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Regal2800
12-30-2010, 05:09 PM
Hi guys,

I have finally gotten my mal4 to run and I am only getting 170 volts on the voltage gauge. Does anyone know whether this generator is supposed to get 220v? It's is a 20kw. The boat is new to me so I don't know exactly what voltage I am supposed to be getting. Any input would be great.

Canuck Dennis
12-30-2010, 05:37 PM
How many hertz are you getting ??

what is spec on rpm ?

Is it running 1800..1500 or 3000 rpm ?

GJH
12-30-2010, 05:46 PM
Good questions by Dennis. I have this genset also, vintage 1991. It puts out 225-230 volts. It is sensitive to fuel flow; have you changed out the primary and secondary fuel filters? Voltage checked low when I had the boat surveyed and new filters did the trick.

Boatsb
12-30-2010, 06:01 PM
Voltage and frequency are the 2 main concerns. A 50 Hz unit turns 1500 and a 60 hz turns 1800 for most applications. Then there is the voltage adjustment to be done after the correct frequency. This is something you may need to bring in an expert for.

GJH
12-30-2010, 07:00 PM
Mine doesn't have a voltage regulator. We goosed it to 61hz to get the volts up a tad. The Cummins 4 cylinder is a sweet little engine if you feed her right.

Regal2800
12-30-2010, 07:34 PM
It's supposed to run at 1800 rpm. Sounds like something is holding it back. I should check rpm. If its low an that hold back the voltage?

Canuck Dennis
12-30-2010, 07:52 PM
Fuel pumps on gen sets are usually set to deliver factory hertz plus or minus 3%, sounds like you have a fueling issue , lazy governor, leaky injectors or something along those lines. I would leave any adjustments to the proper experts.

Regal2800
12-30-2010, 10:00 PM
Fuel pump was recently rebuilt by a professional. The only thing a fuel pump should do is adjust the amount of fuel and timing to each cyl. When i go the pump back it was running a little high on the RPM. It was around 2200 rpm so i lowered the RPM to 1800 using a hand held tachometer using the adjustable throttle on the side of the fuel injector pump. There are no other items from the genset side that would cause voltage to be lowered? I could raise the RPM which should give me higher voltage but that doesn't sound like a proper fix.

scary
12-31-2010, 02:48 AM
Are you sure your hand held tack is accurate. You should be getting 240 volts at 1800RPM. Under load your governor should maintain 1800 RPM.

Regal2800
12-31-2010, 03:31 AM
I will check it again tomorrow. I was just thinking the same thing so it might be a faulty hand held tach. it's an el cheapo harbor freight hand held so it wont surprise me one bit if its not accurate. Thanks for everyones input.

Pascal
12-31-2010, 07:40 AM
On most gensets Rpm DIRECTLY controls frequency, not voltage which is usually controlled by a voltage regulator but the first thing to set is rpm, at 1800 for 60hz units

The fuel pump will not directly affect RPM at least at no load, but as load are increased and the genset needs more fuel to maintain RPM then the fuel pump can cause problem. Same with fuel filters (never hurt to start there though)

mwert72655
01-01-2011, 11:01 AM
I had this exact same problem on my 20kw and wasted a lot of time / money troubleshooting the fuel side only to find out the diodes in the control box needed to be adjusted - the third mechanic figured it out. Good luck!

Regal2800
01-03-2011, 10:47 PM
I just wanted to thank everyone for their input. my hand held tach was off. I got a new one adjusted the motor to 1800 rpm and i am now getting 225 volts and exactly 60hz based off my frequency meter at the circuit board.