[Nash Randall]

It's a stock 2016 with 225k. So I'm driving home today after work and getting the kids from school. I'm in medium traffic and go to accelerate and the truck has absolutely no power to accelerate. I look at the dash nothing new showing up. Shortly after this approx 1 minute limp mode comes on for 10 seconds then the truck dies. Try to restart and nothing, I figured I lost my prime so I go prime the pump and nothing. Go to open the bleeder screw not realizing it's plastic and I break it. Not a big deal AutoZone has the brass version and I found the hot screwdriver trick to get the rest of the threads out. My question is what fuses and relays should I be looking at first? The truck is currently on the street full of tools. They are fairly secure but I need this truck to make money! Any help would be GREATLY APPRECIATED!

 

[Nash Randall]

I'll be looking into the cp4 issue after determining no simple electrical issues. Fingers crossed over here.

The truck is outside my apartment when I say "on the street" my garage is underground so I couldn't get it safe. I was on the freeway when this happened and had my kids in the car so I looked over the codes quickly and reset to see if it would get me started even in limp mode I was 3 miles from home. The only code that stuck around is p128e.

The prime pump was as stiff as it's supposed to be maybe a little harder. But definitely not empty. That's why I think it's an electrical issue. If the pump failed wouldn't the truck have sucked all the fuel out of the filter before dying?

I'm going to go check the fuses that control the fuel rails and try to figure out what else electrical could be the culprit. I'll get my multimeter and try to figure out if the FICM is bad then check the FCA if everything else checks out. Then I guess start replacing stuff until it's back up?

This couldn't have happened at a worse time financially so I'm just praying for a cheap fix. Thanks for your input and help!

 

[Nash Randall]

I just realized that the filter would still be full with pump failure. Still trying to figure it out. About to start testing FICM. Maybe I'll pull that FCA if it's easy.

 

[Nash Randall]

Your truck doesn’t have a ficm, it’s controlled by the ecm on your truck

That explains why I couldn't find it haha. I read some people have had this problem with aftermarket fuel filters. I currently have a wix filter on and it's past due to be changed so I'm trying that tomorrow. After that I'm calling the mechanic because I don't have the skills for that.

 

[Nash Randall]

If the primer bulb is hard then it’s not lack of fuel because of the filter. It likely wouldn’t have a hard primer if it was the filter. It’s unusual to have an air leak between the filter head and injection pump

When the bleeder broke I pumped it to see if air would come out and I did have bubbles come up. Now the bleeder is replaced and the pump is very soft. I'm trying to find a mobile mechanic here in San Diego that can check it out. But I'm starting to plan for the worst.

 

[Nash Randall]

I hope you replaced the o-ring under the bleeder screw. If it fell out and you didn't know it was there, it may still be missing. Did you do the fuse check you mentioned earlier? Easy to do with a test light and will take less than 15 minutes.

Mobile mechanic, if he has some experience with the Duramax, might be the best thing to do.

I did make sure to replace the o-ring the old one broke off with it still attached. I looked at the fuses that were labeled "fuel anything" but beyond that I'm pretty useless knowledge wise. I didn't find anything blown under the hood and I didn't see anything that would controI engine stuff in the cab. I also rotated the two fuel relays to see if that would do anything. I'm replacing the filter tonight then priming for probably 25 minutes if it's anything like when I ran out of fuel. I have a multimeter if you could give me a heads up on where to check I would greatly appreciate it.

 

[Nash Randall]

Update changed the fuel filter. The old one was finger tight. Still no start I opened the bleeder to clear the air out. The prime gets soft after attempting to start so I don't know what that means.

 

[Nash Randall]

So once you crank the motor the filter primer will be soft.

I go with the recommendation that the mprop metering valve should be removed and check for any metal debris. If anything is found, well the infamous CP4 saga has come for your truck.

Stretching out the factory filter changes is not a good idea (unless running a lift pump system with additional filters).

It became due last week so I was planning on replacing this week when I had some time. The threads I have looked at make checking the valve look like a pain in the neck. Is there a simple way to remove it without taking all of my coolant lines off? I'm in a parking lot owned by the city and I don't feel like getting a ticket for spillage haha.

 

[Nash Randall]

So after getting denied or ridiculous quotes to pull that regulator out I went and did it myself. Took a little more than an hour. You guys were right about the cp4. All bad lol looks like I'm converting to cp3 and a lift pump.

 

[Nash Randall]

Going to replace everything but the tank. I can't afford another 1200 so magnets plus thorough cleaning. The kits are ridiculously expensive for the lines and gaskets do you know the exact part breakdown? I know injector lines and return lines plus the lines for the fuel rails and new rails. Filter head and filter even though I just replaced it. A new sending unit for the tank 8 injectors the auxiliary injector and line for the emissions junk. I'm going with the fleece cp3 since it's carb compliment. Faas lift pump. What else? What gaskets are needed.

 

[Nash Randall]

Looking at the service bulletin it's got the complete list of parts. It doesn't require injector replacement but I'll still do it, mine have over 200k on them. I'm honestly thinking about diy'ing this. I am mechanically inclined but this really seams like a PITA should I pay for the labor here, or was it worth the savings for those of you who have done it?