Question about M35BC lift pump

Breakin Away · July 16, 2017, 04:48:37 PM

I know it may take some time for an M35B owner to respond, but the most important question right now is whether the lift pump slows down after running glow plug heater for awhile (as widely reported by many owners, but not sure whether they're B-series owners), or it keeps clicking at the same rate (as I observe on my boat). This will tell me if I have an abnormal situation with my pump.

Jack Hutteball · July 16, 2017, 04:52:39 PM

I never run the glow plug circuit for more than about 10 seconds, but I have never heard the pump slow down at all while doing this. My boat and engine must be similar to yours based on the hull number.

Jack

KWKloeber · July 16, 2017, 05:00:56 PM

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I didn't think that the banjos were downstream of the injector pump.

They are "downstream" from (directly fed from) the injectors only in that the low-pressure fuel from the injector pump bypass hose passes through them on the return to the tank. Except that it probably also helps cool the injector, that bypass fuel could just as well go around the banjos and tee into the return hose after the injectors.

On the early M-25s, no bypass (bleed) fuel goes to the banjos, only the fuel picked up from each injector. The late M-25s and XPs are plumbed more like your B series, with bypass bleed fuel going to the #1 banjo (except that on the late M25s, XPs it can be regulated via the bleed valve -- the B series has a constant bleed bypass from a different port on the pump.)

The banjo itself is fed by (collects from) the injector. Common misconception is that it's "excess" fuel that the injector "can't use." It's not really excess, it's by design. The injector plunger is pushed away from the tip of the injector by the pressure of the fuel, and the nozzle sprays. Each cycle, a tiny amt of fuel travels up around the plunger to the top to cool/lubricate the plunger/injector. The banjo picks up that fuel at the top of the plunger/injector.

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I thought the banjos provided the fuel reservoir for the low pressure side of the injector pump,

No, the fuel pump weeds the injector pump.

also have to go re-count my cylinders, because I could have sworn I had four. I think I'm right about that one.

[/quote]
<<The below for the XPB, add another cyl for the 35B.>>

KWKloeber · July 16, 2017, 05:07:34 PM

Quote from: Breakin Away on July 16, 2017, 04:48:37 PM
I know it may take some time for an M35B owner to respond, but the most important question right now is whether the lift pump slows down after running glow plug heater for awhile (as widely reported by many owners, but not sure whether they're B-series owners), or it keeps clicking at the same rate (as I observe on my boat). This will tell me if I have an abnormal situation with my pump.

There might be a decrease in the lift pump, but because you have a bypass hose that can't be regulated, it is likely just SLIGHT and you likely won't notice it.

Pinch off the bleed bypass hose and your pump should slow to a crawl because your fuel feed line becomes pressurized. Or pinching off the feed hose off the lift pump will do the same thing.

BTW, Kubota tractors have a MECHANICAL pump run off a cam, like olde tyme auto engines.

ken

Ron Hill · July 17, 2017, 01:42:51 PM

Ken : Talk to a Universal/Westerbeke parts guy about the course filter.
I believe that the later M25XPB and M35BC engine have that filter. The earlier models may not?

A thought

Jim Hardesty · July 17, 2017, 02:25:38 PM

Mine didn't come with a course filter. I see no need for one after the racor.

Ron Hill · July 17, 2017, 02:45:47 PM

Jim : You are absolutely correct, but some installations of the M35B engine in other boats may not have a Racor first!!!!!

Hence the manufacturer installed a course filter before the fuel pump!!
It's like the Facet fuel pump for the M25 & M25XP had an internal course filter built in to protect the pump!!

A thought

Jim Hardesty · July 17, 2017, 03:03:52 PM

Ron,
I wanted to say the way my boat was setup and maybe save someone an hour looking for it. That's about what I spent looking when I did my first, change all the filters, on my new to me boat.

KWKloeber · July 17, 2017, 03:38:07 PM

Quote from: Ron Hill on July 17, 2017, 01:42:51 PM
Ken : Talk to a Universal/Westerbeke parts guy about the course filter.
I believe that the later M25XPB and M35BC engine have that filter. The earlier models may not?

A thought

Thanks Ron

I found the Service Bulletin on the filter that was added in 2003, p/n 48076. It's a *must* to maintain the pump warranty (which I suspect isn't an issue with anyone

)

I agree there's not much point in an 80u filter after a 2u or 10u (pick your poison) primary filter (if so installed.) They fact that's it's "on engine" makes it less efficient so it makes even less sense in our application. But to each his/her own. But if one wants one, they can get an similar inline filter at NAPA (unless they want to pay Westerbeke 37 boat bucks for a $7 filter.)

I checked the latest parts manual (April 2013) and, naturally, it's not shown (for us old math folks, that's 10 (TEN) YEARS after the part was added. Low expectations, that's Westerbeke.

BTW, I realized that I didn't have the latest "B-series" manuals on the TechWiki, and so I just updated them.

kk

Ron Hill · July 17, 2017, 04:52:43 PM

Guys : The idea of NO oil pressure to shut off the lift pump and shut OFF the engine (from fuel starvation) is a great idea!!
The only problem is that in the C34 arrangement/installation the fuel tank is higher than the engine so the fuel will gravity feed and bypass that cut off feature.

Then there are some M35B installations where the fuel tank is lower and the lift pump is necessary for the engine to keep running.

A few thoughts