Confirming my Diagnosis

thanks for your input.

ill go back through the system and re check everything to make sure i didnt miss anything. it was getting late when i was working friday night

ok. so just checked everything again. (day off work finally)

no change in regard to air in the fuel system, i can actually see air bubbles in the return fuel in the better light today. and now i have run an alternate return line to a bucket, there is no air in the pickup system. but the engine is running no better for it.

I severed the return from no1 injector to the pump and put in the clear pipe but couldnt see any fuel flowing, I varied the engine RPM's to be sure. so i disconnected the clear pipe and blocked the pump side of the join to divert fuel from the pump down the return line. no fuel at all is coming out of any of the injectors. what the?

so. ill give annealing the copper washers a go, and failing that i guess the only conclusion i can come to is the injection pump is on its way out?
or somebody please tell me im wrong :confused:

I was having power problems with my 300TDI, changed the fuel filter, cleaned the sediment filter, checked all sorts of things. Ended up being the screen in the top of the lift pump was almost totally blocked. All the gunk must have come out of the fuel lines after the main filter. Runs like a train again. Not sure if you have checked that filter or not?

Thanx
Dave

whats coming out of the lift pump?

normal fuel is coming out of the lift pump, no air in it now ive run the return into the bucket.

i did check the filter in the top of the lift pump.

and annealing the copper washers made things marginally better when looking at the air in the return line.

just back from a test drive. no change to the way it drives, still surging under acceleration, still down on power

is the boost line to the boost compensator in good nick?

have you checked the fuel pressure that the lift pump is delivering?

boost comphensation line is ok, boost pressure gauge is working fine aswell.

ive not checked the pressure of the lift pump (doubt i have the tools for that) but the fuel filter is under pressure when the engine is running (checked at the banjo bolt) so it is definitely doing something. lift pump was replaced 10 0000 km ago so i hope it is not the issue

take the output line off of the lift pump put it into a can it should pump about 5ml per turn of the cam...

put your finger over the end of it and crank the engine you should feel about 4-7psi of pressure

ok, ill give that a try, it will have to wait till later on in the week tho.

just going back a few steps in the mean time, its got me quite confused as to why there is no return fuel coming out of the injectors.
can you shed any light on that one?

yep, not enough fuel getting to them....

to fully explain it you need to have your head firmly wrapped around the 101's of

hydraulics
diesel injection and metering systems
governors

basically...

you have enough fuel getting up to the injectors to provide X Hp. as this is not a full stroke of the plunger when at the max power setting and the governor is locked at max power trying to get actual RPMS up to Requested RPMS the plunger is starving for fuel, the injectors are getting a bit of fuel and once the fuel is used up normal injector closing procedure follows as the HP line pressure drops off from lack of fluid even though the plunger is still trying to deliver fuel. as the plunger cycles the IP is now trying to pull fuel back in through the return line from the IP body. Thats most likely where the air is coming from. Back up the return line from the tank.