Hi to all on the forum.

I am a newbie from the UK and have owned and driven my '85 Camaro Z28 for the last 19 years. I know, it is like one of the family !
Some years ago I modified the car. I removed the ECU (computer), all of the wiring loom to it and all associated sensors. I removed the factory dizzy, carb and intake manifold and exhaust manifolds.
I then fitted an Edelbrock performer intake manifold, Mallory dual point dizzy and matching Mallory coil. Exhaust headers were fitted and my exhaust runs from them to the factory rear box in 2.5 inch pipe, (no catalytic converter).
Fueling was taken care of by fitting a Holley 600 CFM carb with a nice chrome air filter.
This car has run perfectly on this setup for years (until recently). Approx 2 years ago I fitted a new timing chain and still ran fine. Had a problem with the Holley though and for speed purchased a new carb, this time an Edelbrock performer 600 CFM (shiny Edition). Gutted, that when I took off the Holley, the only problem was sucking in air through the base gasket. I kept the carb though !
Now to the symptoms I have experienced more recently. The in-line fuel filter drains completely empty when I switch the motor off, as though the fuel is being sucked back along the feed pipe from the tank.
I suspected faulty fuel pump and have fitted brand new mechanical pump, replaced the rubber hoses that connect the metal supply and return pipe to the tank and also fitted a new in-line filter.
The car had been driving along and then faultering as though fuel starvation was the problem! However, the steps above have sadly not fixed the problem.
I have now fitted a new set of points to the dizzy, a full set of spark plugs and also new HT leads. The hesitation factor is still there ?
I am able to get the car to start and runs as if there is nothing wrong around 3,000 rpm parked ! It also will run occasionaly at 700 rpm idle OK. Problem here is that I cannot get it to run long enough to put the timing light on it or fiddle with carb settings, it usually stalls before I get round the front again ?
A very strange thing is happening now and I am totally puzzled. When I sit in the car and manage to keep it running, I try to rev it and it starts to run lumpy and is difficult to keep it going, and then the best bit, a fountain of fuel at quite some pressure blows up through the top of the carb and the motor cuts out.
Armed with new base gaskets I fitted my Holley on again. This is easier to start the car than the Edelbrock managed. The pressure of fuel when this 'Blow Back) occurs is far more significant on the Holley and reached about 5 feet above the carb
2 problems here then really. Why is the fuel going back along the feedp pipe from the tank ? Why is the fuel being Blown at force up through the top of the carb ?
Is there a tank breather ? Could this be blocked and causing some sort of vacumn pressure to suck the fuel back ? I dont know !
All I know is that this beatiful car has been in my life longer than the mrs LOL

Any help or suggestions here would be great

Thanks Guy's.

 

Well, after much head scratching and even taking off the intake manifold, cleaning it and refitting on a new seal, I have found my problem and the car is sweet again.
The condenser on the distributor body was the culprit.
Still, the car is fully serviced and running superb so all good in the end