Please help. '86 Johnson 120hp VRO "hiccup" when running at any rpm.

was wondering if anyone had any insight on a problem I have been having.

I have a 1986 looper VRO Johnson 120HP on my ol 'Ranger. Original motor. One day I had it out and fired it up (always starts right up) and was idling. Well, about every 30 seconds it "hiccups". Thats the only way I can describe it. It doesnt "stall" or anything, it sharply cuts off for half 1 second, then cuts right back on. It does this every 30 seconds. Its not sporadic, it is literally every 30 seconds or so like clockwork. I dont have to restart it, because it cuts right back on. Also, when it happens, during that 1 second that it cuts off, the Gas gauge also cuts off, then right back on. So it might be something electrical? Put in all new sparkplugs, new fuel filter, but didnt fix the issue. Then after about 20 minutes of that, it will stop hiccuping and run fine again.

Yesterday I had it running at my house with earmuffs on and it was doing it again. I turned the motor off to go get my phone (was going to get a video of it to post) But when i came back out and started it up, it didnt do it! lol. I let it run for like 10 minutes with the muffs on at idle, and nothing.

It happens no matter the speed, at idle, half throttle or WOT. I have one little depth finder directly connected to the starter battery (not connected through the dash interface) And it does not hiccup when the rest of the system does.

Thanks in advance for any info you can shed!

Put a timing light on each cylinder when it's doing it and look into it for black spots. That will tell you have an ignition miss. Not fuel which it sounds like.

Sounds like a lean miss.

Is it fairly easy to detect a lean condition on 2 stokes by inspecting the condition of the spark plugs?

Also, when it happens, during that 1 second that it cuts off, the Gas gauge also cuts off, then right back on. So it might be something electrical?

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Sounds like it..When motor starts acting up shut it off,remove cowl, disconnect main harness from control box, jump solenoid to restart and see it problem continues. If not you have wiring problem.

If that miss/hiccup sounds more like a very mild backfire... something spitting back through a carburetor, that caused by a lean running engine. It's usually caused by one carburetor's slow speed jet acting up. However, if a carburetor, it would act up at idle and no other rpm and it would not be intermittent as you describe.

Your explanation brings to mind a irregular shaped throttle roller that would hold the throttle butterflies at improper positions from time to time... or a roller that is a two piece unit that has had it's outer clear shell broken away. The rollers in the past were a one piece unit, about 3/8" in diameter... some brilliant persons decided to make it a two piece unit not too many years ago and the outer piece was/is a piece of junk that breaks away causing the roller's diameter to drop to about 1/8" which screws everything up.... check it!

An irregular shaped roller would intermittently cause the roller to open the butterflies too soon.... a broken roller (too small) would cause the butterflies to open too late.

None of this explains why his gas gauge quits when the motor hiccups.

I was thinking wiring harness....simply because of that....

And I cannot think of a harness problem that would kill the motor and the gas gauge...both of them.

daselbee said:

None of this explains why his gas gauge quits when the motor hiccups. I was thinking wiring harness....simply because of that.... And I cannot think of a harness problem that would kill the motor and the gas gauge...both of them.

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Somehow I missed that... getting old ya'know! No, I can't think of anything either.

yeah...consider: If the red/purple wire from the engine to the ignition, or if the purple wire from the switch...either of them going open for a split second would kill the fuel gauge....
But not the engine itself.

If the black/yellow from the switch was intermittently grounding for a split second...then the engine would kill, but not the fuel gauge...

So....my bet here is we aren't getting the whole exact story...something is not jiving....

OP...more info please.

fleschnb, What's the story??

johnnygjr said:

fleschnb, What's the story??

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sorry guys, i have been busy and havnt made it around to the boat recently. Yeah, i am going to try to get it on earmiffs and get a video of it. I dont k ow what the issue could be. It seems to be too exact of a rythm to be a loose cable somewhere. It happens at any rpm, and it is very exact. Runs fine for 40 seconds or so (i timed ot once but forgot how long ot runs between hiccups) and then a 1 second hiccup. No backfire, the motor just dies for 1 second then kicks back on for another 40 seconds, etc..

I really appreciate yalls expertise here. I am stumped. the lights on the boat dont seem to work at the moment so ill try to get it to do this again, and see what else may be cutting out besides the motor and the gas guage. I assime the rpm gage as well since the motor cuts out but, wouldnt know ot thats neing caused by the electric or becuase the rpms really do cut out.

thanks for all the replies. I am greatful. My apologies for my. absence, just one of those. months.