Engine/Transmission (1994 - 1998) fuel shutoff solenoid relay

[Cavaness]

Ok, here we go. Not too long after i purchased this truck {1995 3500 dually 5spd brand new motor} the truck wouldnt start. So i got on here and perfromed a search {which took forever because the search engine on this site is not the best} and checked the soleniod and the relay. I replaced the relay. Everthing works great. i drove the truck for a month everyday with no problems. Then the other day i was driving through a intersection and the truck died. Well I keep zipties with me and ziptied the solenoid up. truck fired up and i have been driving it since. Question is what is causing my $40 relay to go bad?

 

[Bob4x4]

Check the 12v supply first.



Bob

 

[Ruckuz]

About once or twice a week, i'll go to start to monster... and it will crank but won't fire. I turn the key off, back on, try again, and it fires no problem. Think they just like to make sure you're still paying attention to them

 

[Cavaness]

I have 12v all the way to the solenoid. i do not have 12v to my ativation wire via relay. everthing is good all the way up to my solenoid. hence my dilema. im just not going to buy another relay until i figure out the problem. thanks.

 

[Cavaness]

well i have my wife turn the key and crank the motor and the solenoid rod does not move. but if i reach down and pull it up by hand it fired up.

 

[DBraunig]

This may help





FUEL SHUT DOWN RELAY CAV CIRCUIT FUNCTION

1 A18 10RD/BK FUSED B(+)

2 T40 12BR ENGINE STARTER MOTOR RELAY OUTPUT

3 Z12 18BK/TN GROUND

4 A123 10RD/VT FUEL SHUT DOWN RELAY OUTPUT





Dave

 

[Joe G.]

Check the blue wire on the positive post of the driver's side battery. It's a fusable link. It could be corroded or loose.



Don't spend $40 for that relay. It's a standard 70 amp automotive relay. You can get one for about $10 at an electronics components store (except for Radio Shack). If it has a mounting tab on it (some do) just cut it off. A 30 amp automotive relay from Radio Shack will last quite a while, especially if the truck starts quick. It's about $7. The draw on that circuit is about 40 amps. The difference in appearance between the 30 and 70 amp relays is that the load terminals on the 70 amp are a lot wider than on the 30 amp.



The rubber boot on the solenoid could be torn and getting tangled in the works. Or the linkage is rusty.

 

[JDutton]

I got a bunch of relays from Parts Express a few years back and still haven't run out of them. The price is right and I haven't had any go bad on me:

http://www.partsexpress.com/webpage.cfm?&Webpage_ID=3&CAT_ID=35&ObjectGroup_ID=746&SO=2

(I got the $1. 39 generic ones)

 

[stumphumper]

fuel shut down relay

Having problems with my fuel shut down relay also and thought I could jump on this thread for some help.

I have a good solenoid and relay but the solenoid will not pull up when the key is in the on position but it will stay up and hold if i pull it up. I have no power to my coil side of the fuel shut down relay. My truck is a 95 and my tech manuel shows the first connection suppling power to be C125 and having a T40 12BR wire yet DBraunig's drawing (I got it enlarged) show a C127 connection.

I traced mine back to the engine starter motor relay contact 87. That relay has +12 at contact 30 so I started tracing the Engine Starter Motor Relay coil.

My book showed to look for connection C132 ( I have an automatic xmision) but I could not find that connector so I followed the print to the Ignition Sw.

But this is where I get lost!

It shows +12 v is applied in the start position coming out of pin 7 and I need to have +12 at my Fuel Relay in the RUN position to Pull up the solenoid right.



Help, will the super wire tecH show me. I have looked through a lot of past TDR Issues and threads but I have not found any that trace out the lack of power to the coil side of the relay.



Wow that was a lot of typeing Hope to hear back. Thanks Ken

 

[Joe G.]

You need 12 volts at the fuel solenoid relay in START position. The high current coil in the fuel solenoid is used to pull up the fuel solenoid when the key is turned to start. The low current coil of the fuel solenoid is connected to the run circuit. You should have 12 volts on one of the pins of the fuel solenoid relay at all times. That is the 12 volts that is connected to the fuel solenoid pull up coil by the relay. The source of that voltage is from the blue wire on the positive post of the driver's side battery. Remember, the fuel solenoid relay is ONLY used in start position. NOT in run.

 

[Ruckuz]

I had a shop change the fuel filter on my truck a while back. About 10 starts later, fuel solenoid wasnt going up. Would stay there once it was pulled up though. Found the blue wire from the drivers batt + was ripped right out. Check out the wire, maybe replace that as well... ? could be worn out inside.

 

[Driftwood Ram]

Another vote for "check the blue wire"!! On my buddy's '95 it looked good, but one little tug and it came off in his hand.

 

[stumphumper]

OK, now that make sence! All my reading and line tracing was correct but I misunderstood. I thought it was suppose to have been in the up position before the key was turned to start position. I will go back out today and start the hunt for the missing voltage in the start position. I do have the +12 vdc from the battery to the relay pin 30. Thanks for the help again. ken

 

[stumphumper]

It's a working... but boy do I feel stupid. After replacing the solenoid and seeing it not pull up in the run position, I just started troubleshooting the wiring till it got to dark outside. so. . today I turned the key to start and ... it started! : sometimes it's just toooo easy. Thanks

 

[stumphumper]

I also wanted to pass on that I bought the new fuel shutoff solenoid from "jpwjdiesel" off of ebay for $199 with shipping total = $207. Fast shipping and a much better price then the dealership! Have a Great Day!

 

[Katmandu]

It's a working... but boy do I feel stupid. After replacing the solenoid and seeing it not pull up in the run position, I just started troubleshooting the wiring till it got to dark outside. so. . today I turned the key to start and ... it started! : sometimes it's just toooo easy. Thanks

I'm cornfused. What was the culprit ?? The dreaded BLUE WIRE, the solenoid or what ???

Also, what position "should" the solenoid's plunger be in when the engine is RUNNING ??? I know it is UP when in the START mode, and DOWN when the engine is OFF, but what about the RUN mode ??

 

[JohnG]

Mee Too

I was having same prob, and I'm not a diesel wizard yet, but learning. . anyway, when I looked at the rod pointing down out of what I assume is the shut-off solenoid, it was filthy. . so I just sprayed it off w/ some WD40, and it hasn't done it since. . (Too easy?). . :-laf JG

 

[Joe G.]

John, be aware that WD40 is NOT a lube. It is a water displacement compound. Better to clean things with brake cleaner. Then use a lube like LPS #2. If you need something thicker then use SilGlide from NAPA.

 

[Howard Durand]

To answer Katmandu's question, the fuel solenoid plunger will be in the fully pulled up position when the truck is running. The pull up coil has a stronger current draw needed to overcome the spring tension that holds the plunger down when in the off position.

Once the plunger is pulled fully up, and the ignition key is returned to the run position, the pull up coil drops out but the plunger is easily held up by the holding coil.



If the starting coil remains energized for too long a time it will over heat and burn out. This is what happens when the starter contacts stick and backfeed the fuel solenoid starting circuit.

 

[JohnG]

Joe. . Your right about the WD40, but it was handy. . lol But my main theme was just that the rod was so filthy, it wasn't moving easily, and cleaning it, brought the shut-off solenoid back to proper function. (Did you get my email about my engine prob?), (If not, no prob. . all fixed, and I posted troubles in another thread. . Thanks). JohnG