Ignition issues

[Alfadog]

All,

Recently purchased a 240Z from interstate and now having a few troubles actually getting it to start reliably. First it was only cranking intermittently - after a bit of investigation found it was a dodgy immobiliser. Removed that and the issue is solves - but still not quite right - think I'm not getting spark.

 

Car has a Pertronix elec ignition set up and a 3 Ohms coil. Ballast resistor has been removed.

 

I cleaned and regapped the spark plugs (changed from 0.039 to 0.043 given the elec ign) and was able to start and drive it, however it stuttered and carbs backfired a bit. Now maybe it was a fluke but I can't get it going again.

 

After attempts to start, it does smell like unburnt fuel so I think fuel is being provided.

 

I have so far:

- Checked voltage at battery - 12V

- Removed the red Ignitor wire from the coil positive terminal and connected a jumper wire from the positive side of the battery directly to the red Ignitor wire. Attempted start - no dice.

- Measured the voltage at coil when key is in the 'on' position - 10V

- Measured resistance at coil - seemed to settle at 4.5Ohms

- Checked dizzy cap - one of hte clips was broken so have temporarily secured with zip-tie!

- Replaced distributor grounding wire

- Tried to follow the instructions at this site however they say "Rotate the magnet sleeve in front of the module" - however I can't seem to do this. It only budges side to side a smidge.

 

One thing I have noticed is that the wiring doesn't seem to match the Pertronix installation instructions. I have 2 wires from both the +ve and -ve terminals of the coil. Also note I have a wire that is hanging loose near the distributor that is leading to nowhere!

 

(As a side note, I seem to have a few electrical gremlins. Windscreen washer doesn't work, wipers dont return to horizontal, tail lights go off when lights switch from parkers to headlights, horns dont work) - all to be fixed in good time! First is getting it started though

 

Any other ideas? I am running short now...

 

 

[HKSZ]

How old is the battery and how many CCA is it? the elec dizzy needs a big kick, slow cranking fouls the plugs easy on triples and you end up chasing your tail. What coil are you using?

Get it running and bump the timing up to 17 deg

[Six_Shooter]

Have you checked/set the timing?

[Linton]

the lead that is not connected was for original earth to the side of the dizzy goes on the screw in the photo. but I suspect the timing is out and the carbies are over fueling and wetting the plugs it wont go if the plugs get wet, put a known good plug in the lead and earth the plug on the rocker cover and wind it over to check spark just watch the plug electrode. make sure the coil is NOT a ballast type. not sure what the go with the coil wires, one of those two wires triggers the tacho. you don't say if the car has been sitting for a long time might just need fresh fuel.

[Alfadog]

Thanks guys.

 

Car has not been sitting for a long time, I drove it home from the depot and it ran OK but not great (occasional carb backfire, stumbling under load).

 

I don't know how old the battery is (can't find markings on top) but seems ~3-5 yrs. It's 520CCA.

 

The coil is one of these Pertronix 'flamethrower' units, 3 Ohms.

 

I haven't touched the timing... sounds like now might be the time to learn how. Got to get it running first..

[Alfadog]

OK I took a step back and decided to check that it's a spark issue - pulled a plug and tested it - all was well. As HKSZ suggested the plug seemed fouled again though so pulled them all and gave a quick once over with a copper brush.

 

Then it started first time again, easy. A bit hard to keep it alive when cold but pretty normal in my experience. However what isn't normal is the carb backfiring every now and then, even at idle. Idle seems to get slower and slower until it dies. Does that sound like a timing issue to you guys?

[Six_Shooter]

Sounds like you at least need to check timing.

 

[zeds4ever]

 

 

                    Are you running triples or SU carbs. If it's SU'S check your float levels are OK then check to see if carbies are in sync.

             

                                                                    Regards: Alan.

[Alfadog]

It's running triple Dellorto 40s. Not having much luck unfortunately

 

The car ran well a few weeks ago before being transported from WA to VIC.

 

I have now:

Replaced the Distributor cap and rotor

Cleaned up alternator and battery grounds

Wired in a temp ground from distributor to chassis

 

Still no luck.

[Agno]

Sounds like timing to me.

 

Get a friend to hold open the chokes and see if it starts any easier.

[Alfadog]

I decided to look at the fuel aspect of this since I wasn't getting anywhere with electrics. Before checking fuel pressure, wanted to see if fuel was getting into the carbs when accel pressed. Took off the zip-tied filters and tried one - it sprayed. Silly me didn't check all of them, but will have to do that next time. I put some carby cleaner down them and had another go at starting - worked! Voltage at battery when running was 14V

 

OK I don't have a timing light yet, but thought I'd fiddle with the timing anyway and see what we could get.

 

I turned the cap CW to advance it some more and the idle increased (is this normal?). Seemed to run smoother so took it for a drive. No good - possibly worse than before. So I went the other way. It was a bit rough on idle (and even had a backfire then died on me) but driving results are GOOD. Not great, but good. I have no idea what the timing is of course but it's as far back as the adjustment will let me go.

 

Here's a vid. Sorry it's not very exciting. But you can see how the idle gradually decreases and backfires at 0:42

 

Is this fixed? DUnno, will see how it starts again when cold. Once started I'm happy to take it to someone who can properly tune it to run at its best.

 

[gav240z]

Adjusting the timing without a timing light is going to be best guess. I wouldn't adjust it further until you get a timing light on it. I'm not familiar with the petronix units but I'm going to guess you can't adjust dwell now because the points are eliminated?

 

It does sound like an electrical timing issue with the back-firing going on.

 

Does the distributor look like it's in good condition? Older distributors can wear the shaft out and have slop which makes setting timing almost impossible. But cross that bridge if timing goes erratic under the strobe light of a timing gun.

[HKSZ]

Are you trying to tune the motor while its cold? take it for a run first before adjusting things, more advance and webers like to idle at 900/ 1000rpm

To me its sounds like your plugs are fouling and the carbs aren't balanced.

Ive never needed a choke on webers just one pump start car let them rumble into life then drive the car straight away, never let them sit and idle will foul the plugs for sure.