Truck wants to stall under heavy breaking, If I give it gas its fine but slamming on the breaks coming to a stop light he wants to stop running. Its fine once I come to a complete stop. If I give it gas under heavy breaking its fine, otherwise it wants to stop. Also noticed stuttering when i'm sitting elevated with the nose down like coming out of a steep parking lot. Any one have any idea what would cause this?


1978 toyota hilux.

 

Might wqnt to check vacuum from brake booster. Could be pulling too much or leaking somewhere so when the booster really pulls its stealing from something carb related. The vacuum is the only link btw brakes and engine thqt i know of.

Incline issue probably also carb related. Some people say aisin carbs dont like angles but thats usually rock climbers. Your parking lots shouldnt be that steep.
you should be able to do a vacuum test. I made a diy smoke jar with an air compressor and it does me good. Look it up on youtube.
replace vacuum lines. Dont waste your time spraying starter fluid on everything, that rarely locates leaks.

In the meantime, maybe put new brake pads on if theyre worn so youre not braking so hard.
keep us updated

 

Any chance your clutch might be out of adjustment, creating some drag?

 

No. it does this even in neutral.

 

I will give this a try all other hoses are fine. How do you check the booster it self if its leaking inside and not on the hose?

 

If you can get someone else to press the brakes, listen to the booster from the engine bay. If its bad, itll sound like a whooshing from inside.
You can probably also hear it from the cab. Im sure theres a better test in the fsm but most bad boosters you can hear the air pass thru

 

Had same problem with my 80. Swapped booster, and no issues. No idea how old mine was, but truck sat forever. Depending on which booster you have, mine was single diaphragm with the attached spacer. Do your research, I was able to swap up to a dual diaphragm booster for an 86-87 Turbo pickup and it bolted right in. O'reily sells them.

 

Thanks @NolaToyota I don't think I have many options with my 78, but even changing the old one is still good.

 

I'm having trouble finding a break booster for my 78. O'reily says they can get one but they are not sure if it will fit and might take 2 months. Also do I have to bleed the breaks if I don't change the master cylinder?

 

The only thing I could find on this currently is a "Return & rebuild" service by Cardone through Rock Auto. Apparently the rebuilders are short on cores right now, so no one has these sitting on the shelf ready to go. Looks like turnaround time is 3-4 weeks. Yikes.
Info - https://www.rockauto.com/en/catalog/...e+booster,1884

 

Id check around for a used one to use as a core
brakes only need to be bled if you open the hydraulic system. Seperating MC and booster doesnt require it.

 

Or looking into a swap from the 79+ models might get you more options.

A lot of toyota parts are interchangeable thru generations. If you can measure the MC bolt spacing and the spacing of the studs the booster sits on attached to the firewall, you can see if theyre interchangable. It might require a new MC but you could do swap a new booster and MC and bleed the system in much less than 3 to 4 weeks.

Maybe someone on the forum has their booster out and could measure? Ive got a 3 day weekend so I might be able to.
Or, order a 79 booster from a physical parts store, measure it and return it if it doesnt match up. Just dont try to install it or theyll give you a hard time abt it being scratched up
Them .....................me