Espar D4 not heating, fuel pump ticking fast

[yalla]

Aloha all;
I have an Espar D4 installed in my new to me Aloha 32. When I turn it on via the thermostat the system seems to start normally, fuel pump ticking and air coming from the ducts but it does not give heat. after a minute or two the fuel pump starts ticking faster and faster until I shut off the thermostat.
I traced the length of the fuel line, no leaks and valves are open, the fuel tank is full.
The heater worked at sea-trial 4 months ago, I have been away since then and just got back. I'm pretty sure the PO started the heater from the thermostat and that there was no other step before or after. I have no experience with this type of heater, so before I start pulling things apart I want to make sure i'm not missing something simple.

[yalla]

As I thought, something simple... I let it run despite it sounding (to me) like the fuel pump was going to tick tick tick itself to death, as I detected slowly increasing heat from the vents. It eventually settled down - I also eventually settled down - and it seems to work as intended. Pretty loud, seems there are alot of complaints about the loud fuel pump, the blower in my unit pretty much covers the pump ticking such that I have a nice pleasant (not!) whoosh in the cabin.
but it is warm! and up here, right now that is what counts.
I'm going to look into installing a solid fuel heater - not too expensive, dry heat and silent, as a complement (and backup) to the espar.

[senormechanico]

Try mounting the fuel pump on a piece of rubber.
That made a big difference on our previous boat.

[jamhass]

Our pump is mounted in a rubber-lined hose clamp. We hear it until the blower fires off, then it is not noticeable. Our neighbors, however, have commented on the jet engine exhaust! Fortunately, we don't hear if inside the boat.

[senormechanico]

On our previous boat, we installed an Espar muffler. It made a noticeable difference.
It wasn't cheap, but it was all stainless and well made.