Sport Nautique Fuel Issues

Guys i need some help! Ive been following this forum for along time and enjoy fixing my boat myself. But i cant figure out why my boat keeps bogging down. its a 351 pro boss ho. I recently put a set of hi tek headers on and rebuilt the exhaust with a wye pipe instead of the muffler. The carb is a 4160. The boat ran fine after the install of the exhaust work then i noticed fuel coming from the fuel pump to the carb. Figured the fuel pump was going to die so i replaced fuel pump. Next time i went out the motor bogged down suddenly while at cruising speed(after half hour of wakeboarding). could barely idle and the engine shacked. since then ive replaced the fuel lines and the fuel filter, checked the anti siphon valve, checked the vent line to gas tank, and made sure no water is in the system. The boat runs fine till i turn sharply or after about half hour of use.   removing some fuel from the fuel filter remedies the problem for another half hour where the engine will perform good.
think i got a bad fuel pump?
any thoughts are appreciated.

Your ProTech is on the way out, next time it happens put a damp cool towel over the coil pack and after a few minutes see if it runs better.

SkiDim has a conversion for about $500 or I think there is a way to convert to DUI if so desired.

Oh yeah, is that an air filter or a flame arrestor? if not a flame arrestor you may want to get one, either that or more fire extinguishers.

Thanks I've read up on the conversion. Didn't realize that would be causing the issues I'm having but it makes sense. The engine has 750hours on it. I guess I'll be ordering the conversion from skidim. Ill keep you guys updated. As for the air filter I read a couple guys on this forum were running this filter on their boats. I've had it on a couple years with no issues but the last thing I want is a fire hazard. Ill throw the old flame arrester back on!

TedK wrote: Thanks I've read up on the conversion......... As for the air filter,.... I'll throw the old flame arrester back on!

TedK - I did the ProTec conversion by DUI - it is very good and I'm glad I did it that way. JPASS did a great write up for the 351. Also, I have a K&N Flame arrestor in the style of a blingy Air Cleaner - you may look into what they offer. (often times height is an issue). They make a red cleaner insert that has mesh wire and is USCG approved flame arrestor. See if they got something to fit what you already have! Oh, Look - shiny things!

got the old paperwork and it is a K&N marine flame arrestor.

found the dui conversion write up you were talking about here
also looked up the ski dim alternative. which one is the better choice. I like jpass write up seems easy to follow. I could not find a write up for skidim but im sure i could call them and figure it out.

Yup. Sounds like ProTech is failing. Time to put in a D.U.I. distributor.

Did you check the fuel pressure on the new fuel pump? Too high or too low can cause problems. The problem could also be carb float issues. The carb float bowls need to have the proper fuel level or you can experience a rich condition or a lean condition. I had a float stick open once, and the fuel just poured into the carb. Slow RPM operations were impossible -- high RPM was OK. Fixed the float needle/seat, fixed the problem.

Unfortunately, the Holley 4160 is not the easiest float chamber to adjust. Most will tell you to replace the needle/seat assembly and then hold the float chamber upside-down. The top of the float should be parallel to the top of the float chamber. That is a good place to start.

One more reason to replace the 4160 with the QuickFuel M-600 carb. The float chambers have sight windows and external adjustment hardware!

Nice looking engine. Don't know if your K&N is a flame arrestor or just an air filter. If not, K&N makes a USCG approved flame arrestor for your application.

K&N 59-3264
https://www.summitracing.com/parts/knn-59-3264/overview/

You may also need the following adaptors:

1/4 inch vent adaptor K&N 85-1325 (this is for the clear fuel line above)
https://www.summitracing.com/parts/knn-85-1325

5/8 inch vent adaptor K&N 85-1362 (this is for the starboard side engine vent by the oil filler cap to vent into the carb)
https://www.summitracing.com/parts/knn-85-1362

JQ

TedK wrote: I rebuilt the carb and the float working fine. I always wondered if it was the new fuel pump because it happened right after replacement. but the protec is 24yrs old and it sounds like im not the first person with similar issues. How do i check the fuel pressure going to the carb. there is a metal line from fuel pump to carb. I had debated cutting it and installing a pressure gauge.

Why not just remove the fuel line, get a couple of fittings, one for the carburetor, one for the fuel pump, a length of rubber hose and a t connection to go in the hose and use a vacuum/fuel pressure gauge to check the pressure.

When you're done you can put the metal line back on