Hi everyone
Been having a problem recently with my 406. Had a second hand fuel tank fitted after the old one was vandalised and this seems to be when the problems started. At idle it runs very poorly and even when I drive it there is a heavy crackling noise. I think it is missing and this is causing the noise. It can get a bit better when it warms up and occasionally it runs OK for a couple of days. If I drive a lot it can also run a bit better. I am wondering if there is a problem with the fuel flow from the "new" tank. If I have to stop on a slight uphill gradient it can even stall at idle. One other thing that leads me to the fuel flow issue is that it will run perfectly if I park with the nearside wheels up on the kerb.
I have had an anti pollution fault come up a few times. P0190. On the scanner used it said "Fuel Pressure Regulation - Pressure Coherence" but I have seen this more commonly described as "Fuel Pressure Sensor Circuit Malfunction". If the fuel isn't flowing properly would this cause this DTC? I am wondering if there is something in the fuel tank that may clog the uplift pump but moves away when the car is at a certain angle. This could also be why it runs better when I drive a lot. Maybe the constant movement allows the pump to draw fuel OK. I have tried keeping it well over half a tank full but it still runs badly. Sometimes taking from a quarter to half tank seems to help for w hile. and I wonder if this stirs up whatever might be clogging the pump, if the pump is clogging.
This is all assuming the problem is related to the change of fuel tank. I'm reluctant to keep it too full of diesel because the reason I needed a new tank was that someone tried to drain off the diesel by making a hole in the bottom of the old tank.
VIN number is VF38BRHZF81410209.
Hope someone can help as this is driving me up the wall. All people keep saying to me is that it's a strange problem which doesn't really help at all.
Thanks in advance
Alan
Edited by Dynamic Dave on 19/02/2009 at 18:53
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hi alan,sounds like a daft answer but here goes... has the new tank had vegtable oil in it previously to you buying it. on diesels you can put half diesel/half veg oil. so just wondering if it has,there maybe a bit of sludge in the tank of the oil. also has the tank came from a diesel and not a petrol version...daft answers but you never know.
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Don't know the history of the new tank unfortunately but I do know it's from a diesel. Best part of £400 inc VAT for a new one plus fitting on top or £100 supply and fit for a used one swung it for me.
The fella that looks after my car knows his stuff and hunted high and low for the right tank. One thing that i am also wondering is if there is any damage internally within the tank. From what I gather there is a smaller tank unit within the main tank and this stores fuel for when you are going uphill etc. If this smaller tank is damaged it may be why the car runs perfectly at the right angle. However, I would have thought this wouldn't be a problem with three quarters of a tank of fuel.
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Meant to say in the first post that I have heard that the P0190 DTC is fairly common and is really a bit of a red herring sometimes. I suppose it's fair to assume the fuel pressure sensor will show as faulty if the fuel isn't getting through.
Is there also the possibility that one of the fuel lines has been pinched when lifting the tank bacj in place? What suggests this hasn't happened is the way the car runs OK when sitting at the right angle. (with the nearside wheels up on the kerb the fuel is obviously lying towards the fuel sneder unit etc at the offside of the vehicle.
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on diesels you can put half diesel/half veg oil.
No. Never attempt to run a common rail engine with anything other than high quality diesel.
Was the tank cleaned? what with ? have you checked the fuel filter?
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Fuel filter's been changed. You would assume the tank was cleaned but it's always possible it wasn't. If I can get a pretty good idea it is a problem with the tank and not something else that started at the same time just by coincidence then I can go and get the tank removed and make sure it's clean.
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It does sound suspiciously like a fuel problem either lift pump or injector pump. Do you have access to a dealer tool and live data? Was the engine run on old tank after it was damaged, sounds silly but I was wondering if anything was sucked up into the fuel system after the damage took place? Another possibility would be to fit a new complete fuel filter housing to see if that has developed a fault.
Steve.
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You could position the car at an angle that would normally give the fault symptoms.
Disconnect the fuel feed pipe between the filter & engine.
Direct this pipe into a container then switch on the ignition.
This will start the tank pump which will run for just a few seconds.
You should get at least 100ml of fuel through in that time.
If not you know you have some sort of fuel blockage & will need to work your way back towards the tank pump to see when you get a good fuel flow.
Every time you switch on the ignition the pump will run for the same few seconds.
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