1996 Johnson 225 Venom kill wire short or diode problem?

**jalmond** · 06-04-2023, 08:36 AM

I have been having this random problem that my boat will start but will stall out instantly, on acceleration, and then may not start for a while. To me it is like someone is hitting the kill switch, or turning off key.

This problem has been haunting me for awhile, but it is very random. I am starting to think it only happens on very hot day as yesterday it was hot on the lake and it happened again. I had to troll for a couple of miles, but as soon as the sun went down it started up and ran fine.

Is it possible that there is a kill wire shorting out somewhere? or would that little diode in the wiring harness possibly cause something like this? power pack.

Key switch, kill switch, timing base, stator, and regulator are all new (about 20-50 hrs), motor is rebuilt and has about 50hr (max).

**powerabout** · 06-04-2023, 09:29 AM

Originally Posted by jalmond

I have been having this random problem that my boat will start but will stall out instantly, on acceleration, and then may not start for a while. To me it is like someone is hitting the kill switch, or turning off key.

This problem has been haunting me for awhile, but it is very random. I am starting to think it only happens on very hot day as yesterday it was hot on the lake and it happened again. I had to troll for a couple of miles, but as soon as the sun went down it started up and ran fine.

Is it possible that there is a kill wire shorting out somewhere? or would that little diode in the wiring harness possibly cause something like this? power pack.

Key switch, kill switch, timing base, stator, and regulator are all new (about 20-50 hrs), motor is rebuilt and has about 50hr (max).

How about the shift loom, is it new or tested?

**jalmond** · 06-04-2023, 12:56 PM

Originally Posted by powerabout

How about the shift loom, is it new or tested?

thanks for the quick response.

I have wonder if that could be part of the problem, but figured since am shifting out of gear just fine it should be good. Also, last time this happened I connected my spark tester to all 6 plug wires at once and they were all dead at the same time. If it would have been the 3, I would have suspected the shift switch. Anyway, I replaced the key switch and added a separate kill switch, at that time, and thought I had it fixed for about the last 10 trips everything was fine. I am really starting to think i was just get lucky because the symptoms are very similar each time.

1) boat starts and runs well to fishing site.
2) boat fires up but won't go above 1100 rpm (in gear) stalls on any gas input. pumping ball does not help. pushing choke does not seem to help. this is even if engine has been off for an hour or more.
3) after multiple attempts to go and restarts boat will not fire or idle.
4) when sun went down boat fired up and ran fine.
5) boat engine is running smooth no missing or rough idle (when it works) it just dies on any acceleration when issue occurs.
6) no alarms or lights going off.

Can the shift switch cause a no spark situation for all cylinders? If so how would i verify that it was the shift loom causing that?

**hydra-sports** · 06-04-2023, 07:46 PM

for all 6 plugs to go dead it is not the shift interupter. Do you have the service manual for that motor? If all 6 plugs are dead how does it start and run at 1100 rpm. Pushing in the choke will flood the motor, that's why it won't start after multiple attemps. You can check the shift interupter by disconnecting the blk w/yellow stripe wires from ground, if this is your problem

**jalmond** · 06-04-2023, 08:33 PM

Thanks for the quick response. Yes, I do have a manual.

I agree pushing the choke does nothing but flood it out no increase in RPM. pumping ball does nothing as well. I feel that it is an intermittent short causing all to go 6 to drop ...it does start every time if I don't use the choke too much, but as soon as I put it in drive and give it any gas it shuts down. I can give it gas in neutral and it will rev up without load. Stator and regulator replaced about 3 trips ago. regulator went out (tach quit) got my stator.

**powerabout** · 06-05-2023, 02:47 AM

Originally Posted by jalmond

thanks for the quick response.

I have wonder if that could be part of the problem, but figured since am shifting out of gear just fine it should be good. Also, last time this happened I connected my spark tester to all 6 plug wires at once and they were all dead at the same time. If it would have been the 3, I would have suspected the shift switch. Anyway, I replaced the key switch and added a separate kill switch, at that time, and thought I had it fixed for about the last 10 trips everything was fine. I am really starting to think i was just get lucky because the symptoms are very similar each time.

1) boat starts and runs well to fishing site.
2) boat fires up but won't go above 1100 rpm (in gear) stalls on any gas input. pumping ball does not help. pushing choke does not seem to help. this is even if engine has been off for an hour or more.
3) after multiple attempts to go and restarts boat will not fire or idle.
4) when sun went down boat fired up and ran fine.
5) boat engine is running smooth no missing or rough idle (when it works) it just dies on any acceleration when issue occurs.
6) no alarms or lights going off.

Can the shift switch cause a no spark situation for all cylinders? If so how would i verify that it was the shift loom causing that?

shift switch is only designed to short 3 cyls as mentioned unless there is a diode fault in the kill circuit.
Those diodes are buried in the shift loom.
Your manual should tell you how to troubleshoot that.

**hydra-sports** · 06-05-2023, 06:45 AM

I was having a similar problem on a gt200 and thought it was going into SLOW mode. First of all spark testers are hard to see in bright sunlight. I disconnected the shift switch, pulled the temperature sensors and checked them in boiling water with multimeter as the temp rose and they checked out good, opened at 205 degrees and closed at 170, then changed thermostats, still the same. I could wack the throttle at the top of the throttle bodies but could not accelerate with the hand throttle. Mine turned out to be 2 weak charge coils that were either overheating or shorting out. Also a lync and sync is critical to performance,, if the butterflies are even slightly open , too much air

**jalmond** · 06-05-2023, 08:10 PM

thanks guys, I am going to check the coils. it has awhile since i did that. the lync and sync should be good I check it all the time. I will double check that all the butterflies are close tight. I will let you know what I find. thanks again for the feed back.

**jalmond** · 06-17-2023, 09:17 PM

Well Checked coils all are firing good. I the boat out today on a lake in south Texas it is very hot about 108 degrees and no clouds. the boat started good but would just stall with any throttle at all. It was evening so I waited till things cooled off a bit and then tried again. It started up fine and took of and ran like usual no issues. until I shut it down. On restart it would die instantly if I gave it any gas. It is obvious to me that it is a heat issue I have aftermarket temp gauges on both heads they read about 130-135 degrees when running and heat to about 144 on shut down. the water pump is working it will go to 30PSI when running and about 5PSI at idle. But since I am having heat issues I may just change water pump to try to improve cooling. the motor was rebuilt by a real professional, so i am pretty sure it has to be some kinda wiring harness issue that only shows up in the heat. If anyone has any more ideas plz let me know. I am working in south Texas, staying 1 mile from the lake, so I would really like to get this figured out.

**challenger 77** · 06-20-2023, 07:18 PM

When it is running start and shake the wires, see if there is some kind of change in the way it is running . loose connection some where .

**jalmond** · 06-25-2023, 12:32 PM

What I have done so far...
1)drilled poppet 1/8th hole- was worried because I lost a regulator about 5 trips ago.
2) took out thermostats- runs cooler now but water pressure is way down 10-13 at speed.
3) checked for lose wires- does not change situation.
4) removed line from crankcase that controls fuel pump and pumped ball no fuel is by-passing pump (Ball gets Hard).
5) changed all spark plugs

Now that it is running a bit cooler it seems more like a heat soak problem. Can anyone give me tips on solving heat soak problems?
What should the fuel pressure be at Idle?

**jalmond** · 06-25-2023, 12:48 PM

I am going to change the water pump to see if that helps increase the water pressure, but if a new pump assembly does not make a difference to the water PSI. I guess i will need to add fender washers in the place of the thermostats I took out to help get water PSI back up. the question is what size should the washers be and what size hole should they have? thanks again for all the help...this boat is going to make me old before my time

**powerabout** · 06-25-2023, 07:48 PM

There is another issue if taking the thermos out of an OMC helps on a stock engine

**jalmond** · 06-25-2023, 08:13 PM

Thank for the response powerabout...I agree with you that there is another issue. I just wish I knew what it was ... could it be the fuel pump is week... I don't see how because it works on cool days and it does not help when hit the choke or pump the ball (ball is hard) ...but maybe? The water temp is 95-100F right now, so I want to see if keeping it cool helped. It does but not totally. I will put them back in.