Bad first cold start (DX)

Hello!

Im having problems with my first start of the day on my Mk1 Cabriolet 1.8 DX. 

This happens only on the first start, it's hard to start if I don't push the throttle a little.  once it starts it stays at about 800rpm and goes up to 1100 for a minute, then it stabilizes at 900 and when it's hot at 1000rpm.  If I start and turn off the car and start again it starts perfectly, it also starts perfectly when warm, the problem is only on the first start of the day.  The car runs great both hot and cold. I have verified the TTS and the CSV and they work perfectly, I think the WUR too, otherwise I would have other types of symptoms I think.  the number 1 spark plug is a little black and wet and the other 3 have a good brown color. 

It smells a lot like gasoline when this happens but there are no leaks anywhere.  the pump is new too.  Maybe the fuel circuit is losing pressure when it is stopped for hours?  My idea is to put the mk2 16v relay to prime the pump before crank to see if it improves.  any suggestions?

Thank you so much!!

From the time that you insert your key and then start, do you wait 4 seconds after turning the key before start.  

The Fuel pump relay really needs to be on for 4 seconds prior to you trying to start the car.

Insert key
Turn to first Position (run)
WAIT….4 seconds or until you hear the fuel pump cut off.
Turn key to start to engage the starter.

I have seen this issue on several EFI cars that I have owned, until the Fuel pump pressurizes the system fully, the pump can't pump correctly.  

Like the oldie days and dodges, unless you pumped the accel pedal 3 times, it was an iffy start.

But my Frog-eye, and Midget, pull the choke out, and fire her up.  First time every time.

Nostaglle makes me want those back, but the body can't take the ride.  Save for my 72 Rover3500S, that is the only car I wished I had kept.

Briano1234 said

From the time that you insert your key and then start, do you wait 4 seconds after turning the key before start.  

The Fuel pump relay really needs to be on for 4 seconds prior to you trying to start the car.

Insert key
Turn to first Position (run)
WAIT….4 seconds or until you hear the fuel pump cut off.
Turn key to start to engage the starter.

I have seen this issue on several EFI cars that I have owned, until the Fuel pump pressurizes the system fully, the pump can't pump correctly.  

Like the oldie days and dodges, unless you pumped the accel pedal 3 times, it was an iffy start.

But my Frog-eye, and Midget, pull the choke out, and fire her up.  First time every time.

Nostaglle makes me want those back, but the body can't take the ride.  Save for my 72 Rover3500S, that is the only car I wished I had kept.

Hi Briano, thank you so much for you reply.

My pump is not priming when my key is in position 1.. i dont hear anything never, on my mk2 16v i can hear the pump priming. I thought that in the mk1 because of the relay that has the pump, the fuel does not prime until you start.  that's why I want to put the mk2 16v relay.

Normal not to prime the fuel pump as it should not need it if the accumulator is working as that holds fuel pressure. My car has never primed the fuel pump.

I think your problem is leaking fuel injectors, try and unplug the blue electrical connector on the 5th injector and see if that helps.

I had leaking injectors and similar starting problems, I run without the 5th injector for about a year before fitting new injectors.
I'm on my 3rd set of injectors and find they last about 100,000 miles before needed replacing.

You can pull the injectors out and check for leaking once they are switched off, a few guides on here and online but it can be a pain to pull them out if they have been on the car for many years.

mark1gls said

Normal not to prime the fuel pump as it should not need it if the accumulator is working as that holds fuel pressure. My car has never primed the fuel pump.

I think your problem is leaking fuel injectors, try and unplug the blue electrical connector on the 5th injector and see if that helps.

I had leaking injectors and similar starting problems, I run without the 5th injector for about a year before fitting new injectors.
I'm on my 3rd set of injectors and find they last about 100,000 miles before needed replacing.

You can pull the injectors out and check for leaking once they are switched off, a few guides on here and online but it can be a pain to pull them out if they have been on the car for many years.

Thank you so much Mark,

Leaking injectors it was what i thought. To test that, I could loosen the spark plugs after having been running and check if they leak from the hole, right?

Can you explain me why with the 5th inyector unpluged helps? 

If the problem is the fuel pressure loss, with the mk2 16v relay shoul be better if i prime first the pump right? Should help. 

And last question, hat fuel smell in the first start, can be caused by the unburnt fuel on the cilinders? When car is cold i can hear the tipical "injection advance" noise (like a diesel) on the top end, i dont think if that is normal or is a characteristic noise in this k-jet 

Quick update, with the 5th injector conector unplugged starts perfect and no fuel smell. Next test, stop the car unplugging the pump relay to make sure it runs out of petrol, and try to start next day.

What happens with leaking injectors is some fuel drips into the cylinders when you stop the car, when the engine is cold the 5th injector sprays even more fuel in and the engine has to much petrol when started, it soon burns off when it's running.

I would just keep the electrical connector unplugged and make sure the electrical connector is not flapping about near the manifold, I used a little bit of wire (like you get with new electrical items to keep the cables tidy)

There is 2 type of fuel injectors, later cars have air shroud injectors (there's a rubber air hose going into the back of the head between cylinders 3 and 4) either replace the injectors with new ones or some places can clean them.

If you have the air shroud injectors make sure the "top hat" does not full off when pulling them out.

View topic: MK1 Gti DX Injectors - The Mk1 Golf Owners Club

mark1gls said

What happens with leaking injectors is some fuel drips into the cylinders when you stop the car, when the engine is cold the 5th injector sprays even more fuel in and the engine has to much petrol when started, it soon burns off when it's running.

I would just keep the electrical connector unplugged and make sure the electrical connector is not flapping about near the manifold, I used a little bit of wire (like you get with new electrical items to keep the cables tidy)

There is 2 type of fuel injectors, later cars have air shroud injectors (there's a rubber air hose going into the back of the head between cylinders 3 and 4) either replace the injectors with new ones or some places can clean them.

If you have the air shroud injectors make sure the "top hat" does not full off when pulling them out.

View topic: MK1 Gti DX Injectors - The Mk1 Golf Owners Club

Thank you Mark,

Yes i have the later ones, i just bought a set of 4 Bosch brand new injectors for 120 euros here in Spain.(437502043) 

Sorry but what do you mean with "top hat" full off?

If the injectors leak and drip, shouldn't that gasoline evaporate in hours or leak out of the pistons? Does that excess gasoline caused by the injectors plus the 5th injector really make the car not start well? Is it possible that the 5th injector is injecting too much gasoline than it should?

Thanks a lot!

The "top hat" is the end of the air shroud injector.
If you compare the injectors with the early type, the end (top hat) is just pushed onto the body of the injector.
If the injectors have been in the head for many years they can get stuck in and difficult to pull out.

If your fuel injectors are 10 years old or 100,000 miles then it's probably a good idea to fit the new ones and see if that helps.

Fit a new fuel filter and replace every 20,000 miles.
Check for any rusty holes in the fuel filler neck regularly.

mark1gls said

The "top hat" is the end of the air shroud injector.
If you compare the injectors with the early type, the end (top hat) is just pushed onto the body of the injector.
If the injectors have been in the head for many years they can get stuck in and difficult to pull out.

If your fuel injectors are 10 years old or 100,000 miles then it's probably a good idea to fit the new ones and see if that helps.

Fit a new fuel filter and replace every 20,000 miles.
Check for any rusty holes in the fuel filler neck regularly.

Fuel filler neck has a hole with rust… What is usually done in these cases?

You need a new fuel filler neck. Cabriolet filler necks are different from tin top cars.

You need to sort this out as soon as possible as dirt/sand and water in the fuel tank and fuel system will kill the whole system in no time…

Don't fit the new injectors till the filler neck is fixed.

If you can find a replacement filler neck you may be able to get someone to weld up the hole if it's not to big.

mark1gls said

If you can find a replacement filler neck you may be able to get someone to weld up the hole if it's not to big.

I have found a new compatible one for the DX cabriolet for about 80 euros, do you know if it is difficult to install?

As with everything there's only a few screws and 1 bolt holding the filler neck on and if you can undo them with out any problems it's straight forward.

Buy a new rubber hose which joins the filler neck to the fuel tank as they go hard over time and you'll struggle to fit the new filler neck and buy 2 new jubilee clips.

Rubber hose looks like this.

https://www.ebay.co.uk/itm/393603476619?hash=item5ba4986c8b:g:VHkAAOSwe5ZiGgSA&amdata=enc%3AAQAHAAAAoLILfpFDo3kK5fbeOotok8AwpkSoUvLLS68PyYzJNamAf2GMSnNDRLjgD8uT%2Fqtdxd9qam6hmXqQ6Ru1lj0pQigySBkKG2h5c1A%2Fs5d20JWSEElW1rqSfIhxI9j871aU%2BxRhyU8qPk175Zesslke%2ByVSOzAJdSMOikRNt4hyhC1T7oWvvZAahvpdXSeFuB%2BgjpXJL37Rp8aaa74Ah%2BNbrRc%3D%7Ctkp%3ABk9SR_Dj3YOhYQ


If you run the tank down to just above the red you should be able to jack up the back of the car and remove the filler neck without any petrol draining out.

It's worth giving the filler neck a good coat of paint/stone chip etc as it's exposed underneath the wheel arch and prone to rust.

If you look at my build thread about 1/2 down page 1 you can see my old rusty filler neck.

View topic: My Daily drive 1988 Gti cabriolet - The Mk1 Golf Owners Club

mark1gls said

As with everything there's only a few screws and 1 bolt holding the filler neck on and if you can undo them with out any problems it's straight forward.

Buy a new rubber hose which joins the filler neck to the fuel tank as they go hard over time and you'll struggle to fit the new filler neck and buy 2 new jubilee clips.

Rubber hose looks like this.

https://www.ebay.co.uk/itm/393603476619?hash=item5ba4986c8b:g:VHkAAOSwe5ZiGgSA&amdata=enc%3AAQAHAAAAoLILfpFDo3kK5fbeOotok8AwpkSoUvLLS68PyYzJNamAf2GMSnNDRLjgD8uT%2Fqtdxd9qam6hmXqQ6Ru1lj0pQigySBkKG2h5c1A%2Fs5d20JWSEElW1rqSfIhxI9j871aU%2BxRhyU8qPk175Zesslke%2ByVSOzAJdSMOikRNt4hyhC1T7oWvvZAahvpdXSeFuB%2BgjpXJL37Rp8aaa74Ah%2BNbrRc%3D%7Ctkp%3ABk9SR_Dj3YOhYQ


If you run the tank down to just above the red you should be able to jack up the back of the car and remove the filler neck without any petrol draining out.

It's worth giving the filler neck a good coat of paint/stone chip etc as it's exposed underneath the wheel arch and prone to rust.

If you look at my build thread about 1/2 down page 1 you can see my old rusty filler neck.

View topic: My Daily drive 1988 Gti cabriolet - The Mk1 Golf Owners Club

Thank you very much for your detailed information as always.  mine is practically the same or worse, I think I bought the correct one 155201129c

https://www.oldtimer-werk.de/en/golf-1-co/fuel-system/tanks-pump-and-fuel-lines/1041/tank-pipe-golf-1-cabrio-with-55l-tank-from-08/83-oe-ref.-155201129c

Yes that looks like the right filler neck as we have 55l fuel tanks in a 1988 car.

This is rubber hose between the tank and filler neck, they also show the jubilee clips.

https://www.oldtimer-werk.de/en/golf-1-co/fuel-system/tanks-pump-and-fuel-lines/977/connecting-hose-between-filler-neck-and-tank-injector-golf-1-co-oe-ref.-533201219?c=583

mark1gls said

This is rubber hose between the tank and filler neck, they also show the jubilee clips.

https://www.oldtimer-werk.de/en/golf-1-co/fuel-system/tanks-pump-and-fuel-lines/977/connecting-hose-between-filler-neck-and-tank-injector-golf-1-co-oe-ref.-533201219?c=583

 

Thank you!!

New inyectors fitted and new fuel filler neck and cold starts with 5th inyector are perfect! Thank you so much mark1gls