it's your fuel pump. my pump is on the fuzz to and just ordered one yesterday. i bought an airtex, they are cheap and from reviews are decent.hey guys im new here and i have a 1991 ram 150 4x4 4 speed with a 318 4 my winter truck. but some days it wont start and some days it will. when it does it will run fine then all of a sudden she will just die and wont start but it will crank and crank. i changed the pickup coil and the main coil. and she has spark when its cranking over but wont fire up so can some1 plz help me out here idk what else to try could it b the fuel pump working part time?
if you want to confirm the pump get a fuel pressure gauge hook it up. pump should read AT minumum 35 psi idle now sometimes the idle reading checks out but once the demand for fuel is on the reading will either stay 35 or lower. you want to get a pressure of 40 or more.