Fuel transfer pump

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dstrecker1
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Fuel transfer pump

Post by dstrecker1 »

Recently I decided to drain fuel from my forward tank to the aft tank. The transfer went fast. When I reversed the transfer from the aft tank to the forward tank the transfer was very very slow. I could here fuel entering the tank but the fuel gauges did not appear to move after 15 minutes of running the transfer pump. I am thinking this may have to do with the long fuel suction line from the fuel pump located at the front tank to the aft tank. My thinking is the pressure drop in the long suction line is starving the fuel pump or maybe I have another problem. Has anyone else experienced the same issue?

Dennis and Cindy Strecker
2006 PDQ #95

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AMCarter3
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Re: Fuel transfer pump

Post by AMCarter3 »

Hmmm. I've seldom transferred fuel from my Main tank to the forward tank, but when I have it has seemed to go at about the same speed both ways. One possibility to condsider is microbial growth in your fuel lines and tanks. Do you ever add a product like ""Biobor JF” to kill algae that can grow over time from moisture condensation in the tanks? During the winter, when our boat is mostly NOT active, we add this product to a FULL tank: Main tank: 1.5 oz.; Aux tank: 1 oz.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

scgck
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Re: Fuel transfer pump

Post by scgck »

I recently transferred all the fuel I could from the bow tank to the stern to verify the fuel gauge accuracy. I tried the same thing you did but the pump lost its prime. Even putting more fuel in the forward tank did not help. I removed the forward tank transfer fuel line at the tank valve and filled it with fuel and bumped the transfer switch on momentarily. I did this several times. Be careful as it is easy to inadvertently place the switch into the stern to bow transfer position which will instantly spit out all the fuel you just put in. Please don’t ask.
The last time fill the line and reattach to the valve. Pump is primed again. I will never transfer fuel below about 1/8 of the forward tank unless absolutely necessary again.
Hope this helps.
Chris
Expatriate MV 068

Ortolan
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Re: Fuel transfer pump

Post by Ortolan »

On our boat, the transfer pump will lose it’s prime when the bow tank goes below 1/4.
One tip I have discovered - if you need/want to transfer as much fuel as possible & not lose prime, keep your head down & fingers on the transfer switch - as soon as you hear a change in the pump’s pitch (beginning to suck air) immediately flip the pump to the opposite direction for about 15 seconds, then off - that will re-fill the hoses with fuel again.
Russ
Twin Sisters
2006 MV34 - Hull #100
www.esc-pod.com

scgck
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Re: Fuel transfer pump

Post by scgck »

Great information. Thanks
Anyone know how much fuel is available for the generator once the transfer pump can no longer move fuel aft ?
Chris
Expatriate Hull 068

DickTuschick
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Re: Fuel transfer pump

Post by DickTuschick »

The pick up tubes in the forward tank were cut at a depth to prevent more than about 50 of the 70 gal to be transferred aft.
The practicality of the information however is questionable as we all know our fuel gages are not very accurate. My rule of thumb is that I never take the forward tank down to less than 1/4 on the gage which has worked well to prevent any air locks.
On a separate note , in sixteen years we have never transferred fuel forward only aft. We therefore have all fwd valves open, the switch set to aft and the aft valves closed. When transferring fuel, all I have to do is open the two aft valves and turn on the fuel transfer breaker……then sit and watch the gages until desired amount of fuel is transferred, turn breaker off and close aft valves…all from the inside….nice when underway or in inclement weather.
Hope this helps.

duetto
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Re: Fuel transfer pump

Post by duetto »

i had been told the same on the length of the pickup. the idea being the genset feed was longer and therefore you could never get to the point of transferring so much the genset would run dry. well years ago it happened to us. i transferred too much and genset wouldn't start. now we're hull 23, so maybe pdq learned along the way.
john & diane cummings
duetto mv34 #23

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