Crank but no start

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nbamtx
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Posts: 3
Joined: Wed Oct 25, 2023 6:21 pm
Drives: 6r 1.2 TDI
Location: Wiltshire

Crank but no start

Post by nbamtx »

Hi, first post, just wanted some advice.
My car has decided it doesnt like running. Drove it a couple of hundred miles, pulled into some shops, came back 5 mins later and it wouldnt start.
Plugged my diagnostics tool in and all seemed normal except for the high pressure fuel actual value which sat nicely at 0.
Attached are some pictures of live data of the fuel system with no cranking and then during cranking.
Anyone know good things to check like fuses relays? What could the fault potentially be?
Thanks.
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Le_Combattant
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Posts: 303
Joined: Sun Mar 07, 2021 4:04 pm
Drives: Polo 6C 1.2 TSI 90 Cup
Location: France

Re: Crank but no start

Post by Le_Combattant »

Can you hear the low fuel boost pump at the back when you put the key ?
What engine is it ?
nbamtx
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Posts: 3
Joined: Wed Oct 25, 2023 6:21 pm
Drives: 6r 1.2 TDI
Location: Wiltshire

Re: Crank but no start

Post by nbamtx »

Its a 1.2 TDI, dont think i can, is there a fuse or relay for the low pressure pump i can test?
amer6R
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Drives: Polo 6R 2010 1.6 TDI
Location: budget build

Re: Crank but no start

Post by amer6R »

check fuse 3 ( small ones)
nbamtx
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Joined: Wed Oct 25, 2023 6:21 pm
Drives: 6r 1.2 TDI
Location: Wiltshire

Re: Crank but no start

Post by nbamtx »

Fuses are all good, testing the fuel pump im getting no continuity/resistance across the two large pins on my fuel pump but i am getting resistance across the smaller ones, does anyone know what the designation for the pins are on the pump?
Cheers
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RUM4MO
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Re: Crank but no start

Post by RUM4MO »

It's very easy to to guess, I shouldn't I know, but, as you have considered, there will be a large +ve and a large -ve supply and return for the pump motor, and the typical fuel level device will be a resistor with a moveable (wiper) contact, so could explain the 3 smaller contacts.

So, I'd expect a low resistance across the 2 large contacts - like you seem to expect.
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ciclo
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Re: Crank but no start

Post by ciclo »

Regarding checking the fuel pump:

Image

- Check fuse SB31, SB35, and J643 Relay (1).

Image
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