73 Mercury 1150 wont start cold without spraying fuel

[bobcarter]

My father in law bought a astroglass boat with an old 73 mercury 1150 last year. It has always started and ran great. However, The other week it wouldn't start so he brought it by my house this weekend. The choke wasn't closing all the way, so i fixed that. Still wouldn't start. FYI, we had plenty of spark. I sprayed a little tiny bit of fuel mix into the carbs and she fired right up and ran great. I let it sit a few hours, it fired up again without any assistance. I adjusted all 3 carbs 1/2 further out on the idle mixture and tried it again the next morning, and it fired up. Now my father in law took the boat back home and today it wouldn't start again. He said he tried for 15-20seconds

So...what gives? It basically sounds like it has a cold start enrichment problem. It runs too good at idle and under power to make me think that there would be a carb issue. He always puts stabil in the gas mix.

Whats even crazier, is he didn't know you had to hold the choke down to start it so he's been starting all this time without choke?

Thanks for your help.

 

[Chris1956]

Re: 73 Mercury 1150 wont start cold without spraying fuel

Messing with the carb adjustments is a bad idea. To start that motor, lift cold start lever all the way. Pump the fuel primer bulb good and hard. Hold choke and crank her until she starts.

 

[bobcarter]

Re: 73 Mercury 1150 wont start cold without spraying fuel

Right...but imagine you do all of that and it DOESN'T start. I'm not wanting to mess with the carbs if i dont have to, but feel i have a fairly good understanding of them. Thats why i thought backing out the mixture screw a little more to richen it up might help. What i can't figure out is how it would run so well if it had a carb problem....but i cant imagine anything other than a carb problem causing it not to start.

 

[mr 88]

Re: 73 Mercury 1150 wont start cold without spraying fuel

I agree with Chris,after you have pumped the bulb until you think it's ready,pump it a few more .It takes a while for the fuel to hit the cylinders and by "forcing" more fuel into the system it will fire a lot quicker.Once you have it running there is always some fuel in the reed area and she will fire right up. Sitting for some time,the fuel will dry up and give you the hard start that you described.Adjust the mixture screws back to where they were... IF you have low compression it will start hard as the fuel is not drawn into the chamber as quick as it should be. Had a low compression two stroke dirt bike that you had to lay on it's side until gas came out the overflow on the carb to get it to start, started right up when warm without laying it on it's side,threw new piston and ring in it, started right up when cold after that with no problem.

 

[bobcarter]

Re: 73 Mercury 1150 wont start cold without spraying fuel

I'll get him to try pumping the bulb more. The guy he bought it from said to pump it until you see gas starting to drip out the motor box. Seems strange to me....but I'll have my FIL try pumping it after its hard....no pun intended.

 

[CharlieB]

Re: 73 Mercury 1150 wont start cold without spraying fuel

The stacked six LIKES fuel, cold they need LOTS of choke, a LOT of choke, as in hold it continuously in until the motor fires.

Cranking speed is critical, poor connections, dirty brushes and commutator and they crank slower and seem to take almost forever to start without adding fuel.

Once lit, restarts are fine the rest of the day.

 

[Chris1956]

Re: 73 Mercury 1150 wont start cold without spraying fuel

Bob, Richening the idle mixture will not make it start better. it will screw up it's idling ability. Make sure the choke plates are fully closed, and the motor has good clean electrical connections. You need 8.5VDC at the switchbox, and at the starter when cranking. Check the battery cables for hidden corrosion. I found some on the battery cable, up under the gunwales, under the insulation.

You want the motor to spin as fast as posible so the choke works as well as possible.

 

[Georgesalmon]

Re: 73 Mercury 1150 wont start cold without spraying fuel

My '79 inline 115 is the same way. I'd suggest you do the carb idle mixture screw adjustment again since you changed it. Ya know turn in gently to stops, out 1 1/2 turns warm up and adjust each one until the motor stutters and then back out 1/2 turn. Then check acceleration in the water adjusting each 1/4 turn out at a time until good acceleration. To start as everyone has said pump the bulb until hard then an extra squeeze. Pull up the cold start throttle and hold the choke in until it starts. My other motors start more quickly but they are much newer, this old girl just needs lots of gas. Wish Merc had put chokes on all three cyclinders. After first start she doesn't need all that unless I tilt her up for a while then I need to do a cold start all over again. Seems the gas runs out of the carbs somehow when tilted . New carb kits and floats this spring so I think all the gaskets and float valves are good. Thinking the fuel runs out the backdraft feature, don't know for sure. Runs great, idles great, starts hard cold, but always starts (knock on wood), not touching anything for now.

 

[bobcarter]

Re: 73 Mercury 1150 wont start cold without spraying fuel

I think between the adjustments to the choke, idle, and a fresh battery...that we got it handled. It has started several mornings in a row. I have yet to put it out in the water...but it at least runs. Thanks for all the help.