Hard starting 7.4 hot or cold

[fstalfire]

Hi guys, I have a 1996 250 sundancer with 7.4 and a weber carb....I recently bought this boat, had the carb rebuilt by a local, reputable builder, did major tune up, made sure timing is right on and it sucks to start......when cold i pump the throttle 5-6 times and have it full open when cranking and it finally starts after many revolutions. It runs good when started and when i shut it off and try to restart, it sucks again and I have to go thru the same thing, I checked the electric choke and no issue there....the only thing I havent checked was if fuel is squirting when I pump the throttle to start but i wonder if these carbs just suck or mine still has some issues or is it a fuel supply problem or?????

 

[Boater420]

It's generally hard to start them after a few days of non-use but once mine have been run a while they start up pretty easy. I've read the fuel in the bowls evaporate after a few days which is why you need to crank it a lot initially.

 

[PlayDate]

There should be a number of threads on this. What happens is all the fuel drains out of the carb when it sits for a while which means that when you are pumping the throttle it does nothing for the getting gas into the engine until the mechanical fuel pump pushes some fuel to the carb (several seconds of engine cranking).

Same thing happens when it gets hot.....fuel drains out of the carb and you are back to square one (sometimes the leak down creates a flooded condition which gives the appearance of a cold start problem).

I'm not a fan of Webers, Rochesters or Edelbrocks. I like Holley's because they have large fuel bowls and don't leak down.

 

[hottoddie]

A mid 1990s may have an electric fuel pump. If it does turn the key to run for a few seconds before you pump the throttle when cold in order to fill the fuel bowl. If fuel pumps are mechanical then try cranking 3-4 revolutions before pumping the throttle. In either case when hot and after sitting for a while try pushing throttle to full open before you start cranking. Be ready to pull the throttle back quickly upon start. If both these work it indicates the carb bowl is draining when the engine is not running and may need repair. My Rochester Qjets start easily without pumping the throttles hot and cold.

 

[fstalfire]

There should be a number of threads on this. What happens is all the fuel drains out of the carb when it sits for a while which means that when you are pumping the throttle it does nothing for the getting gas into the engine until the mechanical fuel pump pushes some fuel to the carb (several seconds of engine cranking).

Same thing happens when it gets hot.....fuel drains out of the carb and you are back to square one (sometimes the leak down creates a flooded condition which gives the appearance of a cold start problem).

I'm not a fan of Webers, Rochesters or Edelbrocks. I like Holley's because they have large fuel bowls and don't leak down.

Thanks for the reply, I've always had Q-jets and never had a problem.....if the carbs leak down, how does this happen? I understand the lines loose pressure with no pump working and gravity drains to the lowest point but in a carb bowl how would fuel leak down?

 

[fstalfire]

A mid 1990s may have an electric fuel pump. If it does turn the key to run for a few seconds before you pump the throttle when cold in order to fill the fuel bowl. If fuel pumps are mechanical then try cranking 3-4 revolutions before pumping the throttle. In either case when hot and after sitting for a while try pushing throttle to full open before you start cranking. Be ready to pull the throttle back quickly upon start. If both these work it indicates the carb bowl is draining when the engine is not running and may need repair. My Rochester Qjets start easily without pumping the throttles hot and cold.

Thanks for the reply, I've always had Q-jets and never had an issue with them...this is my first webber and I'm not liking it so far

 

[Nauti-Kal]

I have twin 7.4 with webber carbs and I have the same problem! I found it better to do nothing before pushing the start button, the motor fires for a few revolutions and shuts off due to lack of fuel....the few revolutions help fill the bowl and I push the start button again and while the starter is cranking the motor I throttle up halfway and then it fires! GOOD LUCK

 

[fstalfire]

Update...after a week, I went to the boat today....I looked down the carb while my wife pumped the throttle and there was fuel squirting into the carb every time and you have to have the throttle floored for it to start so my issue isn;t no fuel it must be to much fuel so am I looking at opening the choke flap more to let more air in?