hi all

right i have a problem with my 300tdi, i first noticed it started to get a bit sluggish the other week, then it got worse and worse.
right as of now when it is first started i will drive ok ish if driven steady, my problem were if i went over 2500rpm it would start chugging a if it were running out of fuel and if you held your foot down it does just die!

it has started getting worse now and when its warm it will do the problem stated above and even 1500rpm and you have to dipp the clutch and give it blips of the throttle to stop it dieing.

and if you just keep your foot down while its doin its problem to try and drive through it, it just goes dead as if its run out of fuel and throws a puff of blueish/grayish smoke out of the exhaust.

now i have fitted a new lift pump and done a full service which includes all filters and oils, and that has not sorted.

so i turned my attension to the injector pump.
i put a bit of clear pipe from the fuel filter to the injector pump and there is not one single air bubble comes through, but when i turn the engine off 1 or 2 small air bubbles travel back of the clear pipe from the injector pump.

so i put my clear bit of pipe on the return fuel line which goes into the tank to check for bubbles. i found that when it was ticking over there were no air bubbles but when reved there was loads of air bubbles comeing from the injector pump through the return fuel line to the tank, no i tried this time and time again and 95% of the time there were bubbles in the line.

so is my pump broke and that is my problem or is that just how they are?

also why is my problem worse when its warm?


has anyone had this problem and sorted it
please help as im stressin out here lol


thanks for reading and hope to have some positive replys.

forgot to add that the turbo is whistling like a good un and sounds fine

You have changed the air filter? Check the airbox feed for blockages.

i have put a new filter in the airbox, the vehicle has a safari snorkle on it too but as far as i could see with out taking the snorkel off if is clear

Air in fuel suggests loose connection or knackered lift pump. Don't assume that because pump is new, it must be ok.

there is only air in the return fuel pipe and not in the pipe on the way in so there aint no air coming out of the lift pump or from further back in the system if you get what i mean.

got a second hand injector pump off a mate to try but it aint exactly a 5 min job to fit, so what are the chances it could be that?

Lift Pump could be knackered and pumping air into filter or filter couild be loose? I know someone who changed filter and the small rubber O ring stayed behind & was refitted with 2 O rings..

There is a small diaphram in the IP that can split but don't know if that would let air into system.

redhand said:

Lift Pump could be knackered and pumping air into filter or filter couild be loose? I know someone who changed filter and the small rubber O ring stayed behind & was refitted with 2 O rings..

There is a small diaphram in the IP that can split but don't know if that would let air into system.

Click to expand...

i can remember a problem simular to this that someone had , thought air was getting in the system ,
turned out tobe a loose nut on one of the inectors

right there is no air in fuel to the pump or injector pump as i put clear pipe from the filter to the injector pump so that means also there is no air comin from the lift pump as that comes before the filter.
the air is coming from the injector pump then into the return fuel pipe

just tried the nuts on the injector and there fine too.

have you checked that an intake hose isn't collapsing under boost?

cos mine did exactly what you described, and that was it.

my 200tdi had the same problem wich got got worse and it turned out to be the injection pump

i had the same problem it turned out to be the return pipes on the injectors when the engine was cold the pipes where hard when the engine was hot the pipes went soft and became loose then started sucking air in, i put a new set of return pipes from the injectors to the fuel pump and it ran fine.

Replace the injector leak of pipe assembly, if that had perished it will be drawing in air and returning back to the fuel pump. some of the leak of from the injectors will return to the fuel tank and some of it will re-circulate back into the fuel pump via the banjo union on the fuel pump. if your sure there is air on the return side of things, thats where it's more than likely coming from.

Could be leak off pipes right enough. The sound deadening pad on the rocker box wears through the pipes, I had mine replaced a while ago for this very reason.

It could well be the sediment bowl at the back, it allows air into the system, they are very small bubbles and once its gone through the lift pump it cant be seen through clear pipe as the bubbles are to fine, just bypass the sedimenter and see if the problem goes. We see this problem loads, and bypassing or replacing the sedimenter nealy always cures it.

Could be sticking injector needle allowing compression back into the pump, this would also be reason for rough running.

OldDiscoMan