Westerbeke W30 surge and die

[cr180]

Should have mentioned, I replaced fuel filters, hose, and installed electric pump. Had vacuum leaks. Fabricated a test set up using a hand squeeze pump (outboard motor fuel hose pump) and a vacuum gauge. Then disconnected and tested sections until found leak. Hose clamps must be tight. Screw drivers won’t do the job. Use a socket wrench. Also used ABA clamps that will take more torque.

[fyrfytr33]

Good idea. I may do that.

[donradcliffe]

If your electric pump is upstream of the primary filter, and the lift pump is downstream of the primary filter, and you get bubbles when you turn off power to the electric pump, it points to the primary filter (or the lines on either side of it) as the spot for air in leakage. I am a fan of the outboard squeeze bulb with clear lines as a diagnostic tool. If you put it on the inlet of the primary filter with the output of the bulb to an open container and it pulls a vacuum, you have an obstruction upstream of the bulb. If you can pump easily with the bulb, but when you hook its output to the primary filter you see bubbles in its hoses when you run the engine, you have an air leak upstream of the primary filter. Ditto for the secondary filter.

[fyrfytr33]

Fuel comes from the tank to the shut off, to the primary filter, to the electric pump, to the mechanical lift pump, to the secondary filter.

I was able to hold a vacuum of 5" of mercury for two weeks, pulled from the electric lift pump with the fuel valve at the tank shut off.

[skipperpete]

It definitely sounds like you found the problem and got the engine running again, well done. I had thought that early in the thread you’d established that the entire suction side from the tank up to the injector pump was airbubble and restriction free.
There have been a few discussions over the years regarding DPA antistall devices and until I read a recent post by the 4/108 owner with the engine that would only run with the bleed screw open, I’d forgotten about them as being a problem. If you use the antistall device as a bleed screw it’s possible to lose the spool and spring,(but only if you remove the end plug completely). Usually only found on Delphi DPA’s but may be on the later CAV’s.

[fyrfytr33]

Well I think I have things sorted out....for the most part. I think the biggest problem is over confidence in myself and the new parts installed. I was confident in my work but kept trying to figure out what I did wrong. So I started at the beginning and found the electric lift pump was masking the fact that the new mechanical lift pump was not working. I found this by removing the intake line from the filter and running it into a clear bottle. The electric pump was moving some fuel, but I'm not sure if it was enough. I had one suggestion that maybe the electric pump was restricting fuel flow. So I did install a bypass around the electric pump when not using it for bleeding, could also be a back up if needed. When I cranked the engine without the electric fuel pump I got no fuel at all. So I replaced the lift pump with the old one and bingo, no problems at all.
I think my problem was by using the electric fuel pump I failed to notice I was getting no fuel from the mechanical lift pump.
I'm still not sure where the air was getting in but I have run it for two hours with no problems, no air bubbles. On that note I see some suggest bypassing the secondary filter banjo bolt. I have found the purpose of the bolt and bypass lines is to allow any air to rise to the top of the filter through the banjo bolt and return to the tank. Designed this way to remove small amounts of air from the system.

Thank you all for your suggestions and advice.

[sanibel sailor]

Glad to hear you have it sorted out. I have not regretted ditching my mech pump in favor of electric years ago.