Difficult cold start

MorganKane said
François,
I have added one-way valve after fuel filter. It didnot help at all. So I don't believe it is fuel pump issue.
Also carb accelerator pump gives strong squirt of fuel even cold so there is fuel in carb.
Albeit symptoms are same as yours. Please tell me if you find a solution.. :)

What advice should I follow? I have tested compression, fuel squirt, coil voltage, ballast resistor, battery voltage
Manual says that DO NOT press gas pedal before cold start. However, I have tried all methods:
- Not touch gas pedal at all
- Give it light press to engage choke
- Pump it few times before start

Not any of those methods work. Choke closes fully and also high idle cam seems to work.
Giving a little pilot spray and engine starts right away, so my main suspect goes to carb, but all I can consider is give it ultrasound wash and put repair set to it or replace whole carb. But there seems not to be direct swap carbs available so it is a project also.

It is difficult to take video from engine/carb and start car same time. I mostly start it alone so there is no help available.
It also takes two days or more to this problem arise again so not much possibilities to diagnose or take videos.

A cheap digital camera is more useful than a phone for video. The carb video would tell us if you are fully pumping the carb. Does full travel at the pedal result in full throttle at the carb? If not, then you are not actually pumping as much as you think. Is the pump shot a strong stream or weak with a poor accel pump seal?

What is the quality of fuel that you are using? When is the last time you ran the fuel level down to near empty in the tank? Ethanol absorbs water that collects in the bottom of the tank and your recent fills may have only diluted old gas. Try using fresh fuel from a can and a hose to the fuel pump inlet.

For testing, in parallel to the existing circuits, you could run a long, 14ga jumper between the B+ and the coil+, split by a momentary switch that you can reach while cranking. Engage the starter, then press the momentary briefly to see if it makes a difference.

You could also turn the key, then jumper the starter solenoid to crank while under the hood, working the throttle linkage by hand while shooting video. You only need three hands...

Clearly, the starting manual is not working for your current configuration.