Wont Start

[simon1856]

Well day 2 of trying to start my 1984 GTX. To update i have changed distributor cap and rotor arm, ignition amplifier, plugs, fuel filter and put in decent fuel. Seems to have a spark but wont fire.
I did notice lots of petrol in the oil when i changed that and the filter, engine did turn over very slowly and put this down to current draw however it seems that the injectors were open circuit and fuel was being dumped into the engine cancelling cylinder pressure, also noticed the constant buzzing of the fuel system under the bonnet. Took the plugs out and spun the motor over, lots of fuel pumped out under compression. I have now taken the fuel pump relay out and it know the buzzing has stopped. Put the relay back in and buzzing only when turning over, yet still will not fire. I checked the valve timing and the auxilliary gear was a couple of teeth out so this has been rectified but the rotor seems slightly out with the tdc mark on the body of the distributor.
It appear to have fuel and spark and the timing would suggest that the engine is sparking in the right place is this something anyone can help me with? I hope that it could just be the fuel pump relay causing the issue, bought it as a non runner but would be nice to get it going running to assess everything before work starts in ernest.

[bensspares]

Sounds like you have a set of knackered injectors, ie leaking, worth checking them out for leaks etc........

[dozzum]

Take the injectors out put them in a jar or something , then pull the cover off the air metering vane. Bridge the two main connections where the fuel pump relay plugs in to make the pump run all the time and there should be no fuel coming out of the injectors with the air metering vane in the rest position. Lift the vane and fuel should start to flow. make sure the spray is pretty good. Then release the metering vane and switch off the pump. No fuel should drip out of the injectors, if it does they are leaky and need replacing.

With the fuel pump relay back in, but the cover off the metering head still. Get someone to crank the car over while you play around with lifting the vane varying amounts, spraying cold start into the intake and turning the distributor to get the timing right, when we did this with mine to get it running it ended up 38 degrees advanced, but still ran.

You will need another car and some jump leads while you do this to keep it cranking and I recommend making some sort of mark so you know where you started at with the distributor.

Once running the first thing you want to do is get a decent timing light on it.

Also you haven't mentioned changing the leads, probably worth it as you have changed everything else just to rule it out.

Good luck.

[dozzum]

Although if you are taking the injectors out be prepared you may need to change the seals.

http://www.veedubmachine.co.uk/index.ph ... ts_id=1149

[simon1856]

All,

Thankyou for the replies i will be trying this over the next day or so and will update accordingly. I presume if injectors are faulty then recon units are not available? M friends at GSF will be bending me over again no doubt, unless someone knows where a good set of injectors can be had for decent money...?

[bensspares]

No they are new only...I would recomend Euro ccarparts, when i replaced mine they were the cheapest and the supplied the correct ones to boot.

[dozzum]

If they are giving a poor spray / leaking its worth trying giving them a clean in some sort of solvent, preferably an ultrasonic cleaner. They work by purely mechanically, when the pressure reaches a set level the small pintle opens and then the pressure immediately drops causing it to close, this carries on very quickly and creates the atomisation.

So if some crappy bits have gunked it up it could stop it sealing.

They are expensive new, make sure you get genuine Bosch only!!!

[simon1856]

I take it when you describe pulling the cover off of the metering vane you mean the air pipe off of the air flow sensor?

I will order some plugleads, is it worth changing the fuel pump relay at the same time?

[dozzum]

What was wrong with it exactly? Didn't quite understand that from the above post.

From what I understand the original VAG ones usually don't prime with the ignition on but the GSF ones do.

But if I disconnect the battery on my car then reconnect it the pump primes, also it carries on running for a few seconds sometimes when i crank the car over and stop before it starts. So i think the two are linked.

It shouldn't run continuously with the ignition on either before or after engine running though, If it does then yes I would replace.

[simon1856]

Sounds like a plan. I now have the injectors out and the seals are very brittle. Will replace them once I know that the injectors are ok and car running. Is it the 2 big terminals to bridge to run the pump continuously? Sorry for all the questions just want to check the terminology used on the forum is what I know things to be. Cheers mate

[dozzum]

yeh should be one on the left and one on the right, one vertical and one horizontal. I use a swtitch on some wire with ring terminals on the end that push in quite nicely.

It wont run right with brittle seals as they will allow air in, but should still run.

[dozzum]

Just realised I never replied to the question about the air flow sensor, yeh that is what I meant.

[simon1856]

Excellent, cheers mate and i will look forward to checking it all out over rest days.

Update coming soon!!!

[MikeH]

You need to stop and re-think a bit. The fuel system is mostly mechanical, so doesn't buzz, except for the pump.

In what way are mechanical injectors 'open circuit' ? Can you clarify what you mean here?

Suggest you start with a fuel pressure and control pressure check.

For an injector spray check, take 4 jam jars or bottles, and make a hole in the lid just big enough for the injectors. Bridge the pump relay, lift the metering flap, run for 10 seconds to check spray pattern (control it using the battery connections so you can watch). All the jars should end up with the same or very similar amounts of fuel. Injectors should spray a fan of droplets.

After that you can check for leaks under residual pressure.

PS - no smoking ;)


Also, are you confident that cam and ignition timing are right? Or at least close?

[MikeH]

Also, where are you based? Maybe someone can pop over to see if there's an obvious problem - fresh pair of eyes and all that.