Hey all

I know there could be many possible causes of no spark, but what are the most common?

I have heard that a bad coil is one of the first to look at, what do you think?

87 injected 302

Thanks

 

Check both small wires with key on at the Ignition coil with a test light and see if you have power on both.
If not check the plug on the coil real good as this can give a problem here.
If no go unplug the ICM on the distributor and see if power returns to both sides of the coil.
If you only have power on one side then you may have a bad coil.

If you do have power on both small wires unplug the computer with the ICM pluged in and see if the spark returns.

If the spark does not return with the computer unplugged then more than likely you have a bad ICM but could be the PIP sensor inside the distributor also.
There is also the wiring and the plugs that could be bad.

 

I replaced the icm and the truck started then after an hour it died. NOw i don't have spark. I will try those things tomorrow and let you know

 

Mine had a bad PIP sensor in the distributor and It would cut the engine off when it got warm.

 

thats what mine was doing in the beginning. then it went to where it wouldn't start at all. thats when I changed the icm and it started right up. now it cranks but won't turn over, and when checking for spark I have none.

would the pip sensor have anything to do with spark?

 

Yeah,its the thing that tells the computer to send the spark, if it doesnt send the signal the computer doesnt know. Try swapping out the distributor from a buddies truck to see if thats the problem.

 

none of my friends have a 302. is there any kind of test for it? can you replace the PIP sensor or does the distributor have to be replaced?

 

You can test it by using a meter and put it on the 20 Volt AC scale.
Hook the meter to the PIP wire at the distributor and you should get about 6 VAC with it cranking so they tell me. I have never done it as I have a PIP tester.

You can replace the PIP sensor (Stator Assembly, AKA pickup coil) but you have to remove the distributor and take it all apart. Then make sure you put the gear back on (press it on) in the same spot you take it from (not 180 out on the shaft).
That is why most just replace the distributor if the PIP is bad.

STATOR ASSEMBLY with PIP sensor (switch):


It should say above diagram:




If you want to replace the PIP sensor here is how:

1) Rotate the engine until the No 1 piston is on Top Dead Center TDC of its compression stroke. The timing marks on the crankshaft and the pointer are aligned.

2) Disconnect the negative battery cable. Disconnect the wiring harness from the distributor. Mark the #1 spark plug tower on the cap for reference.

3) Remove the distributor cap. Matchmark the rotor position to the distributor housing. Scribe a mark in the distributor body and the engine block to indicate the position of thedistributor in the engine.

4) Remove the distributor hold-down bolt and clamp - Remove the distributor from the engine. Do not rotate engine while the distributor is removed.

5) Remove the two screws going through the plastic cover. Remove TFI unit.

6) Remove the roll or drift pin and distributor gear.

7) Remove the distributor shaft, clean the shaft with emory cloth.

8) Replace the Stator Assembly.

9) Puts the distributor shaft back in and replace the distributor gear by press it on. Do not use a hammer or it can break very easy and you can not get another gear. You would have to replace the distributor if it brakes.

10) Replace the TFI ICM on the side of the distributor.

11) Before reinstalling the distributor - rotate the distributor shaft so the rotor points toward the mark on the distributor housing made previously. Rotate the rotor slightly so the leading edge of the vane is centered in the vane switch state assembly. Rotate the distributor in the engine block to align the leading edge of the vane with the vane switch stator assembly. Make sure the rotor is pointing to the No 1 mark on the distributor base. If things don't line up raise the distributor just enough to disengage it from the gear and rotate it to engage another gear tooth.




Good Luck

 

so i got a 86 bronco with a 302 and, i have changed my pick up coil in my distributer and have changed my rotor, rotor cap, new pulg wires, new plugs and my icm is good. But i get spark then i dont and i really have no idea on what it could be. would it be just bad wires?

 

How do you know that your ICM is good?
If you took it someplace and had it tested that does not mean much.
You need to try another one or replace it then you will know.
This is how a bad ICM acts.

Yes it could be wires but you would have to take the harness all apart to find a bad wire if you have one from the distributor to the EEC Computer.

 

i know my icm is good cause i took it out, and tried it in my dads truck. and it worked like a champ in his truck. my dad thought it was the timing so we took it out and put it in 180 degrees out and it was back firing like crazy and i had great spark. but then we put it back on the compresion stroke and all that but now i have no spark. i really have no clue what i should do next? do you think my timing chain slipped a few teeth? or what do you think i should try?

 

Timing chain will not stop the spark.

 

unless the chain is completely broken.

 

True but he was asking about his "timing chain slipped a few teeth".
If you want to go that route a sheared roll pin in the distributor gear/shaft or broken cam can do it also.

He needs to check to see if the rotor in the distributor still turns when the engine is cranked.

 

ya i checked to see if it turns and yes it turns counterclockwise. do you think that the distibuter is just too far out?