PDA

View Full Version : Fuel keeps flowing into carb?


MC240
09-09-2012, 04:34 PM
I have been having some problems with the electrical as you can see from last 2 posts. I have worked those problems out. I'm getting fire from coil and plugs. I was trying to crank the engine and realized that gas is flowing into carb for many seconds after I stop turning engine over. Could my problem have been the carb the whole time. Boat is 91' 240 with 454 HO with mechanical fuel pump and Holley 710 carb. I had the carb rebuilt about 10 years ago. Could the floats be staying open and flooding prior to starting?

JimN
09-09-2012, 04:54 PM
I have been having some problems with the electrical as you can see from last 2 posts. I have worked those problems out. I'm getting fire from coil and plugs. I was trying to crank the engine and realized that gas is flowing into carb for many seconds after I stop turning engine over. Could my problem have been the carb the whole time. Boat is 91' 240 with 454 HO with mechanical fuel pump and Holley 710 carb. I had the carb rebuilt about 10 years ago. Could the floats be staying open and flooding prior to starting?

Have you checked the float or needle valves? It could be an ethanol-related problem. If the float is brass and green, your fuel has had water/corrosives in it for a long time.

XtwentyNot
09-09-2012, 05:35 PM
I would say you have a sunken float.


-Jake

j.mccreight@hotmail.com
09-09-2012, 06:00 PM
definatly needs some exploratory surgery, junk caught under needle...

rockcrwlr72
09-11-2012, 01:06 PM
I am with them, take it out take the fuel bowls off and see what's going on inside. Rebuilding a Holley carb is really easy too. You rebuilt it 10 years ago, it might be time for a rebuild anyways. Get yourself clear fuel bowl sight windows so you can easily set your float height. It makes the job so very easy and they are cheap. Once you got that set, then set your timing to 10 degrees BTDC at 750 RPM. Get a manifold vacuum gauge and connect it to the port used on the carburetor for the vacuum advance. First disconnect the carb from the vacuum advance and leave it unplugged until you are done. Adjust the idle air mixture screws evenly in and out and record the vacuum readings. You want to set the idle air mixture screws so you get the highest vacuum number at idle. When you do this your engine will run better than ever. If do this right you most likely will not have to touch the idle speed adjustment screw at all. PM if this sounds like something you want to do and I will write down the detailed instructions on how to do it.

1redTA
09-11-2012, 03:50 PM
Get yourself clear fuel bowl sight windows so you can easily set your float height.

I don't think marine carbs have sight windows, mine doesn't

thatsmrmastercraft
09-11-2012, 04:00 PM
I don't think marine carbs have sight windows, mine doesn't

The 600's don't but some of the larger carbs do. Not sure why.

MC240
09-15-2012, 09:38 PM
Thanks for the input. Rebuilt the carb with a Summit kit. I had a friend (mechanic) come over and set timing with light and other fine tuning. Boat is running like a Swiss watch.

thatsmrmastercraft
09-16-2012, 12:12 AM
Nice to hear it when things work out. :toast:

cptskier15
09-16-2012, 12:30 AM
Good to hear working well! Read in post above about marine carb having vacuum advance, I thought marine carbs did not have vacuum advance?