Need help with what this part does.

[matt194]

I have a suspicion that faulty wiring to the SOLENOID ASSY is causing two of my cylinders to not fire. Could you tell me what the part does in the picture? I have checked compression, fuel delivery, and spark. They all checked out good.

Thanks

Matt

 

[ezeke]

Re: Need help with what this part does.

The part is the starter solenoid. The two wires should not be connected as they are because those posts are for the ignition switch to engage the starter and the posts need to have nothing else connected to them.

The red and yellow wire connected to the top small post runs directly through your harness to the ignition switch, where it connects to the "S" post for start or starter. The other small post on the starter solenoid is wired directly to ground with a short black wire running to the engine block.

That probably has nothing to do with the firing problem because the starter and the ignition have nothing to do with each other except in regard to turning the flywheel.

Take the cover off your carburetors and watch what the throttle plates are doing as someone advances the throttle for you. Are they perfectly synchronized? When the throttle is fully advanced are they both perfectly horizontal?

You need to clean your battery terminals. You may get fire with no load on the engine and the plugs out and get nothing in the water with them in. That's because the starter needs to turn that flywheel at 300 RPM. You need everything your fully charged battery can deliver.

 

[tashasdaddy]

Re: Need help with what this part does.

what motor?

 

[ditchdigger21003]

Re: Need help with what this part does.

will it fire as long as the switch is in the start possion?

 

[matt194]

Re: Need help with what this part does.

The motor is a 1979 115hp Johnson. What do you mean "will it fire as long as the switch is in the start possion"? Do you mean the key switch? I have spark on all four cylinders when the spark plugs are out, but with the plugs in only two cylinders fire.

 

[ezeke]

Re: Need help with what this part does.

If they fire when the plugs are out and not when the plugs are in, then you are not turning your engine over fast enough. You need 300 RPM. It requires a big fully charged battery and spotless terminals.

 

[matt194]

Re: Need help with what this part does.

Thanks for the help. I will try that out. I am using a car battery can that be the problem? What type of battery would you recommend?

 

[ezeke]

Re: Need help with what this part does.

I use only 650 cca or larger deep cycle dual purpose batteries, but I am 6 miles out in the ocean sometimes and I don't like risk at all. If you look at a map of eastern Cape Cod you will see that we are already 40 miles off the general line of the East Coast so when I say 6 miles, you have to interpret a little.

If you are going to use the battery strictly for starting, use a starting battery. If you like a lot of accessories, or, say, use your trim a lot, you will probably find the starting battery won't last very long because it cannot take the heavy discharge/recharge cycles like deep cycle batteries can.

The longest lasting battery I ever had was a big dual purpose marine battery that I bought at Walmart. Edit: [thanks jay_merrill and see below] it was yellow.

 

[HighTrim]

Re: Need help with what this part does.

I too like a large battery, the biggest CCA battery that I can fit.

 

[samo_ott]

Re: Need help with what this part does.

I like multiple batteries. There's safety in numbers.

 

[jay_merrill]

Re: Need help with what this part does.

The yellow Walmart batteries are "Everstart" by Johnson Controls, who makes most of the "house brand" batteries that are bought by consumers in the U.S. I have a pair of them in my boat and like them very much. I also like the fact that I can go to any Walmart, anywhere in the country, and get a new one under the warranty if I ever need to.

Not sure why two of your plugs would fire when out of the engine and not while in but, it might be worthwhile to use a timing light to check for ignition on each of the plug wires when the plugs are in.

 

[TerryMSU]

Re: Need help with what this part does.

Jay:

That is correct about Johnson Controls (At least as far as who makes them). I work for Johnson Controls, but not in the battery group. As far as the not firing in the motor, the cranking RPM is a good bit lower with the plugs in. I have that issue on a 1978 35HP. Niether plug fires in the motor but pull them out and they fire great. In fact the motor will crank and run if I pull one plug out. NOT RECOMMENDED!! The gas just vents out of the plug hole and can make a big boom! I have checked out most of the wiring and it appears that the problem in this case is that the starter is a little flaky. I suspect that the brushes are sticking. Matt's issue is likely different. Mine obviously has cranking issues.

Matt:

If you have a meter, check the voltage drops across the various high current lines in the starter system. It is possible that the solenoid has a high voltage drop across the high current terminals when engaged. Also, you should check your battery.

Another thing to try is to dirrectly connect (using jumper cables) to the starter and see if you get good sparks then.

Terry

Terry