ignition problem

[Kennymonster]

Bear with me guys, just got a s30 after owning a z32 for several years. I got very familiar with the VG platform, but have never worked on a carburetor vehicle before.

 

Quick summary:

 

- Ran fine as of 2 weeks ago, just had carbs tuned by a mechanic.

 

- It sat for a week, few days ago I drove it around the block a few times to get used to the 6 puck clutch. I noticed a major stumbling/hesitation under load.

 

- Yesterday, I had planned to get the timing checked and carbs retuned to address the stumbling hesitation, couldn't get the motor to start. Realized the battery had gone dead. Flooded it in the process of trying to get it going so I can limp to the shop, didn't happen.

 

- Put in a new battery(25-DL), it cranks fine, now it won't spark. Another look see and saw that the ignition coil has been leaking oil.... must've been for few days. It was overly hot to touch. The vehicle is a 240z with L28 and MSD ignition system.

 

Ok.. so I replaced the coil (with a non MSD brand if that matters), cleaned the plugs. Nothing.

 

Distributor spins, rotor is clean, just not getting any spark from the coil. + and - cables on the coil has power, the main cable from coil to distributor has none.

 

I honestly don't understand what could've gone wrong between swapping batteries, but the coil's been leaking for a while maybe that killed the module? I'm not sure where to go at this point since I think I covered the basics, anything more extensive is foreign territory to me.

 

edit: The new ign coil also gets overly hot to touch, can't rest your hand on it for more than a sec. I cleaned all the grounding wires.

Edited December 11, 2010 by Kennymonster

[go 260z]

I am going to watch this one because i've had the same problem for 26 years. On new years eve in 1984, my wife and i came out of a party and my beloved 1974 260z would not fire but just crank it's little heart out. We got a ride home and the next day i went back with a trailer to get it. When i put the key in, the motor did not turn more than a revolution or two before she was purring like a kitten. I called the Datsun dealership a day of so later to see what it could be. I was told it " MAY BE " the transistor ignition unit that cost then over $800.00 plus labor but they were not sure and when they installed it...it was mine. They would just have to try different electrical components one at a time. I elected to try and trace it down myself and after some time and keeping up with a wife, three children, and a job, the car was parked. Now almost 26 years later, this retiree is tring to put the z back on the road. i hate all those relays and interrlocks in this car. i have most working again or changed out and have just purchased a new crane transistor igintion unit and coil that will replace the original ones, as well as, the components in the distributor. i got it from z source for a little over a hundren dollars. it will be here next week and i hope to get it install around Christmas. i will let you know if it works and if you find your problem out first, please post your solution.

[NewZed]

The GM HEI transistor ignition module (look for 1977 Camaro ignition module at the parts stores) is cheaper ($20 +/- range) than the MSD unit or the Crane, but it takes more work to get it installed right. The links describing the connections for a 280Z, and a 240Z with a later electronic ignition are below. Basically, one side of the module hooks up to the pickup coil in the distributor, and the other side connects to the positive and negative terminals of the coil. Grounding is through the mounting hole on the module. One option if you're on a low budget, or your current setup is all buggered up.

 

I installed one on a 76 280Z, using the stock coil and resistor and leaving the wire from the coil resistor negative terminal (which came from the wiring harness) unmodified, to maintain the signal to tach and ECU. No wires cut or spliced, just two jumpers from the coil to the module, and the distributor wires moved over. The original ignition module is just unplugged (as described in a separate writeup from Atlanticz.ca about the E12-80 distributor swap - another option for you guys) and kept installed as a spare. It performs essentially the same as the original module, but it's about 34 years newer.

 

Be careful that you know where all of your wires currently come from and go to as they might have been modified in the last 30+ years. The Zs that run carbs could be wired up completely independently of the wiring harness, for troubleshooting or just better functionality, except for one switched power source (which could even be a switched hot wire from the battery if you wanted to avoid the ignition switch). You would lose your tach signal though, but that could be wired in separately also, using the wiring diagram for your model.

 

 

280Z GM HEI -

http://www.sonic.net/~kyle/hei.html

 

240Z GM HEI -

http://www.sonic.net/~kyle/ztech.html

 

Nissan E12-80-

http://www.atlanticz.ca/zclub/techtips/distributor/index.html

[Kennymonster]

Update: I left the negative terminal unhooked overnight on my new battery (mainly because the coil gets superheated), after failing to find the culprit yesterday. Today I hook it back up, the battery is almost near dead.

 

I've ran out of time officially since the week's started, I'm now looking into getting it towed to my knowledgeable z mechanic. I will update when the situation is resolved, thanks for all the feedback guys.

[Kennymonster]

Here are the updates for those who search similar problems in the future.

 

Got the Z back today, here's the culprit and final verdict.

 

Lack of spark issue: the MSD box was indeed shorted out, along with the voltage regulator on the alternator (280z type.) Apparently the current set up had an internal regulator inside the alternator AND an external regulator somewhere along the harness as well. One of them is now bypassed.

 

What a pain in the ass, it runs good now though.

[go 260z]

I also discovered that my transitorized igition unit was shorted. I replaced it last weekend with a crane xr700 and a new fireball ps40 coil, now there is a strong spark every time....Next problem is no gas coming from the carbs, she will only start if i put starting fluid in the carbs. I am now learning about these Hatachi su (HJG 46W 8B) carburators.