The Classic FJ60 "Stumbling/Hesitating Acceleration/Running Problem

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Sep 23, 2003
I am reposting a question from the old Sor.archive in the hopes that there is some new insights out there. I have the same problem and am stumped beyond the simple fixes. I hope the experts can help:

From DogBoy #1007:

Sorry for the long topic title but it seems that there is a very common problem with a great deal of FJ60's out there, (mine included) and after reading this forum for several months now, I have yet to find a definitive answer to our (all the 60's owners) dilema.

Here's the problem using descriptors from several earlier posts:
•engine "stumbles/hesitates/sputters/stutters/runs rough/chokes out/feels fuel starved/or almost dies" under acceleration, especially in the lower RPM range of the power band.
•in several cases, the engine will idle normally without problem until a load is put on the motor (starting off in 1rst and then into 2nd gear, pulling a load, or climbing a hill...).
• also, many of the posts describe this as being a consistantly intermitant problem...
• sometimes it runs great for a few minutes (10-20) and then starts acting up
• and sometimes it will start/run/drive normally for several miles during a trip and then inexplicably run rough, and then just as mysteriously clear up for the duration of the trip.

Many probable causes have been suggested in reply: • faulty carburation
• poor fuel delivery system
• leaky or plugged fuel filler and fuel breather tubes
• clogged fuel filters
• blocked air filter/air intake
• faulty ignition coil/limited spark
• vacume lines leaks
• faulty EGR valve or other emission equipment failure
• and/or potential exhaust system issue (bad cat converter, O2 sensor, exhaust manifold leak).

Most of the solutions focus on a faulty EGR, with fixes including bypassing the EGR.

What are your ideas? Thanks.
Great post man! I have the same problems with my 87 FJ60 which has 203,000 mi. I have made similar posts in the past here with no definitive answers. What's the deal?(no offense to this board, but surely someone has a answer) The old post from SOR pretty much nailed it--> a very common and agravating problem for 60's with no definitive fix.

Mine usually only does this at normal operating temps and climbing an incline(90% of time). Never on a cold motor. Just like the post says thru the "low rpm band". It is a really embarassing problem. My girlfriend gets a good laugh when this happens every time. I try to humor her, but the steam from my ears gives it away every time. It has made me mad enough(among other non LC issues) to the point where I am halfway trying to sell it. :'(

If I ever get time to chase this mystery I'm gonna replace the fuel pump & filter, inspect the emmision/vac sys with a fine tooth comb, and rebuild the carb. I'd love to cure this ailment with one fix, but I guess there's no way??

If anyone out there can lend some specific advice or experience please let us know. :D
I went through this same thing after I bought my Land Cruiser ('84 FJ60) years ago. Everyone suggested the "fuel issues" route, but after replacing the fuel pump, filter, gas cap, and rebuilding the carb; the problem still existed.

Time for plan B: After reading an article in Toyota Trails about Cruisers and vaccum, I decided to install a vaccum gauge in the truck. BTW- The article is posted in the tech section of this site. I quickly learned that EVERYTIME my truck wouldn't run right, it was evident on the vaccum gauge. I then knew that I had a vaccum leak somewhere. I had already replaced all of the rubber vaccum hoses, so I knew that they were fine. I pulled the EGR system, carb, and intake and exhaust manifolds. I quickly discovered a 3-4" crack in the intake manifold. This explained why the truck, at certain temps. would run fine, then other times it would run like crap. I had a machine shop weld the crack in the intake manifold and machine the mounting surfaces of the intake and exhaust manifolds. Then reinstalled everything. My truck was healed, it had never run better. The vaccum gauge was reading very consistant.

It was not a difficult repair, it just took a while. All of the vaccum hoses can look very intimidating, but they are not. Just take alot of pictures before you tear into it and label as you go.

Hope this helps.


Welcome aboard!! Thanks for the very informative post. You obviously speak from experience on this issue and it translated into an excellent post. It is something that some people on here could learn from. Not that opinions are bad or to point any fingers, but hard founded advice goes a loooonnnng way with me. :cheers:

Anyway, after I read the link in the tech section some time ago I was all about installing a vaccuum guage. But at about that time the water pump locked up and the clutch went out. Needless to say I never got anywhere on the vacc gauge.

Now with the aformentioned problems corrected I am chasing the stumble, hesitation...... I plan on installing the vac gauge soon and seeing where that gets me. I'll post up on the findings (barring any major mechanical issues that like to pop up at the best times)

Once again welcome to the best LC board, PERIOD
fj60s are famous for intake manifold cracks/leaks once you get over 100k miles. I bought a new manifold for mine a while back and had the carb rebuilt, which solved lots of problems.
Well maybe I can shed some light as that SOR post originated from me..... Here's what I've learned and done since that post:

• was successful in eliminating all of the problematic symptoms by simply cutting the EGR valve out of the emissions system: disconnected the vacuum hoses leading from the EGR where they attach to the High Altitude Compensator and plugged the hose ends with (this is high tech) golf tees secured in place with electrical tape. Then proceeded to cap the open ports on the High Altitude Compensator with PVC caps picked up at the local auto parts store. The truck immediately ran great and flagged the EGR valve as the culprit. A year later and I'm still running strong and problem free with the poor man's fix....I guess I just got "teed off"....(bad pun intended) Check out the pic at the end of this reply:

• this "fix" was a last resort and a simple way to test and evaluate which component was troublesome, and although I'm still running with it, the EGR will have to be replaced before relicensing again next year. It also came after several other repairs to the fuel delivery system including: a carb rebuild, new accelerator pump, new carb base plate, new fuel filter, and charcoal canister elbow hose. In addition, all of the spark plugs were replaced, along with a new cap and rotor, a K&N air filter, and a tune-up (our valves didn't need adjusting but I would recommend checking and adjusting these too).

• I've since learned how interdependant all of the vacuum lines are and how even having one leaking, loose, or removed can have a big impact on how the motor runs -- check out your entire vacuum system for cracked lines, leaky hoses, bad connections, etc.... All of the little vacuum switches in the system (BVSV's, VTV's, etc...) if blocked, can also wreak havoc. Pull the top cover on your HAC (high altitude compensator) and check the filter element within for excessive dirt and blockage too. Basically, it could be a series of little problems in various systems contributing to make one big performance problem but the EGR valve is so notorious for being problematic, it's an easy place to start.

Hope any of this helps,

-dogboy- '87 FJ60

the "poor man's EGR fix":
Actually, the thing in the picture is the EGR modulator not the HAC valve. If plugging the hose shown made the engine run smoother, then the EGR valve itself is likely ok. Its the modulator that needs to be replaced - or the hoses leading to it are faulty. A common problem, especially when the carb has been removed, is misconnection of the four vac hoses on the valve cover side of the carb. Two of these affect EGR operation. If misconnected, you may be keeping the EGR open when its supposed to be closed. HTH. Also, don't you get any knocking with the EGR disabled?
Hey Everybody, I think we have a ringer here!..... O.K. 60wag, time to come clean and level with us all: what's your real day job? I've been reading your posts for a few months now and I've got a sneaking suspicion that you're actually a Toyota mechanic or someone who has spent waaaaay too much time around the business end of LandCruisers ;) ha ha ha ha ha

No seriously, I stand humbly corrected. Looks like I need to pay closer attention to my repair manuals. The filter element in my EGR modulator (not my HAC) is filthy dirty, which when it was connected to the EGR valve probably contributed to (or caused) the crummy running condition. Do you know where to find just the replacement filter without having to cough up the $90+ for the entire EGR modulator? And, if it is a misconnected vacuum hose leading from the carb to the modulator, will the under-the-hood factory vacuum diagram show this relationship? If so, where can I find a replacement diagram as battery acid has claimed the original?

The engine is running great, maybe a tad too rich but strong. It's been a little over a year since my "fix" and I haven't experienced any knocking yet (knock on wood). Also have been getting really decent gas mileage with a 13-14 mpg around town and about 15-16 mpg on the highway, this in spite of the addition of a 3" lift, 33 x 10.5's, and a Kaymar rear bumper with tire carrier. Who knows?

Hey if I can make the 2F run any better or more efficiently, please let me (and all of the 60 owners) know -- I'm all ears :D

-dogboy- '87 FJ60
by the way, what does "HTH" stand for or mean?

-dogboy- '87 FJ60
No, I'm not a mechanic although the number of machines that I end up repairing at work makes me feel like one sometimes. I recently spent some time studying the EGR system in the emissions book because I'm trying to track down a random knocking issue with my 84FJ60. I haven't solved it, but I know a lot more about EGRs than I used to. According to a reputable source, "somtimes EGR modulators will test good but not actually function correctly." I think mine is working but I'd like to swap in a known good one just to make sure. The cost of a new one is holding me back. I doubt the dirt in filter is the source of your problem, but I'm not sure. The emissions book says to blow the filter out with compressed air and reuse it. The Toyota emissions book has the complete vac hose routing info as well as procedures for testing each emissions system. I have found it invaluable. I assume you don't have access to one. I might try to post a picture that at least shows the vac hose routing on the valve cover side of the carb. I always suspect these connections because I have personally seen two 60s that have had carb work done and the hoses messed up.
It would be great if you could post some pics/diagrams. All I have is a Hayne's Manual. ??? While it is good for general info and the emmisions sections is fairly impressive, it lacks the specific info/diagrams (for the 2F ) needed to pinpoint this problem.
I guess I need to get off my wallet and order some FSM's.
Keep the posts coming, it sounds like we're starting to make some headway.


ps: Dogboy--> I'm diggin' the golf tees :beer: :beer: Some may call it "shad tree" work, but I garuntee you, it's not below me.
Here is the vac routing from the 1981 emissions book for the 2F. this should cover all US spec FJ60s. The hoses labled 1-4 in red are ones that I've seen misconnected, but you might as well check the whole system.

Thanks for these great replies. I must admit, I made the post last week then headed to a conference. I spent a rather large amount of time at the conference contemplating the potential replies to this post. I know it is a pathetic admission, but definitely not one I would share with my wife.

Good vacuum line schematics can be had, usually for free, from the parts desk at a Toyota shop. Those lines are not intuitive and are easily misplaced. I would recommend buying a roll of the correct gauge, pulling all the old stuff, and following the schematics to replace with new stuff. I went this route and found several cracked and one fouled line.

Because the EGR Modulator likely wears out over time, or becomes particularly problematic, bypassing it seems to be the suggestion. If this is bypassed, what is to stop one from completely desmogging? I mean it seems like that is the likely next step.
Well my FJ60 had the stumble at around 2500 rpm. Happen to read this post a while back and decided to check out the High Altitude compensator. Well the hoses were not hooked up right and the air intake hose and filter were both clogged. Cleaned them out and it ran better but still not right. Went a head and put in a new HAC and it does not stumble anymore. :cheers:
Woody, thanks for a great resource, have a :beer: on me.
This should be a "Sticky" !!!!

Ok my 87 fj60 has a stumble at 1500rpm. I found it is getting a big dump of fuel though the main jet. Fuel leval looks ok in the bowl. I did desmog it. No cat, egr, air pump,or O2 sensor. I have rebuilt the carb and replaced the intake manifold, and the related gaskets. How does the high altitude compesator work? And the fuel shut off solenoid just shuts the fuel off when the key is off right? Thanks for any ideas
This should be a "Sticky" !!!!


I would agree.

I bumped the thread because I've noticed a lot of de-smog questions popping up...and this thread (printed out) was included in the thick file of receipts, tech articles, and schematics I got from Chi-Town40 when I bought his 60. He did the de-smog before I bought the vehicle and I have absolutly no stumbling or hesitation problems so I would say he did it right. He did a lot of explaining about what he did and how he set it up that it kept my head spinning. Between driving the vehicle while simultaniously looking out for downtown Chicago traffic, listening to, and getting a feel for the vehicle, some of his explanation went over my head.

Just thought it might be helpful.


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