Voltage Drop at Fuel Pump

[Stu Jackson]

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Review those below and see if you agree, or can you see where something differs?

Ken,

I wrote that over a DECADE ago, oddly enough literally to the day!    IIRC, at that time, the referenced diagrams were from a manual that was online here, in Reply #49 of that topic, which may well have pre-dated the major expansion of the wiki.  That link no longer works.  The differences were as I described.  There appear to be no compelling reasons for me to attempt to find those two particular pages again.  IIRC, I was on vacation at the time, so had to rely on that online linked version, which I printed out, analyzed and then discarded.

You're certainly right about the two diagrams you posted.  Same numbers, too.  As you've pointed out, it wouldn't be the first time that there may have been errors in documentation.

And thanks again for helping with that wiki expansion by posting a much more thorough set of manuals.

[Ron Hill]

Guys : Now you know why I removed the 2 prong spade oil switch/sender (M25XPB) and replaced it with the single prong oil sender (like the M25/25XP) has and connected the single oil wire from the engine instrument panel to sound oil pressure.
Then I took the fuel line from the Facet fuel lift pump (under the head sink) and conneccted it to the inlet on the engine mounted fuel filter (by passing the engine M25XPB mounted fuel pump).   

Had a simple system rather than the complex Westerbeke fuel pump/oil pressure system that wouldn't work[as designed] on the engines mounted in a C34 anyway!!  
The whole idea was that - if there was NO/LOW oil pressure the fuel lift pump would be shut off starving the engine of fuel and the engine would then shut down!!  However, in the C34 the fuel tank is higher than the engine and the engine will continue to gravity feed and run the engine without the lift pump running!!

Great idea, but it won't work in a C34 whether it be a M25XPB, M35 or an M35BC engine!! Those engines in a C34 will continue to run until the engine ceases form lack of oil !!!!![/b]

A few thoughts

[KWKloeber]

Hey Stu

Mystery solved, David wanted the static manuals (including the one you referenced) moved to the wiki "Manuals" page -- the old link is dead. 
It's here:  http://c34.org/wiki/images/b/b6/200550_M-320B_M-50B_Operators_Man.pdf

I easily see how you concluded there were the two discrepancies -- I thought the same at first glance.  But take it to the bank that 25, 26 are identical, functionally and electrically speaking.  The pump operates the same using 25 or 26.

No agenda other than to point out that they are identical -- so others who use the link that you posted aren't led astray.

-k

[KWKloeber]

Now you know why I removed the 2 prong spade oil switch/sender (M25XPB) and replaced it with the single prong oil sender (like the M25/25XP) has and connected the single oil wire from the engine instrument panel to sound oil pressure.

If owners want the functioning engine-saving safety feature of shutting down the fuel supply, they can "switch" to the single-prong oil switch as Ron did, and install a readily available, in-line, fuel solenoid just before either the secondary filter or injector pump. 

Fuel solenoid valves are typically "normally open" and close when energized.  The alarm, light, and solenoid would activate when the oil switch closes (@ <5 psi oil pressure.)

This works on both the "old" and "B-series" engines.

-k

[Dancrosswis]

It wasn't the voltage.

I'm happy to report that my XPB is running and thought I should send an update.  I installed a new Facet fuel pump.  I ran it a long time before I got fuel at the secondary filter bleed screw.  She started, ran for 30-60 seconds, and died.  I pulled the fuel tank take-up tube.  It had both the hose and screen at its end.  The screen was dirty, but I couldn't say it was clogged.  I removed the screen and ran the fuel pump more, without bringing fuel to bleed screw.  I conferred with our local marina diesel mechanic and we agreed I had either or both a restriction or leak in my fuel delivery system.  So, (to use the transition now favored by all the media) I replaced all of my fuel feed lines and removed the original Facet fuel pump which was still in-line but not operating.  The old Facet pump screen was fully clogged.  And, I found cracks in my fuel line that I may have made worse changing the pump.

I ran the pump and fuel quickly gushed from the bleed screw.  The whole system sounded like it was breathing or gulping more deeply than before.  She fired right up and has now run without a hitch for several hours.  I may be misled by the glory of fixing my problem, but I think she's also running better at lower rpm's. 

Thanks for everyone's help.  Through this process, I've learned a lot more about my XPB.  Now, it's time to head to the North Channel!

Dan

[KWKloeber]

Dan

That points up how easy it becomes to miss the forest when starting to count the trees.

I didn't mention it in this thread because, well just because, but if there's any thought of a vacuum leak I always recommend this first step....
http://c34.org/bbs/index.php/topic,9922.msg75875.html#msg75875
Otherwise it's just too difficult to locate the source, especially if there's multiple ones! 😟

-k