1981 L-jet US 5spd
i just realized the reason why the wiring harness for the (starter/alternator/oil pressure gauge) looked so damn toasted was due to a electrical fire.. the wires were burnt up and the insulation would just flake off.. all the way to the 14 pin connector..

my question is how did it happen? is it possible that water got sucked up into the air tube for the back of the alternator and fried everything? now that i think of it.. what a dumb design.. i notice the volt gauge isnt reading anything. im sure the alternator is toast. does the alternator power the spark box or anything off the 14 pin connector? if so perhaps this is why the plug to my aux air valve doesnt seem to be getting any voltage which means its staying open and not helping the situation of running rich. HMMMMMM

my other concern is do you think this could have fried the spark box? this may be the reason the car seems to be running in limp mode.. hmmm

i re-wired that whole harness and the car still seems to be in limp mode.. swapped L-jet brains and AFM.. still in limp mode..

buying a used car with problems is like solving a mystery case.

 

the air tube is not a bad design. think about driving in the rain and how much water hits that alternator. its a non issue. the harness is just OLD, and 30 years of moisture gets wicked in tot he wires, and they get corrosion, and short out.... very VERY common.

as far as i know, and I'm pretty sure. early cars do not have a "Limp mode" they, run or they don't. the later cars had a limp mode, but not yours.

its always a fun time figuring out stuff. How are the grounds on the car? O2 sensor? does it change when warm? Ignition boxes can go out i would think , but i have never known of one going out.

how is it with the timing fixed?

 

no limp mode eh? hmm well thats how it seems to be running once it warms up.. i havent checked timing yet.. still trying to make sure no other wires or components are fried.. gona do some volt tests later today.. make sure the spark box is getting power but since the car starts and runs ok cold my guess is the spark box might be fine.. however i think the aux air valve pin at the 14 connector is not getting power... ill re-check today... if that aux air valve is not closing when the motor warms up would that extra air entering the motor cause it to run like crap and RICH!? it doesnt make logical sense to me.. because the air valve lets air into the motor after the AFM flap.. soo that air coming into the motor via aux air valve is not metered air which in turn wouldnt tell the L-jet brain to enrich the air/fuel mixture.. if anything wouldnt the extra air from the aux air valve entering a warm motor cause it to run leaner?
thanks for the response!

 

Melted wires in the front of engine harness are not caused by a ground in the alternator.
Battery is behind the alternator. The power flow in that harness is from alternator to jump post then on to CE panel and aux loads from there. Fuel pump and Injectors feed from the battery. Most other stuff through that feeder from the alternator.

The combination of faults you are chasing, including alternator/charging, melted/crispy front harness, and symptoms of ignition and/or injection failure, point to someone trying to jump-start the car from that jump post, with cable polarity reversed.

 

i would not read to much in to what its doing, until you fix the small things. don't over do it. fix the timing. re do some wires. check grounds. check plug gaps.. etc...

then once all that is figured out.. you can have a mental game of chasing issues.

yes. NO limp mode. NONE...

 

ok that makes total sense.. i can see how some idiot would mix up the cables on a jump start.. makes perfect sense now.. thanks bob for the info on the harness operation..

duc, i have done all the small things already . got the car a month ago and been chasin gremlins since.. the PO had tried to fix it and did more bad than good.. but its relatively a solid car.. i ordered a new green wire so we'll see.. thanks again

 

The alternator & battery are connected together by a big fat wire - they power all the same things (everything). When the car isn't running the battery powers everything, if the alternator is working properly then while the car is running it powers everything (and recharges the battery).

If anything electrical in the in the car works - but the voltage gauge reads zero with the ignition on - then there is a problem with the gauge.

Alan

 

That particular set of wires tends to corrode internally from one end to the other, at least its been typical of east coast cars i've worked on, as well as #6 which IIRC was a NV car, and the insulation becomes embrittled. When that happens they are poor conductors. Its impossible to solder new ends when replacing the 14 pin connector. Best action is buy a new harness or make one.

 

that 14pin wire has a few connections that may cause some issues for you. form the blue wire for the exciter/voltmeter, to correct battery voltage. sounds like wiring issues is your cause to me