205 Gti Starting Problems

[scott-205gti 2]

Hi I wonder if anyone can give me some advice on what seems a common problem ? I have a 1.6 1989 Gti which refuses to start intermittently .I have changed the Tachymetric relay for another .Admittedly second hand .But it still does it .I checked the voltages on the relay when it refused to start and got the following Pin 30 = 12v , Pin 50 = 9.5 v , Pin 15 = 12v , Pin 1= 12v and Pins 87B and 87 = o.0 v .Pin 31 Earth = 0.0 v ( which is of course obvious ) . As far as I know Pins 87 & 87B are the contacts to convey power to the Fuel pump and Injectors .Is the voltage on Pin 50 ( the one from the Starter Solenoid ) enough ? Or does it have to be a very close 12 v to operate the relay .Any idea what I should be looking for ? Thanks in advance .

[Simes 248 2 Cars]

When you say start intermittently do you mean turning over or firing?

[grandos 16]

Does the fuel pump run?

Have you tried checking if fuel comes out of the fuel rail hose?

Have you tried supplying the fuel pump with 12V directly then cranking to check if it starts and runs?

Easier ways of ruling out the relay / or proving its broken!

 

Ben

[scott-205gti 2]

Hi I should clarify .When I say start intermittently what I mean to say is sometimes it will start and run fine .Others after sucessfully starting / stopping 3 or 4 times you will attempt to start and it will crank but not run .Once when it did this I did pull the sparkplug cap off and insert and old plug .Then earthed the plug and saw a healthy looking spark .I have checked a earthing point for the battery on the gearbox .Since I have seen it mentioned that this could be a problem .When it does not run there is ( maybe obvious ) no power to the fuel pump .Am I right that there is also a power supply to the Injectors from this ? Which is from the same feed .And these in turn come from the Tachymetric relay ? It runs 8 out of 10 times nearly so I may use it . Do you think that the problem stems from the relay or supplies to it ? Or is it possibly from another area ? I have another relay which I tried but same problem .But this was a secondhand one .Since it runs quite happily once it runs , this would surely rule out many problems and lead back to that relay ? If it obliges me by not starting I will try that suggestion of putting power on the pump directly .Thanks for replying .I hope this post makes things a bit clearer .

[mmcgtk 2]

ive just had a similar problem,look at my post below,turned out to be the coil,it had a weak spark

[scott-205gti 2]

Hi thanks all for the help .However the GTI is now starting all the time again .So I am none the wiser .Looks like I will have to wait for it to pack in again .Probably at the most inconvenient time .Don,t think I have touched anything but the relay and some earth connections .

[MikeC 10]

"Pin 50 = 9.5 v" Is this still the case?

Sounds a bit low, could show a small short.

Edited February 25, 2013 by MikeC