Diesel Primer Bulb In Line?

[olaf hart]

Took a good look at my fuel system today.

Tank to CAV filter line is all pipe, so no way to put a bulb in there. There is a tap at the tank end.

Similarly, line from CAV to engine is flexible, but a purpose made hose which I am reluctant to cut.

The CAV has two inlet and two outlet connections, so I consulted with my local marine diesel guy and we made up a fitting with a CAV screw in connector, a metal tap, and a hose connection.

Plan is to leave it fitted to the spare inlet on the CAV, and prime the system from a separate fuel container, so the bulb pumps fuel to clear air from the lines, I close the tap and disconnect and store the bulb with hoses on both sides.

The idea is to have a setup I can use at sea if I have to replace filters because of blockage.

I am due to change filters in the next week or so, so I will report back.

[colemj]

Originally Posted by noelex 77

This same bulb can be used to prime the generator or the main engine filter. The latter by forcing fuel backwards into the filter.

If you are able to get fuel backwards into your Racor, you have a problem with its check valve.

Mark

[noelex 77]

Originally Posted by colemj

If you are able to get fuel backwards into your Racor, you have a problem with its check valve.

Mark

That is what everyone thinks which is why it is almost never done this way.

If you look at the cross sectional diagram of the Racor and consider how the check valve works you will see fuel can enter the outlet and fill up (and therefore prime) the filter.

[olaf hart]

Report back on CAV lateral bulb primer.

Turn off fuel tank tap, CAV is above top of tank.

Remove bowl, filter, drain, clean, reassemble with new filter and seals.

Remove engine secondary fuel filter, (Volvo 2003 RWC), and replace.

Screw tap into unused "IN" port on CAV, with hose nipple on other end. Connections are all 1/2" UNF.

Attach hose from bulb, other end in a fuel container with 5l of clean diesel.

Open engine filter bleed screw, pump bulb till no air coming out the screw.

Close screw, keep pumping for a while till hear fuel returning to tank.

Close tap on CAV extra "IN" port, remove bulb, hose, nipple, screw cap over tap end for extra security against air ingress.

Open fuel tank tap, start cold engine, kicked straight over, no coughing, no spluttering, just normal engine sounds.

I left the engine running while I ate lunch, to warm the oil before changing it and the filter. Didn't miss a beat for at least half an hour.

Previously, bleeding was a real pain, now I am not even afraid of changing a fuel filter in a swell in Bass Strait.

Keeping the bulb, hoses and nipple on the boat.

And a new vacuum pump made the engine oil change a breeze as well

Life is good.

[SeaSon]

Originally Posted by olaf hart

Report back on CAV lateral bulb primer.

Turn off fuel tank tap, CAV is above top of tank.

Remove bowl, filter, drain, clean, reassemble with new filter and seals.

Remove engine secondary fuel filter, (Volvo 2003 RWC), and replace.

Screw tap into unused "IN" port on CAV, with hose nipple on other end. Connections are all 1/2" UNF.

Attach hose from bulb, other end in a fuel container with 5l of clean diesel.

Open engine filter bleed screw, pump bulb till no air coming out the screw.

Close screw, keep pumping for a while till hear fuel returning to tank.

Close tap on CAV extra "IN" port, remove bulb, hose, nipple, screw cap over tap end for extra security against air ingress.

Open fuel tank tap, start cold engine, kicked straight over, no coughing, no spluttering, just normal engine sounds.

I left the engine running while I ate lunch, to warm the oil before changing it and the filter. Didn't miss a beat for at least half an hour.

Previously, bleeding was a real pain, now I am not even afraid of changing a fuel filter in a swell in Bass Strait.

Keeping the bulb, hoses and nipple on the boat.

And a new vacuum pump made the engine oil change a breeze as well

Life is good.

Cool! Do you not have a secondary filter such as a Racor prior to the 'CAV'?

Sent from my SAMSUNG-SGH-I537 using Cruisers Sailing Forum mobile app

[olaf hart]

First filter CAV.
Second filter is the one on the engine.

[gonesail]

there are bulbs that are rated for diesel that work great. i would replace every few years to be sure.

[olaf hart]

Here is another odd question, has anyone tried a bulb in the fuel return line?

Seems to me it should work, but no problems if there is a small air leak.

[GrahamHO]

Originally Posted by olaf hart

Here is another odd question, has anyone tried a bulb in the fuel return line?

Seems to me it should work, but no problems if there is a small air leak.

As the return line should always discharge into the top of the tank and it starts after the injection pump I'm scratching my head to see what that would do??
Like others my bulb is in the supply line after the tank and before the primary filter. No air or fuel leak problem. Why try to fix it if it ain't broke?

[Jon Eisberg]

Originally Posted by GrahamHO

As the return line should always discharge into the top of the tank and it starts after the injection pump I'm scratching my head to see what that would do??

Yup, glad to see I'm not the only one scratching my head over that one... ;-)

One caveat for anyone installing an electric pump between the tank and your primary filter(s). Many of these pumps come fitted with a coarse screen on the inlet side, and I'd suggest removing it...

About 10 years ago, I had given my fuel tank a thorough inspection prior to heading south for the winter... By the time I was approaching Morehead City, I started to have fuel problems, the engine dropping RPMs or shutting down... I'd swap out a Racor element, it would be OK again for a bit, then the problem would reappear... Had a nice sail down to FL, but having to run inside behind Canaveral, the problem persisted... So, I finally opened up the inspection port on the tank, to have another look inside...

At a glance, I recalled getting a phone call in the midst of my inspection/cleaning of the tank 2 months prior... I had left the tank open for a bit while I climbed out of the lazarette to take the call. It was a breezy fall afternoon, and apparently a loose sheet of paper towel had been blown into the opening, and I never noticed it before bolting the port back on... ;-)

Over time, the sheet had degraded into small pieces, which looked very much like algae when I first noticed them... Sure enough, the inlet to the electric pump was becoming clogged intermittently with these tiny bits of debris getting caught by the screen...

Most folks know a screen on a fuel pickup tube is a bad idea, that the end of the tube should never be flared, and cutting it off at a 45 degree angle is probably the safest bet. But it sure is nice to have some sort of barrier within the tank to inhibit the sucking of sizable debris into the pickup... After the incident I've described, I installed a circular screen that surrounds the pickup, and simply rests on the bottom of the tank, and of course removed the screen from the pump... (the white tube is the pickup for the fuel polisher setup)

10 years on - so far, so good...

;-)

[Cheechako]

Originally Posted by olaf hart

Here is another odd question, has anyone tried a bulb in the fuel return line?

Seems to me it should work, but no problems if there is a small air leak.

Why? Work for what?

[captainwoody]

I'm sure commenters have mentioned it. Squeeze bulbs are not ideal for diesels. My suggestion is to instal an electric pump.
I was just moving a Swan to el Carib. The clean and very expensive big main diesel started running funny. We had fuel and filters were found to be clean. The problem was that someone had installed a squeeze bulb in the line and the rubber on the bulb had failed and it was letting air in. When shut off, it leaked fuel is the only reason we found it. I don't think outboard squeeze bulbs are designed for that much diesel flow or possibly for diesel at all. Consider also that they are not rated for below deck so insurance may not cover an issue created by them. I circumnavigated on a 33' coastal boat. I had a $12 electric fuel pump in line with an engine space switch that I would flip on to fill the Racors when doing at sea filter changes. It worked perfectly.