my mk3 cranks and wants to start, but won't
 

Hi, I've read several threads on here about this exact problem. However, I haven't found a solution. I bought my '87 mk3 with a blown head gasket. I replaced the head gasket. The car won't start though. The engine cranks and cranks but no go. I have spark. I have fuel. I've replaced my spark plugs and wires. I've replaced my ECU. I've replaced my coil ignitor. I've checked the timing. Any suggestions? I'm sure I'm missing something. I'm just not sure what?

Make sure your ignition timing is set right. Sometimes it takes a little trial and error of pulling out the distributor and turning the gear to get it to the right range to fine tune the timing.

Thank you. I'll give that a try. I've done it before, but I may still be off the mark.

my mk3 cranks and wants to start, but won't
 

Hi ! , I had the same problem when I did my BHG . The answer was found underneath the inlet manifold . I had forgotten to reconnect all the earth ( ground ) leads to the manifold . once connected she burst into life.

Thanks. I'll pull the plenum off and take a look. I hope I haven't missed something so simple as that.

I had rthe same issue.

I tried the following which worked for me...

a) Check ALL Earthing points
b) Ignition timing needs to be correct or the engine wont start.

It takes time but its worth it ...

Let me know how it goes...

Make sure that bundle of harness ground wires low down on the intake side of the manifold is tightened down otherwise you'll get weird things. I had mine hand tight and it was acting very squirrelly. When you install the cam position sensor or distributor follow the alignment method otherwise the timing will be off. The same goes for the camshafts and the crankshaft. They all need to be in time to work properly. The firing order is 1 5 3 6 2 4 on a distributor cap. The rotor cap will be pointing to 1 when installed properly and with 1 at the top of the compression stroke. The coil pack wire order from left to right is 1 6 3 4 2 5. Check for spark using a good spark plug held against a ground point while someone cranks the engine briefly. When you get it started and warmed up, jumper T1 to TE1 and set the timing with a timing light to 10deg BTDC at idle with the air conditioning off. You may want to check your fuel pressure to see if you have any. You can "hear" the fuel flowing at the rail by turning the ignition switch to the on position but not cranking and then jumper B+ to FP in the diagnostic block behind the fuse box. Mack sure all electrical plugs are plugged in. Lastly, if yours is a Turbo, you can wiggle the wires that go into the cam position sensor. I had one that was funny that way.

Here are links to the on line repair manual.

valve timing
http://www.cygnusx1.net/Supra/Librar...aspx?S=EM&P=29

ignition timing
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=20

non turbo distributor
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=17

turbo cam position sensor
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=21

ground points
 

by any chance you guys know where all the grounds are in the engine, cause I'm having the same problem i just wanna make sure I'm good.

The 4 grounds I can think of on a Turbo car are :
1. The harness bundles that bolt to the intake manifold.
2. Ground strap at the rear engine installation hook.
3. Ground strap down low where the engine meets the transmission on the left side.
4. Ground strap at the transmission rear support bracket.

I added an extra ground strap in the shape of a Y that goes from the engine ground strap bundle (1.) to a bolt on the igniter and that splash shield that covers the steering column shaft.

Check your codes then pull the EFI fuse and check the codes again after trying to start it.
See if any persist.

awesome
 

great thanks man i'll definitely try that. I was rebuilding also and I'm have trouble with this so its really insightful.