I’m still picking away at this… I’m just going to type the sequence out to help me think it through.
So Airtop stopped igniting and I’d get the no start / no flame fault.
I used a syringe to inject diesel into the line and it fired but wouldn’t keep going. So I thought pump.
Fitted a new pump - same problem.
Read a bit and it seemed that the burn chamber getting blocked can stop it firing - so bought a service kit and fitted it. Came with a new glowplug, which snapped on installation - but the old one was working - so that went back in.
Still the same problem.
I noticed the fuel line joiners were a bit perished - so I thought it might be letting air in.
So bought and fitted all new fuel lines - hard nylon clear ones, so I could hopefully see the bubbles.
Still wouldn’t flame.
I have a 2nd heater - bought to go in the 90. So I thought I’d piggy back that off of the Airtop, check it worked and perhaps end up fitting it. (it did need a different pump fitting - but other than that it piggy backed all the fuel lines)
So I set it up and lo and behold - it wouldn’t fire 🔥 😳 same no ignition issue.
Now, I’d blown through the pick up pipe when I changed the fuel lines and it seemed clear - but to rule it out I tied a weight to another bit of fuel line and dropped it directly into the tank to bypass the pick up pipe.
Lo and behold - the new heater now worked.
So this made me think - is all this because the pick up line was blocked or partially blocked?
So I tried the original heater with the bypassed pick up … and ….it almost works.
The exhaust does get warm and it starts to heat the air, but it doesn’t seem to fully ignite- and I it shuts down with the same error.
Thats confusing … I assume this means there is / was more than one thing stopping it working. The pick up and something else … maybe the glow plug isn’t getting hot enough ?
I’m waiting for inspiration now.
I guess I could try the syringe trick from right at the beginning - and if with that it does fire then it must still be something to do with fuel delivery.