Hi, I know that this forum is mainly based around Toyota trucks and SUV's but maybe somebody will be able to help me out since my car shares the engine with some of them.
I'm new to old Toyotas and still learning things.
I have a 1980 Toyota Celica with an 18R engine and recently decided to convert it to a Weber 32/36 DGEV.
After tinkering with it for a while I got it to run, the car starts right up and drives ok when the choke is closed.
However when choke opens completely, it runs fine on idle but only for a few minutes before it starts having issues.
The engine then basically starts to die or run at like 300 RPM (tachometer just barely nudges above 0), pressing the gas pedal more to a certain point does nothing but if I continue pressing it even more, after about a second or the engine two wakes up and revs up like normal (when it gets below about 1500 RPM it just drops to 300 immediately).
The carburetor is brand new, I adujsted the float (that changed nothing), tried spraying brake cleaner around the base and manifold but couldn't find any vacuum leaks.
Also tried disconnecting the brake booster and plugging the hose in case it was leaking vacuum internally but that also didn't change anything.
I checked fuel pressure with a gauge and when the engine barely runs it fluctuates between 2 and 3 PSI, which apparently should be fine for this carby?
Also, when it's doing this thing where it barely idles, it slightly puffs out the exhaust (no black smoke or anything).
Adjusting the mixture screw does not fix the issue, the idle speed screw also doesn't fix the problem and screwing it in only makes the carburetor draw more air through the top and doesn't increase the idle at all.
Tried putting my hand over the top and it also doesn't seem to affect the rough idle.
When I spray brake cleaner/drip fuel into the primary it stalls out.
Also I should mention that the engine only wants to run with timing cranked up to or around the highest RPM.
When I drove it today it had a weird issue when it warmed up, RPMs were jumping from 300 to about 700 every few seconds like if I was pressing the gas pedal slightly.
What may be the issue here?
The carburetor has factory jetting, I heard that the idle jet may be slightly too large for this engine, but that wouldn't really explain why the car runs fine for some time with choke off and then it starts to die?
I included some videos of the engine idling, how it behaves during driving and the amount of fuel in the bowl (with floats removed) when it starts running rough.
Any thoughts?
Thanks in advance.