The Jet Ski Starting Solenoid

The starting solenoid, or starter solenoid, is a small part; it measures about two inches by one and a half inches. It resides in the electrical box, in-line to the starter just after the fuse. It can be temperamental, tricky to diagnose, and a general headache, until you understand how simply it operates.

I have a couple of articles, now linked to this one, explaining the starting system in the Yamaha jet ski. People reading these articles have a lot of questions pertaining to the starting solenoid; to understand repairs, they need a better understanding of the part. Personally, I can’t read an article that merely says “put this part here” without the knowledge of how exactly that part contributes to the whole system.

This article will delve into the specifics of the starting solenoid for those of you who need to know.

Above is your typical wiring for the starting system. This diagram was developed from the Yamaha XL700 engine, but they are all very similar.

  1. The source of energy to start the engine is the battery. A good charge on the battery is imperative. If the battery is dead or has a low charge it won’t produce enough energy to start the engine.
  2. As you can see in the diagram, the positive, or hot, post of the battery has a good-sized wire attached to it that routes through the firewall and goes directly into the electric box, or E-box. This is where the wire connects to an inline fuse and then connects to the starting solenoid.
  3. The hot wire coming out of the other side of the E-box goes straight to the starter motor.
  4. The negative wire runs from the negative post on the battery through the firewall and is attached to the engine. Where it connects to the engine it must be shiny clean! This connection can, and does, corrode. Many starting problems, especially intermittent starting problems, happen because this connection is not clean. Simply remove the bolt attaching the ground to the engine and take some steel wool or 600 grit sandpaper and clean the surfaces until they shine. Then reattach the bolt. I can’t stress enough how important this connection is for your engine to start!

As the wire leaves the battery it enters the E-box. Next it passes through an inline fuse. This fuse usually has enough wire attached to allow it to be pulled through the capped screw hole in the box for easy changing of the fuse.

After the inline fuse, as you can see in the photo above, the starting solenoid breaks right into the hot wire. The black wire goes to ground of course, and the green wire is routed to the rectifier/regulator. When the rectifier/regulator is in good standing, when the start switch is activated the starting solenoid is activated and the bar rises up and makes the connection between the two positive battery wires at the top. This is the clicking noise you may hear when you push the starter button. When the connection is made, the battery power can finish its journey to the starter motor and start the motor which, in turn, turns the jet ski engine to start.

The internal workings of the starting solenoid are very simple as you can see. It doesn’t matter which post you attach the hot wire to coming in and going out, just as long as one is on one post, and the other is on the other post! Easy.

There are several things that can go wrong with the starting solenoid:

  • The contacts can become fused. This is rare but it does happen. Fused contacts are shown in the drawing below. When activated by the starter button, the bar fuses to the contacts and the starter starts to turn and does not stop. When you release the start button, the contacts don’t release and the starter goes on and on. The battery’s positive, or negative, connection must be removed as soon as possible to avoid burning out the starter.
  • Sometimes the spring mechanism can’t push the bar up to the contacts when the starter button is pressed. This can happen if the spring mechanism is entangled, broken, or can’t move for some other reason. This problem can be caused by corrosion on contacts or a loose ground wire.
  • If the rectifier/regulator isn’t working properly the starting solenoid may not activate.
Fused contacts.

There is an easy method to test the solenoid. Personally, I’m over-cautious: I remove the starting solenoid before I test it.

Attach the positive to one contact at the top, with the screw on it. Just touch the negative onto the other contact with a screw on it. The starting solenoid should click. That is the bar rising up and making contact with the contacts.

The starting solenoid is a simple component, but has such potential to beach your craft when it doesn’t have to.

One last thought for you. If you order a starting solenoid from a jet ski dealership or jet ski website you will pay anywhere from $60-100 for it. If you purchase from a general market you can purchase the exact same starting solenoid for only $10! So shop around!

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