Early seventies Mercury 1250 Wont Start

[maagee79]

Re: Early seventies Mercury 1250 Wont Start

also i have been told that there should not be more than 10% variance between cylinders highest to lowest. also what cylinder is low if its number one the motor has been hot and piston is breaking down. also 90 is a little low but not too low as long as u r within 10%. also when u get it going use a product called seafoam that will clean out the motor and then u might get ur compression up a little. also make sure that u have a very strong battery u r using.

 

[bktheking]

Re: Early seventies Mercury 1250 Wont Start

That motor is a 69, anniversary year and the only year they put the "merc 1250" on the cowl, I just just got a 69 1000 installed on my boat, runs like a swiss watch. They do not have points, distributer with single coil and a switchbox. The switch box is mounted to the front plate. If you have good spark chances are ignition is good. You shouldn't need to spray anything into the carbs if everything is in check.

My compression read 140-145 on all 6, sure your gauge is good???


Hard to start- 1, is the choke solenoid working and are the choke slides closing when activated. They should be connected by a plastic rod from the solenoid down. Looks at your 4th pic I don't see the rod
2, what shape are the carbs in, I just put a kit in the bottom one last night cause it was constantly leaking gas. When I pulled it apart there was crud on the fuel screen and evindence of water in the system at some point, the carbs hadn't been touched for a long long time. Their is an idle tube that screws straight down into the carb, if it gets any amount of dirt in it idle is near impossible.
3, when you start it what is your procedure. Mine- warm up lever up all the way, motor flat (level) and pump the bulb till hard then an extra pump, gas will actually run out of the carbs. I was told this is the way to do it by my local expert merc mechanic, he said it will always start this way.

Here is a pic of my bar, it's clearly visable from the pic. I'm pretty sure you're would be the same, diagram looks the same at crowleymarine.

Hope this helps.

 

[balmoralbob]

Re: Early seventies Mercury 1250 Wont Start

Hi am totally new to this site, am ecstatic to find other 1250 owners out there! I bought the boat pictured with the motor (see before pic) and have nearly completed restoring boat, motor is next step, have an old guy who holds all sorts of Australian racing records in '60s -'70's and he is going to help with getting motor up and running. He was astounded by the condition of motor and believes it has done very little work. Am interested to hear from other members there thoughts on this motor in relation to prepping motor as it is 8 years since used, and also how will this go with boat size? Boat is timber - 23' and pretty solid. I love this motor already and believe it suits the vintage of the boat- just hope it will do the job?
Steve