HELP!! My Audi 100 won't start!

[theschmallfella]

Hey all,

I need some help here. Let me give some background on my problem, a few weeks ago I stupidly ran out of petrol on my way home, got her refueled and on her way but a week later she started back firing and loosing power intermittently. I parked her up and had a look and I can't get her going since. Here's what I did. I originally thought it was the HT leads, I did find one that was damaged so I changed the leads, plugs and the coil just to be on the safe side. She fired up again and I drove it around the block to see if she was ok and it cut out and wouldn't fire again. It had a full tank of fuel but it cut out like it had ran out of petrol. I got her back to the garage and since then I've replaced the petrol filter, bled the system for air leaks, checked the cold start valve, checked for air leaks, fuel leaks and checked the metering head. It's been trying to start, I've been bleeding the fuel at the metering head which seems to help but she never stays going for more than 10-20 seconds. My pump seems ok, I'm not hearing any humming so it seems operational, although I must admit I can't hear it at all which makes me wonder? One other thing that seems to have help get her fired up is leaving the ignition on for a time, like it's building up fuel, she'll fire up when this is done but will die shortly after. Any ideas guys, I'm scratching my head here?

[theschmallfella]

Oh, I should mention that she's a 1991 Type 44 (very last of the C3's), 2.0l, 5 cylinder, engine code RT. Petrol.

[Hoyle]

This to me does sound like fuel starvation, caused by a blockage or air in the system. Perhaps damage occurred to the pump?

It's difficult to diagnose without seeing it really.

Try and listen for the pump changing in tone just before it cuts out.

[theschmallfella]

Thanks Hoyle, I'm thinking the same way, I have my suspicions about the pump, the fact I'm not hearing anything at all when the key is turned on is making me wonder. I'm going to try and get her fired up now and see if I can hear anything from the pump.

[Micky]

if you have run out of petrol then there is a good chance you sucked up some shit out of the tank and blocked the metering head or injectors .i would take feed out of the metering head to see how much fuel is getting there and then remove the injectors to see if you got a good spray pattern out of all of them .

[theschmallfella]

Originally Posted by Micky

if you have run out of petrol then there is a good chance you sucked up some shit out of the tank and blocked the metering head or injectors .i would take feed out of the metering head to see how much fuel is getting there and then remove the injectors to see if you got a good spray pattern out of all of them .

I thought of this, I figured though that if she did pick up crap from the tank she would have forced it through with the first set of backfires that she did, it did run fine for a day or two after that? Still it's worth a look. Is it possible to strip the metering head down to clean it out, it looks like you can? I won't be doing it until Saturday but I'll keep you posted. Thanks for the help Micky.

[Micky]

backfires is not crap getting threw it's fuel starvation .i personly would not take metering head apart unless you know what you are doing .just try the simple things first .i would start with changing the fuel filter if its been on a while then take out the fuel feed to the metering head and crank it over to see if you are getting a good flow rate .it should fill a glass jar in a few seconds . i think there is a small filter in the head also ? its been a while since i did mine .if a good flow rate put the fuel pipe back in and remove all injectors still connected to the lines and crank again .you should see spray fuel coming out of all of them .dont forget there will be quite alot of fuel vaper in the area so no naked flames if you get one injector or more spraying week fuel then i would remove the injectors all together and see how much fuel comes out of the lines .if all the same then its a dodgy injector if not its the metering head .hope this helps

[Hanuman]

There's the old filter in the supply line entering the metering head?

Running the pump to check delivery- 900ml/30 seconds is the target on a UR, IIRC. It's not going to be much different.

[quattro turbo 550bhp]

listen sir its fuel starvation & tank got crap in it iv had the same symptons on my mb quatt but i didnt run out of squirt put new pump on & filter no joy is ur pump gtn quiet loud ie like its running out of fuel mine was took tank out & it was absolutley caked in crap esp the fuel sender it look like its bn in sahara desert had all this sandy looking powdery crap all over it so defo the tank i think

[SteveT63]

Is the fuel pump under the car? Is there a small an inline filter near the pump as per the 80s? If so check that along with the pump ( cant remember if you said you'd done that) also the accumulator. Does it stop when the auxiliary injector in the manifold clicks off? If so, I'd say low fuel pressure and go with the majority that your fuel system now requires a flush clean.