Mercruiser 4cyl

[serrato]

I just bought a 1987 boat with 4cyl Mercruiser engine. I think its a 3.7 alpha one engine. Im not getting any spark. Im getting 10 volts on the + side of coil and then about 6volts when cranking. The boat has been sitting for 2 yrs. could the condensor and points be the problem? The boat was left outside with out covering. any suggestions.. victor

 

[QC]

Re: Mercruiser 4cyl

Welcome to iboats serrato! You'll have much better luck if you repost this question here: Mercruiser Section

 

[Unregistered]

Re: Mercruiser 4cyl

I assume it is turning over, therefore, I woudl replace the cap, rotor, wires and spark plugs. Also, replace the points ignition. If this does not cure it your coil could be bad. I had a 3.0 4 cyl and once when it would not start, we disconected a plug of some sort on the drivers side of the motor. I want to say it was the nuetral safety switch. then it ran all the time. I wish I ahd a pic for you of what I am talking about but you know there are not many wires on the motor so look around and see if something pops out at you.

the 3.0 did 38 to 40 mph at top speed and was really a good motor but could not pull up skiers very well and took a while to to plane too.

It was a great fist boat though and will still have a place in my heart. great times were had on that boat,. Some awful ones too, but the awful ones are really the ones that give you stories to tell. Good luck on your project and hope to see you on the water.

Jason .

 

[serrato]

Re: Mercruiser 4cyl

Thanks for the advise.

Do I need to go to a boat shop to get these parts or can I get these parts at an auto parts store. They seem to be traditional looking parts? victor

 

[Bondo]

Re: Mercruiser 4cyl

They Are traditional Parts,..... But they are also Application Specific as well......

NAPA carries a Marine Parts line,...... You could try there.....

 

[I/O WALDO]

Re: Mercruiser 4cyl

Figure out the problem before you hang parts.

 

[Haut Medoc]

Re: Mercruiser 4cyl

Post the engine serial #.....
Then we will know what engine we are really talking about.....
A 3.7 has a different electrical system than a 3.0.....
Even though they are both 4cyl........
Does your engine have a place to add anti-freeze?
That would be a clue as to it's ID.......​

 

[serrato]

Re: Mercruiser 4cyl

the serial numbers # B600778. Yes the motor is equpied with a sealed cooling system. It has a reservoir. I just replaced the points and condensor. Still no spark. I am going to check the gap on the points next.

 

[mike176]

Re: Mercruiser 4cyl

your voltage readings sigjest high resictence, check for lose or coroded wires.

 

[serrato]

Re: Mercruiser 4cyl

I am still getting no spark after jumping the coil with battery. My engiene is not cranking over very fast, could this cause a no spark? victor

 

[Don S]

Re: Mercruiser 4cyl

Yes a low battery will cause low or no spark. When the engine is cranking over slowly, you are probably only seeing 5 or 6 volts at the coil.
Get the battery charged or replaced, make sure the cables are in good shape, and the starter is in good shape. You need the rpm for it to start.

 

[antsmands]

Re: Mercruiser 4cyl

Hello Don S.

I am a newbee to this and was planning to purchase one. Why should we not used hydrofoils?

antsmnds

 

[Bt Doctur]

Re: Mercruiser 4cyl

In most points setups that have been sitting around the points will "glaze" over,sometimes just in winter layup.REPLACE the points first before buying other parts to try or at least run some sandpaper /fine file across them to see if they were glazed.