Priming fuel bulb inside engine compartment

[TimFromLI]

I use a bulb between the primary and secondary filter in the engine compartment. It's been there for 5 years and I haven't had a problem. I can change both filters in minutes, it was a nightmare changing the secondary before the bulb. Also, if I have a fuel problem and the bulb is collapsed I can tell where the problem is. Since it's on the suction side of the system, above the level of the fuel tank, if it were to fail, the fuel pump would suck air and the engine would stop and I might get a few ounces of diesel in the engine bay- at most. It may not be ABYC approved but I know I can change the filter quick in a sticky situation or bypass the bulb in a few minutes. As a safety, you could plumb a bulb with valves in such a way that it is isolated from the fuel lines during normal operation but available for priming when needed.

 

[jssailem]

@TimFromLI Your system works for you. Not sure if the bulb fails there would be just a few drops of diesel. Clean up can be messy and leave the aroma of diesel for a considerable length of time. With your system, I would set up a conservative period to automatically replace the bulb pump. The material used deteriorates due to heat and chemical conditions. This is evident by their use to prime outboards. They always eventually fail. While diesel is different from gasoline, neither is good to be spilled in a boat. A properly rated electric fuel pump is ABYC approved. Is a more permanent installation.

The joy is your decision, on your boat and all is good with the world. Be careful and enjoy the freedom.

 

[Alan Gomes]

I use a bulb between the primary and secondary filter in the engine compartment. It's been there for 5 years and I haven't had a problem. I can change both filters in minutes, it was a nightmare changing the secondary before the bulb. Also, if I have a fuel problem and the bulb is collapsed I can tell where the problem is. Since it's on the suction side of the system, above the level of the fuel tank, if it were to fail, the fuel pump would suck air and the engine would stop and I might get a few ounces of diesel in the engine bay- at most. It may not be ABYC approved but I know I can change the filter quick in a sticky situation or bypass the bulb in a few minutes. As a safety, you could plumb a bulb with valves in such a way that it is isolated from the fuel lines during normal operation but available for priming when needed.

Your setup is not safe. This is why the ABYC does not approve it.

There is a much better way to do this that is not only even more convenient but also safe. I've attached a diagram of it. It not only serves as a fuel polishing system (if you want that), but is ideal for priming filters with the flick of a switch.

 

[skunther]

air accumulator screw

Is that what that screw is? What is its purpose?
I have pretty much the same setup as you. Maybe I’ll give your method a go next time.
I have the same extractor too, works great.

 

[sesmith]

I just love the autopriming feature on my M35b universal. Turn the key to the glow position several times after changing filters and it primes itself. Never a problem...except this fall when it took me a few minutes to remember I didn't open the fuel shutoffs on the tank after I changed the filters..

 

[Dalliance]

Is that what that screw is? What is its purpose?
I have pretty much the same setup as you. Maybe I’ll give your method a go next time.
I have the same extractor too, works great.

It’s in a raised area on top of the secondary filter, so given the name, “Air Accumulator Screw”, perhaps the purpose is to catch a very small amount of air in the line before it gets to the high pressure pump and injectors.

 

[jssailem]

Could you also identify it as a "Fuel Line Bleed Screw"?

 

[Mark Maulden]

My Racor 500 is located above the tank. It has a valve on the inlet. It is approx the the same height as the engine depending where on the engine. I have a Facet 3/4-1.5 psi electric pump between the Racor and the engine driven pump per Racor’s instructions. At the dock, I shut the valve on the Racor inlet off. Keeps fuel from running back to the tank when I remove the Racor top. I remove the top and pull the cartridge out. Put the new one in and fill the Racor with diesel from a squeeze bottle full of diesel. Install the top. Remove the the secondary filter on engine and discard. Fill the new filter with diesel from squeeze bottle and spin it on. Energize the Facet pump and bleed any air out of the secondary Filter. Start the engine and it dies. Start the engine again and it’s good. The Facet pump runs whenever the engine is running and the psi is low enough to not rupture the manual onboard pump diaphrams. At sea, I’ve thought about carrying a squeeze bottle of diesel, however, I know my my fuel system is clean and I change filters when the vacuum gauge on the Racor starts climbing..
John has good advice and should be followed..

 

[Dalliance]

Could you also identify it as a "Fuel Line Bleed Screw"?

I think so. It‘s the larger of the two screws on top of the Yanmar secondary filter. I’ve seen it labeled “Air Accumulator Screw” and I’ve seen it labeled “Plug” with the only smaller screw labeled ”Air Bleed Screw”. I honestly don’t quite understand why there are two, both screws have bleed holes, but the larger of the two is the one I discovered my Vacuum Oil Extractor tube fits into.
I just changed both fuel filters today and took a photo of the set up with the oil extractor. This method greatly minimizes but does not completely eliminate the need to hand pump.

 

[dlochner]

It‘s the larger of the two screws on top of the Yanmar secondary filter. I’ve seen it labeled “Air Accumulator Screw” and I’ve seen it labeled “Plug” with the only smaller screw labeled ”Air Bleed Screw”. I honestly don’t quite understand why there are two, both screws have bleed holes,

One bleed screw bleeds the lines up to and including the secondary filter. The hose from that line goes to the high pressure pump. the second screw bleeds the line from the high pressure pump to the to the low pressure return line. Both bleeders are on top of the filter housing, the housing only serves as a transition point from the end of the high pressure line to the return line, it is not connected to the feed from the filter.

 

[Dalliance]

One bleed screw bleeds the lines up to and including the secondary filter. The hose from that line goes to the high pressure pump. the second screw bleeds the line from the high pressure pump to the to the low pressure return line. Both bleeders are on top of the filter housing, the housing only serves as a transition point from the end of the high pressure line to the return line, it is not connected to the feed from the filter.

I‘m looking at the Yanmar Service manual diagram and think I see what you’re saying. It appears that the smaller bleed screw may be on the inlet side of the secondary filter housing and the larger bleed screw (or “Plug”) on the outlet side. This would mean that my vacuum oil extractor is pulling fuel and air from the secondary filter inlet (and primary filter and lines beyond), through the Yanmar filter to the outlet side, but potentially also pulling fuel from the direction of the high pressure fuel injector pump. When I‘ve used this suction method, I have also needed to bleed the line at the injection pump banjo bolt bleeder, but not beyond that.

You make an interesting point about the connection to the high pressure fuel injection pump and low pressure return line. Is it possible that too much suction could pull fuel and air back through the high pressure pump all the way from the injectors and return line? If so, it would necessitate bleeding the system all the way to the injectors and that hasn’t happened. At least not yet. It’s only a few seconds of low level suction to eliminate many minutes of awkward hand pumping.

 

[dlochner]

Assuming the primary filter is relatively near the engine and the filter is full, it shouldn't take minutes of hand pumping to get fuel to the filter and fill it. The Secondary filter is pretty small and should fill quickly, especially if you can get gravity working for you. The return fuel lines are pretty small, less than a ¼" (4mm) and fill quickly.

If you are not getting a full stroke on the lift pump, do as @Maine Sail suggests and rotate the flywheel a little. I believe there is a cam that drives the lift pump, if the high point of the cam is close to having contact with the pump, the stroke will be short and there will be a lot of pumping necessary. Also, having a full fuel tank will provide more head for moving fuel through the system reducing the amount of pumping necessary.

BTW, the engine will run quite nicely if the return line bleed screw is not completely tight. You don't want to do this, you shouldn't have to ask.

 

[TimFromLI]

There is a much better way to do this that is not only even more convenient but also safe. I've attached a diagram of it. It not only serves as a fuel polishing system (if you want that), but is ideal for priming filters with the flick of a switch.

Alan, you sold me. It's time to remove the bulb and put in a proper priming pump. I just want to make sure I understand your diagram right. The "fuel rated Y valve " works as a diverter when priming? I would divert the fuel from the engine back to the tank to bleed the system and then turn the valve back to run the engine? Can you recommend a suitable priming pump? I plan to use it with a switch in the engine compartment. I am looking at the Facet Cube 12v Fuel Pump, 3/8 NPT, 4-7 psi.

 

[Alan Gomes]

Alan, you sold me. It's time to remove the bulb and put in a proper priming pump. I just want to make sure I understand your diagram right. The "fuel rated Y valve " works as a diverter when priming? I would divert the fuel from the engine back to the tank to bleed the system and then turn the valve back to run the engine? Can you recommend a suitable priming pump? I plan to use it with a switch in the engine compartment. I am looking at the Facet Cube 12v Fuel Pump, 3/8 NPT, 4-7 psi.

I'm glad you are going to implement this system. You will really, really like it.

When I need to prime my large Racor 500, I set the diverter valve so that the fuel that is sucked (not pushed) through the Racor flows into the "tee" that taps into the fuel injector return line. This line is simply connected back to the tank and dumps the fuel straight into it. When the filter is empty and you first throw the switch to energize the fuel pump, you will hear the pump click rapidly as the empty filter fills up. Once the filter fills up, you'll hear a noticeable difference in the sound of the pump, telling you the filter is full. You can let it run a bit longer if you want, because all it is doing is circulating (and even somewhat polishing) the fuel from the tank and back into the tank.

After the Racor is primed, you will set the diverter valve to direct the fuel from the tank, through the Racor, and then to the engine. It is at this point that you can use the bleed points on the engine to remove air from the system. The fuel pump is sending fuel to the engine under pressure--just as would have been the case if you were squeezing your primer bulb. With the pump energized, crack open the various bleed screws in order to check for bubbles. Once you have solid fuel coming out, tighten down the bleed screw, leaving the pump still energized. Go to the next bleed point downstream, if there is one, and take care of that one. And so forth.

Once all the bleed points are taken care of, shut of the switch (which you would have located conveniently in the engine bay) to de-energize the pump, leaving the diverter valve where you have it, i.e., sending fuel to the engine. Done!

Here is the pump I installed on my Yanmar 1GM.

Hope this helps,
Alan

 

[TimFromLI]

I have a Volvo MD22 with a primary (Racor) and secondary (spin on type). The bulb is between the two filters. The Racor has a built in lift pump for priming and it works fine. I use the bulb to prime and bleed the secondary. I was planning on putting the pump there, in place of the bulb. Now that I'm thinking about it, I wonder if the racor primer would be able to push the fuel to prime/bleed the secondary. I'll give it a try this weekend, I'll drain the secondary and try refilling it with the racor. If it works, I'll just get rid of the bulb and just leave it as is. Otherwise I'll install the facet. I just want to be sure I can change filters quickly in a pinch.

 

[jssailem]

I used a walbro pump. One like this Walbro FRD-2 Fuel Pump - Industrial as a transfer pump to move fuel between to tanks on my boat.

I have since modified my system to install a Keenan Fuel filter system.
I have provided information for the system here.

BAD FUEL can spoil your day

Here we are in the middle of winter beginning to plan our next sailing season. Maybe we are new to using a boat with an inboard engine. Some of us have years of mechanical experience so we know. Some are facing the idea of being alone in the water with a dead engine for the first time. We...

forums.sailboatowners.com

 

[Mark Maulden]

7 psi might be a bit much if you are keeping the engine driven pump in series. The possibility exists that the engine driven pumps diaphrams could be ruptured thus filling the crankcase with fuel. Facet makes a cube pump that maxes out at 4.5 psi. The Napa p/n is 40104. I think there is a prefix. I use it on my Beta 35. I also wired it so it can be energized for bleeding use Separate from the panel.

 

[Alan Gomes]

7 psi might be a bit much if you are keeping the engine driven pump in series. The possibility exists that the engine driven pumps diaphrams could be ruptured thus filling the crankcase with fuel. Facet makes a cube pump that maxes out at 4.5 psi. The Napa p/n is 40104. I think there is a prefix. I use it on my Beta 35. I also wired it so it can be energized for bleeding use Separate from the panel.

On my 1GM I simply disconnected the mechanical engine driven pump. I did not physically remove the pump, though I could have, and then covered the hole with a cover plate. But it doesn't hurt anything to just leave it on but disconnected.

The failure mode for the mechanical pump when the diaphragm goes out is to dump fuel in the crankcase. No bueno. The electric pumps are highly reliable. But should the electric pump go out, the engine will die. I'd take that over dumping fuel in the crankcase any day. And for those who are concerned about redundancy, one could keep a spare electric pump aboard and fit it with quick disconnects so that it could be swapped in quickly.