I need help diagnosing a sudden loss of power on my 12 valve. Driving home from work today , the go peddle went dead. No smoke, no exhaust heat, low boost. Idles smooth & sounds normal. the first thing I did was change the fuel filter , it had no effect. thanks, doug

 

when mine lost power it turned out to be a bad lift pump. does it go up to a certain throttle point then nothing?

 

Yes, it does , the lift pump was my next question. Can I run it like that for a week or two? Or will it damage the injection pump??

 

I am in the process of installing a custom lift pump on my 2004.5. I have had the fuel tank down on the 325 several times within the last week & a half. If it is the lift pump on the 12 valve that would be to weird. I just opened a box of hose and fitting from earls performance plumbing, for my way to expensive custom fuel system for the 325 . Now I have to drop both tanks & it is supposed to rain for the next 5 days. Somehow I don't think my wife is going to believe this. I had the lift pump replaced about two years ago on the 12 valve.

 

hmm..i would think that a new lp would last more than 2 years. how many miles did you put on it? it's a '96 right? if it's the same as mine, you don't have to drop the tank to replace the lp. i took my starter out to get access from underneath.

 

You need to catch it when it's in low power mode, pull over without turning off the key, (doesn't matter if it stalls) and check that the fuel shutdown solenoid is pulled all the way up. I've seen this happen quite often when the shut down relay is making poor contact or the blue wire at the battery is corroded. The solenoid will drop down but not enough to kill the engine due to low amps, truck sometimes will continue to run but the go pedal will be hard to push.
If the boot on your solenoid is rotted out the solenoid should be removed and cleaned up with a new boot.

 

I didn't think of that, I saw a heavy duty solenoid on ebay the truck does have 200,000 on it .But I thought if it went bad the the truck would not shut off. I didn't realize it could partially limit fuel delivery. I will check it buy manually pulling or pushing on the actuator???? thanks

 

Down is fuel off.When mine went out the truck would not start.Have you changed the starter contacts.It is what caused mine not to work.

 

Its the fuel shut off solenoid , I pulled it up manually & it seemed to be binding on something. Its working now but the boot is torn & rotted so I will replace it . thanks again

 

You should remove the solenoid and clean the inside barrel and shaft well. Most likely it is binding on rust and gunk due to the torn boot. A very light coating of silicone grease on the shaft also helps.
Replacing the solenoid is the very last resort, they rarely fail, the problem is most likely elsewhere if the cleanup doesn't cure the problem.

 

When I worked at Dodge on these things I would replace the relays on a regular basis for this problem. The 2 relays over the valve cover, one pulls it and the other holds the solonoid. Fairly cheap repair compared to the solonoid. And they do burn out and get bad contacts.

 

The solenoid plunger connection to the pick up rod failed. So I drilled a 1/8 inch hole in the plunger ( man thats some hard steel !!! )& inserted a drift pin to catch the linkage rod. DC redesigned the solenoid probably because of the failure I experienced, and they wanted $400 bucks for it. I would have hooked up manual choke cable to it if my fix didn't work. doug

 

The fuel shutoff solenoid is a Cummins piece that comes with the engine package.
A lot cheaper to purchase through Cummins than DC dealer. I think Precision Diesel Injection has a good price, too.

When the boot fails and the plunger gets coroded or the linkage to the pump is dry they will self destruct.

I found a good deal on solenoid boots, too. $22 shipped to lower 48 states.
Andy Redmond
Redmond Enterprises
Plano, TX 75026
972-398-3934
redmonde@comcast.net