I hav an 86 with no fuel pressure if you let it sit then turn the key to the on possition you get 40psi. but after that you have nothing if you turn the key off then on it will not turn the pump on. cranking the pump wont come on. let it sit for 5 min and it will come on to prime. any body have any idea.

 

If you have a wiring diagram, check to see if you have power to the fuel pump. This can be accomplished by accessing the wiring harness under the rear fuel access door and piercing the supply wire with a test light. Your '86 has a redundant voltage supply to the pump. This means that you have 2 sources of voltage to the f/p. One is by the fuel pump relay, the other is via an oil pressure switch under the distributor. This is so if the relay goes out, you still can get your car home. A sure sign of this is if your car has extended crank times ( oil pressure has to build for the internal switch to make contact). You might be losing both voltages, if so you need and oil pressure switch and a fuel pump relay. If you still have voltage when the pressure drops out, chances are you have a bad fuel pump. BTW, replace it with a good quality A/C Delco or GM fuel pump, not an Autozone special [:'(] It is fairly easy to replace by removeing your fuel door, then snakeing the rubber recovery bucket out that surrounds the fuel neck, then presto, you can pull the complete sending unit out by removing the attaching screws. Be sure and check your wiring harness for melted connections, because a poor connection will cause the problem you are describing also because it cannot handle the amperage load required. [8D]

 

Well I checked for power at the pump and thier was none. Iput a relay and a presure switch on did not fix. powered up the pump with my computer test light from the relay pump came on and was pushing 50psi. cranked with my scaner hooked up and I have no cranking RPM.

 

If you have no cranking rpm, u probably lost your stator or pickup coil as it is more commonly called. Does the engine have spark? In the base of the distributor. 1 way to check is to remove cap, unplug p/u coil and but both leads of an a/c volt meter while cranking, should have around .500 to .800 volts a/c. If you have voltage, probably is the module. To replace p/u, you have to remove distributor, disassemble ( dist. shaft goes through the pickup). Make sure engine is lined up on #1 compression stroke, line up timing marks on TDC, mark location of distributor housing (makes it easier to get timing close to start). Also, check your power source before the relay and pressure switch (no blown fuses)