8N Carb issues - dies when accelerating

[tin soldier]

I just rebuilt the carb and it dies on acceleration. I have no idea what's going on. I have new fuel, clean lines and it can't get up to 2000 rpm, separate from the gov even. I've adjusted all the needle valves to specs in the book. (main adjustment 1.5 to 2 turns off bottom, idle needle 1.25 turns of bottom). For some reason when you open the thottle plate, the engine dies and I think it's being starved of fuel, but I suppose it could be the other way, too rich. I've taken apart the carb and blown out all holes and cleaned it thoroughly several times. I'm using a temporary fuel jug at ambient pressure/ventable and fuel line (1/8 inch ID). My compression is about 70 psi on each cylinder, but when the engine idles, it can suck my hand into the intake on the carb. I think that's enough vacuum to atomize and mix fuel and air in the carb.

Its driving me nuts.

 

[whodat526]

check and make sure u have the two jets set in the right place it may take a few tries of just turning the two jets the get the fuel mixter just right put that most likely what it is but if that doesn't do it u might have to take it back apart and clean the jets on the inside of the carb again

 

[Soundguy]

sounds way lean.

big downpointing mainjet try an initial setting of about 2 turns out. Out to enrich.

small side pointing idle air jet, try a setting of 1.5 turns out, IN to enrich.

adjust idle jet for fastest idle, not smoothest idle.

adjust 1/8 a turn at a time than check.

good way to check main is to goose throttle.. adjsut till it does not hesitate on acceleration.. or stumble and doesn't make black sooty smoke out the tail pipe.

soundguy

 

[whodat526]

and if all else fails they have aftermarket carbs for about 100 dollars

 

[Soundguy]

and if all else fails they have aftermarket carbs for about 100 dollars

and worth every penny too...

soundguy

 

[whodat526]

yep cause i found some of them old carbs just will not take a rebuild kit for some reason and they can drive u crazy cause just when u think u got it fixed it starts messing up again

 

[Soundguy]

yep cause i found some of them old carbs just will not take a rebuild kit for some reason and they can drive u crazy cause just when u think u got it fixed it starts messing up again

yep.. I have a nice ( had a nice) ms carb on my 660. when that 'new' gas stuff cane out, a few months later my 660 died.. fuel issues.

pulled the carb down, and rebuilt it like I've done to so many other carbs over the years. except this one was pitted inside.. pitted so bad that the new jets and seals wouldn't seal good... tried it twice.. new gaskets.. new seats.. tried a NOS set of brass valves not the viton ones.. nada...

in the end, the high end rebuild kit and a new float ( old one disintegrated ) just wouldn't make her go without choke.. I had to throw in the towel and buy another carb.

sometimes it's money ahead to do that then fight them.

soundguy

 

[whodat526]

thats right cause be time u buy a float and a major carb kit u just about got as much in it as a aftermarket carb cost

 

[Soundguy]

thats right cause be time u buy a float and a major carb kit u just about got as much in it as a aftermarket carb cost

yep.. good kit can be as high as 40-45$.. floats 15-19$ depending..

soundguy

 

[whodat526]

and if that dont work thats about 60 dollars wasted

 

[Soundguy]

and if that dont work thats about 60 dollars wasted

plus an hour of time and whatever time the carb was in the carb dip.. plus yer can of carb spray.. etc.

Sometimes it's just crud in a jet.. but usually when you pop them open you know if they are a gonner or not.

soundguy

 

[whodat526]

thats what i tell people before i work on them if its got alot of rust or pits its better to get a new one cause they wont take a kit but sometimes you get somebody that knows everything about them and will still wont u to put a kit in it

 

[tin soldier]

I think I'm in the same boat as you guys, this thing is driving me nuts. I'm new to tractors, but I gather when you barely pull on the throttle the engine shouldn't die, right? I just cleaned out a hole in the carb that was gunked up, the hole I coul dfind that I haven't blown high pressure air through about 50 times. Its the air tube that leads from the idle adjust needle to the main jet and I thought for sure it would be the answer. No, still dies on acceleration. I think I spent at least $100 in time on this stupid thing. I'm gonna take it to the tractor shop and see if they know what's wrong with it. I've seen other info on the net that the hole diameter tolerances are low and that sometimes the carbs just don't have the right size holes. Maybe the new one is the way to go, but jeez, I have to get tires, and a mower deck just to mow the field. :confused2:

 

[Soundguy]

Did you clean it in a carb dip.. or just using spray cans.

really needs the dip.

soundguy

 

[whodat526]

yea it needs to be dipped in some good cleaner for a day are so but if it is not to rusty u can soak it in meratic acid for about 30 minutes to get it clean then wash it in baking soad and water mixter but don't do this if it is real rusty

 

[tin soldier]

No, I just used high pressure air. I'll soak it in carb cleaner. Although I like the idea of muriatic, that'll do some serious cleanup. Thanks

 

[Soundguy]

yep.. the dip style stuff is needed for anything other than light crud. I use chemtools dip.. has a nice pail and basket.. and has a vapor barrier to keep it from evaping too fast.

watch yer fingers though.. pretty hard on skin... think laquer thinner on steroids..

soundguy

 

[whodat526]

yea the acid can clean more than u wont it to but yea i also use the chemtool dip i got it in a 5 gal pale cause how often i rebuild carbs and i believe it works the best from what i have experinced

 

[drg1]

I posted on the other forum that you started not knowing this one got started might read what i posted on the other forum...Just curious was this doing the same thing prior to the overhaul? of after the overhaul? I was having the same issues like this and wasted a alot of time on it...Like everyone else stated I just bought another carb...The reason I asked if this problem happened after the overhaul then there is porobably something blocking one of the many circuts...might try running a fine piece of wire in all the little holes and see if ;you can break it up or dislodge it...