Found it after two years

[sailaway78]

I have been chasing a very small vacum leak for over two years, and I finally found it. I will admit to it being more luck than skill, and probably because it had gotten a tiny bit worse, and I would not have found it without having an electric fuel pump. What was happening that if the boat sat for a couple of weeks or more, the fuel system would have to be bled. It always started, then would run for about a minute, then die. Only bleeding the system would bring it back to life. I inspected, checked, re checked, replaced fittings, fuel line, everything I could think of, to no avail, and had pretty well resigned myself to live with it. This morning I was doing routine maint. getting ready to go sailing, when I noticed some moisture on top of one of the fuel filters. This boat has two big Fram filters, a water seperator primary, and a 10 micron secondary. They are cannister types, and the cans are held on by a single bolt in the top of the fitting. I had checked them a couple of times, and found everything to look perfect. They use a copper washer, identical to the Yanmar banjo washers as a seal under the bolt head. I do inspect them, but do not replace when changing filters, unless they are scratched up or look damaged in some way. To shorten the tale, one of these was leaking just a very tiny bit. I only noticed slight moisture, not any actual fuel. The washer looked like new when removed, but replacing it cured the leak, and very hopefully my problem. And incidentally, I have been using a fiber washer from Ace Hardware for banjo washers for some time now. They are 45 cents each, and much more important are available. I keep a bunch on the boat, but so far have never had one fail, or leak. I do replace these every time I take one off, and do not reuse them. I know the copper ones are supposed to be replaced each time too, but they are a little hard to come by around here. My closest supply is the local Yanmar dist. and it is a two hour round trip. Last time I went over there, they had 4 in stock. So, the fibers are a much more desirable way out for me.

 

[kloudie1]

Great find, easy !!!
I have used metric oil pan drain copper gaskets under the banjos... found that the OD is too big but in most cases, there is nothing close to foul ID is right on... works fine.. I think I bught them at O-Riley or AutoZone..

 

[Hermit Scott]

I love it when people solve the weird, difficult problems.
How did the electric fuel pump help you find that?

 

[John Nantz]

Just found my leak yesterday

What a coincidence, just found my leak yesterday but it wasn't a recurring one, just started the day before.

The engine would run for a couple minutes and die. Bled the line starting at the engine fuel pump (Yanmar), bleed the engine fuel filter, engine would run for a few minutes and die. Did this several times. It ran perfectly up 'till the day before.

Checked the fuel tank hose valves -okay.
Checked the clamp on the hoses - found one hose, the new one, that needed the clamps tightened. Performed bleed routine (by now it was routine!), engine would run for a few minutes then die.
Long story short, finally found the primary fuel filter (Racor) bowl was just a tad loose. Tightened that, did the bleed routine, and that was it!

Those pesky little copper washers are a pain, not to mention expensive!
Why do they have to cost so much??? They're a regular profit center.

 

[Stu Jackson]

One of our guys

had all sorts of trouble bleeding (or keeping his bled). Finally traced it down to a whacked edge on the new Racor.

That's why Mom said: "Never buy banged up soup cans!"

 

[sailaway78]

Here is how it worked Hermit

I had just changed all the filters, as am getting ready to head off again, soon as these damn storms go away. Bleeding the Yanmar using the manual lift pump is almost an impossible task. It is between the engine and bulkhead, hard enough to just reach without even thinking of pumping that little lever. So, I use an electric pump at the tank. The way it showed up was I had pressure on the system, and saw the moisture. No way it would ever show without pressure on it. The electric puts about 5 lbs on the system, so is pretty easy to check the full length for leaks. Also good for emptying the tank for cleaning when needed.

 

[larryw]

You can check your entire fuel system, from the tank to the lift pump, by draining it, closing the valve at the tank, and cobble up a fitting to your dink pump. pressurize the system as high as your dink pump will go, and use a little soapy water applied with a small paintbrush. leaks will bubble.

 

[Alan]

All very true but the electric fuel pump makes it so easy to find. Just switch the pump on with the engine off and wait to see the seep. My electric pump is rated 2.5 to 4 psi. There's no need to run it under normal operating conditions, it's a flow through so the mechanical lift pump can work as usual. But for bleeding and finding leaks there's no easier way.
BTW the pump is only $20.00.

 

[sailaway78]

Total agreement Allen

I do not understand why everyone doesn't have an electric pump mounted. Just for bleeding the fuel system it is more than worth it. Especially if you have a tight clearance on the starboard side of the engine, and who doesn't. Working that little lever on my boat, could be done easily by Spiderman, but for a normal human appendage, it is nearly impossible. And to drain the tank, coat with soap, etc. etc, to check for leaks, when you can just flip a switch. Maybe there is something wrong with my way of thinking, but to me simple and easy is always best.

 

[John Nantz]

Electric fuel pump and runaway engine

All is not gold that glitters. An electric fuel pump has the potential to exacerbate a runaway engine situation.

There are a couple causes for a runaway engine such as a fuel leak through the fuel pump diaphragm and into the oil pan, and a restricted flow in the fuel return line. I understand that not all engines have fuel return lines now but older ones, like mine, do. Restricted flow in the return line can be caused by a pinched line or sludge buildup inside the line.

Anyway, it MAY be possible that the electric fuel pump could force more fuel through the leaky diaphragm or to the injectors. The second one may not be as plausible because it would have to pass the high pressure pump to do so and I don't know how significant that part would be.

If one does get a runaway engine, there are a couple ways to stop it: (1) shut off the fuel valve at the tank, but this would take a long time before the engine runs out of fuel, or, (2), block the air intake with something like a shoe, but not all at once because those pistons and flywheel have a lot of inertia to overcome.

In a runaway engine situation it may be hard to remember to turn off the electric fuel pump.

 

[Alan]

Hey John, there is no need to run the pump under normal operation therefore the pump will do nothing to harm the engine. The pump is ONLY switched on for bleeding or some sort of maintenance. Other than that it sits idle.

 

[Hermit Scott]

I ran out of gas coming back into the slip Saturday. I thought that since there was air in the system I would have to bleed it. But after filling the tank with a jerry can, the engine cranked ran rough for a few minutes and then started running fine. I will be ready to bleed it if any problems develop next time I take her out.

 

[Snotter]

I pity the poor sailor who tries to bleed a perkins 4-154 by manually pumping the lever on the mechanical fuel pump. An electric fuel pump is the only way to go. I, too, leave mine off and turn it on only to bleed the system. I got ripped off on mine--I paid 29$ for it at my local autoparts store.

 

[John Nantz]

Prime pump - good way to go

Hey John, there is no need to run the pump under normal operation therefore the pump will do nothing to harm the engine. The pump is ONLY switched on for bleeding or some sort of maintenance. Other than that it sits idle.

That's a really good way to do it to avoid problems.

Thanks for the feedback.