Prime the diesel

[Dale Wilson]

Thinking back to a couple of times where I had to prime the diesel and only had to pump the little finger pump on my Yanmar 3G a 100,000 times or so (I may have lost count), I installed a hand bulb type pump on my fuel line. The kind that outboard motors use to prime the motor. Seemed to work fine, but the other day I ran out of fuel even though there was plenty in the tank. I installed the pump between the tank and my larger Racor fuel filter. Did I miss something? Is there some reason why this wouldn't work? It just seemed to me to be an answer to a problem, but did I create another one?

 

[Ed Schenck]

Backwards?

Dale, you don't say whether this worked for awhile before failing. The Yanmar will run for several minutes just from the fuel in the filters. The hose that you installed with the bulb has a check valve and is uni-directional, I think. If it was installed backwards the engine would run for a few minutes but no fuel will get past that bulb.I use a 6-gal outboard tank with bulb for bleeding my fuel system, attaching the hose directly to the Racor. Because of that one-way valve there is a lot of pressure there when I remove that hose.Or did you simply introduce an air-lock? If so then rebleeding using that squeeze bulb should resolve the problem.

 

[Peter Roach]

Check the bulb

I preface with this disclosure - I have never seen this problem occur but I have heard of it. I have been told that since the Diesel will recirculate the fuel it has too much volume for a bulb type pump. It will actually cause the bulb to collapse and close off the fuel line. You may want to run the engine at full speed for some period and watch the bulb. Let me know what happens. I have often thought of installing one in my fuel line. I have heard of electrical fuel pumps that are used in trucks that work fine for the job.

 

[Mike]

Running out of fuel

You may want to check the fuel supply from the tank. You should not have to pump the primer pump as much as you are doing.Either obstruction at tank, air leakat fittings, plugged fuel filter or bad fuel pump.I, and others have had problems with Racor filters in that they do not seem to pull enough fuel on small engines. If you added the Racor and then had the problems, that could also be the source.

 

[John Parker]

Wrong side of the Racor

I was told by a mechanic at work to put the pump bulb in between the Racor filter and the engine filter. Have had it installed for a full season, with no problems at all. If bulb is backwards you should not be able to pump up pressure at all. Plus, most bulbs have an arrow pointing fuel flow. Other possibility is bulb is bad.