Depending on how your specific engine is wired (you have M35B?) you may only hear it clicking when you have the glow plugs activated. My understanding is that the M35 A's and B's have the fuel pump wired through the oil pressure switch so with just the key on it won't click. With the glow plugs activated it should click. Once the engine starts and oil pressure is up it will also click but you won't hear it for all the engine noise.

That is assuming someone hasn't bypassed the whole system as was done on our boat with resultant confusion and difficult trouble shooting until it was restored to original.

I understand that apparently until the tank is below half it will siphon to the engine even with a dead fuel pump and the engine will run at moderate revs with no fuel pump. But when pressed it will starve for fuel and below half a tank or so it will stop totally.

Use a volt ohmeter and check to see if you've got power to the pump when the key is just turned on and then when the glow plugs are activated. If you've got no power at either switch position there's your starting point - you've got a wiring problem. If you've got power but no click, your pump may be dead.

That's a start.

I glad someone asked this question as I was wondering the same thing. On my previous C-30 (MXP-25), the fuel pump was charged when you turned on the key and it "ticked" like crazy. I have not heard the same sound on my M35A when turning on the key. I think Bud nailed it with his answer.

I do have one concern with the fuel pump being wired this way. I am accustomed to changing my primary and secondary fuel filters and using the fuel lift pump "fill and prime" the system....if I do this with the M35A setup, do I risk overheating the glow plugs and causing damage?

Stephen, when I do filter changes or need to bleed the system I just run a jumper to the fuel pump and power it up that way. I have a test probe light with an alligator clip on the end, you can connect that to the battery cable at the starter and then use the probe to power up the pump by poking it into the hot side connector. Don't pierce the wire with the probe, just touch and hold it on the connector.

The filter in the fuel pump is 74 micron according to info I got from Facet who makes that fuel pump. Since the largest Racor for our primaries is 30 micron, and most seem to be using 2 micron Racors, I find it hard to believe that filter could ever get gunked up. Facet only puts it there in the event there is no primary filter ahead of it. I used to check it all the time and it seemed pointless as it was always spotless. So I ignore it pretty much now. Maybe I'm wrong, I was just yesterday.

There is a red button on ours for a breaker reset, that is true, I forgot about that, might be worth giving it a push if there's power and the pump doesn't run.

[QUOTE=bstreet;6893]Stephen, when I do filter changes or need to bleed the system I just run a jumper to the fuel pump and power it up that way. I have a test probe light with an alligator clip on the end, you can connect that to the battery cable at the starter and then use the probe to power up the pump by poking it into the hot side connector. Don't pierce the wire with the probe, just touch and hold it on the connector.[/QUOTE]

Bud, I may have posted this before, it's long, but discusses the "newer" and I think silly double connection of fuel pumps to the glow plug and the oil pressure sender: [url]http://c34.org/bbs/index.php/topic,3347.0.html[/url] Page 4 gets to the meat.

Also, for whatever fuel pump you have the "plumbing" from the fuel tank should go: tank, Racor, fuel pump, and NOT tank, fuel pump, Racor. Those pumps have tiny little screens on the bottom that get gunked up, that's why the Racor is there.

I saw that thread before Stu. It is very easy to bypass all this just by bridging the 3 wires at the oil pressure switch. The PO had cheaped out and installed a single contact oil pressure switch which bypassed that function. However, on our boat, that also killed both of the engine alarms and that's unacceptable to me. That's why I put it back to the way it was originally and once I did that, the alarms magically started to function again. It also makes troubleshooting easier because it matches (mostly) the OEM wiring diagram that came with the boat manual.

Probably lots of other ways of doing it, I don't like the way its set up either, it's totally not necessary and possibly dangerous, but it's just simpler to live with it, for now.

[QUOTE=bstreet;6903] It is very easy to bypass all this just by bridging the 3 wires at the oil pressure switch. The PO had cheaped out ... I don't like the way its set up either, it's totally not necessary and possibly dangerous, but it's just simpler to live with it, for now.[/QUOTE]

Bud, did you add a fuel pump "ON" wiring and switch for bleeding or is your engine self-bleeding? In retrospect, and in re-reading my link, it's funny that no one has noted that the M35s are self-bleeding so my "complaint" about the fuel pump operation may be moot.

Any comments?

Stu, no, I didn't add anything, just put the wiring back to original to get the alarms working again.

I just jump power to the the lift pump to fill the Racors, you can hear the tone of the pump change when it's getting fuel. If I've changed the engine filter as well I then open the bleed screw on the engine filter mount until I get no air, then the thumb wheel on top of the injector pump until fuel comes out which is usually immediately because changing the filters doesn't seem to cause fuel to empty from that area.

My understanding is they are self-bleeding because of the return fuel line to the fuel tank. But when we first got a sailboat that had an M3-20 and I knew nothing about these things, I watched a diesel "mechanic" change the filters and then run the fuel pump and profess as to how it was all self bleeding and once the pump tone changed it'd fire right up. It did fire right up and it ran like crap, missing and backfiring and idling rough and even after 5 minutes it wouldn't settle down. So he then decided to bleed the engine filter housing and open the thumb wheel on the injector pump and then he restarted it and it ran fine. Lesson learned, for me anyway.

What I don't like about the fuel pump being wired through the switch and alarms, aside from the needless complexity, is that if Murphy is at work, and he always is, and I need that engine right now for an emergency situation, that would be time the thing decides to shut down. I'd rather risk the engine than the whole boat. I would do that and shut it down when the danger is past. Even with zero oil pressure it will run a bit longer, for sure not very much longer, but that might be all you needed. At least you get to make that choice, not some engineer in an office at a desk who thought this was a good idea.