'78 40 rough idle, stalling... (1 Viewer)

[Phatty]

so I drove the 40 to work on Saturday and everything was good. I started it around noon and drive it in the empty field behind work. As I was parking it the 40 stalled out and would not start. I tried starting it multiple times and eventually flooded it and the battery became weak. I let it sit for awhile and tried starting it again. 40 started and had a rough idle as well as blowing black smoke that smelled like fuel.
Yesterday it started it right up, but stalled out, still getting fuel smell in exhaust. Changed plugs and wires as well. May do new distributor?

Any suggestions?

 

[corleykj]

Last week I was having a rough idle issue (and low idle) and black smoke out of the exhaust, and it was in a 78. I thought I was having issues with my alternator causing some low electrical issues inside the cab (blinkers not working at a stop sign).

Anyways, I buddy of mine found a broken connector under the hood that might be an exciter wire to the alternator. Point being, I think with the lose (or disconnected wire) the alternator wasn't charging the battery well, and maybe causing poor running/idling. I was bothered by the black smoke and poor running condition for the previous two weeks. I think it was a white wire, maybe with a blue stripe that runs off the battery terminal to the alternator.

After I fixed the lose wire I haven't had any issues with a low idle and black smoke.

 

[Phatty]

Awesome, I'll take a look today after work. Sounds like a similar issue for sure. Thanks

 

[tls3601]

I have a '78 as well. When was the last time your carb was rebuilt??

 

[Phatty]

Carb was rebuilt 5 - 7 yrs ago by PO.

 

[stock]

Check carb and float. Also wires, distributor. Could be loose. Also, was it colder than normal?

 

[JohnnyC]

Two things you need fuel and spark

A sudden shut off leads me to go with no spark... if it were stumbling ... starving ... then die I'd say fuel

Did you check for spark?

Bouncing around does wonders on poor wiring... did you check all wiring in and around ignition components?

 

[corleykj]

The only thing that led me to wiring on mine was it needed jumped a couple days ago, after idling poorly while I let it warm up and it died. But once hooked up for a jump it would not turn over. So that led me to the wiring causing the inability to start, even jump start. We looked around for loose wires and finally found one. It started right up without a jump. I also haven't noticed a poor idle.

Good luck and keep trying things. The rag over the carburetor trick might clean it or a little or a fuel filter could help if you know you have good spark.

 

[Phatty]

Home from work, changed plugs and wires yesterday. Went to start it and heard a pop like it was electrical. Going to go through wiring tonight.

 

[Landpimp]

the pop, may have been from the dizzy vent, when gas or ozone builds up it can make a pop. (I think 78 is like this)

if it were me...because they(wiring) all fail at some-point....I'd check the Idle control solenoid.

how does it run with the choke out?

Home from work, changed plugs and wires yesterday. Went to start it and heard a pop like it was electrical. Going to go through wiring tonight.

 

[Solace in Solitude]

the pop, may have been from the dizzy vent, when gas or ozone builds up it can make a pop. (I think 78 is like this)

if it were me...because they(wiring) all fail at some-point....I'd check the Idle control solenoid.

how does it run with the choke out?

My '78 dizzy is vented to prevent ozone buildup. EDIT: a 3/8"? hose runs from the firewall to the dizzy. A second 3/16"? vacuum-type hose runs from the dizzy to the air cleaner.

^x2^ check idle control solenoid first... The pop could be from a short in the ICS wire

 

[Phatty]

I hear the solenoid when I turn the key. So I believe that is still working, went over wiring, and still nothing.

 

[Solace in Solitude]

Check your choke breaker and carb linkage and make sure nothing is stuck.

I just remembered, I had this situation... thick black smoke everywhere, rough idle... I even disconnected the choke and still... Then, I checked the linkage and found the choke breaker was stuck "choked". Once I fixed that and reconnected the choke, all was good again. Hope this us your problem as well.

Regarding the 'pop', I don't know... I'd first look for any sign of arcing.

 

[JohnnyC]

went over wiring, and still nothing.

Did you check for spark?

Wiring can 'look' good but actually 'not' be working

 

[Phatty]

I plan on tearing into it tomorrow a bit deeper. I'll let you guys know what we come up with. Thanks again

 

[Phatty]

So I have decided to rebuild the carburetor, and while I'm at it replace ignition coil and distributor cap and rotor. Distributor cap has a broken screw, so that will definitely need some attention. Thanks for the help guys! I'll let you know how it turns out.