Fueling

Hi all, another help me please post.

I’m trying to fix my GTI, it’s always had a misfire when cold, this has now progressed and now it won’t even run. It’ll fire up, run for a few seconds then die. I initially thought it was electrical when it was misfiring so have replaced plugs, leads, dizzy cap, rotor arm and coil. Now it’s not running I’m assuming it’s fuelling. Where do I start? Simple things like the fuel filter and go from there? Or is there a way I can test the fueling and see what’s happening?

Many thanks.


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Here's a few guides on the Bosch K-jet fuel injection system and how to check fuel pressures but you will need a pressure gauge and correct connections.

How old is your fuel filter?

Reading your post I guess the 5th injector is working when cold and spraying in some fuel to start the car then when the fuel stops the car cuts out.

After cranking the car remove the spark plugs and smell them for petrol or see if they are wet.

You can remove the 4 main injectors and check to see if they are spraying out fuel, it's not easy to get the injectors out, you will need to by pass the fuel pump relay and lift the metering head plate to see if fuel sprays out. Again there's several threads on how to do this on this site to save me typing it all out.

What year is your car as the fuel injection system changed slightly over the years with extra fuel pumps and anti stall devices etc.

Thanks for that,

So the problem started with it cutting out for a second, just once every hour of driving, then it started doing that a bit more often. Then the next time I drove it, it Veda cutting out and lasting a good few seconds, then became undrivable, would start when I turn the key and idle, but cut out the second I gave it any revs. I got it recovered, parked it up, today starts fine, but would only run a couple of seconds then die, wouldn’t even idle.

I don’t know when the fuel filter was last changed, so I’ll start with that. It’s 1985. [mention]mark1gls [/mention]


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Don't discount a Crank Gear shear first.

Using a timing light verify that the timing is on, and as you rev the engine that it starts to increase…If it is wobbling all over then gets spot on again, then you may want to statically set the timing.

Loosen the timing belt then see if you can move the lower timing gear by hand, if you can then suspect timing gear shear.

Okay, so a little more poking and prodding today and I’m fairly sure I’ve found the issue.

With the ignition on I was listening to the xternal fuel pump, it sounded like it was running dry. So I took the pipes off the sender in the fuel tank, I’m assuming with the ignition on, fuel should be coming out of one of these..? There’s not, completely dry. (There is fuel in the tank - I checked!)
So I’ll order a new lift pump, if someone can confirm there’s meant to be fuel coming out of the lift pump if the ignition is on?

Many thanks.


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What year is your car as early cars have a 45l fuel tank (and a full size spare wheel) don't have a lift pump.

Cars from 84 ish with a larger 55l fuel tank and space saver wheel will have a lift pump in the fuel tank, your car could have either size fuel tank it’s worth to check which tank you have.

There will also be 3 wires going to the electrical connector on the fuel gauge sender if you have a lift pump, if you have 2 wires there’s no lift pump.

Yes, it definitely has a lift pump. It’s 1985.


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That's the original pump which I'm surprised at, I've been through about 5 lift pumps over the 26 years I've had the car.

New one should come with a new filter and replace the little bit of fuel hose between the pump and sender, just make sure it's the same length as the original bit of hose so the pump sits at the same height in the fuel tank.  

[mention]mark1gls [/mention] is it the original? I guessed the 11/97 was a manufactured date. The car being ‘85 I assumed it’s been changed atleast once before. Still, if it’s been on there since 1997 it’s done well too.


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Maybe from 1997, VW stopped using a lift pump in there fuel tanks when they stopped making the Mk1 Cabriolet, Mk2 Scirocco and Mk2 Golf in 1992 ish.

New lift pump and it works again. Thanks for the help.


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A running car and with indicators, productive weekend for you  

Still the pesky cold spluttering though…


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