fj60 no power above 2500rpm

[jbeck53]

hey, ive been a member for awhile and a lurker for even longer. Ive never had much to say, so I never bothered to post, until now. Ive had my 87 60 for a few months now and am taking care of the small things little by little. My biggest problem is the lack of power my wagon has. It pulls really well till about 2500 rpm then it just flattens out and wont keep pulling. My stepfather just rebuilt my carb for me a couple days ago because of this problem. It definitely runs better and smoother but still hits a wall at about 2500-2700 rpm. My first thought was the secondary isn't opening. The kit did not come with a new diaphragm but we did inspect it and it seemed fine. This is my first cruiser so i guess im wondering if this is normal or if in fact something is wrong . Btw, i have done a full tune up as well. The only other problem i know of is a exhaust leak that i need to fix. Im not completely ignorant mechanically, but carbs are definitely not my thing.
Im looking forward to some thoughts and opinions.
thanks

 

[pismojim]

"I'm wondering if this is normal" - No, it's not normal, but it's not unheard of either.

"My first thought was the secondary isn't opening." - Hold that thought.

 

[tclark]

Have you messed with the timing any? My timing was all screwy and that's what it did. Adjusted timing and well, I won't say she flies now but it's better!

 

[chitown40]

Check the heat riser in the exhaust manifold. If the bi-metal coil fails to contract the flapper will remain closed and the exhaust will build up a lot of back pressure and will also cook your intake manifold causing it to crack.

 

[jbeck53]

timing is next on my list, i also ordered a manifold gasket so I will check out heat riser when i install that. Any more info on that? Will it be obvious if there is a problem? Sorry for sounding so ignorant, but well, as far as land cruisers go, i am.

 

[Brock]

It pulls really well till about 2500 rpm then it just flattens out and wont keep pulling.
thanks

My rig did the exact same thing....even after a full tuneup of wires, plugs, dizzy cap, rotor, air filter, fuel filter, etc. It now runs perfect but not positive what was the fix as a did quite a bit the past couple weeks so will list it all out and am sure one will fix your propblem:


1. Replaced ALL VACUUM LINES with silicone lines from Mcmaster Car...I got about 35 feet of 3mm and 10 feet of 6mm...had a piece of each left over of about 2-3 feet for emergencies on mine or other rigs. Did not fix it all but might have helps slightly.

2. Found an Intake Manifold leak so replaced Manifold gasket with the Toyota OEM gasket.

3. Replaced carb diaphragm with one that came in kit from CCOT. Took out old diaphragm..put in new one and was pain in ass getting it smooth and completely seated....used dental tool to help work to edges and tighten down screws...two person job or was for me...one holding and one working edges with tool.

4. Desmogged rig....removed smog pump and all attachments, removed EGR plugging where needed with block off plate and such as listed in MY DESMOG THREAD that is on here. I kept the vacuum advance for distributor, ac idle up, fuel decel cutoff and a couple others but everything else was removed.


Now the rig accelerates up through 3000 rpms with no hesitation or flat spots...mine would lose power at 2500 and require forever to get up to highway speeds. Now I can actually keep up and even beat some vehicles at stop lights when starting off.

I am not sure what made the difference but guessing something on vacuum was not working correctly...not sure if the intake manifold gasket issue would cause it or not.

Things I did NOT change:
I did not change timing...I did not change jets or settings on carb...I did not replace igniter or anything else related to the spark or fuel delivery to motor. Desmog, manifold gasket, valve cover gasket, oil cooler o-rings and crush washers and silicone vacuum lines.


Good luck....

 

[John McVicker]

Adjust your valves....8 and 16

John

 

[jbeck53]

thanks guys, I started replacing vacuum lines the other day, but i haven't finished. I plan to desmog it, but im a little intimidated to be honest. I ordered a manifold gasket from fundametalism or something like that, so when that arrives i will dig deeper. It has quite good power below 2500, more than i thought it would, but after that it really flatlines. I will adjust valves, timing, and fix exhaust leak, and think about desmoging it, lol. I will go from there. Thanks again.

 

[dadbeau]

Reviving old thread. Need help. Been working on this issue for 8+ years.

Same issue as above, no power above 2500 RPM in 1982 2F with 131,000 original miles. Starts, idles, runs smooth, secondary opens, but lack of power beyond 2300 RPM. It takes forever to get to highway speeds and it is challenged on the smallest hills. I have a 1969 and 1972 FST that both walk all over the 1982.

Here is what has been done;

1. Replaced all vacuum hoses and checked all routings. Maintains 19" vacuum at idle.
2. Tested all emission devices for function and replaced defective HIC valve and VCV.
3. EGR diaphragm functions well.
4. Compressions at 163, 159, 156, 146, 147 & 165 dry. (Corrected for 7500' altitude)
5. Valves adjusted.
6. New air filter.
7. New fuel filter.
8. Rebuilt carb 3 times just to make sure it was a close to perfect as I could get. Float level good. I've rebuilt 4 other 40's carbs with great results.
9. New plugs, rotor and cap timed at 8 - 9 degrees. Tried between 6 to 10 degrees. Both HAC and main diaphragm work fine. Weights free.
10. Plugs burn nice light tan color. Jets seem fine.
11. New PCV
12. Can't find any intake manifold leak.
13. Removed catalytic converter. No change. Reinstalled it.
14. Tried disabling the HAC. No change. Reinstalled it.
15. Tried isolating (direct connecting) advancer port to distributor. No change. Reinstalled it.
16. Tried by-passing BVSV's. No change.
17. I'm thinking about trying my 1972 carb on it and temporarily plugging most all the emission hoses to see if that may help.

Perhaps the distributor isn't advancing properly??

Any of the things I've checked that should be rechecked?

Any thoughts out there??

 

[OSS]

For a test ride around the block — disable the EGR valve by disconnecting its vacuum hose and plug the hose.
Take a test ride and accelerate hard. See if the power returns. Engine should ping a bit (or a lot) at certain RPMs and load. If you can't make it ping under any driving scenario with EGR disabled, and vacuum hoses are connected normally to distributor vacuum advancers, distributor isn't advancing the spark enough. Check actuation of vacuum advancers too.

If power returns with EGR disabled, the problem might be the EGR vacuum modulator. When EGR system is working correctly, flooring the gas pedal during full acceleration should disable EGR.

 

[morganism]

Also check the grommet on the vac hose going into brake booster, they rot quickly.

Do you have the weird valve on the looping hose down by the charcoal canister like the 60?

Does your gas tank whoosh when you open the cap after driving?

 

[dadbeau]

OSS and Morganism, thank you for the feedback.
Here is what I tried.

I disabled the egr and same no power result and no ping. When I put a test vacuum on the distributor primary port, the plate rotates fine and the diaphragm holds vacuum. The same with the high altitude distributor port, it rotates too. The HAC port gives me 4 to 6 degrees when running and I disable and enable the HAC. How much rotation should I see with the primary port with a vacuum pulled on it?

I checked the hose connections again (umteenth time) hoping I have missed something. No luck there.
I checked the brake booster hose and the booster. The hose isand the booster holds vacuum.

I do have the hose and valve at the charcoal canister. I accidentally broke the valve hose port last year removing the hose to check the valve, so I replace the valve.

The gas tank / cap does whoosh when I open it.

 

[OSS]

Only thing you haven't tried is the Fuel Pump. Maybe it's weak at higher RPMs.
If you replace it, do yourself a favor and use the genuine Toyota pump

 

[dadbeau]

It idles well, but runs rough coming up above idle through the mid-range.

 

[CruiserTrash]

@dadbeau

You’re holding 19” of manifold vacuum at 7500’ elevation? If the 1”/1000’ rule holds true (seems to be true when I change elevation), you’d be at 26.5” at sea level. This is at idle?

Asking because I’ve got 15” vacuum at idle at 5000’ elevation. I’m not chasing any lack-of-power issues right now (fuel pump and carb rebuild solved that for me), but I’ve always been curious about what more vacuum would get me.

 

[dadbeau]

I am getting 14.2” vacuum at 6500’ A.S.L. which translates to 17.75” wit altitude correction.

I just redid the intake manifold spray test with carb cleaner and am getting a decrease in rpm when sprayed at intake ports 1-2, 3-4 and port 5-6. I’ll try a manifold RE torque to see if it helps. May need a new manifold gasket. Surprise I didn’t see an rpm increase, however I do have the mixture screw pretty dialed lean.

 

[dadbeau]

Oops clarification on 14.2” at 7400’ ASL.

 

[Seth S]

Did anyone mention the possibility of a plugged CAT yet?

 

[BlackCat]

Did anyone mention the possibility of a plugged CAT yet?

No because he said he removed it with no change.

 

[Seth S]

No because he said he removed it with no change.

10-4. I skimmed the thread again but didnt see any mention...but it was a quick pass.