Z dies after warmed up 77 Z Drives For About 10 To 15 Minutes,then Dies.

[Crazy477280Z]

Heres a confusing one,at least it is for me. I have a 77 Z that I drive daily. 4 days ago it died on me. It started up again after a couple of minutes,but died again a few minutes later.Long story shortened...In the last 4 days, I have replaced coil,EFI combo relay,and cleaned and checked every elec. connection I could find. I still have same problem. Car will idle indefinitly,but will only drive for about 15 minutes at best.and then dies. It will start again after a minute or so.Ime beginning to suspect that it might be the TIS on the passenger side behind blower motor. Any body have any ideas? I know those trans. ignition systems arent suppossed to go bad all that often,but I would like to know if this is feasible with these symptoms.

[EuroDat]

My TIU went bad last year. I had similar issue that you described. Drive 15 - 20 minutes and it would start running rough and stop. After 10 minutes it would come back to life and I could just get it back home.

I changed it for a GM HEI module and have not had any problems with it since.

Did you check for spark when it started playing up?

If you take a spare spark plug witb you the you can hse it on the coil lead to see if its still working. Get someone crank the engine while you test it. Also dothis test before it starts misbehaving. That way you will know what the spark will look like when its working properly.

Chas

Edit: added link to my Hei module thread. Note I bridged over my resistor because I was using a 12 volt coil. If you use a 6 volt coil then you don't need to do that.

http://www.classiczcars.com/topic/49588-fitting-a-hei-module-in-transistor-ignition-unit-1977-280z/

Edited March 1, 2015 by EuroDat

[rossiz]

are you sure it's not a fuel issue? could be crud in the filter or in the little screen at the fuel pump, or even an intermittent fuel pump. there are a few posts/threads on here about fuel pumps that pump fine at first, but then taper off as they warm up. 

 

a quick test to see if you're fuel system is at least flowing: engine off, pull the connector off the oil pressure sending unit (passenger side, mid-block) and then turn the key to "on" position and the pump should run, circulating through the rail and back to the return line into the tank. without the engine running you should hear it swooshing through the lines at the engine bay and hear the pump going at the rear (up behind passenger side rear wheel). this won't tell you if you have enough pressure - you'll need a gauge for that - but at least it will test for flow...

 

if you don't yet have one, it may be a good idea to put a clear filter between the tank pickup and the fuel pump - cheap insurance and an easy visual on the condition of the tank.

Edited March 1, 2015 by rossiz

[Zed Head]

Sometimes the tachometer needle starts acting weird when the module is going bad, also.  And the needle will go to zero right away if spark stops and you're coasting in gear, whereas it will still show RPM if you're coasting in gear and it's a fuel problem.

 

Just a clue to look for while you're in the driver's seat.

[Crazy477280Z]

thanks for tips. I willl change filters as it has been a while but I dont think it is a fuel issue.Tach does drop instantly to 0 when it dies and it doesnt take long to start back up...In fact,it died when I was 3 blocks from home,and I was able to compression start it within a block of home.I had thought coil was going bad and failing after warming up due to how tach was acting when it died which was why I had replaced it. It still died after warmed up,and this time I heard EFI relay clickas it died so I replaced that. SAME THING.So Iwent through all connections I could find that were related to fuel,ign.,and spark. then I ran fuel injection tests through ECU,and replaced water temp sensor,and auxillary air valve,and now cold start system works right,but it still dies after warmed up. I will replace filters and see what that does,but Ime still suspicious of trans ign unit.Is there a way to test the ones on the 280z?OR IS THERE A WAY i can connect a matchbox dizzy to my 77 and bypass the one inside car?

[EuroDat]

If you want to bypass the TIU you can. Just buy a cheap GM HEI module and mount it on a aluminium plate next to the coil. Disconect the harness to the tiu so it won't interact with the gm module.

I would be more inclined to test the fuel system before doing this. A gauge between the filter and the fuel rail.

If possible run the gauge out to somewhere you can see while driving. It could be starving of fuel.

Chas

[SteveJ]

If you want to eliminate a fuel issue, check the fuel pressure.

 

Download the fuel injection bible from http://www.xenonS130.com/reference.html, and read through the troubleshooting. Doing proper diagnostics beats the crap out of shotgunning parts.

[240260280z]

.........Tach does drop instantly to 0 when it dies ...............OR IS THERE A WAY i can connect a matchbox dizzy to my 77 and bypass the one inside car?

You found the problem. It is the ignition unit. Here is how to upgrade as you rightly suggest. Www.Atlanticz.ca/zclub/techtips/distributor

[EuroDat]

Tach does drop instantly to 0 when it dies and it doesnt take long to start back up...

I missed that. Blue is right, that is a dead give away the TIU is stuffed.

chas

[Zed Head]

t.Is there a way to test the ones on the 280z?OR IS THERE A WAY i can connect a matchbox dizzy to my 77 and bypass the one inside car?

You could hook up a meter and run it through its paces but the tach is a meter and driving is a good load test.  The problem with testing them is that they tend to fail under usage, when heat builds up internally, so they'll test fine but still fail when they get hot, just from current passing through the transistor.

 

Looks like 77 stopped using dual pickups so either the GM HEI module or a complete ZX distributor swap would work for you.  You might examine your distributor first and see what shape it's in.  If the breaker plate bearings and holder are toaste (common), or there's slop in the shaft (eyeball the reluctor/pickup gap) then a ZX dist. swap might be the best bang for the dollar.  Otherwise, the HEI swap is cheap and effective, but takes a little bit more wiring work.

[Crazy477280Z]

Thanks for the advice. I have fuel injection bible,and ran through tests yesterday because I did have a warm up issue.That led me to replace water temp. switch and aux.air valve.I replaced fuel filters and then drove it.Same thing...tach instantly dropped to 0. then started up one minute later.7 times later,I pulled into driveway.YEP...Ignition unit.So I looked at link from Blue(THANK YOU-MUCH APPRECIATED)and thats the way Ime goingto go since I also own a 80 and a 81 ZX with alot of spare parts.Inow have another question...I have two ZX dizzys...one has the module on side with the two spade conneon top. The other one is the same except that it also has some sort of sensor plug on the side of module.My question is...Can I remove module with sensor conn.,and replace it with correct looking module?The dizzy that has correct module on it is pretty worn and vac. advance doesnt work.NO.-D6K8-02.The other dizzy with incorrect module...NO.-D6K81-01...is in great shape with working vac. advance. So what do ya think?

[240260280z]

Yes you can swap them. Just two wires (red and green) to connect/disconnect.

Note: The vacuum canisters may differ and give different amounts of advance but you can swap those too.