Running rich or lean?

Look at the carb, check the choke stat and make sure it is working correctly. The top butter fly on the carb should be straght up and down after say 5 min or so and check the accellerator pump and float level.

A good starting point on the adjustment screws is to screw them all the way in and back out one and a half turns. The power valve is on the back side of the part the adjustment screws are in. The accelerator pump has a arm connected to the linkage, should have four screws holding it on the bottom of the carb. It will also have a spring inside. Both of these are very easy to change. It should take about 5 minutes to take these off. Be careful not to over tighten the screws that hold the bowl on, those paper washers can tear. If you have a Holley, there is a sight hole (large head brass screw) on the bowl. If fuel comes out while it's idling, lower the float. My holley has a flat head screw with a jam nut on top of the bowl, where the needle and seat is. To lower the float loosen the jam nut and turn the screw counter clockwise and tighten the jam nut. Clockwise will raise the float. One thing you can do is will you're checking the power valve and the bowl is off, turn the bowl upside down and see if the float hangs horizontal. If the power valve and accelerator pump are bad, I would get a rebuild kit and change the needle and seat also. The whole kit for my holley is about $18, which will have all new gaskets and pieces you don't need.

I would check and see if the accel pump is not working before replacing it. Remove the flame arrestor and open the throtle slowly. You sould see gas squirting into both bores if you do then there is nothing to fix or replace if you don't then you have a problem. Is the engine back firing? NO, then leave the power valve alone. If it is back firing then you need to replace the power valve.

Have you checked the timing and dwell? have you check for vaccum leaks? PCV valve? there are several things to check before you start screwing up the carb shooting in the dark trying to fix your problem. With the color of the plugs being light brown odds are the carb is fine.

The spark arrester fits on the top of the carb like an air cleaner. It is made to prevent backfires from setting the boat on fire. It sounds like a fuel pump problem I would change the pump and any filters you see inline between the tank and carberatorThere is a scintered brass disc in many Carbs where the line comes into it.. I had the same problem with my electric fuel pump It would fail intermittently. I rerplaced it and had no more problems.

CC 79
Have you varified the timing? replacing the points will change the timing. Also converting to electronic ign would help. you can get a conversion kit for around 100 bucks or you can replace the whole distributor like I did. The easiest way to check for vaccum leaks is to use 1 lb bottle of propane and open it slightly. Then slowly move it around the base of the carb, vaccum lines and edges of the intake and listen for the RPM's to increase. Usually you can just check the torq on the bolts to the carb and intake and it will take care of it. You can use carb or brake cleaner but I don't like to use them because it will remove paint and makes a mess. Like I said just put a wrench to all the bolts and check the torque on them.

If you have low fuel pressure i.e. bad fuel pump, it will show up on the top end and not lower end of the rpm range. For instance you are cruising along and everthing is running fine then as you increase in speed it falls on it face and starts to stumble then when you back out of the throtle it clears up.

Also can you explain in minutes

"but after a while it struggles and hesitates when pulling then boarder out of the water. It stutters and stumbles and then clears and goes well again."


Is it while coming out of the hole or is it after you are on plane. Then does it do it all of the time or once in a while. Also do you have a rubber hose or steel line running from the fuel pump to carb?

If it hesitates every time you are coming out of the hole then I would focus on the accellerator pump on the carb and adjust it so that it squirts gas for the full movement of the throttle. Timing can add to this as well. also make sure the steel fuel line is not laying on the manifold or against the block if it is bend it slightly so that there is a 1/2" gap or 12-15mm since your in the UK.

As time goes by and hours are put on the engine the timing chain becomes slack and puts the engine retarded. Forget what the inital timing is turn engine to 2500 -3000 Rpm and adjust timing to at least 32-34 Degrees.
To put a marine grade rubber fuel line from pump to carb will eliminate a lot of fuel problems.

On this side of the pond pressurized fuel in a rubber hose is not USCG kosher.

Sometimes just wraping the steel line with hose that you split with a utility knife gets the same effect, but looks like azz.

Even good dial-in timing lights tend not to exceed 25 or 30 degrees, so setting full advance can be tricky.

Take the circumference of the damper and divide by 360, take that number and multiply by 34, and put a secondary mark on the damper from TDC that should equal 34 degrees. Then see what the advance tops out at.

You should be seeing no drips from the primary or secondary venturies at idle, else the needle and seats are boogered. If that is the case, good bet the idle fuel circuit is clogged also.

Like 79nautique sez, accel pump should squirt for entire motion, and also must squirt immediately off idle, else adjust the plunger.

I would also try a different coil.coils are lazy and after warm up?could be the problem if carb rebuild has no effect

yes it will i just got the 542 amazing http://www.correctcraftfan.com/articles/featured_product.asp

i had the same exact problem as you. what is happening is when you shut your motor down when it is hot all of the gas is boiling out of your fuel bowl and into your intake (vapor lock) then when you try to restart it, its hard to start. and when you go to pull up a skier it bogs down because you get air in the accelerator pump circuit and your not getting a full squirt. it eventually works itself out after a few hole shots. so anyways you need to solve your vapor lock problem with what the other guys were saying by running a rubber hose or insulating your steel fuel line