If it aint broke......

ChestersDad · 28th September 2012, 21:13

CDTi Auto (60K):

The above sentiment comes to mind but I did have a problem....honest!

Been doing a fair bit of motorway mileage recently and had the need to kickdown for more speed and there was nothing - in fact she was dying from 75 to 60mph having kicked down to 3rd and the more one put foot down the more she stuttered and jerked as if fuel supply was being interupted....quite dramatic....

Eased off throttle and she changed up - eased back down and (using torque rather than revs) she pulled away fast and nice to 80mph no probs.

Repeated the scenario a few times using kick down and the same jerky no revs and dying effect was evident

Slowed to nearside lane and simulated again without kickdown but by a manual selection off 3rd and floored it - same thing happened - stuttering and no power.....

During this there was no smoke - so my thinking it's not collapsing pipe or a breathing issue....

Immediately thought of fuel pump failure - considering high speed running and then sudden further demand for fuel and so insufficient supply...

Fuel tank was 3/4 full

Only changes recently:

1. Battery change for new one 1 week before
2. Treated myself to a 1/3 tank of higher cetane diesel on the said journey
3. Tesco fill up before that
4. The UBP does seem to be noisier and I cannot say that it turns off after around 30 secs as I thought it should (with engine not running)

After leaving motorway and with an average speed down dramatically and then repeating all of the above there appeared to be no more problem!!???

In fact since then (and a week later) I cannot repeat the problem and car runs lovely - but there is a fault lurking there somewhere...

I have checked fuses and that both pumps are indeed working but had to disconnect the UBP to hear the In-tank one and I did hear it!

Maybe one or the other pumps are failing intermittently?
Maybe a sensor fuel pressure fault on common rail?
Maybe dirty or watery Super Diesel - now gone through?
Maybe a sync problem between autobox and main ecu due to battery change?

Never had a starting problem, never had this before, not got it now?
But if I don't try and track down the issue it will come back and bite harder when least needed....

Maybe a diagnostic check to pinpoint errors?

Any ideas chappies and chapesses?

28th September 2012, 21:13	#1
ChestersDad Still 75less :-( 1988 Defender 90 Join Date: Jun 2011 Location: Carmarthenshire Posts: 531 Thanks: 15 Thanked 93 Times in 37 Posts	If it aint broke...... CDTi Auto (60K): The above sentiment comes to mind but I did have a problem....honest! Been doing a fair bit of motorway mileage recently and had the need to kickdown for more speed and there was nothing - in fact she was dying from 75 to 60mph having kicked down to 3rd and the more one put foot down the more she stuttered and jerked as if fuel supply was being interupted....quite dramatic.... Eased off throttle and she changed up - eased back down and (using torque rather than revs) she pulled away fast and nice to 80mph no probs. Repeated the scenario a few times using kick down and the same jerky no revs and dying effect was evident Slowed to nearside lane and simulated again without kickdown but by a manual selection off 3rd and floored it - same thing happened - stuttering and no power..... During this there was no smoke - so my thinking it's not collapsing pipe or a breathing issue.... Immediately thought of fuel pump failure - considering high speed running and then sudden further demand for fuel and so insufficient supply... Fuel tank was 3/4 full Only changes recently: 1. Battery change for new one 1 week before 2. Treated myself to a 1/3 tank of higher cetane diesel on the said journey 3. Tesco fill up before that 4. The UBP does seem to be noisier and I cannot say that it turns off after around 30 secs as I thought it should (with engine not running) After leaving motorway and with an average speed down dramatically and then repeating all of the above there appeared to be no more problem!!??? In fact since then (and a week later) I cannot repeat the problem and car runs lovely - but there is a fault lurking there somewhere... I have checked fuses and that both pumps are indeed working but had to disconnect the UBP to hear the In-tank one and I did hear it! Maybe one or the other pumps are failing intermittently? Maybe a sensor fuel pressure fault on common rail? Maybe dirty or watery Super Diesel - now gone through? Maybe a sync problem between autobox and main ecu due to battery change? Never had a starting problem, never had this before, not got it now? But if I don't try and track down the issue it will come back and bite harder when least needed.... Maybe a diagnostic check to pinpoint errors? Any ideas chappies and chapesses? __________________ Don't save for the future as someone else will lose it for you!