1998 trans am ws6,low fuel pressure still,after insalling new pump,filter was good..intermittent miss fire, 2,4,8 cyl's..low idle at times..grrrrrrr.. swaped coils around.no diffrent..

Pontiac Grand


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If the fuel pump(s) run while the pressure is falling, replace the fuel pressure regulator and (although I'm sure you've already done this), replace the fuel filter. If the fuel pumps appear to be turning off by themselves, replace the inertia (fuel cutoff) switch.

did you replace the spk plug try it on another cyl switch erase codes and try if you get a miss fire on that cyl then check coil wire to that cyl but a cheap fix replace the plug first then see what happens

CHANGE FUEL FILTER AND CLEAN FUEL INJECTORS,CLOGGED FUEL INJECTORS WILL CAUSE ENGINE TO MISS, MAKE SURE SPARK PLUG GAP IS 0.060, LEAN MISFIRE FROM WEAK FUEL PUMP,CHECK FUEL PRESSURE SHOULD BE 40 - 50 PSI. IF EVEVY THING CHECK OUT OKAY,MISSING PROBLEM COULD BE LOW CYLINDER COMPRESSION OR INTAKE MANIFOLD AIR LEAKS.DO A COMPRESSION TEST IF NECESSARY.

Fuel injection needs 20-30 pound pressure to fire the injectors. Try to check pressure before filter. If its low your pump is no good. If its ok then you have pressure drop after the filter. Filter on backwards or clogged.

check for bad coil PAC and also have scan tool done on it to see witch cyl is missing then do a compression test on that bank of cyl

fuel pump or fuel pressure regulator

Have you changed the plugs, if any are fouled out or if any are worn, it takes more to fire it under load and may be spark knocking because one of the plugs can't fire off all the gas and cause it to skip or idle rough.

you could have partially clogged fuel injectors.or you getting a lean misfire check your fuel pressure .it should be.41 -47 psi.if low replace fuel filter.if dont help.you got fuel pump problems.check all vacuum lines.+ the vacuum line that goes to fuel pressure regulator.

check your fuel pump relay