Difficult cold start

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MorganKane

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I have stock slant 6 (valiant -64) and I Am having hard cold starts.
I have tried different methods, first "don't touch throttle pedal" as manual states, and then pumping pedal few times and then crank. It always needs very long crank. I think it starts best if I keep throttle pressed fully open. Still needs many and long cranks.

Choke works (plate closes and opens when engine warms up). Ignition timing is correct and new spark plugs. Engine runs great and idles well when warm.

Any suggestions? My guess is that old holley 1920, but would it benefit if I put repair kit on it?
It is not really cold now here in Finland, just about +10 degrees (celsius).
 
Make sure choke is adjusted closed enough. Also, make sure that your accelerator pump is working property and actually dumping gas when you pump the pedal before starting. (Make sure the float bowl has fuel in it anyhow)
 
If when cold you get the shot of gas in the carb, Make sure you have 12 volts in the crank position on the coil. it'll be less in the run position. You could run a 12volt jumper from battery to positive side of coil to see if that is the problem. If starts right up trouble shoot wiring problem. Don't run too long with jumper because coil will burn up.
 
Look down the carburetor throat and confirm you get a STRONG squirt of fuel as soon as you move the throttle all the way to wide open and report back please.
 
Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.Tune-up parts and technique suggestions are in this post.
 
I have a 73 Duster with the slant six & looks to be un-modified at all. Sometimes it will sit outside for months without starting it. (it's not road worthy) I just tap the throttle pedal to set the choke, crank it for a split second, crank it again & it always fires right up. Too much fuel on starting (one full pump) & it is hard starting. Try just tapping the gas pedal first to set the choke (confirm that it's working) & see if that works.
 
I am returning to this problem as it still persists. Reason is not cold climate as we have summer here in finland and temperatures have been high (25 degrees celsius).
Problem is still there. If car stays few days without start, it is very difficult get it running. Starter runs fine.

What I have tested so far:
- added one way valve to fuel line to prevent gas flow away from carburetor bowl (i don't know if that is even possible)
- checked ignition coil resistor bybass and tested with resistor shorted.
- locked choke to open position as it is not needed in warm climate.

I am wondering if it is possible that gas evaporates from carburetor bowl causing long delay to get it full again with starter? fuel pressure seems to be very low in this pump.
Bowl vent stays open what makes me wonder if it helps gas to evaporate? How it is designed like that and why is this valve needed?
 
I would NOT disable the choke. Even on warm days the choke is helpful in starting a cold (un-started for a few hours) engine. Like I mentioned in my last post, sometimes it just needs enough pedal pressure to set the choke, at least mine did. Try just pressing the gas pedal, maybe an 1/8th to 1/4 of the way down, let off, remove the air cleaner lid & check to make sure choke closed all the way, then try to start it without touching the gas. It may be like my Duster was, too much fuel & it was hard to start. If I just hit the gas pedal enough to set the choke, it would start right up, even after sitting for a few weeks! Hot out (summer) cold out (mid-winter) it didn't matter, it always fired right up. Maybe I just had a freaky engine, I don't know, but I would try that first, it may be all it is, too much fuel.
 
Install the newer generation "Dakota" Mini Starter.

Cranks the engine over much faster. Newer electronics in the mini starter is more efficient and robs less power from the ignition system to give a hotter longer spark at the spark plugs.

Starts like it has fuel injection.


☆☆☆☆☆
 
Letting car sit for several days, fuel evaporates and now no fuel in the carb bowl. Best way to solve the problem is to an electric fuel pump, if the problem is no fuel after the shut down for any length of time. As was mentioned above check for a good squirt of gas down carb throat after the lay off. That'll tell if it's a fuel problem. Could also be a weak fuel pump. We can only suggest things, but you have to do the work to find the answer.
 
niceolddart said:
I would NOT disable the choke. Even on warm days the choke is helpful in starting a cold (un-started for a few hours) engine. Like I mentioned in my last post, sometimes it just needs enough pedal pressure to set the choke, at least mine did. Try just pressing the gas pedal, maybe an 1/8th to 1/4 of the way down, let off, remove the air cleaner lid & check to make sure choke closed all the way, then try to start it without touching the gas. It may be like my Duster was, too much fuel & it was hard to start. If I just hit the gas pedal enough to set the choke, it would start right up, even after sitting for a few weeks! Hot out (summer) cold out (mid-winter) it didn't matter, it always fired right up. Maybe I just had a freaky engine, I don't know, but I would try that first, it may be all it is, too much fuel.
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I have tried this method you suggested. It didnot help, so I disabled choke temporarily to eliminate too rich fuel issue.
tonysrt said:
Letting car sit for several days, fuel evaporates and now no fuel in the carb bowl. Best way to solve the problem is to an electric fuel pump, if the problem is no fuel after the shut down for any length of time. As was mentioned above check for a good squirt of gas down carb throat after the lay off. That'll tell if it's a fuel problem. Could also be a weak fuel pump. We can only suggest things, but you have to do the work to find the answer.
Click to expand...
Yes, I will test this next time. It is hard to solve issues cause I had to wait several days without driving the car until I can do next test. And in summer I like to drive :)
 
If problem is evaporing fuel, what would cause it? Should not be like that by design. I cannot imagine any reason but bowl valve?
 
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