1989 Audi 200 QT - Hard Start Need Help

[Kaklikian, Gary]

This seems to be a common problem with the 10vt ... in fact, both the '90
200 motor in my 4000 and my friend's '89 200 exhibit the same symptoms.  The
problem seems to occur when the car sits for 30min-2 hours and is
exasperated by warm weather.

This has been attributed to leaky injectors , faulty fuel pump check valve ,
various temperature sensors, etc.   If the plugs are wet, the injectors are
probably leaking; if they are dry and jumping the fuel pump and/or spraying
starting fluid in the intake helps (thanks, Tim!), then it's possible the
check valve has failed, resulting in a loss of residual system pressure.
Btw, the check valve is a much less expensive solution than new injectors.

I've replaced all injectors/seals and the fuel pump check valve on my 4000tq
and still have a warm start problem,  but this is an entirely different
animal with two fuel pumps, additional injectors, etc. I've found that
holding the throttle fully open when starting helps, as does higher octane
fuel.

Gary Kaklikian
'86 4ktq
'92 S4
> ----------
> From: 	Kevin Clinton[SMTP:ksg2000 at AudiFan.com]
> Reply To: 	ksg2000 at AudiFan.com
> Sent: 	Wednesday, August 22, 2001 6:13 PM
> To: 	quattro at audifans.com
> Subject: 	1989 Audi 200 QT - Hard Start Need Help
> 
> 89 Audi 200 QT runs great but has a difficult long hard crank when it has
> sat for awhile.
> 
> Local german auto mechanic performed tune up replacing breather hoses,
> spark plugs etc.  Invoice says that he 
> checked cold start system, warm up regulator, fuel injection system, fuel
> pressure, etc.  He concluded that I needed a new $1,270 ECU.  Says that
> fuel pump is not turning on correctly on start up.
> 
> Now I am certainly not a mechanic but before I shell out $1,300 I thought
> I would do a little checking and ask some help.
> 
> Heres a few things I have done with my limited skills.
> 
> Using a volt-OHM meter I tested the ECU connection to the fuel pump relay.
> It sure looks like the ECU is sending a brief 10 volts or so to the relay
> when cranking the engine.  The fuel pump relay is making a loud click when
> it receives this signal.  Additionally, I jumped the fuel pump relay for
> 10 seconds or so before starting the car noting that it still has a long
> hard crank.  Not positive but this sure sounds like the ECU is doing its
> job and that the problem is not associated with a lack of fuel.
> 
> This mechanic kept the car for three days so he could test the "cold
> start" each morning.  I think he simply ran out of ideas and knew that a
> $1,300 suggested fix would be rejected and he could go onto his next
> project.
> 
> Unfortunately, I still have a car which needs fixing.
> 
> One last thing that might give a clue as to what the actual problem might
> be.  I noticed that right after I tested the ECU connection to the fuel
> pump relay (which required cranking the car with the fuel pump fuse
> removed) the car started right up.  I assume this procedure would have
> eliminated any fuel sitting in the engine.  I also noted that when I go on
> vacation and leave the car unused for 10 days or so it starts right up.
> 
> Any suggestions would be appreciated.
> 
> Thanks
> Kevin
> 
> 
> 
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