1994 SeaDoo GTX - keeps cranking after key and start button released

[machy]

Have an odd one, I am hoping someone else has seen this before and has an idea on what to look at.

1994 SeaDoo GTX. When I connect the lanyard (pre-DESS) and push the start key, the starter cranks the engine. However, when I let go to the start key, it continues to crank. When I pull the lanyard off, it still continues to crank. I have to disconnect the battery in order to get it to stop cranking.

I have replaced the solenoid and MPEM. Still behaves the same. It doesn't start cranking when I connect the battery, but once I start it cranking, it just won't stop.

Any ideas are greatly appreciated! Thanks

 

[artr]

I would try connecting an ohm-meter across the wires going to your start button. It should read close to zero when you press the button. See if it reads open circuit when you release the button. Maybe the button stays stuck closed (zero ohms) until the battery is disconnected.

 

[machy]

Even if the switch was faulty, wouldn’t pulling the lanyard off break the circuit?

 

[artr]

Based on the schematic, there are 2 wires that run to a connection on the solenoid that would energize it. One is from the start button, the other is from the MPEM (which is probably the start switch input to the MPEM). Since you replaced the solenoid and MPEM, I was thinking the only thing left to check is the start button and wiring to the solenoid. But unless you know that the parts you replaced were known working parts, they could still be the cause of the problem. I think it is worth testing if the control input that energizes the solenoid goes to ground when the start button is pressed and then remains at ground even when the start button is released and the safety lanyard is pulled.

 

[machy]

Thanks Artr. I went and made sure both the start button and the lanyard button close when pressed, and open when released (correctly as they should). I then reconnected the positive battery cable and the starter immediately started cranking. So I thought maybe the solenoid is bad, but when I pull the solenoid out, and check it, it is not connected across the main lugs internally. So could the mpem be sending a signal to crank as soon as power is applied regardless of the start switch??

 

[artr]

It could but it would be defective because as I said the start button is an input to the MPEM to tell the MPEM to enable spark to start and run the engine. That input would need to be defective an acting as an output, driving the control input of the solenoid to ground.
Why don't you disconnect the large red cable from the solenoid that goes to the starter for test purposes. Then connect your battery and see if you get 12V in the solenoid post that you disconnected. If you do, check if the control input of the solenoid is at 0V (ground). If it is then successively disconnect each of the 2 wires(start button and MPEM input) on that control input to see which one is driving the control input to ground. Disconnect the battery when you remove wires to make sure you don't short out something by mistake. Visually check the offending wire to make sure it is connected as shown in the schematic and is not shorting to something due to corrosion or missing insulation.

 

[etemplet]

I didn't read every post on the thread but if you have the small red wire connected to the wrong side of the solenoid when you push the start button it won't stop cranking. Once energized it holds the coil in because it is getting voltage from the battery. This may not be your problem but I've had this happen on other equipment.

My second choice would be to make sure your connections from the switches and the plugs are clean. Soiled connections can prevent the electronics from getting signals. For instance I had a 1996 GTI that wouldn't start when I pushed the start button. After several tries it would start and work fine. While testing the ski started and when I pushed the start button and the ski would not shut off. The problem was a dirty contact on the plug on the MPEM. Good Luck !

 

[machy]

Thank you all. I went back through, disconnecting and reconnecting every wire and double checking they were connected in the correct places. Now it behaves normally (electrically at least). She fires over for about 10 seconds and dies. Since I have compression and spark, but original grey fuel lines, I’m going to guess fuel supply is my issue. I’ll be replacing the fuel filter, fuel lines, fuel selector switch. Do I really need genuine Mikuni parts for the carb rebuild, or are the cheap on eBay ok?

 

[artr]

Definitely genuine Mikuni parts. Follow the sticy post at the beginning of this forum. You really don't want to do it twice.
What was the solution to the original problem? Was something not connected correctly?

 

[machy]

I think I had the black and white wire from the MPEM in the wrong place. I looked at the wiki, lots of steps to rebuilding these carbs correctly. Does anyone offer rebuilding the carbs with genuine parts as a service?

 

[artr]

I am not familiar with any rebuild services, I have only rebuilt a few myself following the reference I told you about on this forum. Maybe others on the forum can offer advice on carb rebuild services. You should probably start a new thread with that topic to reach the most members with experience in that area. I'm glad you got to the bottom of your original issue.

 

[mikidymac]

Check with PWC Muscle, I know they were rebuilding carbs at one time @hfgreg

 

[hfgreg]

Check with PWC Muscle, I know they were rebuilding carbs at one time @hfgreg

We are no longer performing the service unfortunately.