I have an 89 mustang 302 was sputtering out every so often and flooding sometimes. replaced fuel pump checked fuel pump relay. now it wont start at all. has spark. heard it might be a relay above the ecm? how do i check this?
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if you have an obd scanner check the codes.....could be as simple as a dirty fuel filter...also shows symptoms of a failing fuel pump (electric, mounted inside tank)....If you dont have access to an obd ll scanner, take it to n Auto Zone, Murrays, Napa, Firestone, or Goodyear, they will usually scan it for free........good luck.
Turn the ignition switch to run, without starting it. You should hear the electric fuel pump, in the gas tank, run for about 3 to 4 seconds, until it builds to proper pressure. If it is not humming along it needs replaced. murf427
can see your are realy into this and your discription is exellance. But i have to tell you something that you don't want to hear Its your fuel pump its an 89 its over due . Chevy had problems with these pumps in the 90s not some much in the 80s they olny lasted 10 years at best unless you have already done if or know the history of the vehicle what you have discribed is not electrical but fuel issues the blinking mil light going up hill under load its a give away . You can try pulling some plugs if the look white instead of a tan color then its the fuel pump . And by the way the fuel relay on this vehicle is not the olny power supply to the pump there is a back up power supply to the pump through the oil pressure sending unit so even if the relay was bad the fuel pump would still get power through the sending unit it runs of fuse #9 for the ECM and fuse and splits one side relay and the other oil pressure sending unit. I have wireing schematics but there for mid 90s but the system is vary close to the same . And i kow what a pain it is to do the fuel pump good luck my frieind email@example.com
This could be leaking fuel injectors, a stuck Fuel Pump relay, and/or faulty fuel pressure regulator. Have you had any of these items checked and/or replaced? If not, it may be time to replace them. Also, check your fuel filter. If it hasn't been replaced in the last year, replace it.
The jets in the carb are too big for a 302 with a stock cam. Take it to a carb shop and have them replace the jets with stock jets. (Or DIY and hope). Whne you converted from FI to carb did you replace fuel pump to get correct 7 1/2 psi pressure at carb inlet? FI pumps put out 50+ psi and a regulator maintians pressure at the injectors on the order of 35 psi.. Of course, that much pressure would force inlet needle valve out of it's seat and would probably flood carb totally, but, check the fuel pressure at the carb just to be sure. Good luck. 302's rule!!!!
PS - Check cam specs - FI engine has different cam - intake duration is longer if I remember correctly. Been a while since I got inside an engine...