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New startup problem J13


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Back story...

 

Truck is bone stock except for a Pertronix ignition and coil I installed when I first got the truck.  The truck has started up all the time, every time without issue for the past 18+ months.  For most of that time, I lived in mild Norcal, where the temperature rarely got above 90° or so.  Truck is garage kept, so morning startup has always been even cooler, but after running stop-and-go type errands around town, everything might be pretty toasty on startup... still no  startup problems.

 

Problem...

 

I relocated to north Texas in June, where it's been 100°+ most days.  About a week ago, the truck didn't want to start after a few around-town errands.  It would spin and spark just fine, trying to kick over, but it took several attempts before it started.  It SEEMED as though I was pushing through vapor lock to get it started.  However, this morning it happened again.  The difference this time was that 1) it was the first startup of the day (so in my garage, cool engine, etc.), and 2) thanks to a welcomed cool front, it's only been about 80-85° all day.  So the typical heat-induced vapor lock seems unlikely.  Perhaps it's just the fuel pump diaphragm getting weak?  Or???  Once started, it runs and drives fine, and I've even taken it down the highway a few times at 60+, which would seem to rule out the fuel pump's ability to deliver to the carb.  The plastic fuel filter on the fender is clean (pretty new) and has about 1" of fuel riding in it at all times.

 

I'd rather understand the issue a little before just throwing parts at it.  Any thoughts from the experts out there?

 

 

 

 

 

 

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The carb would be full of gas so it should start even without a fuel pump in the morning.

 

I would clean/check/set the points or replace if worn. Check the cap and rotor for carbon tracking and the wires for splits/cracks... costs nothing to check.

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The carb would be full of gas so it should start even without a fuel pump in the morning.

 

I would clean/check/set the points or replace if worn. Check the cap and rotor for carbon tracking and the wires for splits/cracks... costs nothing to check.

It has electronic ignition Mike.

 

Mike is correct about checking the wires and cap, if any damage or if dirty, the juice can arc out to a ground instead of creating a spark at the plug, I had a very old and dirty coil wire that had a cap that seemed to be made of metal, as everytime it slid down the wire and touched the column metal, the damned engine would not start, I only figured it out because I used a remote start trigger one night when it was dark and I seen the arcing to ground from the dust cap.

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OK, start the engine and let it run for a while, then touch the coil, how hot is it?

Are you using a ballast resister?

 

Coil has had no issues for 18 months.  It is the Pertronix coil spec'd by their tech support when I called to ask questions about the module, which does NOT use a ballast resistor... again, per Pertronix tech support.  I bought both together, installed both together.  I'll check the coil temp, but I don't think that's the problem.

 

See http://community.ratsun.net/topic/52578-anyone-recommend-converting-to-electronic-ignition/?do=findComment&comment=863496

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I pulled cap and rotor today for inspection.  Honestly, they look like I just took them out of the box... no "dust," no metal flakes from the bottom side of the plug towers, no nothing... just absolutely pristine plastic and shiny metal... both parts.  I am going to order some spares from Rock since those are good to have around (I recall a flying rock cracking a cap on a car years ago and the local auto parts place had nothing for me so I was walking for a few days).

 

At this point, I don't really have anything to fix *scratches head*

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Just 2 cents from a previous owner of your truck.  I replaced the fuel pump just before I sold the truck 3 years ago. I bought an NOS pump and then replaced the diaphragm with a brand new one.  That is not to say that the ethynol might not eat through pretty quick, but my guess would be that this isn't fuel related.  The other thing that came to mind was that the alternator is NOT a stock item unless you have reverted back to original. I replaced the original externally regulated alt. with a new internally regulated one.  The one issue I had was that the ALT light would come on at really low RPMs, I assumed because of the difference in pulley size.  I could be wrong.  Good luck.  I miss the truck like crazy.  I check in here from time to time to watch your progress with it.  

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Just 2 cents from a previous owner of your truck.  I replaced the fuel pump just before I sold the truck 3 years ago. I bought an NOS pump and then replaced the diaphragm with a brand new one.  That is not to say that the ethynol might not eat through pretty quick, but my guess would be that this isn't fuel related.  The other thing that came to mind was that the alternator is NOT a stock item unless you have reverted back to original. I replaced the original externally regulated alt. with a new internally regulated one.  The one issue I had was that the ALT light would come on at really low RPMs, I assumed because of the difference in pulley size.  I could be wrong.  Good luck.  I miss the truck like crazy.  I check in here from time to time to watch your progress with it.  

 

Thanks for the details on the pump.  That's good info to know.  It certainly looked (looks) like a clean new-ish pump.  As for the alternator, that's actually "normal," and definitely not the issue I'm experiencing as posted in the OP.  One-wire alternators have to spin at a certain minimum RPM to energize the field.  Only then does it begin charging.  Depending on pulley size, of course, that is typically in the 500-1500 RPM range.  As such, if you were to start the truck and NEVER bump the RPM's past idle of about 600, running the engine would eventually wear down the battery because the alternator would never have energized.  Just a quick blip of the throttle, however, and the field is energized and the charging begins.

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Here is a quick test, if you are having a "cranks, no start" condition.

Crank the engine for several seconds, and quickly go and smell the exhaust.  Smell fresh gas?  It possibly is an ignition problem.  do not smell gas?  Suspect fuel system.

 

In hot weather, especially after being ran, the engine tends to be too rich.  Gasoline evaporates in the float bowl, and fills the intake manifold, with very little air left.  Gas vapors are heavier than air.

Opening the throttle wide open helps clear out gas vapors faster.  Do not pump the throttle, that makes the accelerator pump pump even more gas in the manifold.

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Here is a quick test, if you are having a "cranks, no start" condition.

Crank the engine for several seconds, and quickly go and smell the exhaust.  Smell fresh gas?  It possibly is an ignition problem.  do not smell gas?  Suspect fuel system.

 

In hot weather, especially after being ran, the engine tends to be too rich.  Gasoline evaporates in the float bowl, and fills the intake manifold, with very little air left.  Gas vapors are heavier than air.

Opening the throttle wide open helps clear out gas vapors faster.  Do not pump the throttle, that makes the accelerator pump pump even more gas in the manifold.

 

Thanks for the post.  That's what I was attempting (quite poorly) to describe in my OP... that, when I do spin the starter for a longer period, as the engine is trying to fire over, it will eventually fire up as though I just pushed through the gas vapor problem.  When I just spin the starter, it takes longer to overcome than when I spin the starter AND depress the gas pedal to open up the butterflies.  This is what led me toward a hot start problem relating to fuel.  There is no "fresh gas" smell on either end unless, of course, I flood the carb with several pumps of the throttle.  I think you've provided a much better description of what I have in my head... so now the issue is how to provide a better workaround (or cure) than just spinning the starter so much... they're hard to find, so I definitely don't want to burn it up doing that all summer.

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Do a tune up.  Check compression, adjust the valves.  Set the timing.   If the engine does not knock, on hard acceleration from low engine speed, you might be able to advance the timing a little more.

The spark should be a nice fat blue spark, and jump at least 1/4 to 3/8 or more.

 

Compression, ignition, fuel.  All three, at the right time, and proper amount the, engine will run.  Millions of engine prove that every day.

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Do a tune up.  Check compression, adjust the valves.  Set the timing.   If the engine does not knock, on hard acceleration from low engine speed, you might be able to advance the timing a little more.

The spark should be a nice fat blue spark, and jump at least 1/4 to 3/8 or more.

 

Compression, ignition, fuel.  All three, at the right time, and proper amount the, engine will run.  Millions of engine prove that every day.

 

Thanks, but that sounds like the car equivalent of "clear your browser cache and reboot."   :angel:

 

All the above are just fine.  Plugs are shiny clean, properly gapped, and throw a nice thick white-blue spark (I pulled a plug and cranked it over).  There are no points, so there's nothing left to "tune up" on the electrical side.  I don't have a timing light at the moment, but when I installed the Pertronix, I set it at (IIRC) +6° at about 600 RPM... the owner's manual says 0° at 700 RPM, which can't possibly be very good.  The truck runs and drives great, it pulls smoothly through whole RPM range with ease, runs down the highway at whatever speed I want, idles indefinitely in the driveway, has power (relatively speaking) under load, gets 26 mpg, etc.  It just has an occasional "hot start" issue, and only recently.  It may simply be that the 100° is creating the vaporization problem you described earlier.

 

As for 'compression/ignition/fuel,' of course... but that is a gross simplification of the subtlety of the issue.  Millions of engines run at less than optimal every day too, and mine isn't even one of them.

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No update on this because the weather has been unseasonably cooler than usual.  It only misbehaved on hot days (except that one morning I mentioned in the OP).  Maybe when I took the distributor cap off to check underneath the gremlin escaped  :w00t:

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Had an issue with my 280z exactly like yours.  Ended up being the dwell setting in the distributor.  I used the wrong feeler gauge and adjusted and the car would run fine on startup cold.  But when very hot it would not start.  The dwell was just barely ok but when the distr. and parts got real hot and expanded a bit it increased the gap and it was too much to overcome.  Tow it home, let it cool and starts right up. Found a thread that mentioned dwell and readjusted and it's been 4 years no problems.  My $.02

Good luck

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Had an issue with my 280z exactly like yours.  Ended up being the dwell setting in the distributor.  

 

I hope that's not my problem because I'm using the Pertronix electronic ignition setup, so there's nothing I can do about dwell angle since that's a function of the module itself.  I'll drop a note to their tech support to see if they have seen this (perhaps there's some variability between production runs???).

 

Thanks.

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  • 1 month later...

New datapoint (or possible red herring).  This morning, the problem occurred again... cold start, coolish morning... so it's not heat soak.  However, after 3 spins of the starter, I noticed that the gas gauge was "empty."  I recall geting gas only a few days ago, so I turned the key off, then back on... and the gauge moved to where I would have expected it to be.  I told my daughter it would start next try... and voila... it did.  

 

What I'm thinking here is that the key switch is failing to energize the ignition system, but of course is still feeding the starter.  So, when I'm spinning it, it has no intention of starting.  The only thing that doesn't jive with this theory is that, in the past I haven't turned the key off and back on again between starts.  I've just spun the starter several times until the engine fired up.  Perhaps the ignition switch is extra flaky???  Thoughts?  Blank stares?

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The OIL and IGN lights get power from the ignition switch.  I think the power from the ignition switch goes back out to the fuse box, throught a fuse, and then back the the combo meter, and the OIL and IGN lights.

 

I do not have a 520 wiring diagram, I am working off a 521 wiring diagram. 

On a 521, ignition coil power comes from the ignition switch, and back to the fuse box, BUT NOT THROUGH THE FUSE BOX.  Ignition coil wiring is not fused.

At the fuse box, power from the ignition switch is also split off, and goes to the combo meter, and the OIL and IGN lights.  If you suspect the ignition coil is not getting power, the problem could just be somewhere between the fuse box, and the ignition coil.

 

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The OIL and IGN lights get power from the ignition switch.  I think the power from the ignition switch goes back out to the fuse box, throught a fuse, and then back the the combo meter, and the OIL and IGN lights.

 

I do not have a 520 wiring diagram, I am working off a 521 wiring diagram. 

On a 521, ignition coil power comes from the ignition switch, and back to the fuse box, BUT NOT THROUGH THE FUSE BOX.  Ignition coil wiring is not fused.

At the fuse box, power from the ignition switch is also split off, and goes to the combo meter, and the OIL and IGN lights.  If you suspect the ignition coil is not getting power, the problem could just be somewhere between the fuse box, and the ignition coil.

 

 

Good info.  I'll do some tracing with a meter to see what I'm getting where.  My gut tells me my latest theory is a long shot (though nothing else has panned out as of yet either) because I don't think I've ever lost power driving down the road, even intermittently (ie, coil losing voltage and engine falling on its face for a second)... which is what I might expect to have happened on occasion if it's coil voltage.  It's possible, I suppose, that the fuel gauge needle simply stuck on the voltage-off position that one time, and my prediction that it would start when I cycled the key and saw the needle move was just blind luck.  Or...

 

*scratches head*

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