1972 mercury 1150 starting problem...

[DVTO2]

I pulled the cover off the boat late in the season and fired it right up. Took her out and it started tough and ran inconsistently, and I could see the fuel line from the boat to the motor was bad. I replaced the line and also replaced the fuel pump diaphragms. Now it won't start at all and sounds like it is not getting any gas at all. The squeeze pump in the gas line pumps up good and hard and when I dissembled the fuel pumps I could see gas flowing freely into the pump chambers when I squeezed the bulb. The only other thing I did was to change the little cork gaskets on the valves of the fuel pumps, but I think I got them back in the way I took them out, with the ones on the bottom protruding into the chamber and the ones on the top protruding out towards the line. Any thoughts or suggestions?

 

[Chris1956]

Re: 1972 mercury 1150 starting problem...

First test is to see if the carbs are getting fuel. Remove the brass hex nut at the base of the carbs and see if clean fuel comes out. If not, you may have messed up the rebuild of the fuel pumps. The primer bulb will always be able to push fuel thru the fuel pumps and fillthe carbs.

If the carbs have fuel, it is likely the isle circuits are clogged with gunk, from sitting too long.

You are holding the choke button down, cold start lever all the way up and crankiong the motor right? You need to just about drown them in fuel to cold start them.

 

[DVTO2]

Re: 1972 mercury 1150 starting problem...

Good tip. I loosened the hex nuts and fuel comes flying out of there from all three carbs when I squeeze the bulb. I suppose I could have loosened some crud somewhere when I changed the fuel pump diaphragms but the motor was at least running before i changed them.

Am holding choke button down and have cold start lever all the way up and really cranking it and not even the hint of a start - are there any other thoughts?

 

[Chris1956]

Re: 1972 mercury 1150 starting problem...

Make sure you have good compression (100PSI+ and pretty even on all 6), and sparp on all six.

 

[DVTO2]

Re: 1972 mercury 1150 starting problem...

Any other suggestions. Again, this was a motor that started and ran, though appeared to have fuel problems, including a leaky 9(eaky for air) fuel line. I changed the fuel line and the fuel pump diaphragms and am getting a good solid pump on the squeeze bulb (till it gets hard) and gas flowing freely to the fuel pumps (I disassembled to check) and the float bowls (removed screw at top of float bowl) when I squeeze the bulb. I can crank the heck out of it and am not getting the hint of a start.

Chris: I don't mean to ignore your electrical and compression suggestion, but I had compression and spark before I made the fuel changes so I am thinking there is still some kind of fuel problem, only now it's worse. Maybe too much fuel, or, maybe I dislodged some gunk that clogged the carbs.

 

[DVTO2]

Re: 1972 mercury 1150 starting problem...

So pursuing that this was primarily a fuel problem, I squirted some carb cleaner in the carbs and it started right up, then died. I squirted a little more and this time the motor kept running. Not sure why I to do this to get it to start - maybe the jets from the float bowl to the carbs are dirty and just wouldn't let enough fuel in to start it? I'll give it a whirl at the local lake to see how well it runs.

 

[DVTO2]

Re: 1972 mercury 1150 starting problem...

So I took it to the lake and it started right up. The high end worked flawlessly - the idle was ok, not quite as purr smooth as I would like but adequate. It'slike I had to "prime the pump" with carb cleaner to get this going and then it ran fine.

 

[Chris1956]

Re: 1972 mercury 1150 starting problem...

I would be concerned that the idle passages are partially clogged or hte high speed jets are partially clogged. If so, the engine can run lean and seize. The best thing to do is to clean the carbs.

 

[DVTO2]

Re: 1972 mercury 1150 starting problem...

Ugh, took me two days the last time I cleaned the carbs, maybe it will go quicker this time.