1971 mercury 1150 115 hp

[djwinter]

I just bought a boat with a 1971 mercury 115 hp motor the motor starts good and runs good out of water but when I put it in the water it will only get up to around five or six on the output gauge, I don't know if this is the same as rpms or not but the first number on the gauge is 5 and thats about all it goes in the water, but out of the water it will hit 15 or 16, and my fuel line keeps losing pressure and I have to keep pumping the bulb and pressurize it I didn't even get going fast enough to level the boat out. What can I do, does it sound like the fuel pump?, oh after a while of running it, it started to not even want to run on idle I had to apply the cold throttle to keep it running, but no problems idling out of water. Thanks for any help.

 

[mellowyellow]

Re: 1971 mercury 1150 115 hp

lot's of possiblilities, pump, carbs, fuel hoses,<br />tank vent, plugged filters.... you really need the<br />manual to diagnose properly! worth the investment.<br />you can do a search on this site under fuel starvation....<br />good luck!

 

[Gold Bear]

Re: 1971 mercury 1150 115 hp

djwinter,<br /><br />I have the same engine.<br /><br />Out of the water the engine will idle faster because there is no back-pressure against the exhaust. You need to adjust the idle when the boat is in the water, so it doesn't stall when you put it in forward gear. Make sure you adjust the control cable and carb mixture screws along with the idle speed screw. <br /><br />You really need a service manual to tell you how to adjust the idle and cable.<br /><br />The gage sounds like a water pressure gage??? I'm not sure (I do not have one). Make sure the tale-tale has a good stream of water coming out so your sure the water pump is working.<br /><br />Having to squeeze the fuel bulb indicates a lean condition. As mellowyellow mentioned this can be due to a number of things, such as a plugged / dirty vent, clogged pick-up tube, air leak into the fuel hose etc.<br /><br />As mellowyellow suggested you need a manual to help you find the problem.<br /><br />Good Luck, Gold Bear

 

[Bry21317]

Re: 1971 mercury 1150 115 hp

For your guys with this engine, how fast does it go and what size boat is it on? I am rebuilding one right now for a friend, and heard it is a real Tower of Power, but havent gotten it done yet to see what it will really do.<br /><br />Thanks,<br />Bryan Cox<br />MTU

 

[Gold Bear]

Re: 1971 mercury 1150 115 hp

Bry21317,<br /><br />I have a 16' Ebb Tide bass boat. My engine is a 1972 model with a 19 pitch prop. My boat runs 52 mph.<br /><br />Regards, Gold Bear

 

[djwinter]

Re: 1971 mercury 1150 115 hp

thanks for the help goldbear and mellowyellow, if I adjust the idle and carbs will this help it get more rpms and speed up or is that just to help it at idle? or does the problem with not getting up and moving sound more fuel related? as I was saying I can't even get enough speed to level out my nose just stays up in the air all I get is about 10 mph at most. This is my first boat so I'm new at all this would my trim have any thing to do with no speed, should I have the engine more or less in the water at the right setting? Thanks again for all the help.

 

[mellowyellow]

Re: 1971 mercury 1150 115 hp

same motor/same problem...fuel starvation.<br />see red "search" link at top of page and<br />read several previous posts re: this problem.<br />mine was air leak in supply hose and broken<br />fuel pump diaphram, she wasn't getting enough gas<br />to go more than 30, now she does 50+.<br />the search function on this site is always the <br />first/best place to start your research (IMHO)<br />good luck,<br />M.Y.

 

[Gold Bear]

Re: 1971 mercury 1150 115 hp

djwinter,<br /><br />If the idle mixture screws are all set to lean, it could possibly cause the problem you are describing.<br />Close the mixture screw, seat them lightly - don't bear down on them, and count the number of turns (to see where they are set now so you can return to the original setting if you have to). Then open them to 1-3/4 turns each. See if the engine still bogs. If it does open them to 2 turns each. If it still bogs then most likely your problem is elsewhere. <br />I would check the fuel pump diaphrams next, then make sure the fuel tank, hose, filter, vent, pickup tube, etc. is in good shape.<br /><br />If your engine starts right up when it is in the water, I would expect some fuel delivery problem other than the mixture screws. Lean set mixture screws usually makes the engine hard to start.<br /><br />Your boat should run like a scalded dog!<br /><br />Good luck, Gold Bear

 

[djwinter]

Re: 1971 mercury 1150 115 hp

Thanks again for the help, I just talked to the guy I bought the boat from and he said he had it out the weekend before I bought it and it hit wot with no problems but he said when he got home he took apart the box with the throttle and ignition to check the ignition switch. I was wondering if this could possibly caused the throttle to have slipped lose and maybe needs readjusting because the motor seemed to run fine just didn't seem like the throttle was opening the motor up all the way and seemed like it moved a little before I noticed any change in the motor speed. could my problems just be that I need to adjust the throttle. Thanks for any help

 

[speedboat]

Re: 1971 mercury 1150 115 hp

What color is the labels on your motor red or blue?