On my engine at the moment I have one dead glow plug and I have to 'glow' it for a good 30 seconds or it doesn't start. Not an issue when the engine is already warm.

Check your glow plug solenoid.

If glow plugs check out, next you might check the fuel pump. Mine starts running as soon as the ignition key is switched to on.
My thinking is that I think our engines will run without the pump, but not easily start?

I think I read somewhere you have to glow it for 45 seconds. I have reduced that time to 30 seconds in the summer but if it is cold maybe increase it.

Had to replace my lift pump last year. It would not start with a bad pump. Lucky I was in the slip when it happened.

[QUOTE=William Matley;20005]Check your glow plug solenoid.[/QUOTE]

Don't know if this is the case for newer C36s, but certainly older ones didn't come equipped with glow plug solenoids. We added one to ours, and it dramatically reduced the time we needed to activate the glow plugs for a cold start (say, from 45 seconds down to about 10). Its an easy and inexpensive modification, and there's a write-up about how to do this in the upgrades section:
[url]http://www.c36ia.com/node/916[/url]

Mk IIs will start and run fine without a fuel pump, if they're above half full or so they siphon strongly. At least ours certainly does. But OP has a Mk I and they shouldn't be able to do that due to fuel tank location difference.

If it's original it should be a canister type pump mounted on the rear of the engine, starboard side up high. It could have been changed for one of the newer plastic pumps which are small square black plastic but should be in the same area. If it is working it should make a ticking/clicking sound when you put power on it.

[QUOTE=bstreet;20024]If it's original it should be a canister type pump mounted on the rear of the engine, starboard side up high. It could have been changed for one of the newer plastic pumps which are small square black plastic but should be in the same area. If it is working it should make a ticking/clicking sound when you put power on it.[/QUOTE]

Or, on my 1983 boat the fuel tank is under the dinette along the forward edge of the galley, and the fuel lift pump is under the outboard side of the dinette (bottom of the U). I can hear it clicking from the helm when I turn the ignition on.

[QUOTE=Nimue;20030]Or, on my 1983 boat the fuel tank is under the dinette along the forward edge of the galley, and the fuel lift pump is under the outboard side of the dinette (bottom of the U). I can hear it clicking from the helm when I turn the ignition on.[/QUOTE]

My engine was hard starting last year so I replaced the engine:) I have the old pump still if you or anyone else needs a spare! Send me a message if interested.

[QUOTE=Nimue;20030]Or, on my 1983 boat the fuel tank is under the dinette along the forward edge of the galley, and the fuel lift pump is under the outboard side of the dinette (bottom of the U). I can hear it clicking from the helm when I turn the ignition on.[/QUOTE]

Same here on our '86.

The symptoms described by the OP, Tony, do seem entirely consistent with a glow plug issue, not a fuel supply issue, no? Otherwise, why would it make a difference if the engine was cold or hot? Its not as if once the engine has been sitting for a while the fuel is going to drain back out of the reservoirs in the fuel filters and leave the engine starved...

Frankly, using the glow plugs for only 5 seconds, as Tony writes he is doing, just doesn't seem enough. Before we installed a solenoid for our glow plugs, we needed to run the glow plugs a good 30 to 45 seconds before hitting the starter when our M25 was cold (this seems consistent with other users).

Thus, it seems to me that the entire problem here is simply not holding down the glow plug button long enough; I'd suggest trying that before looking a fuel supply issues. Certainly, cranking the engine for long period to get a start is NOT a good idea, given that the water-lift muffler can fill up with raw water and back up into the cylinders (If the engine doesn't start right away, make sure to drain the muffler before trying again)