5.7L Mercruiser, with switch mounted to motor??

Hey All! So Here it is, I just got my first boat ever last week!! woohoo!! it's a 1989 Marlin Elite Skier...so needless to say I have been super excited to get it out on the water! so here is a quick rundown leading up to my question...I took it out on saturday, had some trouble getting it started it up, and finally after priming was able to get her going...drove it all day satrud with no issues, turned it off and back on no problems....so I took it out again on sunday, and it fired right up! drove it around the lake for awhile, and came back to the dock and parked it for about a half hour....went out to fire it up and nothing....it turned over, and sound it like it wanted to start, but no idle...? took out the plugs to check spark and nothing....then I noticed a strange circuit breaker, and toggle switch mounted to the motor...the toggle has no description just an "on"... I noticed the switch was flipped the other way (I am assuming in the off position..) so I flipped it to "on" and it fired right up! so I idled it for awhile, and it ran great the rest of the day? strange though is that I didn't flip any switches the day before to get it to run? so I am curious if anyone may know what teh function of this switch may be? I did notice that it had wires going to all over the place, and what appeard to be to the disributor, and the iginition....Forgive me, I am a total newbee,:facepalm: so I am hoping you can all help me to understand what the purpose of this switch is, and if I should leave it on or turn it off...? I have attached a few pictures of the setup in the hopes someone will be able to identify it.... Thank you all for any advice you can give!!

Re: 5.7L Mercruiser, with switch mounted to motor??

The toggle switch is not original equipment, who knows who or why it was put in. Probably a bandaid fix because a previous owner didn't know how to fix something right. The circuit breaker is OEM.

Do you want to fix it right and get rid of it completely?

Re: 5.7L Mercruiser, with switch mounted to motor??

Could be a DIY anti-theft device . . .

I wonder how it got 'flipped' off during your use. ??? or maybe you dumped it when looking at the engine or something like that

Re: 5.7L Mercruiser, with switch mounted to motor??

does this motor use an electric fuel pump,the switch may be a "priming" switch when replacing the fuel sep. filter.

Re: 5.7L Mercruiser, with switch mounted to motor??

Don S said:

The toggle switch is not original equipment, who knows who or why it was put in. Probably a bandaid fix because a previous owner didn't know how to fix something right. The circuit breaker is OEM.

Do you want to fix it right and get rid of it completely?

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I would love to, but I have no idea what it is, what funcition it serves exactly, or where to begin in determining how to fix it? the boat didn't come with a manual so I am not sure....

Re: 5.7L Mercruiser, with switch mounted to motor??

Disconnect the battery and trace the wires from both terminals of the switch to what or where they go to. Then post that information right here and we can probably help you get it back to normal.
Look down on the aft, stbd side of the engine just above and aft of the starter and see what the engine serial number is.

Re: 5.7L Mercruiser, with switch mounted to motor??

Bt Doctur said:

does this motor use an electric fuel pump,the switch may be a "priming" switch when replacing the fuel sep. filter.

Click to expand...

That's a great question....how would I know for sure? I am pretty unfamiliar with marine engines, and know a little about atuo engines....is this common to have a priming switch mounted to the motor like this? I will google it and see what I come up with. Thanks for the tip! still! I hope this produces some results!

Re: 5.7L Mercruiser, with switch mounted to motor??

Don S said:

Disconnect the battery and trace the wires from both terminals of the switch to what or where they go to. Then post that information right here and we can probably help you get it back to normal.
Look down on the aft, stbd side of the engine just above and aft of the starter and see what the engine serial number is.

Click to expand...

Ok sounds good, I will get that info tonight and post it when I get home! Thank you so much for the help!

Re: 5.7L Mercruiser, with switch mounted to motor??

Your engine shouldn't have an electric fuel pump as your engine would have still been using the mechanical pump. But who knows, it shouldn't have that switch either :facepalm:

Maybe some clear overall pictures of your engine might clear up a lot of things.

Re: 5.7L Mercruiser, with switch mounted to motor??

Don S said:

Your engine shouldn't have an electric fuel pump as your engine would have still been using the mechanical pump. But who knows, it shouldn't have that switch either :facepalm:

Maybe some clear overall pictures of your engine might clear up a lot of things.

Click to expand...

Yeah I think you are right, I am just going to try and get some overall pics, and post those, along with the serial numbers, and then maybe you guys can get a better look at it and tell me what you think....thanks again for your help, really anxious to figure this out, I don't want to screw up my new boat! lol!