PDA

View Full Version : weird electrical problem... won't run



K Funk
11-03-2005, 09:04 PM
I posted this on the other faq, but haven't found where to look yet.

Background: 74 with weber 32/36, mostly stock, still points ignition, but all components replaced about 3 months ago (bosch blue coil, points, condenser, cap, plugs, wires). I've got the good Carter fuel pump in the trunk, and replaced the starter a few nights ago. It was worn down bad, and finally crapped out.

Anyways, yesterday at a traffic light, the motor died. It didn't want to start, and I couldn't hear the motor very well over the traffic. So, I got the truck behind me to push me a little, but it still wouldn't go. I pushed it on into a Burger King for a while. At some point when I was fiddling with it, I left the key in the ignition (with the points touching apparently), and I saw smoke come rolling out. The positive wire leading to the coil had shorted somehow and melted all the insulation off the wire. I know the coil can get hot when you leave the keys in it, but why would the wire get that hot?
Anyways, I managed to get it to fire up a little bit, but it'd die out quickly. I double-checked all my connections going to my fuel pump, as they had been loose before. They were still connected, but I tightened them up some more. Tried to start it again, could hear fuel pump kick on, but the engine died within a few seconds. I checked in-line fuel filter leading to pump, it looked clean and full of gas. I then walked to gas station and bought 1-gallon can and 1-gallon of gas, poured it in carb, same thing.
If it were a fuel problem, it could run 10-15 seconds off gas in float bowl alone. In this case, it was running only a couple seconds after I turn off the starter. It acts like like the ignition system is shutting down for some reason.
I've checked all my wiring on the starter multiple times, and every other wire I know about or can see. I've heard that the ballast resistor can be bypassed during the initial starting of the car, then as the voltage is stepped down a failure of the ballast resistor could result in the engine dying. But I don't think I have a ballast resistor, as I'm using a Bosch blue (internal resistor?). The car had a Bosch blue when I bought it.
I checked the passenger side firewall for any electrical boxes, but nothing there.
Since the coil might've been the problem, I tried swapping it with the old Bosch blue that was in it before (probably not bad, but just replaced it cuz I wanted all new stuff). Still, with other coil the same thing happened.

I've got fuel, as verified with pouring plenty of gas in carb, hearing fuel pump, and seeing gas sitting in float bowl. I've got spark initially, so something must be working with the ignition system. I can rev the engine one time pretty hard before it dies.

So, my only ideas are:
A: there's some weird relay that has gone bad. If so, where is it located?
B: Some other problem (loose fuel pump wire?) resulted in the initial dying of the engine, but now the melted insulation on the coil wire is causing a short that kills the engine quickly.
C: Something weird/bad in the relatively new points, cap, rotor, condenser, etc. It's all Bosch stuff, so nothing weird there.

Beaner7102
11-06-2005, 09:08 PM
KFunk that seams a very weird one. Does the carb have a shut off solenoid? If so that could be faulty, or the relay that powers it could be on the way out. I just read the posts on the FAQ and agree that it could be the start relay, giving you high volts but not low. Do you have a wiring diagram? That could help a lot in identifying wires or replacing the PO wiring abortion. Are you in a roadside assistance assoc.?? Drag the car down the road a bit, call them and say it was fine and just stopped, then some guy comes along and tries to get you going. I’ve done it before. Sorry for no real answers, good luck with it. Beaner7102.

74tii
11-06-2005, 10:18 PM
heh. thats a thought Beaner7102 .. get AAA membership and then stand around like an idiot while they try to fix it (gee idono.. it just quit working).

might be worth the $$ dude.. go for it! If nothing else they'll give you a tow

K Funk
11-07-2005, 12:20 PM
I've got AAA already. It's really handy since I like driving old cars and I don't have the family around to tow me home over here.
I had AAA pull start me when the starter died the one day, and that worked great. Then I just had them tow me home after this problem. I wasn't about to have them fiddle around with the wiring. So the car is sittin at home, but I haven't had the chance to mess with it much. I've had to put put together some presentations for a neuroscience conference.....Luckily I have a friend that left their car with me a couple months while they're in DC, so I have transportation.
But anyways, I may tear into it again tonight if I feel like it. I've got the wiring diagram from the Haynes Manual, but it hasn't been much help. I think I'll just hot wire it up to get it going, then work my way back.

K Funk
11-07-2005, 12:23 PM
Oh, and I replaced one relay that was on the firewall for the heck of it, no difference. Then I opened up the rats nest under the steering column, and there's a crapload of PO riggings and weird relays that aren't supposed to be there. No obvious suspects, but I haven't looked too closely yet.

K Funk
11-09-2005, 03:19 AM
finally played with it a little tonight, but it was dark and rainy so I couldn't do much. I've tried hot wiring it up with some 16 guage wire, but no go. Now it won't fire for some reason. No spark from the coil at all. It's essentially wired in parallel with the starter, so I don't know what the deal is... probably something dumb combined with something weird... Hopefully there'll be better weather tomorrow and better luck.