Boat side fuel issue

jkillion

Cadet
Joined
May 28, 2015
Messages
14
Hi,

Boat/Engine Specs: 1995 Procraft SP 200, 1995 Mercury 200 EFI

Last year, my boat starting acting like it wasn't getting enough fuel. It would work fine, then slowly start losing RPM, eventually coming off plane. Usually turning it off and starting it back up would temporarily remedy the issue and I could scoot a little further down the lake before it started again.

So, this spring I redid all of the engine side fuel lines, rebuilt the mechanical fuel pump, replaced the quick disconnect. Took it to the lake and ran it off a 3 gallon external fuel tank. Ran like a top, so I figured bad fuel. Drained all the fuel out of the boat (2 tanks, over 20 gallons) thinking it was just bad fuel. Put new fuel in it (more on that later) and hooked the fuel line up to the on-boat fuel tanks (i.e. not the little 3 gallon tank). Ran good for a while, then after idling it a bit I had to cut it off and back on to get it to come on plane.

Yesterday, I took it back out. Worked great for 2.5 miles then we stopped and swam and fished for a couple of hours. Time to go home, I idle out of the slu we are in and it wont come on plane. Cutting it on and off didn't help, just seems like its not getting fuel. I tried this 4 or 5 times, then hooked my trusty external fuel tank up and boom, on plane and hauling back to the dock.

So, to me it seems like there is something up with the on board fuel tank system. Not the gas, something wrong with the hoses and all that. Unfortunately I have no idea where to start. Any ideas here?

I mentioned earlier that I would talk about filling it up. The boat has 2 13 gallon fuel tanks and a fill nozzle on each side. Well, when I went to fill the boat up, one side took 20 something gallons before finally clicking off. Is that just how its supposed to work or a symptom of a bad tank selector valve?

Any help would be appreciated. Glad I got the engine running good, lots of help from this site to (fingers crossed) get it squared away. No just gotta figure out the tanks.

Thanks,
Jud
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Hi JK,

Does the poor running happen no matter which tank is selected?

With all the fuel line work and still the same issue, I would look at the tank vents, anti-siphon valves and fuel pick ups in the tanks.

Don't know how stuffing almost twice as much gas in a tank is possible with out filling the bilge with gas. I guess the tank selector could be faulty, but once one tank is filled, it would be slow to put another 7 gallons into the other tank via the valve.
 

jkillion

Cadet
Joined
May 28, 2015
Messages
14
The poor running doesn't occur on the external small tabk, just on the onboard tanks. Anything in particular I should be looking for for those things you listed? Just replacing them or cleaning them?
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
I understand. I was asking if both onboard tanks have the same symptoms using the tank selector. Elimination is what it's about.
 

jkillion

Cadet
Joined
May 28, 2015
Messages
14
Ah, gotcha. I've just tried the one tank, I'll check the other next time I'm at the lake.
 

jkillion

Cadet
Joined
May 28, 2015
Messages
14
Couple of other things. When it starts acting bad (hooked to onboard tanks) the primer bulb does NOT go flat. Additionally, the primer bulb never gets very hard when hooked to the onboard tanks but it does get hard hooked to the 3 gallon external one.

Thanks,
Jud
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Again, switching to the other tank before using the primer bulb could tell a lot. too.
 
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