1997 Johnson 115 Fast Strike surging

gjordon

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Jul 6, 2004
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I've got a 1997 Johnson 115 fast strike (J115GLEUC) that starts and idles fine cold or hot but when you accelerate over half throttle it surges bad. You can back off the throttle and the surging stops and you can run like that with no problems as long as you wish but when you get past about 1\4 to 1\2 throttle the surging starts again and will not stop until you back off the throttle.

I've only owned the boat about 2 months now and it's been in the shop twice. I don't know the history of the boat only that it had been sitting a good while. The initial inspection found someone had removed the thermostats and there was a significant temp difference from one head to the other without them. I had the thermostats put back in and tried it again.

The boat ran strong after that with no surging or anything, for about 30 minutes til it began missing and eventually died and would not restart. After getting the boat back home and siting awhile, of course it started back up. I took it back to the mechanic and he said it was most likely the power pack failing when hot. I then replaced the power pack, coils, wires and optical sensor.

All the other issues I had are now gone and I ran the boat about 3 hours yesterday and then the surging started. At first I could open it wide open and it did ok, a slight bit of surge but it wasn't constant but after about 2 hours it started the surging with anything over 1\4 to half throttle. I put a new set of plugs in it on the water, even though the plugs looked fine and it didn't make any difference.

I've check the fuel tank vent and it is open. Pumping the fuel bulb while it is surging has no effect on it. The first thing I did when I got the boat was to pull the carbs and clean them. I even pulled them a second time just to satisfy my mind although everything was clear.

The boat still has the original oil pumped hooked up.

I'm just at a loss and really trying not to put it back in the shop a 3rd time.

The compression numbers ran the first time at 140,140,135, 130... the timing was set as well.

Any ideas?
 

Faztbullet

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Mar 2, 2008
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15,589
Is it surging still or just won't accelerate? Is it a rise fall of rpm or a sudden loss of power and then back like a switch turned on\off?
 

gjordon

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Jul 6, 2004
Messages
9
Is it surging still or just won't accelerate? Is it a rise fall of rpm or a sudden loss of power and then back like a switch turned on\off?

I took it back to the lake last night with a full tank of gas and new fuel filter. Again it started right up and idled fine but as soon as I hit about 1\2 throttle to get the boat up it started surging. It's like you turn the key on and off repeatedly, no engine miss or anything just cuts off and on. I stopped several times and by just easing the throttle up I could gain some but not enough to plane the boat out. That required more throttle and when I got to that point, it would start the up and down surge.
I stopped the boat and started playing with the kill switch (out of lack of anything else to try) After that I tried full throttle from a dead stop and it planed right out and no surging at all, however staying at full throttle it began the surge, not quite as bad but was still there. Backing off to about 3\4 throttle it ran fine. Go to accelerate from there and the surge comes back.
I tried the same thing several times over an hour or so and got the same results each time. I can now take off and run up to 3\4 and all is well.

I'm not sure what else at this point I can try but I will put in a new kill switch and give that a try and thought about rebuilding the fuel pump.
 

Chris1956

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Mar 25, 2004
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27,036
Sounds like a possible fuel restriction. Check the antisiphon valve in the fuel pickup on the tank, or use a portable tank, to rule it out.
 

boobie

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Nov 5, 2009
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That sounds more like an ignition miss. Put a timing light on each cylinder and look into it for black spots. If you see them that's an ignition miss.
 

gjordon

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Jul 6, 2004
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That sounds more like an ignition miss. Put a timing light on each cylinder and look into it for black spots. If you see them that's an ignition miss.

Good suggestions.. I'll be out of town for a few days before I can check it further. I'm still going to rebuild the fuel pump and change out the kill switch but I will take a portable tank and timing light with me.. I'll post the findings.
 

gjordon

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Jul 6, 2004
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9
I got the fuel pump kit put in and as long as I was removing things, I went ahead and pulled the carbs again and went through them with a fine tooth comb and they are about as spotless as they can get. I added the new kill switch as well. Took it to the lake last night and as usual, starts right up but I must say that it idles better than it ever has. It will now take off WOT from a dead stop but starts the surging once the boat is on plane. I can back off the throttle just a bit and its fine, it'll run 40ish with no problems but when you open it wide open the surging starts, doesn't seem quite as bad but it is still there. I couldn't get a timing light but that will be my next test. I have checked the built in tank for water and didn't see anything but will try an external tank. I'm still stumped but took a short video if it will let me post the link.

 
Last edited:

gjordon

Cadet
Joined
Jul 6, 2004
Messages
9
That sounds more like an ignition miss. Put a timing light on each cylinder and look into it for black spots. If you see them that's an ignition miss.

I took the boat out again tonight with a timing light. I checked all 4 cylinders and each time the surging started, the times by light did have dark spots so it?s losing its spark. When I finished the 4 tests and cranked the boat back up, it ran great with no surging at all. After running a few minutes I stopped the boat again and restarted and the surging was back. Definately has intermittent but not sure what the check next. The power pack, coils and wires are new but I know that doesn?t mean there?s not an issue.

What would be the next step?
 

boobie

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Nov 5, 2009
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20,826
You may want to contact cdielectronics.com. for ignition trouble shooting.
 

NM104

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Sep 4, 2022
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Having this same issue on a friend's 1998 johnson 115 fast strike v4. What was the fix?
 

jbcurt00

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I saw that lol was hoping op would comment if they're still on here
Nope, Jordan hasn't been back since Nov 2017.
Start a topic about your motor and ask questions there
 
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