Questionable chassis to engine ground

[grasshopper]

Hi all. My 124 Sport Coupe seems to be running on what feels like 3 cylinders. My alternator light is also coming on. As far as I can tell, the entire electronic ignition system and new plug wires seem to be all good. Alternator is new. I looked at the chassis ground wire. The one that attaches to the transmission. The connection that is crimped into the chassis looks like it is hanging by just a few threads. The wire seems frayed where it connects to the chassis. It is still connected but I will try to attach a better wire. Could this be causing ignition problems ? Any idea on what procedure is to crimp a new wire onto that crimp connection under the car ? Do I just use a vice grip to crimp new wire in or should I solder it ? Thanks.

[18Fiatsandcounting]

Funny, I was just responding to another post on this forum today about this very same ground connection from the frame to the transmission (actually the bellhousing if memory serves). Yes, if this is a poor connection, I would imagine it could cause all sorts of problems, but the biggest problem I would expect would be hard starting as the 200 amps or so for the starter has to go through this connection.

If you think about it, without a ground strap from the engine/bellhousing/transmission to the chassis, the starter doesn't have a very good ground. The engine sits on rubber mounts, is fed by rubber hoses (fuel and coolant), even the exhaust system is really not attached to the chassis (hanging by rubber mounts usually). There are some possible inadvertent grounds for the starter such as the clutch cable, throttle linkage, etc, but they were never meant to carry hundreds of amps.

So yes, you need to fix that ground connection. What I would do is dispense with the existing crimp connection welded to the underside of the body, and see if you can find a 9" or so battery cable with lug connections already installed on each end. Try an auto parts store. Or you can make one yourself by soldering some appropriate heavy gauge wire to some round hole connectors on each end. If you're really fancy, you can make it look nice with heat-shrink tubing. One end goes under the bolt on the bellhousing, and for the other end, you drill a hole through the underside of the car (where the existing crimp connection is welded) and use a bolt through the body to tightly secure that other end. Cover with undercoating or paint or whatever for corrosion protection.

I'm not sure this is causing the ignition and alternator issues you mentioned, but Fiats are notorious for acting really electrically funny when the grounds get rusted or disconnected or whatever, and so fixing this ground strap is a good place to start.

-Bryan

[grasshopper]

Thanks for the reply ! I will get on it.

[76was124]

How old is your battery? Some autoparts store will test your battery, alternator and charging system for free.

[grasshopper]

Battery is good. Alternator was replaced last year and should be good as far as I know. I fixed the grounding wire from chassis to bell housing. Engine still runs week as in week spark and charging light is still intermittently flashing. I have replaced the distributer cap, rotor, plug wires, plugs. Could the pick up coil cause this issue ?

[18Fiatsandcounting]

The fact that the alternator light comes on usually means that the alternator isn't putting out much juice, so either your new alternator didn't last very long (some cheaper aftermarket ones just aren't very good), or your voltage regulator is acting up, or the alternator isn't getting the 12 volts it needs for the field winding (the wire could be disconnected or again the voltage regulator isn't right). An alternator (in contrast to a DC generator, or dynamo) produces an AC voltage that is controlled by the current through the field winding (a task for the voltage regulator). The AC voltage is then rectified by diodes to produce the DC to charge your battery.

By the way, if the alternator is weak, and the idle is very low (a few hundred rpm), the alternator light may flicker on. If the light goes off when you rev the engine, it means the alternator is weak but still working.

As for the weak spark, can you describe this a bit more?

-Bryan

[grasshopper]

I purchased one of those newer styled solid state external regulators a while back from A. R. I'm hoping that the problem is not stemming from that. There is also a relay that I hear clicking (This problem is on my 124 Sport Coupe). Should I have a separate ground wire running to the alternator as well as the usual power coming from battery ?

[grasshopper]

,,by the way, the car is running well now. I think I had a bad spark plug ! Go figure !

[18Fiatsandcounting]

Should I have a separate ground wire running to the alternator as well as the usual power coming from battery ?

It sounds like you have found the problem, but to answer your above question, the alternator is grounded through the engine block. Further detail on the alternator wiring: Connected to the screw post, you likely have one large wire that goes to the battery (mine is dark green) along with a black wire that goes to the ignition switch, one yellow wire that goes to the relay for the battery light indicator on the dash, and a grey wire that goes to the voltage regulator (the field winding). The colors and layout may vary depending on model year.

-Bryan

[grasshopper]

Thanks Bryan