Re: 1987 3.0 Mercruiser Starting issues
I have a 1987 3.0 Mercruiser that will not start properly once I am out on the water. It will start on a dime on land with earmuffs. I have to give it almost full throtle for it to catch. I can not figure it out. I have changed filters and checked the fuel pump. Everything is good.
Any sugestions.
I have the identical problem. I made it slightly better by going over to a Pertronix system and bypassing the resistor wire on the coil, but it still has the same symptoms. First start of the day, it starts after less than two seconds of cranking. Once it's warm, you need to give it full throttle and crank it over until it starts to stumble a bit, then keep it cranking until it runs solid, then you can throttle down and let it run. Idle is perfect, high revs are perfect, there's a bit of a stumble coming up from idle.
I rebuilt the carb last season, the timing is set to spec, the advance mechanism is working fine. I know a couple of people who have 3.0 GM engines who have the same symptoms.
Here are some things I plan to check out, unless you get to it first:
1) Does this happen only after the engine has been idling for an extended period of time, or does it happen if you shut it off immediately after throttling down?
2) Are the plugs fouled?
3) Does it do the same thing on a remote tank with fresh gas?
4) Are the cylinders flooded with gas when you try to do this? On mine the symptoms are the same as flooding.
Additional things to look at:
When was your carb last rebuilt?
Are the check balls definitely in place?
Does your distributor advance mechanism work as it should?
When did you last replace your coil?
This is all assuming that you have tuned the engine, that the points, rotor and condenser are in good condition, etc. As Don points out, there are a lot of things that can cause these symptoms--most of them taken care of by a tune-up.
