Rexx

Since you're new to boats, just an FYI, don't rev your motor past 2000 rpms when you are on the hose or you will burn up your water impeller.

Since you are in a warm climate, delete the chokes. Also since you mentioned mods, the day you do a cam mod, don't go too wild or you get water reversion in the exhaust putting water into the valves and pistons. My suggestion in general, ask a question on this board if you are unsure about something, boat motors need to be treated very differently than car motors...many helpful and smart people on this message board.

apollard

Basically, it's just the design of the pump. However, I've found some high volume aftermarket pumps can over pressure the carb at high RPM. Cars don't generally see high RPM for long periods of time, so it doesn't show as much in that market.

Switching pumps or a a regulator is your best bet for high pump pressure IME.

murdered6.2

Well Im working on adapting my fuel pressure tester to it right now. The Boat has a nice stainless hard line from the pump to the carburetor and i hate to cut it so im working on getting the proper fittings. I think im going to swap to a holley and an air gap intake this winter as well as a cam now that I have realized how easy the engine is to pull out. once we find high fuel pressure as the cause (keeping fingers crossed thats the problem) i dont know what kind of regulator im going to install. either way wouldnt that indicate a fuel pump has a problem. I watched the carb while running the other day and as long as the secondarys dont open for any extended amount of time it wont flood out.

Thanks again for all the help I really appreciate all the advice.

apollard

Interested to see what the pressure is when running at high RPM. Might be that the secondaries open at the rpm where pressure starts to build. I can't think of any other reason you can run on the primaries (on two different carbs), but not the secondaries. Can't see two carbs being that far off, unless they were both completely mis specified (kinda doubtful).

murdered6.2

FIXED! tested fuel pressure! was getting over 12 psi above 3200 rpm the gauge stopped at 12 so i dont know what it was really reading. Installed a fuel pressure regulator and regulated to 6 psi and retested. Engine runs great. I got 58 mph with half a tank and two other people according to the speedometer. I have yet to use a gps to run it so i dont really know what it will run. Now that its running good I have a few other things to fix but for now they can wait. Thanks for all the advice im so glad i got this fixed. i feel like i can trust my boat now. I took it out for the weekend and had a blast with it for the first time since i have owned it.

apollard

Wow. 12 psi is high for a stock mech pump. The internal pressure valves must be completely stuck. I'd watch the diaphram, I'd be surprised if it is rated for that kind of pressure.

Good to hear you got it running.

murdered6.2

Thanks i ordered a holley red pump and regulator with pressure gauge today. I will just block off the fuel pump on the sea pump.

ezstriper

seen that before....

JeremyAnderson

You are correct about the piston accel pump, but I think he is refering to the fuel pump.

murdered6.2

yes the fuel pump is a mechanical diapharm type pump that was putting out way too much pressure at higher rpms. I think someone on here said they had to shim theirs and it fixed the same problem. Either way I prefer an electric pump over mechanical anyway so thats what im going to use to completely solve this problem.

The more i read about baja hammers the more im starting to think my boat is slow for a hammer. I didnt use GPS but my speedometer said I was going 58 mph at 4400 rpm and 4200 to 4600 rpm is what its max speed is supposed to be so im guessing thats all it has. I used a prop calculator and with a 23 pitch prop i think i was going slower because that would only be a 9% prop slip. I was expecting more than 12%.

I guess this is a good speed for a 300 horse 21 foot boat with approx. 640 lbs of people on board and a half tank of fuel. Im going to use a gps this weekend and see what it will do with just me and a little less fuel in the tank. I just want some more top end like an honest 65 mph. So Im thinking a little more power, a good tune up (I have yet to change the plugs since i got the flooding out issue figured out), a few hundred more rpm and a different prop and I will be there, hopefully. Thats all for a different thread.

Thanks again for all the input and advice, Im really pleased with everyones input, most sites have some duche adding stupid comments trying to make you feel like an idiot.