Barely runs , p0300 codes 2012 5.7

[J169bill]

I was driving the truck home yesterday and all the sudden it wanted to die out , would restart but only running on a few cylinders. Got it home and would barely run , full tank of fuel , removed the line from the pump and put a gauge in it , 60 psi at key on , same with cranking , note that in order to do this with the gauge setup I have fuel is blocked going to the engine . Engine was totally rebuilt 10000 miles ago and no issues until yesterday , any help would be appreciated

 

[Burla]

That is a general misfire code, not cylinder specific, so I'd say there is hope at this point. But I don't understand that as an only code if you say it was working on a few cylinders. No other codes? What was rebuilt and why? Can you explain what you were saying about gauges and fuel shut off? Try running engine without mds on? Can you even get to that? not road worthy at all?

 

[J169bill]

Ok , thanks for replying , I tried again and now I have a p050b code . At 113000 miles it ate 2 lifters so I pulled the engine and did a total rebuild using a Jay Greene camshaft kit and I did an mds delete at the same time . I could not hook my fuel pressure gauge into the fuel rail so I tick the pressure line off under the truck and plumbed a gauge to that line , with the gauge in the line the Fuel line is not connected to the engine . And no it’s running so bad as soon as I try to put it in gear it dies .

 

[Burla]

So there ya go, narrows it down. This is what you are looking at from ob2. I'd keep running codes as well, maybe get it more narrow.

• Severe vacuum leak
• Defective ECT sensor
• Open or shorted circuits or connectors
• Bad CKP or CMP sensor

 

[GTyankee]

this is the best trouble shooting site that i have seen

OBD-II Trouble Code: P0300 Random/Multiple Cylinder Misfire Detected

check your EGR valve as a first step

I must ask, do you ever top off when filling up with gas ?
Don't answer that, only you & your mechanic need to know

Nothing good comes from topping off
It ruins the Charcoal Canister, it causes the Tip Over valve to trip, it can deteriorate the catalytic converter

some people top off the tank to get an even number, like 20 gallons even, or $40 even. even dollar numbers make it easier for hackers to get away with theft, when you see your CC statement, your eye does not catch even numbers, as it would if you see $39.98

 

[J169bill]

Thanks for your help , found the issue , see photos . I didn’t think this could cause the issue , but it did

 

[Burla]

Thanks for your help , found the issue , see photos . I didn’t think this could cause the issue , but it did

that didnt throw a code or have any tick? wow nice catch

 

[indept]

Have you looked at the piston & valve with a borescope? That exhaust valve most likely fell in unless the spring cap & keepers stuck to the valve stem. You can get s scope at harbor freight or amazon for less than $100.