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I only changed the alternator! Now runs like crap

Old 06-02-2012, 12:34 PM
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I only changed the alternator! Now runs like crap

Just purchased a 1975 280z w 111k mi, driven 200-500mi a year past 10yrs. Drove it over 300-400mi w no problems. My mechanic(good friend of mine) checked it out for overall condition and determined alternator was putting out only 12amps (explains why battery is bad).
I replaced alternator with a Bosch unit he provided me, started and ran engine for couple of minutes to make it was all good...no problems
Replaced distributor cap, rotor & wires and now runs like crap (like timing is off or not firing on all cylinders). Checked and doubled checked wire order. Plugs are getting spark. Even tried putting old cap, rotor & wires back on but no difference. (btw, this is "transistor", not contact points ignition)
Rotated distributor as far to each direction allowable but no better, just slower when retarded and faster when advanced but still running like
My mechanic put the new plugs in to make sure that wasn't the problem but still running like crap and apparently continues to foul the plugs (hence, no lack of fuel). He tried working with the timing but no success. He checked the air gap on the one part (sorry, dont have manuel with me) located under the rotor. He's stumped at this point with limited amount of time he has been able to devote to it.
Wondering if the additional amps (50 vs 12) fried something? (Is it pretty obvious how much of a mechanical rookie I am yet?) here I thought I would have something simple to work on, if need be...Crap, first simple thing I do, like change the alternator, cap, rotor and wires, and now it's screwed up and off the road!

Signed, "Help The Rookie"
P.S., my mechanic is now thinking the distributor may be bad???

Last edited by RonK; 06-02-2012 at 04:21 PM. Reason: Update on troubleshooting
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Old 06-02-2012, 07:13 PM
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It could be you made a mistake on the firing order and /or crossed two spark plug wires. When you tried to go back you duplicated your mistake.
With #1 at 8-9 oclock on the dizzy cap the counter-clockwise order is 1-5-3-6-2-4.
You have a 50 amp alternator that should put out around 14+ volts.
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Old 06-02-2012, 09:30 PM
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Thank You, Theramz for your reply.

The wires we checked and double checked for the correct position
(according to Haynes manual) and in the correct firing order 1-5-3-6-2-4.

According to my mechanic friend, he's is thinking that the alternator is unrelated to the problem, but that it may be one of those "how does this happen?" events where a part goes out (in this case the dizzy) and has nothing to do with the other work being completed.

Over the past 10yrs, the car has only been driven 300-400mi a year. Maybe this was it's time for the dizzy to say "I'm done."

We'll probably end up replacing the dizzy, unless something else becomes obvious or we're made aware of by Monday.
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Old 09-17-2012, 06:10 AM
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Long Story Short.... looks like the Temp Sensor (not "Switch", which btw only pertains to automatics which have dual pickup distributors and rely on the temp "Switch" to control the retarding and advancing of the distributor... My Z is a Manual, hence, the temp switch had nothing to do with my problem)...as I was saying, looks like I bumped the Temp Senor lead while changing my distributor wires. Apparently, the senor "tested ok" but after fixing the lead the sensor then needed to be replaced.

Car is running well but still working kinks out...such as I'm noticing that if the engine is hot after shuting it down for a few minutes, the engine is difficult to start...acts as if it is either flooded or can't get enough fuel initially and slowly ramps up to normal operation.... Ideas??? And Don't Say "It's the Temp Sensor"!?! LOL
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Old 09-17-2012, 08:13 AM
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Are all the plugs gas fouled? If so then something is causing a cold start condition and staying that way. Try disconnecting the cold start valve injector on top of the intake, once the plugs are fouled they won't work until they are cleaned. You can check the injectors with a 9 volt battery and test leads to see if they are clicking on/off. You need to download the FSM so you can step through each sequence of events. It will seem overwhelming at first but you will be okay if you start at the begining and check everthing.
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Or this http://www.ebay.com/itm/1975-Datsun-...439914&vxp=mtr
Or this http://www.ebay.com/itm/DATSUN-NISSA...ca4238&vxp=mtr

Last edited by theramz; 09-17-2012 at 09:41 AM.
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