Are carbs supposed to dump fuel to back barrels at shut off????

[rollenrock33]

Does anyone know if the back barrels on a holley 4 barrel are supposed to always dump fuel even at idle? I am having trouble getting the boat to start after its been running. The only way I can make it start is by putting the throttle wide open.

The motor is a standard 351 pcm with the stock holley 4 barrel. The boat runs great other than the start up. If I take the air cleaner off and look down the back barrels of the carb, and shut the motor off at idle, it dumps a lot of fuel into the barrels for probably 15 seconds after the motor has been shut off. Is this flooding out the motor causing my hard start? As I said before, it runs fuel all the time to the back barrels, and a lot of fuel even at idle.

I took the boat to a marina and had them rebuild the carb but the problem still exists. I am going to check the fuel pressure at the carb tomorrow. Any ideas?

[michael hunter]

NO. Check the needle and seat being stuck open. Float level too high. Make sure the secondary throttle plates are folly closed.

[89supracomp]

Does anyone know if the back barrels on a holley 4 barrel are supposed to always dump fuel even at idle? I am having trouble getting the boat to start after its been running. The only way I can make it start is by putting the throttle wide open.

The motor is a standard 351 pcm with the stock holley 4 barrel. The boat runs great other than the start up. If I take the air cleaner off and look down the back barrels of the carb, and shut the motor off at idle, it dumps a lot of fuel into the barrels for probably 15 seconds after the motor has been shut off. Is this flooding out the motor causing my hard start? As I said before, it runs fuel all the time to the back barrels, and a lot of fuel even at idle.

I took the boat to a marina and had them rebuild the carb but the problem still exists. I am going to check the fuel pressure at the carb tomorrow. Any ideas?


My boat does the same thing. It runs perfect, but if I shut it off and try to start it two minutes later, I have to hold the throttle wide open. I haven't looked to see if it dumps fuel into the back barrels? I did replace the power valve assembly last year, but that didn't help.
I was gonna have the carburetor rebuilt this season, but I just found out I'm gonna have to buy a new driveshaft so I probably won't have the extra cash to have it done.

I am going to check the things that michael listed.

[rollenrock33]

Thanks for the info Mike.

I tore the carb apart tonight and the float and needle seemed to be ok but I adjusted the float to close a little bit sooner than what it was previously set. I also sprayed some carb cleaner in the needle and seat.

No more flooding. Engine fires every time with just a blip of the key. This is running it with a garden hose so I won't now how it acts under load and being run all day but so far its running perfect.

Anyone that is having trouble with sever flooding, and you have to hold the throttle wide open to get the boat to start, should check the carb. With the air cleaner off, I could actually see fuel dumping into the secondary tubes (rear tubes of 4 barrel carb) while the motor was running, and even after the motor was shut off it would still dump fuel for a couple seconds. If this is the case then you should really take the carb off and unbolt the rear bowl. Chances are pretty good it would be the float or needle/seat. Easy fix. I just wish I would of done it before I took it to a marina that charged me 200 bucks for a "carb rebuild" that did nothing to fix my flooding problems. live and learn

[L-Robby]

Not sure what shop you took your boat to, but a carb rebuild should include new needle and seats. I just rebuilt mine and they came with the kit.

[cadunkle]

Note a Holley rebuild kit runs about $50. Takes an hour or two to go through the carb and is very simple. Anyone can do it. Just have a clean flat work area and if it's your first time lay the parts out as you take it apart so you know what goes where. The kits also come with an exploded diagram to help with reassembly.