Voltage Regulator Life Expectancy and difficulty cranking - ?Related?

GAG

Recruit
Joined
Jul 27, 2010
Messages
4
1985 Evinrude 150 XP, model E150STLCOH,
580 hours
Fresh and some saltwater use
Primary use - water skiing and tubing
Garage kept

The voltage will vary between 12.3 and 14.8. Will occasionally go up to over 15 - reading from gauge and fathometer. The tach is very irratic, often not working at all. As the day goes on, the engine becomes harder and harder to crank, unless you let it sit for over 30 min. But the stopping to pick up a skier, then recranking becomes very difficult.

Engine signals a solid tone OFTEN - but can not make it do it. I do not think it is overheating due to checking water pump outgoing water temperature and engine with an infared heat sensor gun does not indicate a problem. I am not sure how to check for a blocked fuel line. Once cranked, performance does not seem to be affected.

My concern is with the life expectancy of the regulator - due to prior problems. We bought the boat on 1/31/1987. It went to the shop in 2/10/1987 for voltage regulator replacement - after 30 minutes of run time. On July 17, 1988 the voltage regulator shorted out internally and caught fire. It was again replaced in 2005.

Any assistance or suggestions would be greatly appreciated. My husband and I bought this boat new and it was his "baby". He passed away in 2010 and I am trying to keep it going to continue that part of our lives. My oldest son will be home in 1 1/2 weeks and wants to go skiing!
 
Last edited:

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
That engine has the high capacity 35 amp alternator with the vented flywheel on it. The voltages you see appear to be normal, regulated voltages. These combination regulator/rectifiers are easily fried if the battery cable connections are loose, either on the battery itself, or on the engine end. Loose cables will eventually fry that expensive rectifier/regulator and can even overheat it so much it will melt or even catch on fire-as you have experienced. If the tach is erratic, it is possible that the rectifier/regulator is again not working properly and may need replacement. (it not only re-charges the battery, but sends the signal to the tach.) Poor re-starting after skiing could be a sign of a weakened (uncharged) battery-which again may be a sign the rec/reg is bad. You will get a constant horn on that engine for two reasons: the engine thinks it's overheating, or it thinks there is a fuel restriction at higher throttle positions (high rpm's). Normal laser temps on the cyl heads would be 145-155 when idling. Maybe 20 degrees less when the boat is on plane. A hot horn will go off when the block reaches around 212 degrees. It will shut off when the block cools down to 175 (still too hot.) Keep in mind that at idle all the cooling water goes thru the thermostat. When on plane, the pressure-relief valves in the thermostat housings will open, flooding the powerhead with extra cooling water. It could overheat at idle, then run normal temps when on plane. So, check the cyl head temps a idle to be sure one of the stats is not stuck closed, or partially closed. High fuel vacuum is an unusual failure. Typical at high rpm's when the fuel suction is at max. Could be a problem/restriction with the ball valves in the fuel bulb, or even a restriction in the anti-siphon valve (if you run from a built-in tank). Be sure the fuel hose bulb does not get sucked flat at higher rpms.
 
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