1988 Johnson 120 VRO RPM issue

[Riceyboy287]

Ok guys... I will start by saying I type this in frustration! I just finished restoring an 88' Islander 220v, pushed by a 120 VRO and 28spl kicker. Finally got it on the water and big motor will not rev anymore past 1/4 throttle. Last year testing the boat before buying I ran out of fuel and had someone bring me enough to get home which I found out was about 20 year old gas after the fact! After re fueling about half way back the motor fell on its face and wouldn't push the boat over 10mph. Anyway getting back to what's going on now.... I have spark on all cylinders, fuel lines are clear, in floor tank is spotless. Fuel/water separator was full of junk and I bipassed it right to the the tank line to see if that was the issue... No change. I took the VRO pump apart and to my eye look cleaned as a whistle. Just now I stripped the carbs down and they are spotless from floats to jets. Does anyone have any idea what else I could look at? I wanna be cranking kings not wrenches!!!

[Roughrider IV]

I had similar issues with a 86 johnson 70 hp vro. Power pak went bad, more than once, it would get to 25 percent speed tops. I believe they redesigned them shortly after that.

[Riceyboy287]

How did you find out it was the power pac? Ohmmeter?

[Xxx]

I had a 1988 88SPL Evinrude and I also had a power pack go bad but that caused me to loose two cylinders, I got a new one from a marina just before the TGI bridge. But your troubles sound simular to a problem I had after I put the new power pack on, it wouldn't rev up, this was because the timing was way off. I gave the book to the fellow that bought the boat, but from what I remember I used a timing light and you need the engine at a certain rpm to adjust the timing, I do remember it was higher than what it is on a I/O. It sounds to me like a timing issue, mine also worked fine at low rpm but the rpm's wouldn't pick up and it was due to the timing being way retarded. I needed to advance the timing but had to back off the throttle adjustment as it increased the rpm's. I needed to do this several times until I had it right. After I had the timing set correctly she would crank to 7 grand instantly, like a hole different motor. Google the timing procedure and just check it, it only takes a few minutes, just for a piece of mind. Make sure your butterflies are opening all the way first. Good luck, I hope you get it figured out as you said the Kings are just around the next turn!!!

[lily]

Can you manually move the throttle. May be something easy like a bad throttle cable. Start simple. Make sure you have compression. In all of the cylinders. I had a 140 johnson do the same thing and All it was was a stretched out cable.

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[Roughrider IV]

By no means am I a mechanic, the motor was next to new and took it to dealer, twice. Motor destroyed itself shortly after warranty ran out.

[john1947]

I got a 120 also.Still runs great.A few problems like yours

Fuel line had collasphed inside and restrcied fuel.Cant see it from outside.

Fuel float stuck ,motor would surge.

I would take the boat out on a seperate tank and see how it runs,

Oil injectors are very reliable,few problems on mine except top elbow popped off

A;sp check if alarm works ,you should hear it when you try and start it.

I always check my motor with a laser heat senser.High temp would shut motor down to lazy mode .

I check cylider ,compression,sprk jump before replacing parts

Any further help im always here

john

[jimski2]

The power wire, small one, may not be connected to the power pak.

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[buckboardjr]

My 1989 88spl would do that when I 1st bought it.It had sat for 6 years and it was a function of very fine un seeable gas vanish flakes plugging the main jets of the carb. If you are out there running it and it won't come up on RPM/Plane, push the prime button in "your key" if it straightens up, it is a fuel starvation issue. Those carbs are very simple, but just because they look clean doesn't mean they are. You need to spray choke cleaner via the red straw though every orifice/ air bleed passages, bowl vents, ect. and see it come out some were else on the carb.You can also use a rubber tipped air nozzle hooked to your air compressor to blow passages out.Do the idle circuit as well. I had to clean mine 3 times till it quit acting up. I presumed it was flaking off the inside of fuel lines on the engine after the fuel filter.

[G-Daddy]

My '92 100 hp Johnson acted that way one time when it needed thermostats. Make sure yours are opening as needed. Those motors have a "limp home mode" to give you a reduced speed when overheating.

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[Total Chaos]

I had an 86' 140 vro had similar issues. It was always the carbs being plugged. As stated earlier you can't always see it. Choke cleaner in every orifice was needed numerous times. Also may want to check your fuel ball. I had one go bad and it would suck closed and restrict fuel flow. Fuel lines could be bad. Those motors didn't have the new stuff that's resistant to ethanol. You could also have debris in your diaphragm fuel pump. Just some more things to check that you didnt want to.

Total Chaos

[buckboardjr]

When I said I had to clean them 3 times, I mean I'd clean them, It would run good for a trip or two., act up again, Clean them again, then finally after the 3rd cleaning of the contamination that I think was being fed to the carb from flaking off the inside of engine fuel lines after the filter, it has been fine since 99.

[Riceyboy287]

Hey guys, took it on the water last night, did everything I could think of, carbs have been cleaned and sprayed out with air. It almost sounds to me that it's getting the fuel it just isn't burning it. All of my plugs are getting spark. I disconnect wires to test cylinders on water and they all are functioning. I have basically narrowed it down to some thing electrical. I'm thinking either lower pack is bad like others have suggested or I have a weak coil. On the cdi website for both coils and power pack it gives me an option for "looper" or "35 amp"... How do I know which one I need. Also does anyone know what that black tube with the thread on cylinder stopper is for? It's hooked to the throttle linkage. With cap off if rod that runs through tube is pushed in it almost kills motor, if pulled out it open up motor and then quits having an affect when it hits a certain point. Really at a brick wall here guys any and all help is worth it's weight in gold to me!!!

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[lakebound88]

Refer to my post a month or so ago on t stat jobs.

Nick

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[buckboardjr]

When you make this statement: "All of my plugs are getting spark. I disconnect wires to test cylinders on water and they all are functioning." Why would you then conclude this statement? : " I have basically narrowed it down to some thing electrical."  Seeing spark on each cyl. and also pulling plugs on each cyl. and seeing a change versifies the electrical system is working. Does your engine use a prime function of squirting fuel in to the intake when pushing the key in during cold starts."No Chokes on carbs", If it does, you should have tried that when trying to come up on plane. If it doesn't have prime, get a squirt bottle of fuel and squirt it in to the carbs when trying to come up on plane. If you have tried these two and it didn't help, then and only then would I start chasing a compromised ignition syst.

[Riceyboy287]

Buckboard,

The motor has a priming solenoid thAt is engaged when pushing in the key. That is functioning as I did that when boat was in gear and can hear change in motor. The only thing that I have not looked into fully is replacing coils and powerpack. Everything else has been cleaned and examined... Fuel wise. I am gonna try running down seafoam this evening and see if that does anything for me

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[rolmops]

A pin hole in your fuel line will cause the engine to suck air instead of fuel.A pre 1991 VRO pump should be torn out of that engine and replaced with a post 1991 or a regular fuel pump ( mix your own juice).

Remember,always start with checking out the simple and cheap solutions before throwing money in the wrong direction.

And then there is the funny one.Are you sure that you have the right wire going to the right plug?If not,even though all the plugs fire fine,they don't fire at the right time.

As for something trickier. Pull your plugs and check if one is very clean compared to the others. If so there may be water coming into the cylinder which can be caused by a blown head gasket or a part of the exhaust cover (internal) having blown.

Then even simpler ,the engine may overheat because of a bad impeller,in which case these engines go in emergency mode.

I can think of a few more,but this is something to start with.

Edited August 13, 2015 by rolmops

[buckboardjr]

Rolmops hit a home run with his statement about being sure you have the correct wire going to the right plug as last year when I was troubleshooting a coolant leak, I induced that very "Extra problem in to my situation. Also be advised when I say to hit that primer when you are trying to get more RPM, I'M saying to do so as a troubleshooting technique. IF the engine is helped by it, then it should be sending you down a path of "lack of fuel" troubleshooting verses ignition troubleshooting. Did you pull the needle valves out for floats? Where the tips, rubber, viton, or steel. The ethanol has been raising heck with the rubber ones causing them to stick.

[Roughrider IV]

You can look up cdielectronics.com , they have a trouble shooting service you can contact.