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Fuel pressure sensor testing??


Mattypompy
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My TDCI has suffered intermittent glow plug warning light coming on, turbo cut out and occasional engine cut out.

After doing some research the ecu thinks there's a low fuel pressure problem. Amongst other stuff, I have tested the sensor on the fuel rail following this short vid;

 

https://www.youtube.com/watch?v=85IP8eY1nXY

 

Now, my results from testing  the three wires, 5v ref, signal wire and ground are as follows.

Ignition on, multiplug detached.

5v ref = 5v, (correct)

Grnd =7.1v (should be batt v)

Plug attached probing signal wire,

aim 0.5v actual = 0.03v.

 

Would this indicate a defective sensor that needs to be replaced (ie signal value too low) or would I have sort out the grnd first and retest?

 

 

Many thanks I you can help and sorry for the intrusion.

 

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21 hours ago, Mattypompy said:

Would this indicate a defective sensor that needs to be replaced (ie signal value too low) or would I have sort out the grnd first and retest?

Hi,

It is me again, I am afraid. I seem to be the only one interested in pressure sensors! But then it is my job, I design & manufacture stuff to measure / control pressure.

That gnd reading looks very badly wrong. I guess you were measuring from battery +ve to the gnd wire on the connector, as said in the vid. You could also put the meter on ohms or continuity, and with the ignition off, check continuity to the engine metalwork. I suspect a measuring error, it is quite difficult to make good contact with DMM probes. I often have to try several times.

I would have thought a ground failure like that would give DTCs, and the fuel pressure would be completely out of control.

BTW: I did not like the sound of connecting 12v via a light bulb to any of the pinsohmy.png. That sounded Very dodgy to me. It is a 5v system.

 

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Thanks Pete. Well someone has to design such gubbins! You're obviously the right guy to ask! I'm going to retest today. As I said 7.1 v sounds a bit weird! Will try impedance test or to the metal work instead of Batt -ve. Cheers.

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Omg. Retested sensor today. Still got the weird electrical readings. Put the car back together, after fitting egr plate and cleaning Maf sensor, got 400m up the road and the car broke down just before a big roundabout!

 

Called RAC and the outlet hose from the fuel filter to the pump was leaking and perished. He put in a temporary hose, got it started then it promptly broke down on the entrance to a busy 3 lane roundabout at rush hour! Got it home though. Now I have to replace the hose and still haven't worked out fuel pressure issue! You got to love cars! 

How in the name of Zeus do I source this hose! Can't find the specs on line!

😀😀😀

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3 hours ago, Mattypompy said:

How in the name of Zeus do I source this hose! Can't find the specs on line

http://www.ebay.co.uk/itm/252549884252?clk_rvr_id=1105411370553&rmvSB=true

 

Seems to come up right. Bit expensive though!

You could buy generic hose & make one up, but the connectors might be a problem.

If air was getting in to this hose, it could cause fuel pressure drops.

 

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The RAC guy said that. It might have been leaking air all along. Definitely worth replacing then re-testing. Will get a quote from Ford tomorrow, thanks for link BTW. Tiis expensive!

He reckoned make one up from appropriate hose myself. Will cogitate on it.

 

😀😀

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Rang Ford today. £54+ vat (I think) for the pipe!

Gonna try and make my own with the connectors I have. Ordered a metre today from FleaBay for £3.75 delivered lol 

If that cures the low pressure issues it will make me laugh getting it fixed for £3.75 when I was near throwing in the towel!😁😁

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Update!

Received the fuel hose in the post yesterday. I asked for inner bore diameter of 10mm instead I received 9.5. But for £3.75 delivered, I can't really grumble. Anyway cut and fitted the hose to the old connectors. It was difficult due to smaller diameter as mentioned. The connector tip are tapered though. Filled hose and filter with fuel as best I could then jubileed  it up. Took about 10 secs of cranking today but then it did start. Checked hose connections no apparent leakage. Low and behold putting it on Forscan the required and actual pressures were identical, 260 bar at idle!

Have done a little road test, so far so good. I then used a can of STP egr cleaner straight into manifold. After a couple of flame wielding back fires I put everything back together. Fuel pressures again are equivalent. Obviously I need a longer road test and am going on a trip next week so we'll see. Fingers crossed. It does seem more responsive and a touch more torquey!

So basically; repaired leaking hose, cleaned inlet manifold, changed fuel filter, cleaned Maf/FP sensors and blocked off egr valve. Cost £30!

 

😀😀😀😀😀😀

Will update..

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  • 2 weeks later...

Thanks for the advice Peter. Yes I was miffed too! The required and actual pressures are equivalent at idle still. I just PMed you to ensure you received the message. I will update this thread when there's an update.

Yes I thought about having the real time data to establish if there was a pressure discrepency  at fault time but when reading live data from the FIP the engine sometimes stalls, Forscan warns about this. I was doing 60mph.

There's a good diesel/Ford specialist here in Portsmouth, £54 for diagnosis. The IMV  has a 30 day returns policy at about tye same price. I may just get it, fit it then test it and return it if it doesn't resolve it.

The engine seems so sweet, quiet and responsive after the servicing I've done on it however. The saga continues...

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I've decided to buy the Delphi pressure sensor just in case it has an intermittent fault and is lying to the pcm, Cheaper than imv and easier to fit. Will fit and test by Tuesday. If no joy i'll try for a refund! We'll see!

Thanks again.

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Replaced fuel pressure sensor today but the supplier sent the wrong one. It was reading 1074 bar at ignition on lol.

I cannot find a new one anywhere, part nums 51hp02-01 9307z502a.

 

Strange????

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2 hours ago, Mattypompy said:

It was reading 1074 bar at ignition on lol.

Very Strangeunsure.png

It could be the pins are in a different order from yours, but it could also be a bad connection, especially in the gnd (0v) wire. And you did have a strange reading from the 0v wire in a post above.

Hmmm.

I think I would do a bit more testing before sending it back or ditching it!

 

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Update. I was given a refund by the supplier as he said he received a functionally suspect batch. It was the wrong one though anyway, my fault I used the eBay part sorter which was erroneous. So happy with the refund. Another supplier said he hasn't been able to get this sensor from Delphi for two years! There seems to be no aftermarket version that I can find, only used from breakers!

I'm cutting my losses and getting a good garage to runleak off and diagnostics. Think it my be partial injector blockage perhaps due to pump award down stream.

I looked at return fuel, had some deposits, also did pressure test with injectors/imv  disconnected and it seemed low according to another post.

Shame as it's purring now and very responsive.

:unsure:

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when my 1.6tdci had low fuel pressure problems it was cured by changing the fuel filter. Are you sure your filter is good? (mine had been on there for 120k miles)

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Hiya.

 

Yes my filter is fine. I've had two in 2 months! Have a Bosch one atm.

Update: Pretty sure it's RIP for my car now. Took it into a Ford specialist to investigate the metering valve limp mode fuelling problem and he was agog with two other issues so didn't test it!

Basically he said it's the worst vibrating Focus he's ever driven lol

He said the DMF is distorted or sticking in engaged position and the the tranny mount under the airbox has perished and needs replacing. Pics attached. The vibration is bad and happened around the time the engine backfired out of the inlet manifold when cleaning/using snuff on it.

I'm dropping it off to another mech to see if it's worthwhile repairing economically or to sell for spares/repair. Tbh I've had loads of trouble from the day I bought it and was probably a bit of a sucker. Shame as it has 4 good tyres and I've enjoyed driving it. My first diesel experience hs been a mare! Might go back to petrol and try another make. 

20161102_132019.jpg

20161102_132012.jpg

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2 hours ago, Mattypompy said:

Shames as it be 4 good tyres nd I've enjoyed driving it.

:sad:

DMF problem, Fuelling problem, 15 years old. Not a great combination.

sad.png

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'Shame as it has 4 good tyres and I've enjoyed driving it.' I meant!

 

Do you think a solid flywheel conversion may be superior to installing a new dmf?

Thanks for all the help nonetheless!

3 hours ago, Mattypompy said:

 

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