Spark plug wiring diagram

missing is not always the plugs ,HT leads distributor . Most times it is from misfiring injectors and low fuel pressure.

go to a parts store and open a book called specs for that type engine or call the dealer and they will give you the order of firing you need free also ask for distributor firing order this will allow you to match the distributor to the spark plug order on engine

i just put a new fuel pump no a 1999 chevy 2500 cargo van,it still will not startit has a 350 in it,can someone help me

Below is a diagram which shows the wire numbers and their corresponding position. Best of luck!
Greg

1999 Chevy Suburban K2500 7.4L

firing order for 5.7 v8 is 1-8-4-3-6-5-7-2 mostly all of the chevy v8s are the same firing order. the rotor button in distributer turns clockwise, the cylinder numbers are 1-3-5-7 on drivers side, 2-4-6-8 is on passengers side. To get started get your distrutor cap[new one] look on the top you will see a #1that's where you begin you must know if if rotates clockwise or counter clockwise start in that direction then follow the firing order and cylinder line up. good-day!! if cap is not marked, just pull out #1 plug, put a straw or similar in plug hole on top of piston. turn engine over by crank in front of vehicle with a wrench, when the piston comes to the very top just before it starts going down. this is tdc. and rotor button should be pointing to #1 wire on dist, cap. follow from there. good-day !!

firing order is 1 8 4 3 6 5 7 2 standing in front of truck. cylinders on passenger side facing you are 2 4 6 8 cylinders on driver side facing you are 1 3 5 7 now this is your spark plugs wires location on distributor cap.with distributor facing you.2 plugs wire on cap 6 oclock position 1 plug wire on cap 8 oclock position,8 plug wire on cap 9 oclock position,4plug wire cap 10 oclock position,3 plug wire on cap 12 oclock position,6 plug wire on cap 1 oclock position, 5 plug wire on cap 3 oclock position, and 7 plug wire on cap 5 oclock position. in order for this to work you must be standing facing the engine all plug wire location on cap should be correct.

1-8-4-3-6-5-7-2 chevroletpics.blogspot.com
I found the firing order and a picture of the engine. Hope this helps.

Check the plug wires with a spark tester, to see if they all spark good. That will verify all of the parts you replaced. If they look good, do a compression test on cylinder five.

Have you checked the coil

this trucks have very coming problem with the injectors stuck open or close, and some times they just works great and some does not, dealer has an updated injector assembly, i recomend you to install this update and spark plugs and plug wires, if you had replace plugs and wires recently just redo the spark plugs with the injectors