Hey guys,

I have a 1976 Toyota pickup, 20r stock. I have been daily driving it for about 2 years. And recently have been having issues with idling and running.

I replaced all the vacuum lines, one by one, so they are all went to the right spot. And that helped the idling out.

Then I had the issue of it feeling very low on power, so I set the timing with a friend who is a total yota nerd and that helped on power significantly, and idling.

Then recently I had the issue of it dying on me on the way home from work (see my introduction thread from the other day). So I did a new cap, rotor, plugs, and wires. Which I thought fixed my problem, took it on a short test drive, it started strong, idled up on choke then idled down in phases as it warmed up, felt fine on power, and idled fine when I stopped.

I drove it to work this morning and right before I got there it started running really rough, hesitating, and when I tried to throttle up it hesitated more and backfired super loud. Then it died as I rolled into my work parking lot. Let it sit all day, ordered new points and a new coil so hopefully it fixes it, or at least I can rule out ignition problems (let me know if I am wrong about that too please).

Now I am on my way home from work (it's about a 30 minute drive), and it ran fine until about 15 minutes in, started hesitating really bad again and backfiring, so I pulled into a gas station and it died on the way into a parking spot. Gonna let it cool off and try to make it the rest of the way home to do the coil and points.

I'll report back after I do the coil and points. Also planning on running some seafoam through it for good measure.

Just looking for someone with more knowledge than I have, or who had a similar problem. Please help me get this thing back running good. Let me know if you have any ideas, thank you!

 

Engine backfiring = running rich and detonating the unburnt fuel in your exhaust pipe, at least according to a member in my thread about a small coolant issue turned carburetor rebuild/tuning you can find HERE <<<

Unusual that it only backfires once it's warm and progressively gets worse. If it was the float sitting too high, it would be continuously feeding too much fuel into the motor and getting a rich condition all the time, which is what I experienced.

Not an expert on the 20R however so it could have some discrepancies between it and the 22R. Is it also a 2 barrel by any chance?? you said you ran through all the vacuum lines, sounds odd though...

 

The first thing you should have done is replace your points and condenser. Bad or burned points and improper dwell will create all the issues you’re having right now.

I believe I mentioned this in your first post. You have replaced everything but what is the most important. Throwing money at a problem won’t make it go away.

If your coil was bad the engine wouldn’t run at all.

 

Coil overheating can cause these issues, also kinda sounds like its not getting fuel. Gets enough to the bowl at idle then dies after taking off. Fuel also evaporates in the bowl especially in a hot engine.

id check the filter and pump

 

Usually backfiring is due to excessive heat/timing, in this case I’d bet it’s losing fuel, possibly because of a bad pump or crap in the tank. As it loses fuel it ends up running lean, which will cause the backfiring.

 

Thought backfiring was only from running rich, but it could also be that too. Although I've not heard of a lean condition backfire though... Then again, I still have much to learn

 

Thank you all for the responses, the points and coil came in finally. Gonna put them in tonight, hopefully, and see how she does. Haven't gotten my manual yet, so hoping it's pretty straightforward.
I wasn't able to find a condenser, but it kind of looks like the condenser is integrated into the points assembly.
Good point about the fuel delivery, carb, fuel pump & filter are my next steps if it still isn't running well after I rule out the ignition system. Gonna seafoam it before I dive into that end though, might just need a little blow out.

 

Backfire is ignition in the intake. Commonly misused for afterfire, being ignition in the exhaust. Not a big deal but you will throw some mechanics off misusing it.

 

Good piece of info, I always just called backfire whenever my truck makes gunshot noises haha

 

I had an overheating coil once that gave these conditions.. have you resolved the issue with points/condenser?

 

I believe the main issue was a bad coil, but the rest of the ignition system got a full replacement and I also believe it needed it. I ended up replacing the points, rotor, cap, wires, plugs, and coil. All of the original stuff seemed really corroded, so I'm not upset about replacing all of it. Truck has been running a whole lot better since then, and I've been daily driving it.

It doesn't diesel or after fire nearly as much when I turn it off now. Although sometimes it does diesel a little bit and rarely it has a super delayed after fire when I turn it off (like at least 30 seconds after), and I think that is more of a fueling issue.

I know it has plenty of carburetor air leaks, and lots of exhaust leaks. Planning on ordering a stock reman carb from guaranteed carburetors, replacing the fuel filter. And maybe running a can of seafoam through the gas tank on the current carb. I already replaced all the vacuum lines, so those should be good to go.

Thanks y'all! Can't wait to get these repair/maintenance items ironed out, and be able to move on to making it look better, handle better, sound better items!

 

That was a smart move on a truck of this age. Now you can enjoy your truck a bit more with some piece of mind.