Aisan carburetor issue, I'm stumped????

[winchester383]

hi there, new to this forum. I have been over everything and still come up short. Car is a 1982 toyota corolla/tercel 3ac, car is all stock. The engine started running poorly at idle and had half power, and is not required to run through deq where i live so after all my preliminary checks and tune-up (cap,rotor,plugs,wires) I removed all vacuum lines and all egr equipment. Didn't change a thing, so at the suggest of my brother I replaced the head gasket. I got my power back right away but still runs poor at idle and dies......so i removed the carb and rebuilt it. Still no change, then I replaced the fuel pump & filter, still no change, so I replaced the carb with another used one i had, it ran great for 15sec then back to sputtering at idle. So I checked the two fuel solenoids on the carb, one worked the other had no power or ground at the factory green connector so i jumpered the pos & neg got the solenoid to work but neither one of them effect the engines runnability (weird, cause they should). The timing is set at the best spot for performance but my timing (on timing cover) have never lined up with crank pulley (another issue I've been researching) anyways the engine has ran perfect for 4yrs before this issue and never had a problem frying the tires up to 2nd gear. Like i stated i have plenty of power off idle. I look down at the primary and it seems to pulse a little and looks to be squirting plenty if not too much fuel at idle. Also note i have throughly checked for vacuum leaks and pressure, no leaks found 5psi@ idle and 15psi@ 3500rpm. Is there something I'm missing, any help is much appreciated

[Petros]

Welcome to the list,

Sounds like you have done a lot of the normal things, but it sure sounds like a vac leak. Sometimes throttle shaft wears out and causes vacuum leak in the carb. Check the vac advance at the distributor, a bad diaphragm is the same as a vac leak. Also a bad TVSV valve could also act like a leak (presuming you are still using it).

I presume timing belt is on and timed properly (a worn belt can skip but still run, but badly). check for a loose engine ground, there should be one off the head and one off the block, check ground at battery too. Check your EGR system, it could also act like a vac leak.

Good luck.

[winchester383]

Yes i have removed all vacuum lines including the dist. adv. for testing purposes. Egr is completly removed and all ports pluged. I have also removed the rocker arm and sealed the top of the carb and with a vacuum test applied 5psi to the engine/carb/intake system and it holds 5psi for 30min which tells me all valve/seats and ports are sealed. I was just reading about how another person had a simalar issue, he said how his vacuum at his ports on the carb had low vacuum (so do mine) his issue turned out to be the number 1 fuel shut off solenoid, it was clicking but not opening so he sawed off the end and reinstalled. If the engine doesnt have deposits build up on the valves or pistons there wont be anything to ignite the fuel after the ignition is shut off, which as we all know is what causes run on and dieseling. Strange situation for me though because i have replaced my carb with a previously working one and still same issue after 15-20 seconds of running perfect....Im going out now to cut the solenoid end off and try it and see where I am. Thanks for your support.

[rer233]

have you checked the a a p diaph in the carb? if ruptured it will let raw fuel run into #1 cyl [as i recall] also, i once had a problem setting ignition timing on a 3ac [couldn't quite advance timing far enough- advanced dist one tooth and then timing would not retard quite enough] turned out the cam timing was off 1 tooth. someone had recently installed a timing belt just before i bought the car[probably why he sold the car-NO power.] good luck!

[winchester383]

Yes, I replaced the aap dia. upon rebuild, however I did solve the poor runnability @idle issue though, after removing both 1 & 2 solenoids and plugging the ports with bolts, I blew the carb out one last time before giving up on it and re-inst. to find it was a piece of dirt the whole time. Far as the timming, my Haynes manual says to line up the cam gear with the small arrow on the front cam cap, when doing so it puts my cam gear one tooth to the right @1:00 approx. and then later it stated the cam gear should be pointing straight up @12:00 so I will try that and see what happens, if I can get the timing marks to line up on the cover and have correct runnability. Thank you for all your support, everyone on here is so nice and user friendly.