Marinette Boat Forum

Hello all,
I have a 74 Marinette with a single 318 Carter 4bbl. Last trip out couldn't get more than 11mph out of it and found secondary throttle plate stuck and not opening. Played with it and got the secondary throttle plate to open at about mid throttle position but no fuel comes with it. Engine breaks up past that point(probably leaning out). Cant see accelerator pump or anything exterior to carburetor that adds fuel to secondary squirter. Any idea on something internal stuck? Have not checked fuel pressure yet!
Thanks Dave Long
74 Marinette 28 Express Hardtop

Same here on the hard and "hosed up"! Noodling on this today...will let you know what I see at my end. I suspect pressure.

Dave,
I am assuming that you have a Carter AFB on your 318 The primary are at the front of the carb under the choke plate and the accelerator pump squitter's are also under the choke plate. The secondary's are at the rear and usually start to open at half to full throttle. The secondary's are controlled by linkage on the side of the carb.

Now if you look down the top of the carb with the flame arrestor off and the engine shut off open the throttle all the way. Now looking down the throats. the choke and the primary's should be open, but you will notice the secondary TOP plate "flop over valve" is closed (engine is not running-no vacuum) NOW take a screw driver and open up that top plate "flop over valve". You should see the secondary throttle plate underneath and it should be OPEN. With the choke plate held open you should see the accelerator pump nozzles spaying fuel on top of the primaries when you goose the throttle.
bill

Bill,
Thanks for the response-yes the primary squirt ears are shooting fuel thru each front throttle bore and I see no fuel coming from rear squirters leaning over motor when linkage opens rear throttle plates. I suspect a poorly performing mechanical fuel pump-i can and will measure fuel pressure at carb inlet-don't want to pull carb apart if I don't need to.

The choke mechanism stops the secondaries from opening until IT is open. (It's in the linkage on the right side.) The secondaries get the fuel they need via a flop over valve instead of an accelerator pump. If that is stuck in place, the carb won't open up. You might not see fuel shooting in even if the flop over is working unless you really whack it one in neutral, or if the boat is underway.

Did this problem suddenly develop?

Jeff

Jeff,
Thanks for the help-yes it did happen suddenly. I swear the rear throttle bores are bone dry past 1/2 throttle!