loss of power on highway- won't go over 45 mph!

[40Flipper]

Got the engine up to 4100 rpms in neutral no problem.

Now the engine is staying revved up when I slow down so I believe that is the diaphragm. I have a new one to be put in anyway.

Drove it again and you really need it floored in 4th gear and even then it's very slow gaining speed. I need to downshift on the slightest hill.

What is the stock axle gearing in a Canadian spec 70?

 

[hoser]

What is the stock axle gearing in a Canadian spec 70?

3.7 ratio

 

[40Flipper]

so according to that rear end and this chart, I do need to re-gear the truck since I have 31" tires

 

[Sporin]

go right to 4.56's, you know you want 35's

 

[prado t]

There is what is called a SEDIMENTER on the inside fender I believe on the BJ70 with a 10mm wrench open the little bolt on top pour sea foam into it , (could be plugged with s*** over the years) Get it running right first and then modify

 

[40Flipper]

Already seafoamed it. Still craps out. I've checked out a few other places and it seems to be the universal opinion that the axle ratio needs a fixin....

 

[LDowney]

so according to that rear end and this chart, I do need to re-gear the truck since I have 31" tires

I ran 33" by 9.5"s on my old '85 BJ70 that was naturally asperated and it had power to hold speed up most moderate hills. If the hill was steep and/or long, then I would have to down shift. My current BJ70 is an '86 with a turbo and it performs better on hills, but down shifting still occurs. I am skeptical that gearing is going to resolve your situation.

Do you have a smaller diameter set of tires or borrow a set that will fit the truck? My thought is to run a test with the smaller tires before you invest in the gearing. ... just a suggestion from the peanut gallery.

 

[David*BJ70]

Everything is a matter of perception! 3.70 can be used alomost very well until 33. You have 31. I live very well with the stock ration and 32" ... lots of people do so.

I recommend you to drive it with the original tire size (29") just to see. Remember that the 3B is an ox. Do not waiting for dazzling performance.

Since I used to drive a BJ70 w/3.70 on 32" and I drive your BJ70 w/3.70 and 31"... I did not find anything wrong with... I strongly belive it's a matter of perception.

 

[hoser]

I'd also do a compression check on the engine.

 

[40Flipper]

Everything is a matter of perception! 3.70 can be used alomost very well until 33. You have 31. I live very well with the stock ration and 32" ... lots of people do so.

I recommend you to drive it with the original tire size (29") just to see. Remember that the 3B is an ox. Do not waiting for dazzling performance.

Since I used to drive a BJ70 w/3.70 on 32" and I drive your BJ70 w/3.70 and 31"... I did not find anything wrong with... I strongly belive it's a matter of perception.

Issue is that when it hit 4th gear all the acceleration stops. You can feel that the engine wants to go faster but just gets bogged down. It has to be more than perception. Having it floored in 4th gear but not going anywhere is definitely not just a 3B being a 3B. It goes well through the first 3 gears but the jump to 4th seems to be too much. Re-gearing it should solve the problem. I am going to do a compression test but it's a recently rebuilt engine that doesn't smoke at all.

I'm going to re-gear as a last resort. Going to try everything else first anyway.

Not expecting to win any speed records but I sure would like to see 5th gear someday!

 

[roscoFJ73]

Issue is that when it hit 4th gear all the acceleration stops. You can feel that the engine wants to go faster but just gets bogged down. It has to be more than perception. Having it floored in 4th gear but not going anywhere is definitely not just a 3B being a 3B. It goes well through the first 3 gears but the jump to 4th seems to be too much. Re-gearing it should solve the problem. I am going to do a compression test but it's a recently rebuilt engine that doesn't smoke at all.

I'm going to re-gear as a last resort. Going to try everything else first anyway.

Not expecting to win any speed records but I sure would like to see 5th gear someday!

Were the pump and injectors rebuilt along with the engine?
A good engine with a worn pump will only go as fast as a worn pump will allow.

 

[40Flipper]

That's a good point and I was thinking of that too. Is there a way to test the pump??

 

[roscoFJ73]

That's a good point and I was thinking of that too. Is there a way to test the pump??

The proper way is to remove it and have it bench tested by someone who is trained.
My mechanic puts the vehicle on a dyno and adjusts the pump while watching the smoke.
He aims for max HP with no(or little ) smoke.

I would get one of the 3B owners to give you a run down on fuel adjustment.
Download the free manuals and read through the trouble shooters.

Do you know how many klms since the rebuild? They can be tight for a long time before everything beds in.

 

[40Flipper]

It's only been about 2 years since the motor was put in. Not sure if the injectors were touched.

Want to make this my daily driver so hopefully it isn't anything big.

 

[roscoFJ73]

It's only been about 2 years since the motor was put in. Not sure if the injectors were touched.

Want to make this my daily driver so hopefully it isn't anything big.

With the cost an engine rebuild,the fuel injection system often gets left out.
If its not blowing clouds of smoke,breaking down or overheating,its probably ok .

You have checked the air intake for any obstructions,bad filter?

Might be a good time to seek a prefessional opinion.
Find someone with Toyota experience

 

[40Flipper]

I swapped out the fuel filter yesterday. dumped diesel purge in the filter plus added Diesel Doctor to the tank. The PO said he had changed the filter and added the seafoam. I'm guessing he dumped the seafoam in the fuel tank instead of the fuel filter and he never put on a new filter.

Ran the truck for 20 mins then took it for a drive and it definitely improved performance. Got it up to 100 km/hr with 31's instead of 29's so I need to do the math and figure out exactly how fast I was going.

Either way it was a great improvement.

Thinking I'll still re-gear it as I have an M101 trailer to pull and will be wheeling it occasionally. Turbo and A/C will be happening a bit later.

 

[roscoFJ73]

How about the air filter?

Its odd it needed engine cleaners with low klms but its good news

 

[prado t]

I thought you did that already, anyways I was starting to wonder, Re member these are different than gas motors, the best thing you can do for now providing there is oil in it , is too take it for a long drive , work it and work it hard, if it has been sitting around and only short trips have been taken is get it running go through the full RPM range, the more you drive it the better it will get, I PROMISE!

 

[prado t]

How about the air filter?

Its odd it needed engine cleaners with low klms but its good news

If it has been sitting around and not properly used , the conditioners are a cheap remedy providing nothing is worn or damaged.

 

[40Flipper]

It definitely sat for about a year with very minimal use. The PO said he changed it and put in a can of seafoam but I think he was BS-ing me.

Looking at the air filter it should be changed. I ran it for 2 miles on a dry day with no filter in it and it helped a bit.

I've ordered a diesel compression tester and that should be here early next week. Always handy to have.

Definitely think new gears are in order since I have my heart set on 33's. Should pick it up a little.