Electric fuel pump.

G

Graham_Wright

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www.mastaclimba.com
I have fitted one of these to each tank;-
12V General Electronic Fuel Pump, Car Modified Car Fuel Pump Gasoline Pump J9X1 | eBay

They pick up via a coarse filter in the tank and feed the main engine filters in the engine bay. The tanks are lower than the engine.

The fuel system also feeds the diesel heaters.

The in-tank filter is quite coarse and the pump interior valve regularly becomes blocked. The pump is supplied with a filter (and no instructions as usual) which I suppose should be fitted before the pump. The filters I have are sealed. Although the pumps can be dismantled, the mechanism is fiddly.

I have purchased one of these;-
Low pressure SU replacement carburettor Fuelflow 12v electronic fuel pump 15LM12 | eBay

and look forward to improvement.

Any observations?
 
Why do you need pumps? The engine's lift pump should be able to suck diesel up from the tanks. As for feeding pressurised diesel to a heater, I'm not convinced that's wise.
 
Clean your tanks if "the pump interior valve becomes regularly blocked" as the improvement you seek may not happen. If not fitted consider drawing fuel off via a standpipe fitting, instead of a tank low point fuel outlet.
 
Graham_Wright said:
I have fitted one of these to each tank;-
12V General Electronic Fuel Pump, Car Modified Car Fuel Pump Gasoline Pump J9X1 | eBay

They pick up via a coarse filter in the tank and feed the main engine filters in the engine bay. The tanks are lower than the engine.

Any observations?
Click to expand...

This is quite common practice in the USA where they have found the the tiny lift pumps now fitted to many smaller diesel engines struggle at times especially with fuel tank in the keel area. I think many posters here would have an easier life if they had one fitted as it makes bleeding the system a doddle
 
pvb said:
Why do you need pumps? The engine's lift pump should be able to suck diesel up from the tanks. As for feeding pressurised diesel to a heater, I'm not convinced that's wise.
Click to expand...
It doesn't!
I have had a long standing issue with air entering the feed to the filters and, in desperation, have replaced most of the copper with hose. Anticipating a significant advance in leak finding, I was thwarted by the failure of the pump to produce more than a sporadic dribble.

Once the engine is running, it can indeed suck adequately but it needs priming and a switch is more convenient than grovelling under the lockers to a manual one.
Insofar as the advisability of feeding the heater pumps with pressure, I share your concerns. It may be possible for the tank pump to overpower the dosing pump. A test will prove one way or the other. If there is a problem, I have a solution ready.
 
pvb said:
Why do you need pumps? The engine's lift pump should be able to suck diesel up from the tanks.
Click to expand...

I guess a pump would be useful in changing filters, bleeding, etc, similarly to the manual squeeze-bulb I have. And as a "boost pump" it would provide some emergency help when a filter blocks and the engine starts to falter just as you're in a critical position - flick a switch and you get a few more minutes' running before you have to change the filter.

pvb said:
As for feeding pressurised diesel to a heater, I'm not convinced that's wise.
Click to expand...

Certainly if we're talking about a blown-air heater, it will expect to regulate the fuel supply using its own pump and a pressure supply is not a good idea. I suppose a drip heater that expects a head from an elevated day tank could benefit, if the pressure is in the acceptable range.

Pete
 
prv said:
I guess a pump would be useful in changing filters, bleeding, etc, similarly to the manual squeeze-bulb I have. And as a "boost pump" it would provide some emergency help when a filter blocks and the engine starts to falter just as you're in a critical position - flick a switch and you get a few more minutes' running before you have to change the filter.

I can select between the two tanks each of which has its own filer (but the final engine mounted one is common obviously)

Certainly if we're talking about a blown-air heater, it will expect to regulate the fuel supply using its own pump and a pressure supply is not a good idea. I suppose a drip heater that expects a head from an elevated day tank could benefit, if the pressure is in the acceptable range.

Pete
Click to expand...
It is probably a vain hope, but there may be some indication in the chinaspacher heaters instructions I have concerning maximum head. I don't recall any cautions concerning above heater tanks. Instructions are on the boat.
 
Graham_Wright said:
It is probably a vain hope, but there may be some indication in the chinaspacher heaters instructions I have concerning maximum head. I don't recall any cautions concerning above heater tanks. Instructions are on the boat.
Click to expand...

The installation manual for Planar heaters says the maximum fuel level in a separate tank should be lower than the fuel intake pipe to the heater.
 
Graham_Wright said:
It doesn't!
I have had a long standing issue with air entering the feed to the filters and, in desperation, have replaced most of the copper with hose. Anticipating a significant advance in leak finding, I was thwarted by the failure of the pump to produce more than a sporadic dribble.

Once the engine is running, it can indeed suck adequately but it needs priming and a switch is more convenient than grovelling under the lockers to a manual one.
Insofar as the advisability of feeding the heater pumps with pressure, I share your concerns. It may be possible for the tank pump to overpower the dosing pump. A test will prove one way or the other. If there is a problem, I have a solution ready.
Click to expand...

Air leaks are incredibly frustrating, but it would be better long-term to solve the air leak than paper over the cracks with pumps.
 
Graham_Wright said:
Please elaborate.
Click to expand...

A fuel pipe that enters into the tank at the top to a few inches off the bottom. Fuel is sucked up and out the top of the tank. Avoids low points when healed over and rolling but does not replace filters and f course will not work for suspended debris. The advantage is that water and dirt remains on the bottom and does not get sucked up. Common for fuel heaters, check sizes are suitable for engine fuel supply.

490mm Fuel Tank Stand Pipe Low Profile Heater Parts For Eberspacher Webasto | eBay
 
BlowingOldBoots said:
A fuel pipe that enters into the tank at the top to a few inches off the bottom. Fuel is sucked up and out the top of the tank. Avoids low points when healed over and rolling but does not replace filters and f course will not work for suspended debris. The advantage is that water and dirt remains on the bottom and does not get sucked up. Common for fuel heaters, check sizes are suitable for engine fuel supply.

490mm Fuel Tank Stand Pipe Low Profile Heater Parts For Eberspacher Webasto | eBay
Click to expand...
That is what I have. However, "a few inches" in my tanks is a lot of fuel! There is a pretty fine gauze over the pick up.
pvb said:
The installation manual for Planar heaters says the maximum fuel level in a separate tank should be lower than the fuel intake pipe to the heater.
Click to expand...
Perhaps, once primed, the dosing pumps will suck through the priming pump once running. The run is quite long but the piping is generous in bore.

I have chased the air ingress leak forever! Pressurising with air and the use of a bubble detecting fluid (i.e. Fairy) showed a completely air tight system. My theory is that the leak occurs only during suction. The original pump is not inherently airtight and relies on close fitting sleeves. If submerged, it may have been ok. The replacement looks more promising but doesn't apparently dismantle (at least easily).

The new pump is specced at 3-4 psi. If push comes to shove, I could instal a pressure switch and an accumulator.

I'll report back.
 
Knowing little about fuel pumps, I see you went for a diaphragm rather than a piston pump (at much lower cost). What do you consider the advantages are?
Does one type handle running dry better than the other?
As you are also feeding a heater, I assume that you will have to switch the pump on manually. Will you switch it in parallel through the ignition?
 
I hoped (from a look at the illustration) that there diaphragm pump would be easy to dismantle. (It has so far defied my efforts and the seller can't help).
As explained, the piston pump is a fiddly mechanism and the N/R valve clogs easily.

Se #12 for the other.
 
If my fuel system starts to entrain air, it will either be from air being pulled in from a low level in the tank, or......

my pre-filter, which is higher than either the fuel tank or the engine lift pump.

In effect, my pre-filter is at the top of a siphon and if any of its hose connections, or the filter itself leak, they will suck, not blow.

By the way, if I ever do fit an electric pump, should I put it downstream of the pre-filter?
 
My boat has fuel tanks in the twin keels. The engine fuel pump on the Beta that we fitted would not pull the fuel so we fitted a diaphragm pump with a simple in line filter before the pump on each side. It has worked for the last fifteen years like that, It is also a help when changing the primary and secondary filters and needing to bleed the system.
 
WoodyP said:
My boat has fuel tanks in the twin keels. The engine fuel pump on the Beta that we fitted would not pull the fuel so we fitted a diaphragm pump with a simple in line filter before the pump on each side. It has worked for the last fifteen years like that, It is also a help when changing the primary and secondary filters and needing to bleed the system.
Click to expand...
That was my experience until the piston pump became clogged. Encouraging to hear the diaphragm pump was a success.?
 
WoodyP said:
My boat has fuel tanks in the twin keels. The engine fuel pump on the Beta that we fitted would not pull the fuel so we fitted a diaphragm pump with a simple in line filter before the pump on each side. It has worked for the last fifteen years like that, It is also a help when changing the primary and secondary filters and needing to bleed the system.
Click to expand...

For some reason, Beta engines seem to have a feeble lift pump. Beta say a suction lift of 0.25m is about the limit. I had a keel tank in my last boat, and Volvo Penta engine happily sucked the fuel up from about 1.0m down.
 
Graham_Wright said:
It doesn't!
I have had a long standing issue with air entering the feed to the filters and, in desperation, have replaced most of the copper with hose. Anticipating a significant advance in leak finding, I was thwarted by the failure of the pump to produce more than a sporadic dribble.

Once the engine is running, it can indeed suck adequately but it needs priming and a switch is more convenient than grovelling under the lockers to a manual one.
Insofar as the advisability of feeding the heater pumps with pressure, I share your concerns. It may be possible for the tank pump to overpower the dosing pump. A test will prove one way or the other. If there is a problem, I have a solution ready.
Click to expand...
Just a thought.
Is there a return pipe from the engine filter to the fuel tank?
if so, is there an upward anti syphon loop in it?
My old Perkins 4108 was hard to start - just as if there was air in the system. No leaks were found but i discovered fuel was draining down the return pipe allowing air to get back up the pipe and into the filter.
Once the engine started, there was no running problems.
Forming an upward loop cured the starting problem.
(if the return pipe in the tank had been long enough to stay below the fuel level, this would have helped)
 
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