Changed ITP, now getting 'low fuel pressure'

[agw_01]

Hi guys,

Need some pointers please.

My car had a dead ITP so I was always sure to keep the tank over 1/4 full. Had no problems at all with it running.

Replaced the ITP with a genuine VDO pump from Jules and decided to see how low I could get the tank. It started cutting out at 1/8 with a low fuel pressure warning.

Filled the tank and ended up having to replace the pump seal so the car sat around for a few days. Started to use it again, drove about 150 miles without issue. The car had just over 3/4 at this point.

I started the car the next morning and shortly after setting off it started cutting out with the low fuel pressure warning. It'd restart fine but must have cut out about 10 times before I got to the petrol station 200 yds up the road.

Thought that perhaps air was getting into the corrugated pipe that I'd slightly damaged so filled the tank and drove to work. Everything seemed to be ok.

Got some fuel hose and fuel hose clips so with an almost full tank, I've just 'fixed' the scavenger and fitted the new fuel hose. Started the car, haven't even attempted to drive it and it keeps cutting out. It'll restart without issue and cut out again.

When I first let the car run low and refilled it, when I turned the ignition on, I could hear air rushing through the pump which is what made me think perhaps air was getting in. Now the tank is almost full and I'm still having issues.

What could I have done wrong when changing the pump? Do the rubber hangers have to be a certain way up? Does the pump have to be orientated a certain way?

The cutting out does seem as though it's linked to the fuel sloshing around the tank and away from the pump pick up, but at 3/4 of a tank and above?

Wish I'd left it alone now!

[agw_01]

Checked HP and LP sensor voltages and they seemed ok. Didn't really show any problems and the voltage only dropped after the engine stalled, not before.

While I was testing the voltages the car appeared to keep running so after a little while, decided to take it out. Gave it a good workout and it seemed to be ok. It did cut out once when I pulled out of a junction fairly swiftly (what was I saying about the fuel moving away from the pickup) but that was it.

I'll keep a very close eye on it as the fuel level drops but there's absolutely no reason for it to be sucking up air (if that's what it's doing).

[agw_01]

Used the car last night and it was fine. Came to use it this morning, started it and left it idling. Sure enough it cut out.

Restarted and drove off, cut out about 6 or 7 times and was then absolutely fine until I reached my destination.

So it's either something that happens when the car has been sitting for a while, or it's temperature related. I used the car yesterday afternoon (it was a warm day!) after it'd been sat overnight and it was fine.

Now there's a bit less fuel in the tank I'll see what it's like when I go back to it later.

Something else I've noticed recently is the car running for a couple of seconds after I've turned the ignition off. I thought this was due to the worn pump/tank seal letting air in (is the diesel tank vented anyway?) and allowing the HP pump to draw it in but it's still doing it after I've changed the seal.

Is my thinking of this being related to changing the ITP a red herring and I've got an electrical/sensor issue on my hands?

edit... Another thought, if leaky injectors could cause it to run on, could they cause the cold start issue? The LP and HP pressure sensor voltages looked ok when I tested them yesterday.

[genpk]

Could it be the cam or crankshaft sensors ?

[agw_01]

Don't they generally cause a hot start issue?

The car will start, and restart without issue when it does stall which seems to be mostly from cold.

I'm not sure if this is a bit of red herring that I'm linking to a fuel issue. For a couple of days after changing the ITP the car was faultless so I can't be completely sure it is a fuel pressure issue, I'm just going off the IPK.

I've ordered a K-CAN cable and am going to give TOAF a try to see what diagnostic information I can pull.

Lots and lots of threads on similar issues though, which a couple of people mentioned started after they changed the ITP, some mentioned it being an ECM.

[wullie480]

You make no mention of replacing the under bonnet pump?
This maybe where the issue lies a non working in tank pump puts extra strain on the under bonnet when fuel level runs low this is why it should be kept above 1/4 tank, the fact you've ran low has probably damage the under bonnet have a listen to it to see if it's running smoothly or gurgling.

[agw_01]

Hi Wullie,

I've not replaced the UBP, the car has been running off it for 12 months without issue. It whirrs pretty nicely, perhaps not as quiet as the brand new ITP but that's to be expected I guess.

I didn't run the tank low until after I'd fitted the ITP, in fact, the first time the car cut out after fitting the new ITP it was a smidge over a quarter.

The car has been a PITA today. Got out of work and went to the car, it's a hot day so I didn't expect much trouble. Set off without any real incident but then within the space of 1/2 mile it was cutting out pretty much constantly, showing 'low fuel pressure' on the dash.

I can't tell whether there's a link between it cutting out and left hand turns. I went round a roundabout a number of times and it was fine, but as soon as I pulled off to the left, it cut out. It's done it before on left hand turns.

It was getting so bad I had to keep my foot on the throttle while braking (luckily it's an auto so I don't need 3 feet!) to keep the engine running. Strangely, this worked. It also doesn't seem to cut out if you're doing NSL speeds, almost as though the engine/HP pump is contributing to the fuel flow. I dropped it into neutral and it cut out.

If you held the revs at 2k in neutral, it'd also cut out when cold. The car is now sat at work because it's doing this when hot and shows a different message 'low oil pressure'. At first, I crapped myself but believe this to relate to diesel oil, not engine oil. The tank is 3/4 full.

I'm going to brim the tank tomorrow and I bet this goes away, temporarily.

The car will restart instantly btw, doesn't hesitate or take a long time to start. Both pumps prime with ignition and there's no gurgling of air.

Very annoying!

[Mike Noc]

It is only showing low oil pressure because the engine has stalled and the engine driven oil pump has stopped.

Try unplugging the EGR valve solenoid - it sits just above the starter motor (or dangling over it if the bracket has broken), and if that doesn't improves things try unplugging your MAF.












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[agw_01]

Ahhhh ok, cheers Mike. I'll be honest, I've only noticed the IPK before when moving. It was only when I was revving at standstill and actively watching the display that I saw the low oil pressure warning. I was questioning myself as to whether there was actually a fuel pressure warning.

I should mention my IPK isn't great. Another job for the list!

I've been dealing with this as a fuelling issue due to me recently replacing the fuel pump but am aware this could be a red herring. There does seem to be a link between fuel level and how often the car cuts out though.

I'll try what you mention tomorrow, thanks for the input.

[wullie480]

Was just in case under bonnet was on the way out.
Clean the connection to the in tank pump the on top of the tank it maybe contaminated with some fuel from when you changed the pump out causing a poor connection. Give it a good clean with electrical contact cleaner.