Problem with getting fuel to my Yanmar

[ReMetau]

I have a Yanmar 3QM30F. I ran the engine today as I normally do about once a month. After about 20 minutes the engine stalls out as if it is out of fuel. I check the Racor, and the filter looks dirty so I replace it, fill it back up using the manual lift pump and bleed the system.

I try again, and the same problem occurs. The Racor is about half full only, but I can pump fuel into it using the manual fuel lever. I tried the second Racor with the same results so I replaced the lift pump. Since it is such a pain to bleed using the lift pump, I only run it for about 10 minutes, and then shut it off. The Racor is not filling back up.

I can siphon from the fuel line and lift fuel manually using the lift pump, but it doesn't seem to be pumping when running.

Any suggestions are greatly appreciated.

Thanks.

[mikefossl]

On our Westerbeke 44a, if the oil pressure switch doesn't close, the fuel pump doesn't get power. Of course that would mean the oil pressure alarm should be going off if one is fitted.

[ReMetau]

It is a mechanical lift pump, but I do get oil pressure (gauge and alarm).

[Snore]

I am assuming that you checked for obvious leaks. The way I confirmed I had a vacuum leak in the fuel system was to remove the fuel hose running into the high pressure pump. Secured the hose and bled it into a rag. I then let the hose set at the same elevation I bled it at. The fuel level went down, so I felt this was confirmation of a leak.

Changed the old style Racor and the hoses into and out of the Racor.... problem solved. Still not sure if it was the Racor or a broken hose clamp I found.


My engine has two filters. The racor and a spin on filter. Did you check BOTH filters?

[ReMetau]

Originally Posted by Snore

I am assuming that you checked for obvious leaks. The way I confirmed I had a vacuum leak in the fuel system was to remove the fuel hose running into the high pressure pump. Secured the hose and bled it into a rag. I then let the hose set at the same elevation I bled it at. The fuel level went down, so I felt this was confirmation of a leak.

Changed the old style Racor and the hoses into and out of the Racor.... problem solved. Still not sure if it was the Racor or a broken hose clamp I found.


My engine has two filters. The racor and a spin on filter. Did you check BOTH filters?

I did not check the other Racor after it failed too, but I is out of the loop since it is switched to the other Racor. I did not check the secondary filter yet, but thought that this appeared to be an issue before it. I did check all the hose clamps and tightened before trying it the last time.

I gave up for the evening, but I'll check the secondary filter and see if I can discover a vacuum leak somewhere in the lines tomorrow.

[bstreep]

As noted above, you probably have a screw on filter ON the engine?

Also, are you getting any water in the racor? Water will very quickly destroy a filter.

[ReMetau]

I replaced both primary filters and secondary filter, but still having an issue where the engine runs for about 15 minutes and then empties out the fuel filters. The lift pump is new and appears to work fine since I use it to bleed the system before starting again.

I opened the fuel fill cap just to be sure that it wasn't a clogged vent line, but still same issue.

I checked all the hose clamps so the only thing I can figure is left to do is to replace all the lines. Any other suggestions?

[motion30]

perhaps the pick up in the tank could be cloged. try.
blowing some air back through pick up into the tank

[ReMetau]

Originally Posted by motion30

perhaps the pick up in the tank could be cloged. try.
blowing some air back through pick up into the tank

I had done that by removing it from the lift pump and blowing into the tank.

I just ordered some new O-rings to replace on the secondary filter, and then I'll tackle replacing the hoses. Figured it has to be an air leak somewhere.

[River Cruiser]

Originally Posted by ReMetau

I had done that by removing it from the lift pump and blowing into the tank.

I just ordered some new O-rings to replace on the secondary filter, and then I'll tackle replacing the hoses. Figured it has to be an air leak somewhere.

I would guess that you are on the right path, one way to find out is to use some clear tubing after the supply pump. If while running it has air bubbles you have a leak in the plumbing between the tank & supply pump, if no bubbles you can eliminate those parts as the problem.

[charliehows]

double check you got the seals in the filter right when you replaced it - i made that mistake a while ago, they are fussy little bastards on my boat, and the filter didnt leak any fuel out, it just leaked air in.