I have a '90 RS with a 383 and a holly 750. The car has the stock fuel pump in the tank. I dont know if it was TBI or TPI. It has a fuel pressure regulator in the line going into the carb with a fuel pressure guage on it. My problem is I know my gas gauge is off and i knew the car was low on fuel. I started it up in the garage and was letting it warm up one day before taking it to the gas station. It died so i assumed it ran out of fuel. So i put a few gallons in it and could not get it to start. I let it sit for about a week and all the sudden it started right up. I went to pull it out to go to the gas station and it died again and wouldnt start. At this point I know there is fuel in it. Long story short the fuel pump fuse is good. I replaced the fuel pump relay. Still couldnt get it to run. Let it sit for a week and it starts right up then dies. I pull the gas cap off and it sucks a bunch of air into the tank like it were out of gas. So i put a new gas cap on it and that seemed to fix the problem other than it would stall if there was a load on the engine unless you kept your foot on the gas. So i thought i just needed to ajust my idle which wouldnt make sense cuz it was fine before. So i tried to do that one day and now its doin the same thing and wont even start. the only thing i can think of is that the pump is bad. But why would it work some times really crappy or not at all. Its electric so i dont think it would just get weak i figured it would just go out completly. Im about to drop the tank and replace it but i dont think thats going to fix my problem and i dont want to wste the money and effort of pulling the tank. Please help if you have had this problem or know how to fix it. Thanks

 

i have a 90 rs but it has a carbed 383 withe what im assuming is the factory electric pump ion the tank. that being said theoretically it should be a tbi pump. If I turn the key on should i be able to hear the pump prime??

 

What you didn't say is what your fuel pressure is doing when it acts up. Can we assume you don't have any fuel pressure?

Electric pumps can be intermittent. If the pump in the car now is the one that came from the factory, it is either a TBI pump, or a V6 pump (since you said your car is an RS).

 

{merged your posts since they are about the same topic}

I'm assuming you didn't do this 383 swap, correct?

Depends upon how the swap was done. Originally, there was a timed relay that would start the pump when the ignition is turned to "on", but who knows how the swap was done.