This is another "what do you think?" post!
Recap; I bought the car about a month ago, I've done about 2000 miles in it with no problems. When I got it, I changed engine oil and oil filter, fuel filter and air filter. All was fine, then I took the heat exchanger/fuel heater off my old Terrano so that I could use SVO/WVO (I'd run the old Terrano for about 40,000 miles on 100% WVO). Then I went on a trip of about 250 miles, about 30 miles on, the car started puffing out white smoke and lost power, this would clear intermittently. I put this down to air working it's way through the fuel system after it was recently disturbed. Then 100 miles into the trip it was clearly lacking power so I pulled into a layby whereafter it would start and tick-over but would not pull at all. So I got recovered by Autonational Rescue. Having got the car home, I removed all fuel pipes and blew them through with air, I cleaned the gauze banjo filter on the pump and primed the system as best I could. The only time it tried to start was when I pressurised the line between the filter and the pump with air. then this morning, after pondering over all the work needed to replace the fuel pump with an 'unknown quantity' secondhand pump costing £200+, I had one last try at starting it. After about 15 seconds of cranking, it fired and after a bit of rough running and white smoke it settled down into a Swiss watch tickover. I've just been out for a 10 mile drive, and after half a mile, there was no sign of white smoke and the car starts and runs perfectly. Now, a theory is that crud from the heat exchanger (which has had about 4000 litres of WVO through it) could've been dislodged by the detergent qualities of the neat diesel I was using, and blocked fuel lines or somehow breached the filter. BUT.. is there possibility of there being an intermittent mechanical or electronic fault with the pump? Do they just fail, or can their failure be intermittent?
I would be extremely grateful of any advice!