Motor won't start

[Paul Thompson 'Hooligan']

Hi Tim

When you say you tested MSD as per MSD ins, did this involve cranking the motor, or grounding the white trigger wire?

If it was whilst cranking, then fine but if not, then it could be that the MSD is not being triggered by the ECU output. (assuming ECU timing output is connected to white wire input of MSD unit)

Also, if you line up the rotor arm with a dizzy cap tower, you can then manually check the transfer of spark through dizzy by manually firing the MSD (earth white wire input having isolated from ECU) and check the spark reaches the output of the plug lead to which the rotor arm is pointing (hope that made sense).

Also - HP pump will likely run for a few seconds on switch on, but does it restart as soon as you crank the motor?

Keep us posted.

 

[Tim Kay]

When you say you tested MSD as per MSD ins, did this involve cranking the motor, or grounding the white trigger wire?

Paul,

Yes, I grounded the white trigger. MSD says not to crank the motor, so I thought that may damage something.

if you line up the rotor arm with a dizzy cap tower, you can then manually check the transfer of spark through.....

In other words, if I were to do the same white trigger wire test and ground a spark plug wire at the plug and line up the rotor, this would indicate the dizzy cap and rotor were normal?

 

[Paul Thompson 'Hooligan']

Paul,
In other words, if I were to do the same white trigger wire test and ground a spark plug wire at the plug and line up the rotor, this would indicate the dizzy cap and rotor were normal?

Basically yes - I am assuming that the white wire is normally the trigger wire from the ECU and was disconnected when previous test was done.

So, rock car in gear till rotor lines up with a dizzy cap tower, say plug 1.

Then, replace cap in this position and remove plug lead from plug 1 and fit a spare plug to it and lie on a convenient chassis earth.

Take out of gear, ignition on, test fire the MSD with white wire, the spark should jump the plug gap.

Of course this does not test the plug under load but proves spark is getting to plug.

My thought is that the ECU is not firing the ignition. If it is trying to, the injectors will be firing, too in sequence or in pairs. You say plugs get wet, but how wet? It could be that they fire when ignition is turned on, esp if throttle is depressed to 'wet the manifold' so to speak (depends upon how setup).

So assuming spark gets to plug, I'd check that pump runs and injectors are repeatedly firing under cranking conditions. If they are and still no start, then I'd guess the ignition out from ECU is either defective or not getting to MSD.

If the injectors are not firing, then check the crank trigger. I've had several Electromotive items fail in short succession and I know there was definitely a 'bad batch' about a few years ago. If I recall correctly, there is a staus LED on the ECU which IF you can see it, it should repeatedly flash when cranking to indicate that a trigger signal is being received by the ECU.

See how you get on with that and fingers crossed.

Please note, a dizzy cap that has a carbon track on it would likely pass this test but could possibly STILL be an issue when turning as the spark 'might' see the carbon track (if bad) as an easier path to ground than the next dizzy turret.

 

[Pat Buckley]

I once helped a friend diagnose his no start by finding the brass tab at the end of the rotor had slipped toward the center of the rotor....

 

[Tim Kay]

So far, using Paul's trouble shooting, the dizzy is getting the charge from the coil. (Ask me how I know!! Inadvertantly finger on ground - wow, what a shock, those MSD Blaster coils put out the juice, swear I smelled wire smoke exiting my ears!! Had to take a moment to get my thoughts back, who am I? where am I?) Still no spark at the plug using the MSD white wire trigger and the rotor on the corresponding plug tower.

This procedure sure seems to indicate the cap and rotor are the culprits albeit by visual inspection they don't appear to be faulty, i.e. cap is making contact with rotor, rotor tip seems ok.

I couldn't find the parts local so I had to order a new cap and rotor, won't be here until Tuesday. At which time I will let you guys know.

Thanks for all the help :bow:

 

[Doug S.]

So far, using Paul's trouble shooting, the dizzy is getting the charge from the coil. (Ask me how I know!! Inadvertantly finger on ground - wow, what a shock, those MSD Blaster coils put out the juice, swear I smelled wire smoke exiting my ears!! Had to take a moment to get my thoughts back, who am I? where am I?)

Congrats! I'll NEVER forget the time I grabbed a cracked distributor cap while trying to set the timing on my step-son's SBC, which was running roughly. My ears still ring!!!!

Hope you've truly found the problem!

Doug

 

[Paul Thompson 'Hooligan']

Fingers crossed then Tim...

And you've probably actually felt the blast of half a dozen sparks from the MSD because it would have given Multiple Spark Discharges from that single dab of the white wire trigger....

 

[Tim Kay]

Sorry guys, I had high hopes a new cap and rotor would resolve my issue and you would all be deserved of a cold one!

Still not able to get any spark at the plugs using Paul's suggestion

..rock car in gear till rotor lines up with a dizzy cap tower, say plug 1.

Then, replace cap in this position and remove plug lead from plug 1 and fit a spare plug to it and lie on a convenient chassis earth.

Take out of gear, ignition on, test fire the MSD with white wire, the spark should jump the plug gap.

Then I proceeded to attached all spark plug wires back to normal and tried to start the motor. Same result, no fire.

Ground wires to dizzy are good, ground to motor is good. The dizzy led's light up. The ECU was serviced last week for any issues.

How is it that the MSD, via white wire test, has voltage to the dizzy cap but that voltage won't transfer to the plug tower via the rotor? Seems to me that would take place regardless of the ECU, no?

 

[Tim Kay]

After a little brain storming with my fabricator, next step is to pull the Accel dual sync electronic distributor out and have it tested.

 

[Paul Thompson 'Hooligan']

So even with a replacement cap and rotor arm you get no spark at a plug, when rotor aligned to a tower, but you do get one at the end of the king lead that goes into the top of the dizzy cap....

VERY strange indeed.:huh:

Was there a light on the ECU? - does it flash on cranking? does the fuel pump run for a few seconds on powering on, then stop but restarts as soon as you crank?

Stranger by the minute this one.

 

[Tim Kay]

Paul,

Yes very strange.

No lights on my ecu (AEM ecu), probably necessary to connect to a laptop which I can do but not too versed in the program.

Fuel pump is constant on, recycles to the swirl pot, fuel pressure is normal (via gauge on the fuel runners).

For certain voltage is reaching the king pin on the cap. Lets say the dizzy is faulty internally, could it prohibit the voltage delivery to the corresponding plug tower? Or, under the white trigger test, should that voltage transfer to the grounded plug regardless?

 

[Scott Calabro]

Do you have a ballast resistor installed Tim?

 

[Tim Kay]

I don't know. what is it, what does it do? (sorry to sound ignorant but electronics.....let's just say I'm learning!!)

 

[Tim Kay]

Scott, if it's what I am thinking then I assume the MSD Blaster coil has it built in, no?

 

[Scott Calabro]

It drops the voltage going to the primary windings in your ignition coil, so it does not overheat and burn out.

It could be that its resistance over the years has gone up, further dropping voltage to the coil which could result in little to no spark.

It is a white ceramic block that looks like the picture.

I am not familiar with the MSD coil, but it can't be hard to OHM out that coil with some info from MSD's website.

At least you can then eliminate the coil.

 

[Al Jones]

Take the wire from the coil out of the dizzy and place it NEAR the block,assuming you have the block well grounded,about 1/4 to 1/2" away. When you turn the engine over it should jump that gap. If not,coil wire is NG. The only place the spark travels from there is through the cap node to the rotor and out to each cap plug node. If the cap and rotor are new,it means the coil is being fired out of sequence with the rotor lining up with a node. Mark your present dizzy location with a line on it and the manifold/block. Now rotate the dizzy a little bit at a time - it should line up at some point and fire the plug. That will verify the crank trigger. Possibly a tooth off for whatever reason (dizzy never seated, sheared drive pin you can't determine by 'finger tight testing', etc). Go from there.

 

[Tim Kay]

If the cap and rotor are new,it means the coil is being fired out of sequence with the rotor lining up with a node. Mark your present dizzy location with a line on it and the manifold/block. Now rotate the dizzy a little bit at a time - it should line up at some point and fire the plug.

Al,
Using the MSD "white wire trigger" method (decribed above) there is no fire sequence by the coil. The coil sends voltage as soon as ground is made. Once the rotor lines up with a tower that has a grounded plug it should fire that plug. It's not.

 

[Randy V]

Sorry to hear that you're still unable to get her going...

If you have secondary current to the cap, but not to the plug - the only thing I can think of is that the trigger is out of phase with the cap/rotor..

How does that happen? Some distributors have adjustable cams/trigger wheels. It may have come loose or moved somehow.


--edit--

Al,
Using the MSD "white wire trigger" method (decribed above) there is no fire sequence by the coil. The coil sends voltage as soon as ground is made. Once the rotor lines up with a tower that has a grounded plug it should fire that plug. It's not.

The Trigger event and the alignment of the cap to rotor must coincide.. If not - there's a phase issue..

 

[Jac Mac]

Hook your timing light up, refit all leads etc as per normal. Place the plug inductive pickup over the Coil/Dizzy HT lead & crank the motor ( You should have lots of flash's evenly spaced--- this means that all is well in the dizzy & triggering as per normal--- now place the inductive pickup on the individual plug leads--- flashing should now be even @ longer intervals......if nothing or intermittent then its a dizzy/msd problem or possibly a faulty connection in the small red? wire that supplies 12v to the MSD from key.)

 

[Randy V]

Using Jac's Timing Light idea....

If you put a mark on the distributor body that is in perfect alignment with each of the 8 spark plug lead towers on the distributor cap, then install the rotor and clip your inductive pickup on the coil wire - you should see the rotor's action FREEZE on each spark delivered to the timing light. When the rotor freezes - it should be in almost perfect alignment with the mark on the distributor body...

This should verify phasing...