Outboard Compression

Dave R · 10-10-2019, 11:16 AM

Quote:

Originally Posted by Formula260SS

Since this thread speaks to older outboards here's one - My 1987 60HP Johnson which runs great melted it's Rectifier and somehow the engine still ran and has been this way for who knows how long. (only use the boat on occasion)

I do have a service manual and the stator and new rectifier check out OK using a Fluke. However the output from the rectifier is up around 16 Volts which is really too high. Question is - do all the old outboards with Rectifiers run high on voltage? I did order a Regulator / Rectifier which I believe will cure the high voltage but thought it a good question to throw out there. I don't have any electronics on the boat besides Nav Lights but worry about the Power Pack and other engine components burning out. It has eaten a few choke solenoids which I'm now thinking could be a victim of the high voltage.

Thoughts ? - Thanks

As far as I know, the charging system on that engine is unregulated, so 16 volts is probably normal if the battery is charged up fully. It will be a lot lower if the battery is discharged. If you are concerned about too much voltage, CDI makes a regulated rectifier that should bring it down to 14 volts or so. It's part number #193-3408 and they cost about 70 bucks.

Formula260SS · 10-10-2019, 11:34 AM

Quote:

Originally Posted by Dave R

As far as I know, the charging system on that engine is unregulated, so 16 volts is probably normal if the battery is charged up fully. It will be a lot lower if the battery is discharged. If you are concerned about too much voltage, CDI makes a regulated rectifier that should bring it down to 14 volts or so. It's part number #193-3408 and they cost about 70 bucks.

Thanks Dave that's what i thought and ordered.

Denny Crane · 10-13-2019, 09:30 AM

It would have been too easy if my outboard story ended there. The engine was running beautifully in my driveway and I was planning to winterize it when it stopped out of the blue and I couldn't turn it over again. When I went to prime it again I noticed the prime bulb was compressed and I couldn't return it back to normal. Any ideas?

Denny Crane · 10-13-2019, 02:50 PM

I know where the vent is but I don't know how to check that.

Dave R · 10-14-2019, 03:08 PM

It's either a clogged vent on the fuel tank or a clog blocking fuel from flowing from the pickup in the tank to the bulb. The clog cannot up downstream of the bulb.

Assuming it's not a clogged vent, one common cause of this is a blockage in the fuel line caused by de-lamination of the inner layer of fuel line itself. If the fuel line is more than 10 years old, consider replacing it.

It may also be caused by crud clogging the fuel pickup in the tank. Pull it out and have a look.

There may be a check (anti-siphon) valve where the fuel line comes out of the tank. Check that, might be stuck shut.

Denny Crane · 10-14-2019, 08:27 PM

Great ideas once again. I changed all the fuel lines from the gas tank out a year or two ago. Come to think about it when I went to siphon the old gas out with a small 12v pump I had trouble pulling gas at first. I may try an external gas tank first and go from there. Thanks!

Dave R · 10-17-2019, 06:28 PM

Quote:

Originally Posted by Denny Crane

Great ideas once again. I changed all the fuel lines from the gas tank out a year or two ago. Come to think about it when I went to siphon the old gas out with a small 12v pump I had trouble pulling gas at first. I may try an external gas tank first and go from there. Thanks!

If there was any sign of water in the old gas, I bet the check valve ball is rusted and sticking in place.

10-13-2019, 09:30 AM	#3
Denny Crane Senior Member Join Date: Mar 2010 Posts: 100 Thanks: 28 Thanked 21 Times in 17 Posts	I'm Back! It would have been too easy if my outboard story ended there. The engine was running beautifully in my driveway and I was planning to winterize it when it stopped out of the blue and I couldn't turn it over again. When I went to prime it again I noticed the prime bulb was compressed and I couldn't return it back to normal. Any ideas?

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The Following User Says Thank You to Formula260SS For This Useful Post:
Dave R (10-10-2019)

10-13-2019, 02:50 PM	#4
Denny Crane Senior Member Join Date: Mar 2010 Posts: 100 Thanks: 28 Thanked 21 Times in 17 Posts	I know where the vent is but I don't know how to check that.

10-14-2019, 03:08 PM	#5
Dave R Senior Member Join Date: Jul 2004 Posts: 2,985 Thanks: 246 Thanked 744 Times in 444 Posts	It's either a clogged vent on the fuel tank or a clog blocking fuel from flowing from the pickup in the tank to the bulb. The clog cannot up downstream of the bulb. Assuming it's not a clogged vent, one common cause of this is a blockage in the fuel line caused by de-lamination of the inner layer of fuel line itself. If the fuel line is more than 10 years old, consider replacing it. It may also be caused by crud clogging the fuel pickup in the tank. Pull it out and have a look. There may be a check (anti-siphon) valve where the fuel line comes out of the tank. Check that, might be stuck shut.

The Following User Says Thank You to Dave R For This Useful Post:
Denny Crane (10-14-2019)

10-14-2019, 08:27 PM	#6
Denny Crane Senior Member Join Date: Mar 2010 Posts: 100 Thanks: 28 Thanked 21 Times in 17 Posts	Great ideas once again. I changed all the fuel lines from the gas tank out a year or two ago. Come to think about it when I went to siphon the old gas out with a small 12v pump I had trouble pulling gas at first. I may try an external gas tank first and go from there. Thanks!