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Weeping injectors

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Weeping injectors

After running all the usual pressure tests etc. I discovered that my warm-starting problems were due to leaky injectors, despite these having been renewed only a few k/miles ago. Another new set completely cured the problem, but these are now showing signs of weeping after only 2,000 miles.

Mine are the unshrouded ones (I believe the shrouds were later added to prevent heat soak from causing carbonisation of the injector tips after switching off a hot engine).

I wonder if this weeping could be the result of modern fuels? I fill up with leaded Thrust fuel once out of every four fills (it's expensive!), using standard unleaded for the rest of the time.

Has anyone else experienced this problem?
Geoff.

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That's a really odd problem - or at least you wouldn't expect it. Were the injectors VAG or from GSF/similar? Have you spoken to the supplier about the problem or any warranty. Surely there must be some sort of come-back?

Andy

LINCOLNSHIRE REGION - https://www.facebook.com/groups/467122313360002/

1983 MK1 Golf GTI Campaign Model - Under (looooong) resto!
1962 Rover P4 80
2002 BMW 745i
2008 BMW Z4 2.5Si

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A couple of questions:

Are these genuine Bosch injectors?

Have you been changing the fuel filter regularly (every two years or 20K miles)?

Were there ever any there any problems with the fuel metering head?

Were there ever any problems with grit in the fuel tank / rusty filler neck, etc?

Sounds very odd all the same - grit that would damage two sets of injectors that quickly would have ruined the metering head long before now.

Decent-quality (Bosch) injectors should last for ages - my '83 Campaign (currently "resting") has 210,000 miles on the *original* injectors, and while I'm sure the spray-pattern is a bit imperfect (they will be changed before she returns to the road!), there are still no leaks, and the engine still starts on the first turn, whether hot, warm, or cold.

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Thanks for your questions guys…
Yes, both sets of injectors were genuine Bosch from a local, well respected motor factor. I suppose they could be copies, but from this supplier I would find that hard to believe.

Metering head seems fine (nice and clean), and the filler neck, the filter and the pump have all been renewed in the recent past. I've checked the residual pressure when switched off, and it's well below the 3bar at which the injectors should operate. I've also examined the injector tips with a magnifying eyepiece, and can find no evidence of deposit build-up (although it's not posible to examine the seat itself of course).

The dribbling injectors still manage to give a nice spray pattern, and apart from the seepage, perform perfectly well.

How can something so simple be so complicated!!!?
Geoff

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If you have a fuel pressure gauge handy I would be tempted to run through the full set of hot and cold pressure tests in Haynes to see if that highlights any components that might need replacing.

I learnt the hard way you HAVE to be systematic with the fuel system tests and check for concrete proof of any suspected faulty parts before replacing.

Is it possible you have blockage in one of the fuel lines or a defective warm up reg that are causing the pressure irregularities? If the system is not retaining pressure after switch off then maybe the check valve on the fuel pump or the fuel accumulator are not working correctly. Haynes has diagnostic tests for both of these I think.

Not sure why it would cause dribbly injectors though….

Cheers,

Chris

ex '83 Mk1 Golf GTi Campaign owner and missing it already!

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Weeping injectors

Thanks Chris,

No, everything checks out pretty well on the pressure and flow tests. The control pressure regulator (warm-up) is a little high when cold, so the car initially fires up a bit weak (about 2bar), but it doesn't seem to affect the starting or running, even on a winter's day. When warm it runs at a healthy 3.4bar.

I posted this topic primarily to find out whether others were having similar problems. If not, then it's something peculiar to my car. I must say, my other Golf (Cabrio GTI) doesn't seem to suffer, so it is looking rather like an individual fault. The Cabrio however is a 1990 model and therefore has the shrouded injectors. The Golf ('82) doesn't.

It's possible that the fuel filter might be a cheap version, so I think I'll change it for a genuine one. If it's dirt though, I would have expected the metering head to be suffering.
Might also pop down to the local Bosch Centre for an opinion. I will post any developments.
Thanks again for replying.
Geoff
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