Engine won't turn off
09-28-2017, 08:56 PM
#1
Junior Member
Thread Starter
Join Date: Jun 2017
Posts: 24
Likes: 0
Received 1 Like
on
1 Post
Car: 1984 Z28
Engine: 350
Transmission: TH350
Axle/Gears: 3.73
Engine won't turn off
I have an 1984 Z28 that I just put a 350 in. The key starts the car but does not turn the engine off. Any ideas?
09-28-2017, 09:17 PM
#3
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Engine won't turn off
Did you install an MSD ignition box at the same time?
It is common for the alternator to back feed through the ignition box and keep the engine running. The fix is to install a diode.
It is common for the alternator to back feed through the ignition box and keep the engine running. The fix is to install a diode.
09-29-2017, 01:40 PM
#4
Supreme Member
iTrader: (1)
Join Date: Sep 2005
Posts: 26,029
Received 1,663 Likes
on
1,261 Posts
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Engine won't turn off
As always, see my signature.
Changing those parts didn't make the parts, or the design of the system, suddenly defective. That is not "the simplest explanation".
The simplest explanation is a workmanship issue.
Check for a short between the "motor" terminal of the solenoid (the one with the little copper strap going into the motor body) and the wire to the S terminal. Wire wrapped around something, loose strands, hooked up wrong, etc.
It's not impossible that the solenoid itself is bad, but it isn't as likely. Probably the second most likely: 95% chance it's wiring, 5% the solenoid, 0% anything else.
Changing those parts didn't make the parts, or the design of the system, suddenly defective. That is not "the simplest explanation".
The simplest explanation is a workmanship issue.
Check for a short between the "motor" terminal of the solenoid (the one with the little copper strap going into the motor body) and the wire to the S terminal. Wire wrapped around something, loose strands, hooked up wrong, etc.
It's not impossible that the solenoid itself is bad, but it isn't as likely. Probably the second most likely: 95% chance it's wiring, 5% the solenoid, 0% anything else.
09-29-2017, 07:54 PM
#5
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Engine won't turn off
Did he mean continues to crank, or continues to run?
09-29-2017, 07:56 PM
#6
Supreme Member
iTrader: (1)
Join Date: Sep 2005
Posts: 26,029
Received 1,663 Likes
on
1,261 Posts
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Engine won't turn off
Right: sorry. That's what I get for doing this on a phone. Ignore me.
Trending Topics
10-08-2017, 09:37 PM
#8
Supreme Member
iTrader: (1)
Join Date: Feb 2017
Location: Meriden, CT 06450
Posts: 4,030
Received 511 Likes
on
428 Posts
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Engine won't turn off
Yes, that'll do that also. I assume you added a relay?