Mk3 Golf Intermittent start problem

[Jagstang]

Hi.

I wondered if anybody might be able to point me in the right direction to solving some problems with my 1992 mk3 golf 1.3 CL.

After standing overnight the car will often not start. The starter turns over but the engine will not fire for up to a minute. When the engine does finally start it does so by the skin of its teeth and shakes the whole car for a minute or so until either it begins idling normally or stops and I have to go through the whole process again.

If I touch the Accelerator during this process it usually results in the engine stopping.

Once the car is running it's fine, I can leave it for a few hours it starts instantly, but every now and again I get this problem after the car has been standing for longer than 4-5 hours. Not every time though!

The plugs and distributor seem ok but thats about the limit of my knowledge.

Many thanks for any ideas,

best regards

Paul.

[Jagstang]

Just tried to start the car again and had the same problem. After turning the engine over for a while I removed one of the spark plugs and it was totally dry and sparking ok.

This leads me to believe the problem might be a lack of fuel. What could cause a lack of fuel when cold starting?

First though was fuel pump but after getting the car started it runs fine so I doubt the fuel pump itself is broken. Could it be the fuel pump relay or some other electrical component thats not operating correctly intermittently?

Any help much appreciated.

Paul.

[jarovagolfIII]

i had a similar problem just the way you described
on my car...
after a few times decide to check it and found several problems convined...
1.- cold start relay part # 813 906 064
2.- idle control valve part # 037 906 457c
this valve was stickin on all the time thats wy there was a lack off presure to much air going on(thats wat the mechanic says)
3.- fuel filter was changed too part# 1H0201511A
the mechanic says this was clogged 85% , even known that i changed 9000 milles ago

he said that problem its lack of fuel so you better check fuel supply to your car, cause is not going to be spark problem ...... by the way all the part number i gave to you are for a 1992 vw golf GL

good luck

[Jagstang]

Thanks for the reply - I'll check into those things and see if they help.

Many thanks for your advice, much appreciated.

Paul.

[Jagstang]

The problem was the ignition coil.

Although it was sparking it wasn't generating a strong enough spark (according to the mechanic who checked it out). Fitted a new one and it starts well again

Thanks

Paul.

[Jagstang]

I take that back, it wouldnt start again today

I've been trying to do some troubleshooting with it today and have made some interesting discoveries.

Firstly when it won't start, if I remove the fuse for the fuel pump it will start straight away, although it doesn't last long of course. As soon as I put the fuse back it refuses to start again and just floods. While the starter is turning over it stinks of fuel and when it eventually starts it only does so on 3 cylinders and shakes the whole car. In this state is never really gets going, it just sits shaking on 3 cylinders till I either touch the throttle or turn of the ignition, both of which cause it to stop.

ANy ideas?

Is there a fuel management system that could be telling the fuel pump to send too much fuel during the starting process?

Paul.

[Jagstang]

Solved it!

Took the car to VW who put it on a test rig and discovered that the ECU was seeing the engine running at only 17 degrees C, even though it was actually hot.

I replaced the coolant temp sensor two days ago and it's been sweet as a nut ever since

It seems the ECU pumps more fuel into a cold engine, and was thinking it was always cold so continued to do so even when it was hot which flooded it.

This has been mostly a one way conversation, but I hope it might help somebody in the future.

Paul.

[dag65]

Great info , thanks