Ok so i'm trying to figure out possible reasons my truck is running so rich. Its a 4.8L engine. i've done the following to it:
220/222 110lsa comp cam
SLP valve springs
LS1 intake manifold w/ 28.8 injectors
Return style fuel setup
Walbro 255 fuel pump
Professional Products Fuel Pressure Regulator
SLP shorty headers w/ no cats into magnaflow round mufflers
Only front 02 sensors
Blackbear tune
Removed EGR and EVAP
Electric Fan
MAF right in front of the throttle body w/ cone filter in front of it (sticking right off the front of the engine)

Ever since I did this motor work its not run right. Its very rich. If i get on it if bogs out / shuts off briefly. It backfires really bad too. I'm already on my second set of plugs and thats just loading and unloading it on a trailer to go to maybe 4 shows.

It smells very hot when its running but it is probably the exhaust from all the extra fuel dumping out.

The fuel pressure goes down to almost 0 within a minute of turning the engine off.

I'm not 100% i have all the vacuum lines in the correct placement. I used the LS1howto.com as reference though.

I did have to extend the lines to the injectors, MAF, throttle body, 02 sensors.

What should I check? I plan on having a friend scan it tomorrow or friday but i'm affraid it wont help me here.

 

has it been retuned since all the work?
what if the timing was off a tooth when you did the cam swap...
what about a stuck open or leaking fuel injector causing the fuel pressure drop
could be many things causing this have you checked anything on it?

also running that rich killing plugs in minutes will wash the rings out too

 

Is Justin aware of the injectors that you have in there? If it's tuned for the stock injectors, they will be duty cycling more than the newer injectors need and dumping more fuel. What is the fuel pressure at idle and with the vacuum disconnected from the fpr?

 

Sounds like leaking fuel injectors to me. It should hold pressure for more than 1 minute after shuting the engine off. The fpr cant do its job if the injectors are leaking.

 

I believe that the walbro pumps don't have a check valve or anything that retain fuel pressure like the factory pump, I remember reading that they drop pressure pretty quickly after the engine is shut off, and sometimes may take a few seconds to fire up also

 

im not sure the 255pump has a check valve so the loss of pressure is normal i think.

I would do 3 things
1. check your wiring really good and make sure there right..(you listed three things that are important to proper fueling that you messed with)
2. check your vacuum hoses and be 100% there right, also maybe intake gaskets if you removed or messed with it..
3. try and move the maf more away from your TB

 

I will double check the wiring again this weekend. When i disconnect the TB and MAF it doesnt effect how it runs at all. I know i should move the filter away from the MAF but it ran fine when it was the stock truck intake and engine that way. As soon as i put the cam and intake manifold etc on it started runnign like this. Will the injectors visibly show leaking gas? Should i take the rails off and double check all of them? The fuel pressure is at 58psi idling. He did tune for everything except the cat removal. I need to send it back to him for that still.

 

I'm trying to find a diagram to route all my vacuum lines and such and noticed the PCV valve. I do not have one of these. Do I need to get one? Does anyone have any helpful diagrams to confirm my lines are going the right way?

 

Well i got the motor running good. I found out why it was ****** up (I think anyways). I had the vacuum lines all hooked up like i saw online (did a LS1 intake manifold swap so i was going by the car setup). I had it all hooked up as if i was using the pcv system but i wasnt. I capped everything off like i found to do when removing the pcv system and she ran great. It was late last night when i figured this out so today if its not pouring im gonna take her down the road to confirm. I did get to 4th gear in my driveway though and didnt bog out at all!