue?

I won't be able to figure that out right now however as the stud on the left side broke in half and doesn't want to be extracted with my extraction set.

Also, is this Fel-Pro gasket for the manifolds a good one to use?

Any input would be appreciated.

 

[OSS]

That plate you removed on the rear of the manifold arm is a previous owner attempt to block off the EGR exhaust port. Normally a pipe bolts to that spot that leads to the EGR cooler then up to the EGR valve.

There’s nothing wrong with doing that once the EGR system is removed but that plate may have been leaking. It would be an exhaust leak, not a vacuum leak.
Exhaust leaks can sound unpleasant but they typically don’t suck power. Engine will still run fine but sound yucky.

 

[Yankee]

That plate you removed on the rear of the manifold arm is a previous owner attempt to block off the EGR exhaust port. Normally a pipe bolts to that spot that leads to the EGR cooler then up to the EGR valve.

There’s nothing wrong with doing that once the EGR system is removed but that plate may have been leaking. It would be an exhaust leak, not a vacuum leak.
Exhaust leaks can sound unpleasant but they typically don’t suck power. Engine will still run fine but sound yucky.

Yeah I was thinking it'd cause an exhaust leak as well, but that wouldn't cause the issue i started having once I had put everything back together. what seems to be the issue after I put the manifolds and carburetor back on is maybe there's an intake leak through the gasket, but I'm not sure as the front has been resurfaced and a new gasket was put in place.

Maybe it's a vacuum leak somewhere that came about when I tore it all apart? That wouldn't explain the loud whistling noise coming from the intake manifold however. Is there a way to test whether it's the intake or a vacuum issue?

 

[OSS]

Big Vacuum leaks can be seen on a vacuum gauge when the engine is idling - vacuum is low.
On a tight engine at sea level it should be around 20 inHg. At higher elevations it’s lower because the air is thinner.
That gap you pointed out on the exhaust manifold arms is normal. There’s supposed to be a gap.

A vacuum leak pulling air past a right sized oriface can definitely whistle. An exhaust leak generally creates a pft, pft, pft sound

 

[OSS]

Maybe one way to find that damn whistling sound is get the engine idling so it whistles — then start spraying a water squirt via a hand pump at every suspicious joint you see. If the water covers the noisy air leak for even a moment, you might be able to hear the difference - no whistling for a second or too.
Then explore that area more carefully

 

[OSS]

If the manifold assembly has never been machined flat by a machinist in the past, it’s guaranteed to be warped and not sitting flush on the head. At this point- all virgin 2F manifold assemblies are warped. Mine was warped in 1988 when the engine only had 42K on it.

 

[Yankee]

If the manifold assembly has never been machined flat by a machinist in the past, it’s guaranteed to be warped and not sitting flush on the head. At this point- all virgin 2F manifold assemblies are warped. Mine was warped in 1988 when the engine only had 42K on it.

The manifold was machined flat before I put it on.