Is the timing off ? Have you put the wrong leads to the wrong plugs? Have you tampered with the engine in anyway. What happened PRIOR to these misfires?
Firstly, it is unlikely that three plugs are going to go bad simultaneously.. I suspect it is none of them.
Could be loose or bad wires, bad gas. your timing is off or some of the other concerns above. determine right off if you are actually getting spark to each cylinder, and go from there.
most likely plugs, could also be the fuel injectors. not too complicated
A misfire could be from many issues. Spark plugs, spark plug wires, dirty injectors, bad injectors, dirty valves, stuck valves, bad PCV. Get a OB II meter and check your engine. This will likely show the reason for the misfire.
JAK!! !C'mon now WHICH V* made by WHOM?? A misfire is nearly ALWAYS caused by a dirty IDLE AIR CONTROL VALVE and THROTTLE BODY! Here, the final AIR/FUEL mixture is fine tuned and adjusted for CITY< stop and go driving! The use of VERY CHEAP OIL makes sludge and TAR that can glue engine sensors TOGETHER! It is the AIR side of all injectors systems ta\hat causes trouble! INJECTORS from BOSCH and DENSO rarely get clogged up, but the IAC and T body WILL from CHEAP OILS that BAKE tar into engine parts, and sensors! This is why there is MOBIL ONE 0W-30 ( most cars) and other REAL synthetic oil like AMSOIL< and PENNZOIL ULTRA EUROPEAN! ULTRA gives a 15 year 500k mile WARRANTY with it< IF YOU PROVED that you used it!
Won't be fuel pump. If fuel injected ? Can be injectors . Plugs. Leads or coil.
If carbs? Can be lack of fuel supply one side though unlikely.
Ideally isolate the misfiring cylinders . Then try plugs..then leads if all misfiring is from one side? We may have coil issue etc.
Why would you think it would be the fuel pump, do you think it would only cause three cylinders to miss fire? Yes it could be the plugs, could be other things to but start with the plugs. Surprise yourself and do all eight.
So I've got 3 misfiring cylinders in a v8. What could possible cause? I was thinking fuel pump, or could it be simply spark plugs?
