I've a Weber 38/38 with electric choke on a 82 Starlet with cams, head work, and manifold work. Fuel pressure is 3.5psi.
I've been chasing this problem for a six or so months. This carb has been on the car for 6 years and looks good inside and out.
When I try to start the car from complete cold, I pump the pedal twice, turn on the ignition and fuel pump, and crank. I get a few week coughs and the odor of gas from the exhaust. I have to hold the throttle wide open to get the engine to light off. It's obvious the carb is flooded because until the extra gas gets burned the engine runs really rough but after a few seconds it clears. I've replaced the choke and confirmed that it is operating.
However, the carb will not engage the fast idle cam. I can manually move it into position and get it to fire and high idle at 2000rpm. So, I might have a combination of issues.
I have plenty of spares if I need to rebuild. My working theory here is that the float isn't set right, the needle seat in the fuel reservoir could be bad...but I'm thinking the pump jets are squirting way too much fuel when I prime the engine at cold. I currently have 70 pump jets but I also have 60s in my spares.
The spark plugs are black. Replaced them, same issues. Once it's warm the car will fire off instantly.
Any thoughts or comments? Informed opinions are always welcome.
Thanks
John
On a warm day you shouldn't need to pump the pedal any.
In reply to BrokenYugo:
You have to pump it once to get the choke to close and engage the fast idle cam...at least that's the way it appears to work for me. I don't pump it if the engine is still warm and it does fire right up when warm--like instantly--half a crank and bam!
Right, but I'm saying you probably don't need full choke (an electric/thermal choke will choke down on its own some when cold) or fuel from the accelerator pump (which should be tuned for driving the car, not starting it) to get it going in nice weather. You say it's flooding (which sounds right) but also say you're going straight to double pumping the pedal on a cold start, which puts way too much gas down the hole, flooding it.
As I recall with the Yugo (weber based carb) I almost never pumped the gas in that car, and never bothered to get the fast idle/choke lock setup, because it didn't need it in the above freezing weather I was running it in. Get in, maybe pump it once if it was below 50 out, crank, normal idle (maybe give it a little pedal to keep it happy), drive. The choke controller box was also messed up so I had it wired to go hot on key on.
Black plugs (assuming black after driving) indicate you're tuned way too rich. Weber tuning isn't really my thing, so I can't offer much advice there, just that it should be corrected. A wideband is a nice thing to have here.
In reply to BrokenYugo:
I actually do have a wideband and once driving, the ratios are pretty good. I assume the plugs are just turning black at startup.
I shall try no pumping and report back shortly.
Gracias.
Problem solved. I went ahead and rebuilt the carb which is super easy. I couldn't see anything wrong with any of the old parts but replaced them anyway. Once back on the car and with fuel in the bowl, it fired with one crank. Didn't even pump the gas. It even went up to the correct idle speed. I tried this several times with the same results.
I suspect the floats were maybe set wrong or the needle valve wasn't sealing.
For anyone interested I'm running 55 idle jets, 142 main jets, 180 air correctors, and 60 pump jets.
