cranking No start.

[PowerAddict]

This started after I did a compression test.

There appears to be no power at the coil. I cannot figure out why? However, if I pull the main wire off of the coil and leave it loose on top, I can see spark when I crank it....what?!

I have the troubleshooting diagram, and it says to check harness and such if there's no voltage at the coil, no step after that.

There is a kill switch, but that just cuts power, If I put 12 volts from the battery to the coil, it still doesn't start.

Any ideas?

 

[Maclin]

Re: cranking No start.

Well, there cannot be spark at the coil wire if the coil has no power. Be sure you are checking for voltage correctly, with key On and one lead (black) on a good ground (not coil negative terminal) and the other lead (red) on the positive terminal of the coil.

Are you sure the rotor is installed?

What all work was done just prior to the compression test? Was the engine running just before this, or is the compression test part of a verification of some level of rebuild.

 

[Maclin]

Re: cranking No start.

If this is after some sort of major work, was the distributor removed? If so how are you sure it is installed correctly or not?

 

[boat1010]

Re: cranking No start.

If you crank it and there is spark from the coil then the next step is to see if there is spark to the cylinders. pull a spark plug wire and see if you have spark. If you have spark at the cylinders then you start looking for fuel... and compression.

 

[PowerAddict]

Re: cranking No start.

Well, there cannot be spark at the coil wire if the coil has no power.

Hence why I'm going nuts!!! It doesn't make sense, I've checked and re-checked a zillion times. Key on, yes.

The rotor is in.

Engine was running just before this. Pretty simple system, frustrating I can't chase it down.

 

[Maclin]

Re: cranking No start.

If it is sparking when cranking that could be because the coil is getting power via the ballast bypass circuit. It may not be getting power when not cranking and key in On. That would indicate a problem in the ballast circuit, assuming your ignition system is wired like that and has a ballasted coil. Even with that problem it should try to start though, then die immediately when the key is released from Start back to On.

 

[gabe4560]

Re: cranking No start.

Hence why I'm going nuts!!! It doesn't make sense, I've checked and re-checked a zillion times. Key on, yes.

The rotor is in.

Engine was running just before this. Pretty simple system, frustrating I can't chase it down.

FIRS T I ASSUME IS A THUNDERBOLT IV DISTRIBUITOR, IF SO UNPLUG THE GRAY CABLE THAT IS THE ONE GOING TO YOUR RPMS GAUGE, SOME TIMES IT CAN BE GROUNDED INTERNALLY. IF NOT FIND THE TROUBLESHOOTING CHART FOR THE THUNDERBOLT IV AND FOCUS ON THE MODULE ($500 PIECE) IF IS THE MODULE THINK ABOUT TO CHANGE FOR SOMETHING VERY SIMPLE AS I DID TO AC DELCO ELECTRONIC SYSTEM AT http://www.michiganmotorz.com/ignition-distributor-parts-distributor-kits-c-32_41_193.html FOR ONLY $300

 

[PowerAddict]

Re: cranking No start.

It is a thunderbolt IV.

Now that you say something Gabe, I remember reading posts about an issue with the grey tach wire causing problems if the tach fails. What are the specifics with that?

 

[Bondo]

Re: cranking No start.

It is a thunderbolt IV.

Now that you say something Gabe, I remember reading posts about an issue with the grey tach wire causing problems if the tach fails. What are the specifics with that?

Ayuh,... Unhook the grey tach wire from the ignition coil, 'n Try it...

If it starts, it's the tach...

 

[PowerAddict]

Re: cranking No start.

okay, update.

So, I do have 12V at the coil. Disconnected the grey tach wire, and it still didn't start

I was able to go through the troubleshooting diagram now and I need a sanity check. The WHT/RED and WHT/GRN wire has a barrel connector so you can pull it apart. So starting with the WHT/RED, I pulled them apart to perform the test. On the wire going into the distributor, there is NOT 12v but on the wire coming out of the harness going TO the distributor there IS 12v.

Then, if I go to the next step below (hooking the main wire from the coil to spark plug/tester and grounding it, out, tapping the WHT/GRN to ground and looking for spark) from the wire coming OUT of the distributor I do NOT have spark when I tap, but from the wire coming out of the harness going TO the distributor I DO have spark when I tap.

I do not like the description of which wire is which, so I had to test them both, and don't know which one is correct. However, it seems that BOTH scenarios point to a bad ignition sensor inside the distributor.

 

[Don S]

Re: cranking No start.

What engine? year? serial number? Lots of answers for not even knowing what you have.

 

[PowerAddict]

Re: cranking No start.

don't have access to S/N at the moment.

1994 7.4l br1

 

[Don S]

Re: cranking No start.

Is this the troubleshooting chart you are using?

 

[PowerAddict]

Re: cranking No start.

Yessir. Except it doesn't have the alpha addition to it. Everything else is the same.

 

[PowerAddict]

Re: cranking No start.

so is the diagnosis correct? Should I get a pick-up for the distributor?

Thanks.

 

[dingdongs]

Re: cranking No start.

a lot of assumptions have been made on this as you never stated your engine or ignition system and people are looking at your picture or profile.the sensor will be the correct component to replace but when you order the new one it will have an extra black wire .make sure this is grounded to a very good ground as many have made the mistake of either not grounding at all or a bad ground was chosen

look here; http://www.ebay.com/itm/NEW-MerCrui..._Accessories_Gear&hash=item231e38ce3d&vxp=mtr

the rotor normally gets destroyed too when removing so this kit may be better if its suitable; http://www.ebay.com/itm/Mercruiser-..._Accessories_Gear&hash=item35c0c3cf38&vxp=mtr

 

[Don S]

Re: cranking No start.

So starting with the WHT/RED, I pulled them apart to perform the test. On the wire going into the distributor, there is NOT 12v

Then you should be going to step 3A (of my picture above), not step 4.

but on the wire coming out of the harness going TO the distributor there IS 12v.

What does that matter? It wasn't even asked in the troubleshooting guide. Follow the guide, and don't make up your own tests along the way, it confuses you and everyone else trying to figure out what you did.

 

[PowerAddict]

Re: cranking No start.

Don, that was my point, I didn't understand which end of the wire they wanted me to test. Thats why I tested each end of the barrel connector.

I did go to step four, and on the one side of the wire there was spark when I tapped to ground, on the other side of the wire, there was not, but it is worded poorly as to which side you need to test from. Thats why I told you what I did, so hopefully someone could decipher which is right.


(example: "remove WHT/GRN lead from distributor terminal" I don't have a terminal on the distributor, they are hard wired into the base. All I have is the barrel connectors located a little further down the wire, that's why I didn't know what the heck they were talking about )

 

[Don S]

Re: cranking No start.

Ok, I see where I confused things. You have the molded in terminals, not the bolted on. DO NOT disconnect the white/red bullet connector. Just use your meter probe to go under the insulation to the connector to check the voltage WHILE it's hooked up.
if you still have 1-12 v. Then go to step 4, if you don't go to step 3A.