Cougsfan

Recently my 12 valve has developed a case of the engine not shutting off when the ignition is turned off. It only does this when the engine is cold. After I drive 10 or 15 miles, it shuts down fine. I assume there is a fuel shut-off valve that is normally closed when there is no power, but that is a guess. Any ideas on what it really is and how to fix it?
Thanks

CarlJensen

Fuel shutoff solenoid has a boot around it that falls apart with time and will jam it up. Easy replace.

http://www.genosgarage.com/prodinfo.asp?number=LB-FS21

Get one here..

infidel

Most times the cause of run-on is worn out starter contacts sticking on and supplying the high amperage lift up coil of the solenoid.
This will burn up the $200 solenoid for lack of a $20 part, take care of it ASAP.
In the meantime learn how to disconnect the shutdown solenoid by pulling it's connector apart to prevent extended run on that will burn up the solenoid and can result in melted wires and even a fire.
You can get contacts here http://www.fostertruck.com/dodge/default.htm

Cougsfan

OK Bill, I believe you, but let me see if I understand. When the starter is engaged, it has a contact that sends power to the fuel shut-off solenoid, letting it send fuel to the injection system. When the contacts stick. it keeps power going to the solenoid after the engine shuts down. Or are there two solenoid lifting currents, one to high amp one lift it and another to hold it open? Is that the danger, the high amperage load? If so would that be a danger at all times, every time you start it?
When you say to disconnect the electrical plug until I replace the contacts, I would assume you mean do that rather than put it in gear and stall the engine if run-on occurs, so it doesn't set there and burn up. And if it shuts off, there is no need to disconnect the plug. Or should I disconnect it every time I start it. (seems like it would die if I did that)
The rubber boot looks and feels fine Carl.
I have never driven it after it stalls, but just stalled the engine the couple times it did happen. The engine seemed to stall easier than expected when it happened. Could it be just out of adjustment?

TRCM

Since you say it stalled easily, it may be out of adjustment, and is supplying just enough fuel to let the engine run, but not support a load.

Either way, it has to be getting an electrical signal to stay open that little bit, or it has a mechanical blockage that isn't letting it fully shut

infidel

You've got the idea. Normally the lift up coil is only energized while cranking
If you just stall it the lift up coil will still be energized. Better to disconnect the connector to the solenoid. If that makes the engine die then you know the problem is electrical, not mechanical binding from corrosion in the linkage.
It could also be the relay (also available from the above link) on the firewall is sticking, not the starter contacts.
Way to check that out is to whack the starter with a hammer, rock, etc when it's running on and see if that shuts it down.

No real set mileage on how long the starter contacts last, depends on how much you start it, but most should be replaced by 100k.
Much better to do it before they give you trouble.
Also a good idea to carry a spare relay in the glove box. They do go out and can leave you walking.