View Full Version : Bing carb problems - help badly needed

Pat Tobin - n/a
13-Aug-08, 09:32 PM
Hi all

Hoping somebody can help

I have a 503 with dual bing carbs. I prime the carbs and the engine starts and runs fine. If I anchor the craft I can run the engine to max revs and hold it there no problem hovever when I move the craft and then make a turn it dies like it is only running on one cylinder.

I have been through the electrical checks and all is well. I took off the carb bowls and the fwd carb has verry little fuel in it whereas the aft carb is full.

Thinking the fuel pump was to blame I swapped over the fuel lines but the problem was the same. Then thought it was a sticking float valve but took that apart and it is clear and moved freely.

I am making the assumption that the low level carb is the problem....or is it.

Some other things I have done is to swap floats around to no avail.

I have run the engine to max power held it there and then pulled the kill switch then checked the bowls and one is

practically empty while the other is full.

Both carbs have been totally stripped and cleaned prior to this problem. I dont know if it was there before I had the craft as it was not running when I bought it

Any help or thoughts gratefully appreciated


Hornet - n/a
14-Aug-08, 01:46 AM
I am not familiar with the Bing Carbs, but if one bowl is empty and one is full then it must be a float level or needle & seat problem. The fuel level in each carb should be the same or atleast very close. Have you checked the float adjustment to ensure they are both set correctley. If so then it could be a neddle & seat problem - the full carb may not be seating properly and is basically flooding. However I suspect that the empty carb is the problem because the fuel bowl level should stay resonably constant - it should not get to the stage where at full throttle the bowl is almost empty.

Sean Atterbury - n/a
14-Aug-08, 06:59 AM
I have been having the same problem this last week, I found that the valve that lets the fuel in was a bit sticky, just pull it out and give it all a good cleaning with a earbud. That sorted my problem.

The pump may also not be pulsing properly, check the line from the motor to the pump for blocks, this too has been the cause of some of my own probems, I had some how got some gung in there and the pump did not pump enough.

Check those two, thereafter you should be sorted. http://hovercraft.org.uk/images/icons/smiley_icons/icon_smile.gif

Iceman - n/a
14-Aug-08, 07:35 AM
The problem is between the pump and the float bowl:

Check the fuel hose is clear (you could swap hoses from carb to carb to see if the problem migrates)

The inlet into the carb has a small space where debris can collect so take the hose off the carb and look in the hole to check for debris (common fault)

The float arm pivot can wear and cause problems with fuel supply (as I have recently experienced with my own craft!!)

As with all faults on a twin carb system, the easiest way to find a fault is to swap components (only ever one at a time) from cylinder to cylinder and check if the problem migrates across with the component and hence identifying the problem part!

I hope this helps.