pauljoanss

S Max 1.8 TDCI fuel pressure drop during starting.

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(Follow on thread from my original one about not starting)

Car will not start, does one cough then nothing. Problem developed over a month when it slowly got harder to start then finally failed completely at fuel garage (engine warm at this point) and has not started since, despite lots of efforts. 

Fitted new glow plugs, no improvement, and run FORScan. Trace below shows fuel pressure for two consecutive attempts at starting, note pressure drop to zero occurs while still cranking.

Gave up and delivered to my usually trusted garage, they have dismissed air in fuel line and fitted new cam shaft position sensor, but no improvement and they now seem to be very short of ideas and I think would like to give up.

Any advice welcome, including anything else I can look at on FORScan since it is new to me.

1958987596_SMaxFuelPressure.thumb.jpg.6d5eb800316859393ded69e79026ded0.jpg

 

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GW

What about the fuel pump? did you check it?

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Many thanks rbitton782, no i have not checked the fuel pump and I have no idea how to check it.

Since this is a diesel, I imagine the pump is quite complex, my only experience of fuel pumps is the old diaphragm ones we used to have on petrol engines.

My feeling was that the pump must be mechanically driven and therefore must either rotate normally or not at all, hard to imagine it suddenly stopping. If it was worn, then could give low pressure but cannot see why pressure should suddenly go to zero.

The garage seem to think there is some sort electrical problem, I have no idea, but could there be some sort of dump valve which is activated by a signal from something?

Still not clear why garage have eliminated air in fuel pipes, whenever i change the fuel filter on this car, it will never start and  have to tow to garage for them to "bleed". Same garage that I am using now so must believe them on this point.

Certainly must not eliminate the pump, need to know more about its workings and how to test.

All information welcome and thanks again for your reply.

Paul

 

 

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GW

Hi Paul
If you will send me the vin number + exactly what engine type you have, I'll try to help you with numbers (fuel pump pressure, etc...) in PM.

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Quoting direct from log book

Model/Type S-MAX ZETEC TDCI 6G

  Variant QYWA1S

  Version EURO47CEA RG

Vin/Chassis/Frame No. WF0SXXGBWS6J06919

Engine No 6J06919

Cylinder Capacity (cc) 1753

Max. net power (kw) 92

Is there any way to test a fuel pump, other than replacing it and is there any logical process that a dodgy fuel pump could cause this characteristic of sudden pressure drop to zero.

Thanks

Paul Longworth

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GW
Hi
I have manual workshop, I'll hope the have fuel pressure numbers.
Ill scoop you soon, God will.

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Update - garage have concluded that the pump has failed and at a predicted cost of £1200, then advised scrapping, bill for their work £200.

Car now towed back to my house and deciding what to do. Only 140k and 11 years old so very reluctant to scrap. New pump on Ebay about £400 but very concerned about how difficult to fit and not 100% sure it is the pump? There appears to be a pressure relieved valve on the pump with an electrical connection, could a fault be causing this to trip and drop the pressure.

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GW

Usually, you are buying the pump as one assembly, I don't think you can buy specific parts from the pump.

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