Difficult cold start

[French demon]

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.

Where did you install the one-way valve?
I tried to install one between the fuel filter and the fuel pump, and it didn't help at all either.

I plan to replace the fuel pump, and if it doesn't work, I'll change the carb.

François

 

[MorganKane]

Mine is between fuel filter and carb.
Please write here if you decide to replace carb, how it goes and does it help Or if fuel pump solves the problem.

By the way, my valve looks exactly same. I am not 100% sure that it does not leak to wrong direction. But because carb accelerator pump works, I assume that there is fuel in carb.

 

[MV8]

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.

 

[MorganKane]

Forgot to say that I already ran jumper wire from battery to coil, but it made no difference.
Gas tank has been changed and filled with fresh 98 gas with 5% ethanol, we do not have non-ethanol gas here.

I will make new video under the hood. I have jumper switch to engage starter but that will not short ballast resistor as turning key does.

 

[slantsixdan]

Manual says that DO NOT press gas pedal before cold start.

If it actually says that, then somebody mistranslated that part of the instructions. I'd love to see a pic of what the manual says.

Not any of those methods work. Choke closes fully and also high idle cam seems to work.

Are you checking this with the air cleaner removed? It is certainly possible for everything to look like it's working okeh without the air cleaner on, but for it to bind up and not work properly with the air cleaner in place.

It also takes two days or more to this problem arise again

Wait, you mean it will start easily from cold the morning after you've driven it the day before? It only has difficulty if it's been sitting for more than one night?

 

[Bugman]

The link to 1920 manual Dan provided,go to page 5 of pdf. Under adjustments during assembly,figure 15 wet fuel level testing.Put that info in your tuner note book.If bowl is dry or fuel level is below spec,add fuel threw economiser opening.

 

[Bugman]

The link to 1920 manual Dan provided,go to page 5 of pdf. Under adjustments during assembly,figure 15 wet fuel level testing.Put that info in your tuner note book.If bowl is dry or fuel level is below spec,add fuel threw economiser opening.

Also page 6 of pdf Vacuum kick pull downadjustment,figure 16 and 17. check vacuum pull off,see if holds vacuum

 

[Bugman]

Also page 6 of pdf Vacuum kick pull downadjustment,figure 16 and 17. check vacuum pull off,see if holds vacuum

Service manual for your car should have in section 14 fuel,service procedures, for testing fuel pump on vehicle. Pressure vacuum and volume.