K Jet metering head rebuild

[Duffy3074]

Having driven the Coupe and appreciated that my 90 isn't 100%, I spoke to my friendly local garage (who are German specialists and have a good depth of knowledge)

They've suggested having the metering head and pressure regulator overhauled by KMI in Welwyn Garden City.

Now, here comes the rub. They can service both, they'll come back as new but it's north of £600 to do both.

Researching the subject brought up this lot

https://www.ebay.co.uk/itm/Audi-Quat...QAAOSwRLZUIty-

who do kits for both the head and the regulator.

Anybody any relevant experience of them or this subject?

I should add that Colin has very generously offered me a known good set to swap over and see if it improves the situation at all and I'll do this prior to splurging in any way!

[larry49]

I have read on other forums that it is very difficult to DIY rebuild, I would make sure your problem isn't another problem first before attempting.............

[larry49]

If you have the equipment you can do a full pressure/injector flow test on the metering head and warm up regulator.....

[Duffy3074]

I don’t have fuel pressure gauges albeit they might be an investment in the near term.

[Duffy3074]

http://www.autotoolworld.com/S-G-Too..._p_166581.html

My best mate lives in the States but is coming over in August

An opportunity there methinks

[msh]

Well, if you want to overhaul just as assurance, without any flow measurements, then it's not really needed - metering head is tested by measuring injector flow in a few vane positions, and in case of different flow rates, swapping the injector to see if that's head outlet or injector with different flow rate, and seeing if the head doesn't leak fuel when vane is in rest positions and pump is running.

As for K-jet fuel pressure regulator, I don't know anything about it, as I prefer NG, although when mine will finally run, it will do with the help of digifant or VEMS.

[larry49]

Originally Posted by Duffy3074

I don’t have fuel pressure gauges albeit they might be an investment in the near term.

If you were nearer you could borrow mine, which I made quite easily but it does have the banjo type metering head fittings............

[Groundhog]

If after due diligence you come to the conclusion that the meter head and/or the regulator need refurbishment then £600 seems very reasonable to me. The warm up reg is quite simple in operation and readily reparable but meter heads are very very difficult indeed. When I worked on quattros I did do lots of them but I'm not to proud to admit that the first few were a complete disaster. The key thing is a need to be scrupulously clean-as in operating theatre/medically clean, the tiniest speck of dirt between mating surfaces and it will leak. Essentially you have metal to metal surfaces ( some that move)that have to seal fuel at several bar of pressure, they are incredibly finely machined.

[Duffy3074]

Originally Posted by Groundhog

If after due diligence you come to the conclusion that the meter head and/or the regulator need refurbishment then £600 seems very reasonable to me. The warm up reg is quite simple in operation and readily reparable but meter heads are very very difficult indeed. When I worked on quattros I did do lots of them but I'm not to proud to admit that the first few were a complete disaster. The key thing is a need to be scrupulously clean-as in operating theatre/medically clean, the tiniest speck of dirt between mating surfaces and it will leak. Essentially you have metal to metal surfaces ( some that move)that have to seal fuel at several bar of pressure, they are incredibly finely machined.

Thanks for that very worthwhile info.
I’ll swap out what’s there with a working set and if the running improves then that will confirm the problem.
If it’s faulty then there’s no point me diagnosing it with pressure gauges as, being realistic, the DIY servicing of it looks like a marginal proposition. The cost of the guages and the gasket set would be a significant percentage of what it'd be to get KMI to do it.

[John.]

Originally Posted by msh

... metering head is tested by measuring injector flow in a few vane positions, and in case of different flow rates, swapping the injector to see if that's head outlet or injector with different flow rate, and seeing if the head doesn't leak fuel when vane is in rest positions and pump is running.

Is this basically measuring how much fuel is delivered in a certain time period?.....like testing a fuel pump.

Like the idea of swapping injectors.

Would save stripping the metering head if all is good here? yes/no