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75 Ignition question

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Guest Anonymous

Hello all,

I have a 75 2002 (std. w/ carb. ) that I have recently replaced the head and head gasket. Upon reassembly I now can't get spark to the plugs. Power is going to the starter and acessories but when I turn it over there is no power to the distributor. The coil has been tested and is good. From what I can tell the problem lies in the wiring from the battery/ alternator to the ignition switch and then out to the coil as I get no conductivity from the leads at the coil. None of this though was touched as the head was removed. Has anyone run into this or does anyone have any suggestions on what to test? Thanks for your help.

Brian.

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dude were you at my house this weekend?

im have the exact same problem

im pulling the harness apart in the am.

there's not much to these cars

im sure its some stupid greasy ass wire some where

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Guest Anonymous

Frustrating isn't it?! Let me know what you come up with. I agree these thing aren't that complicated. I thought it may be the ignition switch but the switch has power enough to turn on all the lights and operate the starter.

Good luck.

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mine does the same

i changed out the coil

same business

i know its some stupid ground that is dangling some where...

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On the later 02s, there should be two power supplies to the ignition. One normal power that goes through the resister wire. Another temporary power supply comes from the starter relay when the starter is turning, bypassing the resister wire to give a little extra voltage during startup. To not have any juice to the ignition when the car is turning over means two independent power supplies have failed.

That resister wire is usually all brittle and cracked because, as a resister, it has been dissipating heat all these years. It may be shorting out on on the frame or another wire...that's where I would start.

I ended up putting in electronic ignition and a coil that does not require ballast, so I replaced the two original ignition power wires with a single fresh one.

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well thanks for that....

the prospero chart showed anther wire from the start straight to the coil...but i dont think i ever had one... im gona go make one now thanks

in frustration this is what i ended up doing

real educational.... hope i didnt open a can of worms

:)

post-2785-13667606840981_thumb.jpg

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where is this "resistor" of which you speak?

in the lead that runs from the ignition key to the coil (+), possibly the tail connected right to the coil spade, unless you have a 76, which has a ire that supplies the resistance, no actual resistor.

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Guest Anonymous

Thanks for the schematic. Still can't find the resistor though. On it car the two wires coming off the +on the coil (one blk with red stripe and one solid tan or greyish) feed into a harness that spans the firewall and then enter the car towards the driver-side fender. Then tracing from the ignition switch the bundle if wires enter the firewall but with nothing resembling a resistor. Do you have a picture of where that should be? Thanks

Brian

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yeah that was gone years ago!

gona regap the spark plugs in the am

that fixed a motocycle once that i was workin on

if not ...in goes the msd!

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Hello all,

I have a 75 2002 (std. w/ carb. ) that I have recently replaced the head and head gasket. Upon reassembly I now can't get spark to the plugs. Power is going to the starter and acessories but when I turn it over there is no power to the distributor. The coil has been tested and is good. From what I can tell the problem lies in the wiring from the battery/ alternator to the ignition switch and then out to the coil as I get no conductivity from the leads at the coil. None of this though was touched as the head was removed. Has anyone run into this or does anyone have any suggestions on what to test? Thanks for your help.

Brian.

Put a test meter on your coil (+) to test for voltage (meter + to coil +, meter - to chassis ground), turn your key to start & see if there's any voltage there. If there is, your getting initial voltage off the starter solenoid. Should be 12 Volts. If that's teh case, looking for your resistor would be pointless at this point.

did you remove the distributor for any reason and replace it? is your wire connected from the starter solenoid (top small spade) to the coil (+)??

Did you touch the points? New Cap & Rotor? Ctr ignition wire off coil to Dist tested or replaced?

what color coil do you have? if it's blue, your resistor may have been removed, if black, possibly the wire used in the 76's (?) is in place. I had a 75 & don't recall ever seeing where the resister was, and have seen it's location on a 74 which was quite obvious. A little Too much Resistance won't keep it from running at all though, just make it a week spark vs. a healthy spark.

If you use a test meter you could test the length of wire for resistance. Maybe the wire is the same as used in the 76's. ??

Pictures of you coil and starter solenoid would be helpful.

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Guest Anonymous

Thanks for the info. I'm intrigued by the lead off the selenoid, I don't recall seeing one. I'll get back into it this weekend and then post some pictures.

Brian

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im thinking im may have blown the pertonix....

anyone ever have this experince?

plus im getting 1.8volts on the negative side of the coil

that dont seem right ....

thoughts?

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Thanks for the info. I'm intrigued by the lead off the selenoid, I don't recall seeing one. I'll get back into it this weekend and then post some pictures.

Brian

It allows for a hot spark to get the engine fired on start-up, then when the key turns back, that line is disconnected, and your voltage is then fed via the 2ndary line which has the resistance added.

Your car would still start without that line connected but it would be a slower start. (ask me how I know)

** as noted below, maybe earlier years did not run a wire from the solenoid to the coil, but had a relay that jumped past the resister. I had not heard of that before ****

Good luck.

Scott

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