desperate box of matches next

This may be a long post but would love any help please
300tdi auto .first I had a starting problem on a morning which seemed like glow plugs so I took them out and checked them and found 2 failed so I replaced the set ,no better next morning ,after the first start it would start fine the rest of the day,mornings spent ages cranking before firing then clouds of smoke and would go great with loads of power. Once started would run great not using any oil or water. put up with it for a while then decided to delve deeper. Thought it may be pump timing after reading about the woodruf key in the crank pulley so fitted a new timing belt kit and crank pulley, carried out a compression test all 4 seemed ok ,reset the valve clearances, replaced the fuel line from the tank and fitted a non return valve in the line ,fitted an electric lift pump ,fitted a new battery as it seemed slown to crank ,cleaned all the earth piont and fitted a new direct earth cable to the engine, still no good then another problem not only difficult to start but once started it would not pick up on the road ,it would run fine in the garage but had no power when driving, forgot also had the injectors tested in case they were dribiling ,tested ok ,
So deceided to buy an injection pump and set of injectors (second hand but was assured they were fine) ,fitted them and it seemed to start ok after bleeding the fuel system so thought that was it fixed then after a run of about 10 miles stopped it for an hour to visit my parents when I tried to start it it cranked for ages until it started but it ran fine home ,stopped it again to open the garage door restarted it and now it has what can only be described as a missfire and won't rev ,cracked injectors off and all seem to be getting fuel but when I try to rev it it just pops and bangs ,checked the pump stop switch and it's working fine,
I now think it may be an electrical fault ,sensor or ecu .
Can any one tell me the location of the engine speed sensor ?
And does any one know of anyone in the chester le street area with mobile diagnostic equipment to check the electronics even though there is no engine managment light on,
I checked the 4th injector for resistance as its the timing injector and it check ok at 98ohms
also is it correct that when the ignition is switched on the injection pump can be herd running all the time
totaly fed up now but need to fix it as I realy like the old tank
said it would be a long one so thanks for readihg this far
any ideas would be gratefully appreciated
looks like war and peace

Diesel leak of lines from the injector can cause this.

Start with the simple stuff first! If air can leak back down the leak off's, then the pump can empty over night causing the long cranking with NO smoke, so NO fuel.

Take the leak-off banjos off remove the copper washers from both sides and anneal them (heat them up cherry red and then leave them to cool naturally) then put them back on and replace the 3 pieces of pipe, make sure the one going down to the pump is OK and has a good seal at the banjo union.

The next time you go to start it, open the bonnet and with the ignition on, pump the fuel up with the lift pump, you should feel resistance as the fuel is pumped up. If not turn the engine one blimp to get the lift pump off cam then try again. pump it up till you can feel that it is no longer pumping fuel.

Now start the engine as normal, does it start? If yes it is air in the system over night.

thanks discomania
all leak off pipes and washers have been replaced ,fuel primed to filter and I put a clear piece of fuel pipe to the injection pump to check for air in the system
now starting to think the second hand pump I fitted is faulty and not holding fuel pressure

forgot to say when checking the pin outs at the ecu connector the coolant temp was way out so I replaced the sensor ,still not correct so started checking the wiring and located the wires melted together at the back of the cylinder head,so my original pump may be ok as it started fine when engine was warm, the replacement dosen't even want to do that ,so I think tomorrow night i'll try me original pump back on

Are you parking on a slight slope?

If air is getting in through lines etc then it heads for the highest point gently and slowly, which would explain a ****e start in the morning but ok throughout the day. Check fuel lines and connectors on filter.

not on an incline parked flat in the garage ,fuel lines to the tank replaced ,sedementer removed

Have you tried manually priming it before starting? If this cures it then you can be certain air is getting in somewhere and letting fuel fall back to the tank - worth a quick check on the first start of the day before going to the bother of removing a pump.

i would put clear pipe in between pump and filter to rule out air,if air remove cover in boot for tank run 8mm rubber hose from passenger side outlet to inner pipe in front of rear wheel bypassing sedimentor ,hose can be pushed over hard plastic pipe or joiner used,tank unit might need changing if pipes heavily corroded,if no air look at pump /operating system