I need the firing sequence on the 1994 GMC Sonoma from spark plugs to the distributor cap. My brother got the wires mixed up...he doesn't know where the wires go.

My first concern is: how do you know there isn't fire? Did you
1- Check it with a screwdriver inside the spark plug wire at spark plug end to ground. This isn't the right way.
2- Have you check fire with HEI spark tester.
(The right way). To see a spark with the tester there will be 25k the spark to jump to ground and it test the coil working properly.
Now the fire system or ignition spark work this way.

When the engine is turning up to 400rpm the camshaft gear inside the engine makes distributor shaft turning. We often see the distributor gear at the end worn like an eaten apple.
Remove the Dist. Cap Somebody starts the engine look for the rotor if it turns. This will tell you the gear is OK.
P.S; What you call the SENSOR = Ignition Module just to let you know
Hope it helps

You can google the engine size and "firing order" to get a drawing or photo of the firing order online.
Example - - 1990 GMC 350 firing order diagram

seems you,ve replaced just about everything,but i did,nt hear any mention of the coil?

TEST IF THERE IS POWER GOING INTO THE COIL. A FAULTY IGNITION CAN ALSO CAUSE THIS PROBLEM AS IT DO NOT ALLOW CURRENT TO THE COIL.

Need to know engine size however follow this link and it will give you the firing order. Good Luck and a grt day. http://autorepair.about.com/library/firing_orders/bl-gmc-firing-94.htm

Replace the spark plugs and wires along with a distributor cap and rotor. Be careful to leave the old wires and plug wires connected to dist.cap, just remove dist. cap from the distributor and lay aside with plug wires on it then install rotor then new cap and proceed to replace each wire for cap and spark plug one at a time so you don't mix up the spark plug wire firing order. Cap laying to the side is used for reference purpose.

FIRING ORDERS

To avoid confusion, ALWAYS replace spark plug wires one at a time.

The most important thing to remember about the removal and installation of a distributor, cap or spark plug cable is that all wires MUST be labelled before they are disconnected. Keep in mind that these figures depict a firing order where the distributor cap terminals are relative to EACH OTHER only and they do not necessarily depict the tower positions in relation to the rest of the engine. This is true because any distributor which has been removed and reinstalled may have been installed with the No. 1 spark plug tower at any position (360 degrees) in relation to the rest of the motor, as long as the rotor aligned to the No. 1 tower when the No. 1 cylinder was at TDC of the compression stroke (valves closed, ready for the plug to fire). As long as the remaining wires were connected in the correct firing order sequence (depending on direction of distributor rotation) the engine will run. DO NOT EVER remove more than one wire from the distributor cap at a time unless you tag ALL wires and towers to assure proper installation.



Fig. 1: 1.9L engine . Firing order: 1-3-4-2 . Distributor rotation: counterclockwise



Fig. 2: 2.0L engine . Firing order: 1-3-4-2 . Distributor rotation: clockwise



Fig. 3: 2.5L engine . Firing order: 1-3-4-2 . Distributor rotation: clockwise



Fig. 4: 2.8L engine . Firing order: 1-2-3-4-5-6 . Distributor rotation: clockwise



Fig. 5: 4.3L engine. Firing order: 1-6-5-4-3-2 . Distributor rotation: clockwise

I hope help you with this (remember rated this help) Good luck.

Standing at front of truck, looking under the hood.

The closest cylinder to you on your right is #1. #2 is close left. #3 is middle right, #4 middle left. #5 is back right and #6 is back left.

Firing order is 1-6-5-4-3-2. This is the sequence for placing the wires on distributor cap in a clockwise direction. #1 spot on cap is the 3rd post after the wiring harness (clockwise). This post should be closest to cylinder #5.

Question 4.3 Litre V6 or 2.2 Litre inline 4 cyl.

Procedure as follows: in either case remove # 1 cyl spark plug and rotate engine until # 1 piston is at top dead center , with a suitable marking pen make a reference mark on crankshaft harmonic balancer and timing mark indicator on engine timing cover. Make a notation on the distributor cap of the number one spark plug wire and also note the remaining wires firing order sequence on cap in order of rotation. Remove cap and note and mark rotor location , make a reference point on distributor body as well as engine block . Remove cap and wires , loosen distributor lock down bolt , disconnect distributor wire harness and label harness for reference to reconnect upon re-installation. Twist as you pull up on distributor , distributor should come out freely with minimal effort but occasionally they can be a little tough and need to be helped out with minimal extra persuasion...

If you find that upon re-install you get a trouble code P1345 don't threat just start over the process of placing # 1 cyl at TDC and then reference the marks you made during dismantle, There is a + - 3 degrees tolerance that the computer can adapt... But you will have to erase any trouble codes... You should not have to remove the hood, maybe just the air box and or filter housing for easier access.... Unless you are removing entire engine then yes remove hood by all means, mark hood hinges and mounting holes before removing for easier alignment during install of hood... Hope this helps...

Firing order is 1-8-4-3-6-5-7-2 Cylinder numbers looking at engine from front Left Bank 1-3-5-7 Right bank 2-4-6-8 Distributor has clockwide rotation,