80 Quattro KK engine won't start

Mike671 · 24-05-12, 11:13 PM

Right ok it's been sat for awile matey I got it off reckon he last started it one year ago though. Spark is lovely that's all there, compression is nice and strong around 13 bar per cylinder, so I'm guessing it's fuel well you crank it over first time and you have pressure of around 130-140 psi on line out the pump, but no fuel out the metering head on crank, is this correct? the cold start valve spits fuel but it doesn't even hesitate to start. So then I placed fuel pressure guage on line out metering head no pressure on crank, but lift metering head flap slightly first time of cranking you have no pressure let off the key pressure builds to around 30 psi then turn key again and you have around 60 psi. Can someone help me out? As k jet is doing my head in I would love to hear it run :-( and yes it has fresh fuel in it

8690q · 24-05-12, 11:44 PM

Seized fuel pump ?
Not sure how safe it is but I've run 12v right to the pump and it freed it off and the car started.

Mike671 · 24-05-12, 11:47 PM

Pump pumps fuel lovely on crank, pressure on end of line is approx 140 psi so that's working

msh · 25-05-12, 05:30 AM

Putting manometer at the end of the fuel line can do two things - to check if pumps backflow valve doesn't let the fuel back, which isn't important to you currently, and also it can blow apart rubber fuel hoses at the pump

You need to measure system pressure, without interrupting system, if you have such manometer, of course.

Although it would be better to remove main injectors and see what they are doing. And the best way how to get pump running is by shorting two fuel pump relay terminals, because starter sound could prevent you from hearing something

P.S. I'm wondering - KE-jet has small sieve in incoming fuel line bolt, clogging of which could cause interesting things, maybe K-jet has the same?

Mike671 · 25-05-12, 06:45 AM

Yep this also has the small sleeved gauze in the incoming fuel line which I cleaned out but seemed ok anyway, yes my fuel guage was inline which on feed side of meterin head I have around 140 psi, what number is that relay? Also when I come off crank the pump stops running what out of interest keeps the pump running when the engine starts?

Many thanks

90 B2 quattro · 25-05-12, 07:08 AM

Sounds to me like the fuel pump relay, i had the exact same problem, took the relay out and plugged it halfway in and car started, pushed in all the way it would stall at random or not start at all. I took the cover off it and found the solders had come apart on the cicuit board.
Easy fix but bloody frustrating to find the cause. Hope this helps?

4v6 · 25-05-12, 07:22 AM

140 psi on the feed side? Too high! Check the fuel return lines not crimped.

KK should have 68 to 78 psi at the pump, control pressure should be should be around 59 to 63.

Mike671 · 25-05-12, 09:28 AM

Well you take return off at metering head and only a small amount drops out, what pressure should I see if I connect the guage directly on the pump line and not passed through?

4v6 · 25-05-12, 10:02 AM

The fuel must pass through and down the return line otherwise the pump will pressurize to its maximum output which is far too high for the system to run properly.
You cant simply measure system pressure by pumping into a dead end, the fuel has to be passed down the return line past the pressure regulator.

If you connect a fuel pressure gauge inline with the system (ie in series) you should see the first set of pressures i stated, ie system pressure.
If you checked it at an injector in series youd get the second set of pressures iirc.

So long as the pressures meet the specs it should all work fine, the fact that youve got just a dribble coming out the return and an excessively high system pressure means the return is blocked or obstucted either in the metering head or associated pipework.

Mike671 · 25-05-12, 11:59 AM

Ok 4v6 I'll have another play and see what pressures iv got there well I wanted to test total pump pressure as last owner put a new pump on it, I'll reconnect it up again in series and see what iv got inline to metering head, on crank should injectors fire off?

24-05-12, 11:44 PM	#2
8690q Grown up member Classic Audi Club Member Join Date: Jun 2009 Location: Coalsnaughton Posts: 190	Seized fuel pump ? Not sure how safe it is but I've run 12v right to the pump and it freed it off and the car started.

24-05-12, 11:47 PM	#3
Mike671 Grown up member Join Date: May 2012 Posts: 50	Pump pumps fuel lovely on crank, pressure on end of line is approx 140 psi so that's working

25-05-12, 05:30 AM	#4
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Putting manometer at the end of the fuel line can do two things - to check if pumps backflow valve doesn't let the fuel back, which isn't important to you currently, and also it can blow apart rubber fuel hoses at the pump You need to measure system pressure, without interrupting system, if you have such manometer, of course. Although it would be better to remove main injectors and see what they are doing. And the best way how to get pump running is by shorting two fuel pump relay terminals, because starter sound could prevent you from hearing something P.S. I'm wondering - KE-jet has small sieve in incoming fuel line bolt, clogging of which could cause interesting things, maybe K-jet has the same?

25-05-12, 06:45 AM	#5
Mike671 Grown up member Join Date: May 2012 Posts: 50	Yep this also has the small sleeved gauze in the incoming fuel line which I cleaned out but seemed ok anyway, yes my fuel guage was inline which on feed side of meterin head I have around 140 psi, what number is that relay? Also when I come off crank the pump stops running what out of interest keeps the pump running when the engine starts? Many thanks

25-05-12, 07:08 AM	#6
90 B2 quattro Grown up member Join Date: Mar 2011 Location: Dunedin, NewZealand Posts: 168	Sounds to me like the fuel pump relay, i had the exact same problem, took the relay out and plugged it halfway in and car started, pushed in all the way it would stall at random or not start at all. I took the cover off it and found the solders had come apart on the cicuit board. Easy fix but bloody frustrating to find the cause. Hope this helps?

25-05-12, 07:22 AM	#7
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	140 psi on the feed side? Too high! Check the fuel return lines not crimped. KK should have 68 to 78 psi at the pump, control pressure should be should be around 59 to 63.

25-05-12, 09:28 AM	#8
Mike671 Grown up member Join Date: May 2012 Posts: 50	Well you take return off at metering head and only a small amount drops out, what pressure should I see if I connect the guage directly on the pump line and not passed through?

25-05-12, 10:02 AM	#9
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	The fuel must pass through and down the return line otherwise the pump will pressurize to its maximum output which is far too high for the system to run properly. You cant simply measure system pressure by pumping into a dead end, the fuel has to be passed down the return line past the pressure regulator. If you connect a fuel pressure gauge inline with the system (ie in series) you should see the first set of pressures i stated, ie system pressure. If you checked it at an injector in series youd get the second set of pressures iirc. So long as the pressures meet the specs it should all work fine, the fact that youve got just a dribble coming out the return and an excessively high system pressure means the return is blocked or obstucted either in the metering head or associated pipework.

25-05-12, 11:59 AM	#10
Mike671 Grown up member Join Date: May 2012 Posts: 50	Ok 4v6 I'll have another play and see what pressures iv got there well I wanted to test total pump pressure as last owner put a new pump on it, I'll reconnect it up again in series and see what iv got inline to metering head, on crank should injectors fire off?