03 cat 248 fuel solenoid issues

[Brian_216]

I found my way over here after a few posts popped up similar to my issue but I’m at a loss.

I just bought an 03 cat 248 high flow machine. The seller didn’t tell me the fuel solenoid was missing and you had to pop a plug out and use your finger to move the rod to shut it down. Thankfully he showed the guy I sent to haul it home. I expected to fix small issues, but this just made me mad.

I ordered a solenoid and it works but smokes the fuse in a few seconds. I found a schematic that claims to be for my machine and I have been doing some testing.

With the key on I get +12v on the green green wire, and 1.5v on the heavier gauge red wire. The solenoid has a start and run input. One isn’t meant to hold it open, the one that does that is the heavier wire that comes off the relay.

Through process of elimination I found the red from the solenoid plug and it’s other end at the relay. The other heavy wire in the relay is +12v regardless of key position, I am not getting anything at the other two wires that drive the coil in the relay. Like 7.5 volts or something.

Now for the part I can’t seem to wrap my head around. The schematic shows color and wire size for all the relays in that position, none of them match what’s in front of me on my machine.

 

[Brian_216]

If there is anyone that can get me an actual schematic by my serial number I’d be forever grateful

 

[Nige]

If there is anyone that can get me an actual schematic by my serial number I’d be forever grateful

Without a Serial Number it would be no more than a guess, and my crystal ball is broken........

 

[Brian_216]

Sorry about that. CAT00248P6LZ01368. Thank you!

 

[Nige]

I'll send you one. Check your messages.

 

[Nige]

It might pay you to be aware of this......
Originally the engine in your machine was fitted with the 160-6376 solenoid. The updated solenoid Part Number came about 1 year later.

 

[Brian_216]

Thank you for that. This machine has a reman engine in it that was installed in 2018.
We found the issue in the wiring, well at least sort of we found it. The socket for the fuel shutdown relay has 12v constant on one side, other side is the output to the solenoid. The wires that should activate the coil are the issue. I’m getting a ground on one side, but when I turn the key on it’s no longer grounded. I then get 7.5v on each of the smaller wires that would actuate the coil in the relay. Hopefully the schematic helps me trace it. I’m half tempted to run fresh wires to a new relay and go run it. Just get keyed power to one side and I should be ok. I know it’s not the right fix, but it beats sticking your finger inside the pump to kill the engine.

 

[Nige]

This machine has a reman engine in it that was installed in 2018.

Do you have a S/N for it.? It may not have exactly the same engine wiring harness that is shown on the schematic.

The fuel shutdown solenoid should have 3 wires. Switched power (with key ON) comes from the shutdown fuse in the fuse box via wire 110 Green, through the closed Charge Pressure Switch and into the solenoid on wire A309 Green. Wire 200 Black is ground and the "signal" to activate/deactivate the fuel shutdown solenoid is on Wire 327 Pink from the fuel shutdown relay.

Power to pull in the fuel shutdown relay comes from the Interlock ECM "Start Relay" connection on Pin 64.

 

[Brian_216]

Once I had an understanding of how the relay works I realized I was looking for power on the pink wire to the solenoid with the key on. Now I understand that only gives power to the solenoid when cranking and it won’t hold the relay open in the on position, just when cranking. Pretty sure I have this figured out. Thanks for the responses with the schematics! Anyone else that finds this I suggest reading this a few times so you don’t even up like me

Fuel Shutoff Solenoid Wiring 101

www.sbmar.com

 

[Brian_216]

And one last thing that may be helpful to others. Once I dug into the old solenoid and looked at the wiring they had red to red black to black and white to green. On the updated solenoid the red wire is the hold open wire. They were drawing all the power to open the solenoid through the wrong wire and smoking the 10a fuse. I’m headed out to the machine now to cross some wires inside the connector and hope for the best. I found another post here where they had it wired incorrectly.