ChrisPickup

My son recently purchased his dream pickup, a 94 dodge with the cummins diesel. The prior owner indicated the fuel shutoff solenoid was bad, and that it needed to be replaced (he said he had already replaced it once before). It has worked on an intermittent basis, but not consistently. In working through the problem, however, I'm concerned it may not be that simple. This weekend I replaced the starter in the truck for him, and while sitting in the shop I heard a sizzling, and looked up to see a puff of smoke coming from the fuel shut off solenoid, and it was extremely hot. When this happened the key was in the off position, so I'm presuming it should not have been under power. In checking the plug for the solenoid, it had power with the key off. Backtracking, I pulled the relay, and had 12 volts at two of the terminals even when the key was off. In addition, the ignition switch will not activate the starter now..... The switch has been touchy in the past, so I believe it is tired...

My questions -
- Should the relay have power when the ignition switch is off?
- Is there an interlock between the fuel relay and the starter - I thought I read this somewhere, but now can't find it.

I have a new relay, but am hesitant to install it because of my concerns about the ignition switch. Also, I have to figure out if the shut off solenoid was totally fried by the "sizzle" or not.....

Any suggestions would be greatly appreciated.

Mark

rharveysr

Mark...

http://www.fostertruck.com/dodge/default.htm

Call them and talk to Larry...they are great folks to work with!

Rick

infidel

My bet the only problem was the key switch although the solenoid may have burned up in the process.
Napa has the '94 key switch for about $30.
You will need a torx security bit to remove the old one.

bdshort86

I read somewhere on the site (now I can't find it) that Radio Shack sells a relay that seems to at least *work* for temporary use. It also gave the part # for that relay. However, the part number it gives is for a male pronged relay. It's the right size and the contacts seem to be arranged correctly, but there are already contact prongs up in the fuel pressure shutoff relay socket.

Anyone got any suggestions for a different Radio Shack part number to try for the relay, or another suggestion of where I might find one? The dealer isn't open on Sunday and it's a little annoying to have to pop the hood and raise up the fuel pressure shutoff plunger everytime I want to start it...

TIA

kerryneb

Mark,
Internally the fuel shut off solenoid has 2 coils. The 1st is to help initially pull in the solenoid, the 2nd is to hold it in. Pull in is activated when the key is in the start position, hold in is activated while the key is in the run (and start) position. Pull in draws more power and will cause the solenoid to overheat (and possibly fry), and should only be activated with the key in crank position. There should not be power to the solenoid (neither pull in nor hold in) with the key off. Follow the link in rharveysr's reply for more info and a wiring diagram.

TIA,
There's a blue wire coming from the battery bolt, the connector often gets corroded and makes poor contact. It feeds power to the pull in relay.

bdshort86

That's good info... but it really doesn't help my case. My relay actually fell out of its socket and that's why it's not working.

John Faughn

Go to NAPA and get a new pigtail for the relay , then when you go looking for a new relay from aftermarket , it will need to be a 70 amp rated .
But like Infidel mentioned , replace the ing. sw. 1st then see if the solinoid works , but you'll want to check the draw of it [ not over 70 amp ] if it burned the wrong way it could work but draw too much and cause more probs.