The has been an on going issue for some time with my brothers 95 Formula A4. I am interested in buying the cra but need to get this issue fixed first. The car is on it's third fuel pump in about 3 years, but the current Granatelli (sp?) 255 pumps great. Car ran strong until yesterday, it began the symptons that is has done in the past. Car started fine and got about two blocks away when it lost power, you could nail the gas and it was like not being on the throttle at all. All it would miss than stall out, waited about 5 minutes (sucked in 107 temps in a black car with leather). Car started and I got it back to my brothers house, but it began to do it again about a block away so I managed to coast there. Because of the issue my brother made a access panel after the last pump install (getting that tank out was a challenge neither of us wanted anymore). We pull the panel in the trunk and disconnect the lines to examine the pump. Weird thing is when we disconnected the return line I got blasted with fuel coming out of the line. I figured if it would ever hapen it would be on the push side, but I guess not. The gas cap was off to relieve pressure in the tank prior to pulling the lines. The pump looked fine, but last time the car had issues the line in the middle of the pump (short one about 3 inches) was just a rubber one since the original with the metal sleeve couldn't be swapped over.

I didnt think it would be possible but could there be a vapor lock issue? It has been in the high 90 and 100's for the past few weeks. Also the car ran out of gas about a week ago and after putting gas in it ran great until yesterday. Also when the car is running while having the problem it will run rough almost like a bad misfire, and if you bump the gas it will stall out. After we reinstalled the pump the car started and idled for a good 10 minutes and reved just fine, we took it down the block and when you hammer it, again it is as if you werent on the gas at all and then it would start to shudder.

This has been an on going issue for some time and the fuel system has been flushed, fuel filter is about 6 months old, pump is about 6 months old, and also the fuel pressure regulator has been replaced with an adjustable unit....can't recall which company. I really like the car and would buy it but I dont want to have to deal with this issue 100 miles from home or even 1 mile from home.

 

Any ideas, someone on another forum said it may be the coil getting really hot and losing spark. It was about 105 yesterday and the a/c was on about 10 minutes prior on the way to my brothers house, but wasn't on when the issue arose. Still doesnt explain the return line shooting out fuel as soon as it was disconnected.

 

Let's look at this as if it's a fuel problem for the moment. Fuel gets pumped out of the tank to the fuel rails. At the end of the fuel rail is a regulator that allows fuel to run back to the tank at a variable rate to keep the pressure constant based on engine vacuum.

Assuming you pulled the correct line (you said the return line) and got sprayed with fuel, then there is indeed a problem. The return line is unimpeeded after the regulator. The only thing that could prevent fuel from flowing is a pressurized tank. That's a tough one since there is a vacuum line for the purge canister going to the tank and a vent line. Vents have been know to go bad. If the vent were bad and the tank was being pressurized, in essence plugging the return line, this would also account for the pumps going bad.

The first thing to try is to remove the vent from the line. Just run without it for a while and see what happens. I would also run a fuel pressure gage taped to the windshield for a while so you know if the problem is related to pressure dropping or not.

let us know what you find.

Dave