L24 - Poor spark... debug ?

[biddljj]

I am currently trying to get my 72 240Z running... It tries but won't keep running.... Plugs are wet looking...... With the ignition "Nn" I see

very little spark at the points... I get little sparks when I short the points

using a screw driver..... I tried hot wiring the car to the positive side of the

coil without success. I am thinking I need paints and a condenser at least.

All help is greatly appreciated

zdisease

[biddljj]

I ment to say With ignition "On" I see very little spark at the points.

[Weasel73240Z]

How old is you coil? Low spark, I'd look there 1st.

[biddljj]

The Coil age is unknown...... Does it make sense to just replace it...

Thanks, zdisease

[beandip]

I have never seen much of a spark at the points. What does the spark look like when you short the main coil wire to ground? Or doing the same with a plug wire. The coil wire should have a blue spark jump about a inch or so. You will need to have someone cranking the engine over to do this test . Just having the key to run does nothing here. This is vary basic, and I don't mean to be talking down to you. Not knowing your level of experience . Your points are only receiving about 8 volts so any spark there is always minimal.

Gary

[Weasel73240Z]

The Coil age is unknown...... Does it make sense to just replace it...

Thanks, zdisease

Disconnect the coil plug wire from the distributor. Put a philips screwdriver inside the coil wire, and place it about a 1/2" away from one of the 3 strut tower bolts (they are grounded). If you don't get a bright blue spark when you crank the engine over, jumping across the gap to the bolt, the coil is probably bad.

P.S. - Don't hold the coil plug wire when you turn the engine over, if there's any flaws, cracks or tears in the wire insulation, you could get a good shock.

[biddljj]

I did the Coil test tonight.....

I grounded the coil wire to the Strut tower and got a very health spark.

I used a plastic handled screw driver and still got zapped a bit...

Is the next test t check if the spark plugs are firing ?

Thanks for the advice,

zdisease

[Curtis240Z]

If you grounded the spark plug wires and tested it like you did with the coil wire, then time to concentrate on the fuel side of the equation.

[Weasel73240Z]

I'd confirm you're getting spark at all 6 plugs the same way. You could have a damaged dizzy cap or rotor, perhaps only 4 or 5 of the 6 are firing. So test each plug individually, you should get a good spark, not as god as the straight coil spark. I usually test plugs by holding the plug itself against the strut tower bolt, that grounds it like when its screwed into the plug hole. If you get spark at the plugs, spark/ignition is not your problem.

Have you checked timing? You should be around 7 degrees BTDC. Have a friend crank the car over while you use a timing light. Even without it running, this should tell you if your at least close to correct timing.

Fuel, spark and timing. Thats what you need to run. You seem to have confirmed spark, now confirm timing, them move to fuel. Thats how I always approach these things anyway. If your timing seems right, try using a little starter fluid into each carb before cranking. If it runs for 5 or so seconds on starter fluid, you probably have a fuel problem.

Edited October 27, 2008 by Weasel73240Z

[beandip]

If you are running the stock air cleaner, just spray some starter fluid in the intake ''horn'' of the air cleaner. About a 3 sec. burst. this should get the engine to at least try to start, if you have spark and the timing is right. Gary

[biddljj]

I will test tonight.....

Plan 1: remove each plug and ground against the strut insulator bolts while son turns over engine confirm good spark.

Plan 2: Hook the timing light to #1 cylinder and check timing for 7 degrees BTDC

I've already tested starter fluid straight into the carbs.... no change

As always... Thanks for the clues

Not just a Z - zdisease

[biddljj]

I tested all the plugs one at a time by removing the plug, putting it back into the

plug wire and short it out directly to the strut insulator bolts.... All the plugs have about the same spark.... All the plugs were wet looking also.

Next I hooked the timing light up to number 1,, high lighted the timing marks on the crank

When we turned it over the timing marks were no where to be seen.....

I had the valve cover off and found top dead center on the #1

Timing marks lined up... I noted where the rotor was pointing (pointed up toward number one cylinder or about 12 oclock). I started started

replacing the wires according to the timing order 1,5,3,6,2,4 counter clock wise around

the distributer cap. Still no timing mark

I did replace the oil pump on this motor but never messed with the distributer.

There is very little play in the distributer shaft.....

All clues greatly appreciated....

Not just a Z - zdisease