Stuck at MAX revs 2000 50HP Johnson

[Jonny1/2Cab]

HI Guys-need some help. Today another gremlin popped up after days of issue-free boating. Here's the Story - After a good start-up at the ramp, I shot off to where other boats were Anchored fishing, some 1 km away. I blasted out at cruising revs - 4500 rpm. BUT, when I came to the fishing ground I could not get it out of gear and it was revving at 3000 at idle position. I switched it off at the key and selected neutral. Started it again and it ran to 6000 RMP - too much, so switch off. Made it back to ramp and went home to investigate. 1st thought - stuck cable - NOOOOO. The cable was disconnected and all linkages set to the idle position. With no choke, the beast fires and ran up to 6000 RMP. NEXT - Adjusted idle set Screw to min (Should not have started) Nope! - The Beast fires and ran to 6000 rmp. Next thought- stuck timing advance issue - Cleaned w carby cleaner and lubed w WD40 all engine control linkages and timing advance areas. Full range of movement and no sticking linkages. You Guessed it - The Beast fires and revs to 6000 RMP !!!!!!. At that point came inside with beer and wrote this message - Can anyone help? Thanks in advance Jon.

 

[racerone]

Checked flywheel key ?--

 

[tblshur]

throttle butterflies closing properly ? disconnect primer fuel line

 

[Jonny1/2Cab]

Checked flywheel key ?--

Bit of job to take flywheel off- can you explain the reasoning.

 

[Jonny1/2Cab]

throttle butterflies closing properly ? disconnect primer fuel line

This I can check. I will investigate and let you know how I go. Thanks

 

[Jonny1/2Cab]

To Racerone - Have removed flywheel and inspected key and advance /stator etc - all good.

 

[Jonny1/2Cab]

To tblshur - removed intake cover = butterfly plates in carby working properly.
Have start tested with primer power and fuel line disconnected - same result - revs out to 6000RPM

 

[tblshur]

check and clean carbs

 

[tblshur]

check fuel pump diaphram

 

[racerone]

I say it is a timing issue if throttle plates are closed.----And take control box apart as there could be issues in there.----You stated that you could not get it out of gear !

 

[racerone]

Bring it over ----I think it would be an easy fix !

 

[ct1762@gmail.com]

what about a bad pack or sensor coil? could that cause it? if the timing advance is all the way to idle, and the throttle butterflies are closed, what else could it be besides a random nitrous bottle stuck open haha. these don't have the center ring magnet for the timer base like larger motors which can shift, but even then im struggling to see why it would advance timing.

 

[ct1762@gmail.com]

is it possible the cam lever the throttle lever is attached to is all jacked up, but the throttle cam is at idle? the timing must be advanced, but the fuel part isn't otherwise if both were like that, it would explode to redline with a touch of the key

 

[Jonny1/2Cab]

Bring it over ----I think it would be an easy fix !

LOL - love to Mate- I'm in Melbourne Australia

 

[Jonny1/2Cab]

I say it is a timing issue if throttle plates are closed.----And take control box apart as there could be issues in there.----You stated that you could not get it out of gear !

This was my first thought on the water however, the Control box had been cleaned and adjusted when I got the engine - plenty of spiders but all good. It works fine. The getting out of gear issue was the revs being too high preventing the dog clutch from disengaging. As I mentioned earlier I have disconnected the throttle, primer, some linkages that advance the timing and the problem presists.

 

[Jonny1/2Cab]

check and clean carbs

Thanks for your input. I have eliminated the fuel pump since I am getting loads of fuel to the carbs allowing for this outrageous amount to revs at idle position to occur. I could actually see the fuel pumping in when I checked the butterfly valves as you suggested.

Carby clean = This is my next step today. Dismantle and clean, then test. IF that fails new kits to be ordered (no harm in that anyway). I'm thinking one or both of the floats has failed which could allow the fuel pump unstopped by the float valve to pressurise the system dumping excessive amounts of fuel into the carbs. But then again that could cause flooding- so the mystery continues.

 

[Jonny1/2Cab]

what about a bad pack or sensor coil? could that cause it? if the timing advance is all the way to idle, and the throttle butterflies are closed, what else could it be besides a random nitrous bottle stuck open haha. these don't have the center ring magnet for the timer base like larger motors which can shift, but even then im struggling to see why it would advance timing.

My understanding is that the coils and power pack only respond to the charge sent from the stator. They have no effect on timing. The stator sends a charge to the power pack that converts the charge to high voltage (see what I did there - High Voltage -I'm from Australia -ACDC? no?) which then sent to the coils to distribute to the plugs. So basically if one fails or is faulty = NO Spark = NO Start or intermittent firing. Learned this from a mechanic trying to sort out an issue on a different engine. I think this Engine does actually have a center magnet - I'll post a pic, but is bolted into place so can't shift.

 

[Jonny1/2Cab]

is it possible the cam lever the throttle lever is attached to is all jacked up, but the throttle cam is at idle? the timing must be advanced, but the fuel part isn't otherwise if both were like that, it would explode to redline with a touch of the key

Hi, Thanks for your input. I have attached a pic so you can see the advance levers and throttle positions - NB I have reattached the throttle cable in this pic since it has been eliminated from the checks. This is the idle position. All linkages are as normal for normal running once warmed up. The disconnected primer power lead and fuel hoses are clearly seen. I'm still looking for the Nitros bottle - Lol. Wish it was the case.

 

[racerone]

I say throttle is stuck OPEN too far !!----Remove airbox cover look in there with a flashlight.-------Do a simple inspection.

 

[tblshur]

is the adjustment screw above the cam follower suppose to have the locknut locked down could it have backed out im sure you saw that just checking