2003 golf 4 not starting on incline

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Clint2003
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2003 golf 4 not starting on incline

Post by Clint2003 »

Hi there, I'm having an issue with my 2003 golf 4 tdi (AHF engine). It won't start if left to stand on an incline, I noticed some air bubbles in the fuel line and if I disconnect the fuel line from the filter and try turning it over it doesn't seem to be pumping any fuel. The car would start and cut out a few times before eventually running and then start fine again later in the day when on a flat surface but now it's not starting at all.
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marzbars
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Re: 2003 golf 4 not starting on incline

Post by marzbars »

Sounds like the in-tank/pickup fuel pump
But that is just science speaking and not mechanical talk
Clint2003
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Re: 2003 golf 4 not starting on incline

Post by Clint2003 »

I pulled out what I thought would be the fuel pump inside the fuel tank under the back seat but there's no motor inside the housing, only the level transmitter so I'm not really sure how the fuel gets pumped to the engine
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missioner
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Re: 2003 golf 4 not starting on incline

Post by missioner »

Clint2003 wrote:I pulled out what I thought would be the fuel pump inside the fuel tank under the back seat but there's no motor inside the housing, only the level transmitter so I'm not really sure how the fuel gets pumped to the engine
What side of the car did you open?

Some models have 2 fuel sender's. Pump will be on the drivers side.
'87 Golf 1 Olde Skewl OEM+
JCTPUBLISHERS
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Re: 2003 golf 4 not starting on incline

Post by JCTPUBLISHERS »

By the fuel rail there is a pump check it and also have u check for any fuel leaks?
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Re: 2003 golf 4 not starting on incline

Post by VAG Fan »

The AHF has mechanical injection, i.e. a mechanical VE pump (only the quantity controller is managed electronically), and mechanical injectors.
Hence the AHF has no fuel rail, no tandem pump, etc. etc.
Also, to my knowledge, it has no lift pump, neither inside the tank, nor outside. The Diesel is only "pulled" by the VE pump itself. The line therefore needs to be primed in order for the syphon action to work.

@ Clint
Seeing that air leaks back into the lines, this tells you that the lines, fittings or pump itself are leaking somewhere.
For a start, you might actually use this to your advantage. Park the car facing downhill, then observe the pipes, fittings and the pump itself.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
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Re: 2003 golf 4 not starting on incline

Post by missioner »

VAG Fan wrote:The AHF has mechanical injection, i.e. a mechanical VE pump (only the quantity controller is managed electronically), and mechanical injectors.
Hence the AHF has no fuel rail, no tandem pump, etc. etc.
Also, to my knowledge, it has no lift pump, neither inside the tank, nor outside. The Diesel is only "pulled" by the VE pump itself. The line therefore needs to be primed in order for the syphon action to work.

@ Clint
Seeing that air leaks back into the lines, this tells you that the lines, fittings or pump itself are leaking somewhere.
For a start, you might actually use this to your advantage. Park the car facing downhill, then observe the pipes, fittings and the pump itself.
That is an excellent point and keen observation.

Leaks on diesel systems go both ways. Just because there isn't diesel dripping off the car does not mean it not leaking.
'87 Golf 1 Olde Skewl OEM+
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