MK2 GTI filling the intake manifold with petrol

[martinijosh]

Hey guys, my MK2 pooped this morning.

Basically, I drove it 40km to work. Forgot to turn the lights off, came out a few hours later to a flat battery.

No worries I thought. Lets just hill start it and go on our merry way. Nope, no joy.

Then the fun part happened, I noticed a nice rainbow spewing out from under the car and on to the wet road. The strong smell of petrol filled the area.

I got it towed to the nearest mechanic as I was at work and didn't have the time or tools to check it out. He rings me a few hours later and tells me the intake manifold is full of fuel, they drained it and as soon as they turn the ignition back on and try to start it it fills itself with fuel again. Great, the fuel on the road is actually coming from the intake manifold, overflowing out through the air filter and out of the drainage holes in the airbox.

TL;DR - does anyone have any ideas as to what could be causing fuel to flow into (and fill up) the intake manifold? Injector stuck open?

Hopefully after an oil change and cranking the motor with pump fuse and plugs removed will sort it out...


Thanks guys....

[h100vw]

A bad earth between the gearbox and the chassis could be the culprit. The next best earth seems to be through the ECU. This frags the ECU and this triggers all the injectors. The usual result is bent rods from hydraulic lock.

Gavin

[Jmac]

Yeah injectors go 100% duty cycle and fill it, washes the bores lock stock the lot. Ive changed a couple of Ecu,s back in the day for that, bare in mind the ones im talking about were back when the cars were still under warranty!! yep wee while ago. Now woth age im sure the earths will be bad but wouldnt be surprised the ECU is defunkt too
Cheers
Jmac

[martinijosh]

Should have it home tomorrow afternoon... best thing to do first is check the earth is clean and secure?

Its already had the ECU replaced by prev owner for a different problem, but the drip tray that covers the ECU is a pretty poor design so it could be getting wet...

[h100vw]

That's what I would do. They aren't completely waterproof so being submerged wouldn't be good but I don't think I have come across one that has died from getting damp.

Gavin

[martinijosh]

Have potentially tracked down another GTI ECU locally, so failing the earth I will buy that and give it a whirl.

I popped out the dipstick too, can definitely confirm there is fuel in the oil. A familiar smell for someone who rides carbied bikes...


edit: I just remembered that when I was taking the battery out last night, there was a black cable hooked up to the positive battery terminal, just thinking about it now, could that actually be the ECU ground to the battery (which should be on the neg terminal)???

[The Fonz]

Can you see Where is the other end of the black cable goes to??

[martinijosh]

Going to check when I get home, I think there are 3 cables on the pos terminal and another three on the neg...

[martinijosh]

Upon checking it again, everything looks fine. Black cable is the positive lead, just something I'm not used to seeing.

Earth from battery to block is tight and all looks fine. Can't find the earth that is meant to go from gearbox to body, though?

[h100vw]

It goes onto a stud on the gearbox mount. Follow the earth lead to the body stud then it is covered in black tube.

Gavin

[The Fonz]

MK2 GTI filling the intake manifold with petrol

There should be another from the engine block ( rocker cover) to the body as well


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[martinijosh]

There should be another from the engine block ( rocker cover) to the body as well


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Yep, looks fine. Solid on both ends of the wire/cable. I also checked the relay for the ECU, looks brand new. I'm running out of "easy" options



edit: just noticed some dodgey looking wiring to the right in that photo. Hmmm.

[h100vw]

Inline crimp to fix that busted looking wire.

You can't say a connection is good by looking at it. Ideally you need to check the resistance of it with a multi meter.

The braided line with no cover leaving your earth clamp goes to the stud on the chassis rail. Then it should go to the engine mount from there. This section is covered with plastic.

Gavin

[Jmac]

Ill alter that slightly, you dont check for bad earth with resistance, you check it as a voltage drop and use Volts on your multimeter, with resistance all you are doing os checking the cable not the connection, check between the block and the cable, any more than 0.2 v is a bad earth, same as when checking a bad connection for your starter, if you use a jumper lead straight to battery and it starts better then it s a bad earth.
Jmac

[hamza]

you should really be using those star type of washers which improve current. forgot the name...