Erik Myers

Hey guys,
So I finally got the Audi back together and got a tag on it! I drove it out and got some new bulbs for the taillights and it did great yesterday. I was super pumped. However, I parked it around 3pm after taking a friend for a drive at the University. I came back around 5:30 to go home and, to my surprise, nothing. The car refuses to start up. I tested the following things:

- Spark
- Timing
- Fuel Pump
- Metering Flap
- Fuel Pump relay
- Fuses
- CO Screw

I'm really confused because it ran fantastic when I parked it, it ran like a champ. Not even three hours later it refused to crank up. The starter is fine, the car turns over fine, it just won't fire up. Any ideas?

Erik Myers

Hey guys, just an update. I've checked over most things, but I think the problem is fuel delivery. I'm getting good fuel pressure to the distributor, and in the return line as well. I've tried this: unhook one of the injector lines on top of the manifold, crank the engine. I would think that I should be getting excellent fuel flow out of that hole, right? I mean, it has to push a lot of pressure for the injectors. But when I crank the car fuel barely trickles out of that hole.
​​​​​​i took the cis unit off and looked at the plunger- it moves back and forth freely with gravity. However it does spin. Is it supposed to be able to spin? Also the metering plate is fine as far as I can tell. It raises and lowers well with gravity. I've tried unhooking the boot and raising the flap while someone else turns the car over. No dice.
i might have to pull an injector to see if it is actually spraying. I'm running out of ideas here, any suggestions as to why I might not be getting fuel? Or is fuel even the problem?
Cheers.

Rogviler

Hmm... The plunger itself is fine to spin, as it's basically a cylinder with a wide channel machined around the middle, so it doesn't matter the orientation (it is constant injection, after all). However, if the barrel around it spins, that's definitely a problem, as the barrel has slits that correspond to the channels that go to each injector, so if the barrel moves then those channels will be blocked. I had that problem on my 4-cylinder and was never able to get them lined up right. When I took it apart I found the O-rings were disintegrated and plugging up the ports anyway.

Your problem is probably more upstream though. I've been trying to come up with an easy way to permanently install a fuel pressure gauge. On the 4-cylinders all you need is a banjo bolt they make for the brakes on motorcycles, but there's nowhere to put it on the 5. But that's really what we all need. That way you can tell at a glance if it's a clogged fuel filter or even a bad pump. I had a pump that I resurrected (was brand new before it sat for a few years) and it turned on and pumped, even sounded good, but wasn't able to build enough pressure to even get the fuel to the front of the car.

You'd definitely have fuel spraying out if the pump was on and good though.

-Rog

Erik Myers

Hey Rog,
I've been troubleshooting all day yesterday. It turns out the fuel problem was caused by a lack of air movement. I pulled the #1 injector and did the same thing- had a friend crank it while i lifted the metering plate. The injector sprayed beautifully. So I'm assuming at this point a random major vacuum leak has developed somewhere? I'm going to check all of the lines. I'm also going to plug the #1 injector hole and leave the injector out while I turn the car over. Ill update soon. I tried turning the car over with the injector out and no fuel came out, but then I realized it's probably because of the vacuum leak I had created by leaving the injector out.

Erik Myers

Hey y'all,
I forgot to update this post when I got everything fixed. Turns out for some reason the car had totally flooded itself. I pulled the fuel pump relay and removed the spark plugs and forced the gas out of the cylinders. Then I cranked it up without the fuel pump on and burned al of the excess fuel out. After that I hooked the pump relay back up and the car fired up. Who knows why it randomly flooded itself?

Sharktrainer

Rogviler

When my Audi Fox was doing that it was just a couple of cylinders but it turned out to be the o-rings inside the barrel in the fuel distributor. After I replaced the fuel distributor I took the old one apart and the o-rings were all in pieces and stuck in some of the holes. So I would keep a close eye on it. I would put more money on it being an electrical problem though.

Also, if your oil smells like gas at all I would definitely change it. Would be a good idea anyway, but if you can smell it then it's definitely affecting the lubricating qualities of the oil at that point.

-Rog