305 V8 starving for fuel

Okay, this is my first time posting on iboats even though I have answered many of my questions just reading other people's threads.

I have a 1985 Chris Craft Viking with a 305 Mercruiser v8. All together the engine runs great, the only issue is that after it has been running on plane for a while the engine then stalls and will not start. After the boat sits for a while the engine will start right up and runs great until it has been on plane again for a while. I can start the boat in my driveway with the muffs on it and it will run great for hours even when I give it some throttle. A prime example is last weekend I put the boat in and drove around for over 45 minutes at a slow speed and it ran fine, I then cruised for about 10 minutes on plane, after this i drove another 30 minutes at a slow speed, once I tried to go on place for a second time it ran great for abou 3 minutes and stalled out like it was starving for fuel.

I have replaced the fuel filter and confirmed that there is no water in the fuel. I think it is possibly the carb getting clogged up or the fuel pump starting to go. Just wondered what anyone elses thoughts on the situation were.

Thank you!!!

Re: 305 V8 starving for fuel

Try a remote fuel tank.

Re: 305 V8 starving for fuel

Sounds like a common case of vapor lock. Make sure your fuel lines (or filter) aren't close to anything hot and re route if they are.

Re: 305 V8 starving for fuel

Pete104 said:

Try a remote fuel tank.

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Thats a really good idea. Is there a filter in the gas tank that could possibly become clogged?

The fuel lines go above the engine is that to close?

Re: 305 V8 starving for fuel

One other thing to look for ( I speak only from personal experience ) is your anti-siphon valve. Its possible it could be clogged up and restricting your fuel flow.

Re: 305 V8 starving for fuel

mmajor97 said:

One other thing to look for ( I speak only from personal experience ) is your anti-siphon valve. Its possible it could be clogged up and restricting your fuel flow.

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Ayuh,... Or the tank Vent, too...

Re: 305 V8 starving for fuel

I'm thinking tank vent. Next time it stalls, open the fuel fill cap. If it sucks air in, then your vent is blocked. Whats probably happening is the tank is pulling a vacuum, and eventually the fuel pump just can't overcome it. Had that happen on a car I used to own. It was really annoying until I figured it out.

Re: 305 V8 starving for fuel

Did you check the fuel filter at the carb?

Re: 305 V8 starving for fuel

Hey Guys,

Okay, today I replaced the fuel pump, cleaned the carb, and checked the tip of the gas pickup in the gas tank and it was not restricted (I dont believe my fuel cell has an anti-siphon valve, there is just a screen on the end up the tube) . After I did all of this I put the boat in and took it out on the lake and it did the exact same thing. After this we checked the vent on the gas tank and it was clear. We removed the hose from the fuel pump and we had suction on from the fuel pump. We bypassed the fuel filter. After doing all of this it still did the exact same thing. We pulled the pickup hose from the gas tank and there was absolutely no suction whatsoever. I am stumped and have no clue now

Re: 305 V8 starving for fuel

Okay, so i placed a see through in line fuel filter between the fuel pump and the carb and after the engine heats up I am getting a lot of bubbles in the line. Does this mean my new fuel pump is bad???

Re: 305 V8 starving for fuel

Sounds like you are getting air in your fuel system. Check in the stickys i think Don has a write up on this.

Good Luck!

Re: 305 V8 starving for fuel

sounds like the pick up tube that goes to the bottom of the tank has a split along its length somewhere.connect a remote tank as stated previously or your gonna have to find the source of air.is the tank full?

Re: 305 V8 starving for fuel

Still sounds like vapor lock to me especially since you can see the bubbles and because it does it hot.

You might want to change your fuel lines before your pump or at least check the fittings for air leaks.