Need help diagnosing Fuel Pump failure

[Mark Sutherland]

Today, my mechanic was performing routine annual maintenance on my engine.  He started and ran the engine earlier in the day, and it(and the fuel pump) ran fine.  After changing the fuel filter, he wanted to bleed the fuel line, but said he could not get the fuel pump to turn on(I'm assuming the fuel pump turns on when you roll the ignition key over into first position).  He says he checked the connections at the pump and all seemed okay.  He also substituted a spare/new fuel pump, which also did not work. I'm assuming that the fuel pump gets it's power directly from the ignitions switch, correct?  If so, is it possible that there is a blown fuse? Any ideas what might have happened to cause the pump to stop working?  Thanks.

[Ted Pounds]

First thing to check is, as you mentioned, the power to the pump.  Put a meter on it to see if it's getting voltage.  Since a new pump didn't work I would suspect there's no power.  Just a thought...

[Jim Hardesty]

Don't know for sure how your pump is wired.  On my MKll it's wired through the oil pressure sending unit.  If you want to run the pump with out cranking the engine, jumper the sending unit.
Jim

[Stu Jackson]

Mark,

Jim's Mark II fuel pump wiring is completely different than yours.  From the "Critical Upgrades" topic, page 3:  

http://c34.org/bbs/index.php/topic,5078.msg41829.html#msg41829

Sounds like a dead pump or no power (more rare).  As suggested, check the voltage there, first.  Most older boats didn't have fuses on the wiring to the pump.  Wouldn't hurt to add one.  Somewhere here someone mentioned the suggested size.  A search on "fuel pump fuse" oughta find it.

Good luck.

[Ron Hill]

Mark : Hard to believe that your pump suddenly died, but that can happen.  

It gets it's power in a 1986 Mk I from the key switch (battery ON).
The wiring on a Mk II lift pump is completely different for an M25 & M25XP engine.
I'd run a jumper wire from a positive connection under the head sink (or from the starter solenoid or any another positive) and any other ground - to see if the pump operates.  
Also check those posts with a multimeter to insure you have 12V first.

If not, then the pump died!!  A few thoughts

[2ndwish]

The second pump not working suggests that it is electrical - not the pump itself. Just out of idle curiosity- have you completed the harness upgrade? The pump power comes through that harness. Mucking around the engine could have broken the connection.

[Ken Juul]

Is the battery switch turned on?  Some folks turn it off when working on the engine.

[mainesail]

On many Universal/Westerbeke engines you need to turn the key on THEN depress the glow plug button to get 12V to the pump..

A MUCH easier trick I use all the time is a fused alligator clip jumped directly to the fuel pump from either the starter lug or a glow plug solenoid.. Allows me to turn the pump off at the engine when bleeding......

[Mark Sutherland]

Update: I had to do all of my diagnosing using the wiring diagrams I could find on this site, and by communicating via phone with my mechanic.  As a point of information, I have a new engine panel with the glow plug activation integrated into the ignition key; my engine panel-to-engine wiring has been upgraded, not using a new "harness", rather, it is now hardwired at both ends.   During the diagnosing process, I learned that my boat doesn't have a pre-heat solenoid, hence my fuel pump is NOT activated by activating the glow plug.  There was no power to the fuel pump in any key position.  The fuel pump DID work when I brought a temporary power lead to it, as suggested by mainesail and others.  So, my conclusion is that the power lead to the pump has failed somehow.  My next step then will be a)figure what the power source for the fuel pump is(I'm guessing the ignition switch), and b)determine what the problem is(bad connection, damaged wire, loss/lack of power at the ignition switch, etc).  Let me know if I'm overlooking anything.  Thanks

[Ron Hill]

Mark : Your problem is simple - you up graded to a MKII engine instrument panel for an M35BC engine which will not directly work with your MKI wiring and an M25 engine!!

All you need to do is to wire the fuel pump + into the continuous post of the ignition switch and your glow plug wire + into the intermittent pole (spring loaded) of the ignition switch. 
If you have not already done it, you need to wire a solenoid into the glow plug circuit.  There are many many articles - Mainsheet tech notes, Projects, critical updates and Message board posts - on that topic. 

A few thoughts

[Stu Jackson]

Mark,

This may be the Critical Upgrades item that Ron is referring to:

http://c34.org/bbs/index.php/topic,5078.msg41829.html#msg41829

[Mark Sutherland]

Update: To review a little, my fuel pump is not working, it's not getting power to it, and it works when I bring a hot wire to it, so the pump is functional.  (Note: I'm guiding my mechanic via phone for all of this, so my descriptions are based on conversation, not visual inspection).  My mechanic exposed the engine panel in order to do a continuity test to make sure that the fuel pump was connected to the ignition switch.  My fuel pump wire is RED, and there was no red wire connected to the ignition.  Hmmmm.  He said there was a red wire coming out of the loom(lume?), but that it turned 180 degrees and disappeared back into the loom.  When he worked his way backwards into the loom, he said that the wire "dead-ended" with a crushed coupler on the end of it.  On the surface, it would seem the the installer just neglected to connect the fuel pump lead to the ignition.   The only other thing I can figure is that possibly the installer spliced the fuel pump lead to the Alternator excitor lead(which is connected to the ignition) somewhere in the middle of the loom?  At this point, my mechanic said he couldn't see such a connection from either end of the loom, and "did I really want him to crawl behind my fuel tank to solve this mystery?"  I opted not to hunt for the mysterious connection, it one even existed.
So, I told him to simply connect the fuel pump lead directly to the ignition like it is supposed to be, and to install a 10amp(?) fuse in the lead.  Everything works fine now, fuel pump ticks away when the key is on....  So, one might ask, if the fuel pump lead really wasn't connected at all, how have you been running your engine for the past 12 months since the new panel install???  According so Stu, our boats will "syphon" fuel to the engine, as long as the tank is half full.  As best I can tell, I've never actually run my tank more than half empty since the panel was installed.  Go figure!

[Ron Hill]

Mark : Back in 1995/6, I knowingly ran my engine without the help of the electric fuel pump!!  So it fuel will syphon as long as the fuel filter is not too clogged!!

As I recall the wire to the electric fuel pump was not part of the wiring harness upgrade (wire bundle) and has always been a separate wire direct from the key switch to the fuel pump.

I'd leave it as you have it now and just note that wiring in your engine manual.  A thought