hi i been having this problem which i cant seem to solve its a carb from a a15 engine brand new on a a12 engine and the engine revs smooth in neutral as soon a in drive and you accelerate it dies!

things i have tried!

new points cap and plugs points are at 49 degrees
checked vacuum advance which it working
checked for vacuum leaks with ether and none present
pressure tested fuel pump which is at 4psi but im buying a new one just incase!
also i checked the timing set it to 7deg than advanced it a bit but no difference!
checked accelerator pump and is squirting fine
checked auto choke and it opens fully


before i put on this new carb on my previous one didnt stall the engine but it had a flat spot so of idle no matter what position the accelerator was it would stay same revs and speed until the secondary kicked in

any ideas?

Thanks!

Is the line down to your fuel tank blocked

Fuel pressure at 4psi is a little high, but should still run OK. New fuel pump should be 2.6 to 3.0 psi.

If this is an automatic transmission in Drive, there are some common problems that cause these symptoms.

After the engine dies are the spark plugs wet or dry when you take them out?

sounds like massive air leak,have you changed manifolds or anything else.

hi thanks everyone sorry the pump pressure was 3.0 psi not 4.0

i have checked every single piece that joins for a air leak but have not found any

i have changed most of the vacuum hoses to also checked fuel hose if blocked and the tank breather hose!

the spark plugs were light tan yesterday but today was playing around with mixture made it a bit richer and the plugs were blackish but not wet!

i cleaned them and put them back on!

im still very lost on what to do i took it to a mechanic and it left him scratch his head his suggestion was that the throttle valve dosnt line up on the manifold so when you accelerate it lack air/fuel and dies!

but i checked it and it lines up like standard as it is from a a15 engine!

also i used the manifold from the a12 carb is the a15 and a12 manifold any different?

Thanks!

Yes A15 manifold is different to A12 manifold. But not enough to make a difference.

Remember, I'm running A15 carby on A12 engine, and so is Thomen who had mechanic troubles (different symptoms) but finally got it running right.

You might be experiencing spark problems. Disconnect the choke electric wire and see if it runs better when cold.

hi thanks i will try that choke thing!

but first i realised somthing i dissconected the vacuum hose that goes to the auto transmission and blocked it off at the manifold then took it for a test drive i realised that from a dead stop it still hesitates but not as bad but from low speeds when you press the throttle it would normaly die or stumble (from roll start) now that dosnt happen only from dead stop!

is this possible as its connected to the transmission what is that vacuum unit in the tranny any way is it likely to cause it if its faulty?

also before i remvoed the hose i made sure the wasnt a vacuum leak from their!

Thanks!

probably shouldn't change much but there is two positions the accelerator pump linkage can be placed, if you move it to the one further out it makes the accelerator pump come on quicker when you press throttle... may help (im talking about the round bar that goes up from throttle linkage, where it is connected tot he main arm of the accelerator pump)

use soapy water (spray on through a spray bottle) on connections and hose ends and stuff to detect leaks, with engine running it will bubble if there is a leak there

hi thanks yer this a15 carb dosnt have that linkage setting but my old carb did! i tried finding leaks with starting fluid ether but didnt find any!

could it be the fuel pump but i am getting around 3.0PSI!

so this transmission modulator wouldnt cause these affects?