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Amp Gauge Flicker


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#1 chieffan ONLINE  

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Posted August 24, 2016 - 12:43 PM

QT 16 had a electric fuel pump for the Onan engine.  Without it would only get the top half of the fuel in the tank.  Pump that was on the tractor quit working.  Put on a new aftermarket pump.  Works good as far as pumping fuel but now the amp gauge needle flickers.  Seems to be in sinc with the fuel pump.  Any way to stop the flickering?  Guess it don't hurt anything but wear out the pivot on the needle a lot faster.  Annoying also.


Edited by chieffan, August 24, 2016 - 12:44 PM.

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#2 stiemmy ONLINE  

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Posted August 24, 2016 - 12:48 PM

Maybe try tapping in somewhere else under the hood to power the pump, but Im not quite sure if that will totally cure that?
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#3 Bud W OFFLINE  

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Posted August 24, 2016 - 01:57 PM

When the pump clicks, it's drawing current and that's what the gauge is showing.


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#4 ol' stonebreaker ONLINE  

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Posted August 24, 2016 - 02:27 PM

  Maybe try wiring an ignition condenser in parallel w/ the pump wire. I've never tried it, just a thought.

                                           Mike


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#5 MiCarl ONLINE  

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Posted August 24, 2016 - 02:37 PM

When the pump clicks, it's drawing current and that's what the gauge is showing.

 

I agree.  The gauge is doing its job.


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#6 chieffan ONLINE  

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Posted August 24, 2016 - 03:53 PM

I agree with what you guys have said.

 
Gauge is doing it's job, pump draws and drops currant during the cycle.  Must be a different type pump than the old one as it did not cause any flicker.  Also have an electric pump on the CC 1512 diesel and no gauge flicker with it.  That is why I was asking.  Have a couple different pumps coming so may swap this one with one of them and see what happens.  Appreciate the suggestions.  Will let you know the outcome in a couple week when the boat from China makes it across the pond.


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#7 MiCarl ONLINE  

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Posted August 24, 2016 - 06:01 PM

I'm familiar with two types of electric fuel pumps.

 

The ones used on motorcycles use a spring loaded diaphragm to push fuel toward the carburetor.  When the diaphragm gets to the limit of its travel it closes a set of points activating a solenoid that pulls the diaphragm back against the spring and drawing in a fresh charge of fuel.  Of course when the solenoid pulls the spring back the points are opened and it quits drawing power.  These pumps make a "tick, tick, tick" sound when fuel is flowing.  This sounds like what you might have and you're seeing the needle bounce when the solenoid is energized.  I can imagine they draw a lot of power when they energize.

 

The pump I put on my old lawn tractor seemed to be a vane pump.  It just made a whirring sound whether fuel was flowing or not.  That type would run continuously and so there wouldn't be much change in power draw for the ammeter to register.

 

Another thing that will come into play is damping on the gauge.  If there isn't damping it'd bounce all over the place just from the tractor vibration.  I suspect most gauges, at least the inexpensive ones, are damped by just the bearing friction.



#8 Eric OFFLINE  

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Posted August 24, 2016 - 08:48 PM

I am not sure but isn't this what a small capacitor would solve? I know in car audio they use capacitors to store power for when an amp draws large amounts so as not to dim the headlights seems as if a small one would solve your issue but just a thought.

#9 EricFromPa OFFLINE  

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Posted August 24, 2016 - 10:14 PM

Wire fuel pump to a separate switch or wire it to a simple 4 pole 12v relay.Both will fix your problem.Relay would be the best way to isolate it.

 

Just like the PTO they are on a separate circuit  or have a Relay.Some have Both.


Edited by EricFromPa, August 24, 2016 - 10:15 PM.





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