Curcuit interrupter

[pontoon chief]

I have a 1990 50 hp VRO Johnson that has been giving me fits.Runs fine at idle,but when it heats up under use it begins to run poorly,and will barely run.The water pump is not the most steller pump,but it does still pump,weak at best.I notice when this poor running starts the motor is very hot,yet no alarm sounds.<br />Does this motor have a high temp curcuit interrupter that will put the motor into a reduced RPM mode?

 

[OBJ]

Re: Curcuit interrupter

The SLOW mode will only let the engine up to about 2500rpm. If this is the case or the block really feels hot, then your engine is overheating. If the pump don't look like it's pumping well, change it out. A new t-stat wouldn't hurt either. I really wouldn't run it until I'm sure both the impeller and t-stat are good.<br /><br />You can test the overheat alarm....really just the horn...to see if it works. Look on the head for the lead from the heat sensor. Single wire coming from the head. Pull back the rubber boot on it exposing the knife connector and ground it against a clean engine ground with the key in the on position....engine doesn't have to be running. The alarm horn should sound a steady tone untill you unground the connector.

 

[pontoon chief]

Re: Curcuit interrupter

OK,Here goes...The alarm horn does not work,the waterpump inpeller was shot,as was the pump.Both were replaced.<br />The motor runs fine at idle,however as I raise the RPM using the connecting bar on the two carbs the moror begins to run rough as as I hold the throttle linkage bar in one place the motor will run rough for a few seconds and then begin to pop and then kick.Some times after the kicking and popping the RPMs will begin to rise sharply as if it is going to continue to rise to full throttle.All the while holding the throttle in one place.At the higher RPMs the motor will begin to almost "roll",with the RPMs going up and down in a cycle.<br />I did clean both carbs,and at the time both were not in bad condition.This was done prior to the overheating problems.Spark plugs are also new and gapped correctly,and the fuel filter is new,as is the gas.Any ideas?

 

[bigtwin]

Re: Curcuit interrupter

Remember your outboard has mechanical advanced timing. If you are using the carburator linkage to throttle your engine you are only opening the carburator butterfly valves not advancing the timing. Try using the throttle control and tell us what happened.

 

[pontoon chief]

Re: Curcuit interrupter

I used the throttle control and the motor pretty much acted the same.It still rolls when I hold the throttle at the same position at about 1/3 throttle.<br />Could the two carbs not be correct?Where can I find the correct procedure to adjust the carbs,if that might be the problem?<br />I am at a loss here guys.Any suggestions would be helpful.

 

[OBJ]

Re: Curcuit interrupter

The sync and link procedure is kinda' long and drawn out to post here Pat....I would maybe suggest a manual (OEM) or maybe pop over to the local library and see if they have a Clymers or Seloc that might help. For sure if the timing and throttle plate opening aren't correct, the engine will not run right.<br /><br />One thing you can check, see if both throttle plates are opening at the same time. Just take the front cover off so you can see down the throats of the carbs and push on the cam roller while watching the throttle plates. They should start to move at the same time and both close all the way at the same time.

 

[pontoon chief]

Re: Curcuit interrupter

Thanks OBJ,<br />Just a note,when I crack the throttle the motor appears to fire perfectly.It just begins to roll when the throttle is held steady open.Could there be a problem with the SLOW system that is preventing WOT,and preventing a steady high RMP?

 

[pontoon chief]

Re: Curcuit interrupter

H

 

[OBJ]

Re: Curcuit interrupter

Pat...next time, squeeze the primer bulb and see that makes a difference. Might have a fuel flow problem. Any lose connections that might suck air or hard fuel lines?

 

[Silvertip]

Re: Curcuit interrupter

Since you had the carbs off for the rebuild, are the idle mixture adjustments correct? You can only get those in the ball park running on muffs. Idle mixture and idle speed need to be adjusted in the water. You really need a service manual so you can do the link&sync and at least get that part correct. Not only must the carbs and ignition be synchronized, both carbs need to work in unison as well. Both butterflies need to be closed fully at the same time as well as wide open at the same time. The roll pins in the end of each butterfly shaft should be perfectly vertical at wide open throttle. Any more or any less the motor will not perform.

 

[pontoon chief]

Re: Curcuit interrupter

Thanks Guys,I hate to buy a service manual but I guess I will have to bite the bullet.<br />I did inspect the fuel hose and bulb and they seem fine.I did not attempt to squeeze the bulb while running,and now I will give that a shot.<br /><br />Thanks

 

[pontoon chief]

Re: Curcuit interrupter

OK,did adjust the Link and sync as well as the timing.<br />Again the motor runs great at idle.I did change the fuel filter to a clear see thru type of filter.I pumped the bulb hard and started the motor.After raising the RPM's you can see the filter empty and also see the fuel trickle in very slowly,but not fast enough to fill the filter.In order to fill the filter I have to pump the bulb again.<br />This is a VRO type of fuel pump.Could this problem be a fuel pump problem?The fuel line up to the filter appears to be clear with no blockage.I also pumped the bulb with the filter off and the bulb pumped a full stream.<br />With the filter in the line,when I pump the bulb it fills the filter,however there is some air trapped in the filter.When the motor runs the air pocket gets larger,until it is almost empty and at that time I can see the fuel entering the filter slowly.<br />Any idea's.

 

[pontoon chief]

Re: Curcuit interrupter

OK,did adjust the Link and sync as well as the timing.<br />Again the motor runs great at idle.I did change the fuel filter to a clear see thru type of filter.I pumped the bulb hard and started the motor.After raising the RPM's you can see the filter empty and also see the fuel trickle in very slowly,but not fast enough to fill the filter.In order to fill the filter I have to pump the bulb again.<br />This is a VRO type of fuel pump.Could this problem be a fuel pump problem?The fuel line up to the filter appears to be clear with no blockage.I also pumped the bulb with the filter off and the bulb pumped a full stream.<br />With the filter in the line,when I pump the bulb it fills the filter,however there is some air trapped in the filter.When the motor runs the air pocket gets larger,until it is almost empty and at that time I can see the fuel entering the filter slowly.<br />Any idea's.

 

[pontoon chief]

Re: Curcuit interrupter

.

 

[pontoon chief]

Re: Curcuit interrupter

Anyone?

 

[Dhadley]

Re: Curcuit interrupter

Are you doing all this with the motor in neutral (or not in the water) or in gear in the water?

 

[pontoon chief]

Re: Curcuit interrupter

In neutral on the hose muffs.