whirlybird

Hello, all.

I haven't been able to find a solution to this exact problem via the search function or in the FSM (although I certainly may have just plain missed it...)

Picked up an 82 that has been sitting for a few years...the PO was able to get it to fire by pouring gas in the carb when I looked at it.

While trouble shooting I put in a new(er) fuel pump and a new(er) carb (from a previous vehicle in known working condition). Upon the swap of both components I was able to get the truck to fire up and run!

The problem came when I decided to figure out where the problem actually WAS by putting the original carb on and leaving the new fuel pump on the truck (which is what I suspected the problem was). Nothing....so back on with the newer carb...and...NOTHING!

The fuel pump is good as it's spitting fuel out when I crank it...but for some unkown reason NO fuel seems to actually be entering the carb and filling up the site glass like it did the first time! There is still spark as it will run with a little fuel in the carb or some starting fluid, but it will quickly die after it burns all of whatever is there off (usually three-four seconds).

I may have turned the carb on it's side at one point but didn't really leave it like that for very long (Pardon the newbness but I THINK I've read that it's not good to do that)...I'm just completely stumped as to why a working carb would have been fine one afternoon and then not good a few hours later...

Any ideas??? I'm almost certain it's something VERY simple that someone who knows what they're looking at will be able to figure out quite quickly...I'm just very frustrated as I've been tinkering with this thing and trying to get it to run off and on for a few weeks now!

Thanks so much in advance for ANY help you could provide!

Best

suncomb1

Check your fuel tank return line first to make sure it is clear with no blockage or obstructions. Next check your fuel supply lines, hoses, filters, etc. Remove your gas cap so the tank vents and try running the motor. If the motor runs with the cap off check your fuel tank vent line, vapor canister(s), tank vent control system, etc.

str8yota

what type of carb is it? issues with the float?

whirlybird

Ok...problem MAY have been resolved...just finished messing with it some more and VIOLA! It runs!

Just a few minutes after I posted I spoke w/ a coworker who said that while I was "manhandling" the carb off and on I may have turned it over or something and got the float/needle stuck; he suggested knocking or tapping the carb around where the float was with the handle of a screwdriver and it may knock it loose; I took his advice and after a few more cycles of: Tap-crank-tap-crank-carb cleaner down the little tube above the butterfly...bam! it runs! I noticed the sight glass was full for a few minutes of it idling and then looked a bit empty...I suppose time will tell when I go to crank it in a few days. I think I'll respray with a bit of carb cleaner and then run some seafom through the system.

str8: It's a stock Aisin carb

suncomb: AWESOME advice...I'll start messing with/checking all of that out as soon as I can in a couple of days regardless of whether or not it's still cranking/running...I'd imagine that all needs to be checked out anyway.

Thanks again guys...why I love this forum so much!

slow-mo

Yes, that is exactly what happened. Tilting the carburetor cause the float needle to stick in the closed position.

ThatGuy1295

I hope your being sarcastic. A carb thats designed for off road isnt going to stick from tipping. Not to say the float isnt clogged or stuck from gummy build up. But if thats the case then why have 2 carbs done the same thing?


Another thing thats worth checking is that the fuel pump is providing proper pressure. Just because it spits out fuel with no resistance doesnt mean it will push fuel with resistance.

slow-mo

Define off-road. Is a carburetor at a 90 degree angle off-road? Is a carburetor at a 180 degree angle off-road?

Rotating and/or inverting, he himself did not remember, can and did cause the float needle to stick closed. It has happened to me with the carburetor off the engine. When tapping on the carburetor, i.e., creating vibrations, caused it to dislodge. A running engine is already causing vibrations that if the float needle did stick, it would naturally unseat. When driving "off-road", fuel in the bowl is moving around as well. This will create force on the float needle to prevent it from sticking.

His original comment regarding tapping the carburetor was when it was off the vehicle. Then the carburetor was re-installed. At that point fuel did not fill into the float bowl.

But as you said, gunk in the float circuit could have caused the float valve to stick. But stick it did.


It is quite possible that two carburetors did not do the same thing. The original (first) non-working carburetor never did work the first time nor the second time with the "new(er)" fuel pump. Whirlybird did not state the result of why the first did not work. Gummed-up float circuit? Sure, possible. Gummed-up idle circuit? Could be. We don't know.

The second carburetor did work the first time he tried it. He removed the working carburetor, then tried the first non-working carburetor, yet still with the new fuel pump. That one still did not work. So back on goes the once working carb.

whirlybird

Hey, guys.

I REALLY appreciate all of the insight/ideas and help...but I've done it again! I've managed to fix something so well I broke it!

I was able to get a few minutes to tinker with it last night; it was the first time since I was able to tap on it and get the vehicle started and running well. After a couple of quick pumps of the pedal it starts right up!....and then immediately dies after a few seconds...but it IS improving: now I don't have to pour gas in the carb or anything (trying to be an optimist here), but now I CAN see fuel through the sight glass... maybe even a little too much as it looked like it continued to rise after a few tries/cycles. I think that fuel is getting IN there now but just isn't making it to where it is supposed to to be atomized.

I'm sure something is stuck somewhere in there but the battery died before I could continue much further. Ah well.

I'll tinker with it again as soon as I am able...may be a few days as I have a busy work schedule for a while.

I think the BEST solution would just be to rip it off and try to rebuild it (would be my first)...we all have to learn sometime, right? What kind of intimidates me is the jigsaw puzzle on the back (firewall side) of the carb that looks like it has to be taken apart and reassembled when I split the top and bottom half...

This should prove to be interesting! I may just try to keep tinkering. I'll keep you guys posted for sure. It's the LEAST I could do for you guys taking the time to try and help.

Thanks again!

slow-mo

So this is that second carburetor, the one you said it did work the first time? That's what it sounds like your saying.

Since you state have fuel in the bowl, then it is quite possibly fuel is being hindered at the main jet or in the passage ways after it. On a cold engine, when the choke plate is closed & the Fast Idle Cam is engaged, fuel will be drawn from both the idle/slow speed circuit as well as the main nozzle. Fuel has to pass through the main jet to get to these circuits.

The main jet controls all the circuits on the primary barrel, except the power valve as it circumvents the main jet. The secondary barrel has it's own main jet.

The other option is that the choke system is not working correctly and starving the carburetor for air.



When rebuilding the stock Aisan carburetor, the issue is not the internals of the carb, that's the easy part. But, like your seeing, the issue is all the different external linkages this carburetor has.

Take a lot of pictures before you disassemble the carburetor from every conceivable angle. And take a lot of pictures as you disassemble the carburetor and linkages.

ThatGuy1295

Dude!! If floats stick by simply turning the carb upside down, then motorcycles would never run, and all carb'd vehicles would need to be takin apart after every speed bump.
Floats shouldnt stick period unless somethings wrong, such as gunked in the carb in which case thats a different problem.

And the floats dont rely on "engine vibrations" to unstick after every bump. That would be stupid.

whirlybird: Might aswell pull the cover off the float bowl and clean it out real quick.
and check to make sure that toyota didnt engineer some way for the float to stick while your in there. Ive rebuild around 20 carbs from old fords, dirt bikes, and yotas, and have never had a float stick from me tiping the carb upside down.

ThatGuy1295

Disregard this post
Dont wanna sound like a dusch

whirlybird

Yeah, guys; the one I'm talking about IS the one I put on (the replacement one that originally worked)...what's so funny (to me at least) is that I had two extra carbs to swap in: one that was from an 82 and one from an 84 (both sealed up/stored etc) that were both in working order when pulled...they both look SIMILAR but the one from the 84 is the one I used becuase it was the one that had the electrical connector that matched my truck's harness. So strange (again....to me at least), I figured the exact same truck (federal model) would have the exact same connectors, both were the SR5 model (with same gauges: tach/ammeter/oil pressure etc). What's even funnier is that the 84 model it came from was a california model (again, this truck is federal)!

Who knows.

I'll keep you guys posted if I can make some time to mess with it tonight or tomorrow.

Thanks and all the best

85TurboRunner

ThatGuy you really do live up to your screen name.

slow-mo

I must not be explaining myself well.

The second working carburetor was pulled off the engine. When the carburetor was off the engine it was "manhandled". Then it was reinstalled. Then it did not work, untill tapping on it.

The only way to know if the second carburetor float was really sticking is to know what was the fuel level in the bowl before the tapping and after.

Yes, you are correct in that the float should never stick on a functioning engine. The post was when the carburetor was off the engine then re-installed. A stuck float has happened to me before when the carburetor has been reinstalled, so it can stick closed.

ThatGuy1295

THATS A LONG WINDED WAY OF SAYING THE CARB IS DIRTY!!

CLEAN EITHER CARB AND START YOUR YOTA......

Model 70

iTrader: (1)

Let's get back to the OP. Truck has sat for a while. How's the condition of the tank. How much crud is in the tank. Has the actual pressure and volume output of the fuel pump been checked? No point in rebuilding and cleaning out a carb just to possibly pump a bunch of crud back into it.

CyMoN

also check the vacuum assist and make sure the fuel line is air tight I had air leak and it would suck air in the line from my inline fuel filter.

I spent a bunch of time cussing my truck over 2 very simple things.

str8yota

I am still gaining experience with toyota mechanics but have encountered the sticking float on several carbs of american makers. That is why I originally posted it as a possible question as to the cause of the problem. The problem carbs where all in good shape and one factory rebuilt. the only reason I looked at the float as a problem on those rides was a old rodder friend of mine suggested it to me. apparently not unheard of then and not now. The unrebuilt carbs needed some cleaning and the rebuilt one just had issues.

whirlybird

Apologies for the delay...I'm hoping to have some time to tinker with this again tomorrow morning.

I'll check the fitment of the hoses, didn't even think about air getting sucked in...I guess that could potentially be a problem.

I THOUGHT about dropping the tank but wanted to see if it would run prior to me doing it (that's when all the "drama" started). The PO said he had it running/idling a couple of times a few months prior to me picking it up from him (said he got it to run long enough to take it around the block once), the PO before him is the one who didn't run it for a few years.

What I'm planning:

-fuel filter (I know: I should have done this FIRST...I was just so excited when I got it and the PO got it to run for a bit when I purchased it originally...really thought it was just the fuel pump initially)

-drop tank and clean (maybe cleaner/degreaser w/ nuts and bolts to aggitate and "scrub", buddy told me that worked GREAT on his triumph. Also read of a method with toilet bowl cleaner of all things over on pirate)

-while tank is out maybe blow carb cleaner/air through hard fuel lines to clear any gunk or garbage out.

And basically go from there...

I actually have TWO 82's and I'm in the process of figuring out which one to keep...this one or the other...each has a list full of pros and a list full of cons...decisions decisions. (I'm just really greatful to have the opportunity to actually get to CHOOSE one!) This latest one was really just picked up on a complete whim...sometimes I feel like I really have a bit of a problem w/ old beat up toyotas...I just love 'em. I'm sure you can all relate.

Thanks again, guys.

All the best!