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RCMike



Member Since: 30 Apr 2015
Location: North Wiltshire
Posts: 70

United Kingdom 
Fuel pressure advice
Hi All,
I've been trying to track down a rough running issue at 2500-3000 rpm. More noticeable under load but can also feel it just reving the engine out of gear. Lots of searching leads me a fueling type issue.

I've cobbled together a fuel pressure guage (from a mains water guage) and screwed it into the temperature sensor hole on the FPV.

Engine off but fuel pump running shows me just over 4bar (around 4.2). When i start the engine - the guage needle fluctuates between 3 and 5 bar (very quickly) - i'm assuming this is either the guage not being damped or indeed pressure dropping as the fuel is used and the guage in that position is a bit sensitive to change.

When the pump stops (ie 20 seconds after ignition off), the guage pretty much immediately drops to zero - ie not a gradual pressure reduction over time, it just drops.

So 2 questions really -

1 - would the guage fluctuation be normal or should it be a more constant pressure with the engine running?
2- Is it normal for the fuel system to immediately drop pressure when the pump isn't running?

So far i've changed the pump, air bleed, FPV, injector washers and seals and have no oil level increase or coolant decrease. I do have a nanocom but from what i can tell all reading look normal, but i do get a constant error of "fuel pump open load" or something like that. Wastegate is working fine and i've de-catted and de EGR'd. Also changed engine mounts.

Any pointers would be great.
Thanks.

(its the TD5 15p engine 110K miles)
Post #435530 3rd Jul 2015 12:47pm
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mk1collector



Member Since: 17 Sep 2009
Location: West Yorkshire
Posts: 6769

England 2004 Defender 110 Td5 CSW Bonatti Grey
When you switch off the engine does it make a chirp noise? And when rolling up to a junction or lights does it feel like the engine is rocking a bit. I had a vibration/rough running problem that turned out to be the crank pulley which as its a duel mass one it was sort of coming loose from the rubber. Ray
My build thread
http://www.defender2.net/forum/topic17615.html
Post #435638 3rd Jul 2015 9:51pm
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bob neville



Member Since: 30 Apr 2009
Location: Marbella
Posts: 3248

Spain 2001 Defender 90 Td5 SW Epsom Green
My TD5 (15P) had an issue with rough running/flat spot ay 2500rpm.

After replacing lots of bits it turned out to be the spacer missing on the crank position sensor. Easy to check and cheap to fix if it is not there.

Bob 2015 Jaguar XE240 R Sport - goes like ....... !!
2013 Defender 90 CSW - sold
2009 Defender 110 Double Cab - sold
2001 TD5 90 CSW - offroad project - sold to a forum member
2011 Porsche Boxster - for the sunny days !
Post #435642 3rd Jul 2015 10:13pm
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RCMike



Member Since: 30 Apr 2015
Location: North Wiltshire
Posts: 70

United Kingdom 
mk1collector wrote:
When you switch off the engine does it make a chirp noise? And when rolling up to a junction or lights does it feel like the engine is rocking a bit. I had a vibration/rough running problem that turned out to be the crank pulley which as its a duel mass one it was sort of coming loose from the rubber.


Hi Ray,
No chirp. I did check the pulley and no play (i also changed the belt and tensioner) - the old and the new tensioner does however seem to jump in and out a lot when running (hence changing the belt and tensioner) but nothing seems loose (pulley wise).
Post #435682 4th Jul 2015 6:57am
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RCMike



Member Since: 30 Apr 2015
Location: North Wiltshire
Posts: 70

United Kingdom 
bob neville wrote:
My TD5 (15P) had an issue with rough running/flat spot ay 2500rpm.

After replacing lots of bits it turned out to be the spacer missing on the crank position sensor. Easy to check and cheap to fix if it is not there.

Bob


Hi Bob,
Not thought about checking that, i'll try it and see.
Post #435683 4th Jul 2015 6:59am
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RCMike



Member Since: 30 Apr 2015
Location: North Wiltshire
Posts: 70

United Kingdom 
Just thought i'd post up the results of changing various bits in an attempt to reduce the vibs at 2500rpm under load.

The CPS spacing did seem to make a difference, i had wondered about it as the o ring was missing so it had clearly been out before i got the truck.

I've changed so much over the last few weeks and everything seems to have helped. I'm not sure everything was strictly required but at least now, there is less to fail/change in the future - so not all wasted.

I basically ended up doing the following list,

Main belt and tensioner changed - no difference but peace of mind - the tensioner still bounces around quite a lot however (i guess that must be normal as all the other pulleys feel good - no wobbles.
Engine mounts - old ones weren't collapsed and the new ones helped a bit
Injector harness changed/oil in ECU plug checked - hardly any oil so no difference
Injector washers and seals - not much difference but the nanocom readings look much better now so i'm sure it helped a bit
Viscous fan replaced - the old one had a slight wobble (the pulley feels fine) - again helped a bit
CPS - there is a definite difference with spacing it, so helped a bit
Ran new earths from the battery to the ECU and drivers seat box (found black wire syndrome on one earth, but no idea what its for as its just plain black and goes into the big bundle of wires that exit the seat box). Again i don't think it made a difference but i'm sure i'll be glad i did it in the future.
New FPV gasket (2nd new one just in case as there was a definite fuel "whooshing" sound when you put your ear close - may be air bubbles ) and i also did the 3rd FPV pipe (the one that's a pig to get to at the front of the engine - didn't do it when i replaced the FPV as it was such a pig to get to.)
New fuel filter head just in case it was letting in air - replaced it with a really nice machined aluminium one off ebay - don't think it helped but it looks really shiny (when its not covered in mud).

So after all that, almost no unusual vibrations under load left (relative to a TD5 of course). So i'm happy now and think i'll get on with all the rest of the stuff i want to do happy in the knowledge the engine seems a good un.
Post #440794 27th Jul 2015 7:36pm
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