140 hp mercruiser fuel problems

[cautionneeded]

I have a 1975 140hp mercruiser that is having fuel problems. I removed old fuel from the tank and it was heavily contaminated with water. I replaced the fuel filters both in the pump and in the carb several times after adding new fuel. I still have trouble on the water and just broke down again and I am not getting any fuel to the carb at this time. It ran great at medium and low speeds but bogged down at WOT and finally died while in idle. Should I replace the entire length of fuel line and is there anything more that I should be aware of. I have worked on auto engines but never a boat motor so there may be some basic things I am missing. I do know about marine parts vs auto however. I need to make sure it runs both away from the dock and back to the dock! Help will be greatly appreciated. Thanks

 

[elkhunter338]

Re: 140 hp mercruiser fuel problems

I would replace all fuel lines, make sure vent is working properly, I would also add a spin on fuel filter/water separater.
I have seen old fuel lines swell shut. Also maybe your fuel tube pickup tube is not clear. I would check things from tank to carb. You could also try running the boat from a portable tank hooked to the fuel pump to see if your problem goes away, then you would be isolating where the issue is.

 

[oldsub86]

Re: 140 hp mercruiser fuel problems

Try running it on a remote tank. A tank intended for an outboard would make a good test tank. Hook up your fuel line to the test tank and see how it does. Might be in the fuel pump or carb rather than the lines or inboard tank.

Randy

 

[fishrdan]

Re: 140 hp mercruiser fuel problems

Check out this page;

http://forums.iboats.com/showthread.php?t=283269

 

[cautionneeded]

Re: 140 hp mercruiser fuel problems

Thanks for all the good advice. I will try running off a spare tank and see if that suggests the location of the problem. I will also add the vacuum test when I can.