Hi, I ran my pickup down into town last Friday (+/-3miles?) on my return trip it kind of popped a little and the check engine light came on. The further I went the the worse it got. It would accelerate then drop off then accelerate and drop off then have nothing at all and almost die. When I pulled in the driveway I noticed the WIF light came on along with the check engine. I checked the codes I got p2266 p2269 p0340 p2121 p0341 p0237 p0193 p2127. I drained the fuel from the housing changed both filters cleared codes ran it around the block ran fine. Hooked my trailer headed into town when I was pulling in to where I was headed it acted up again. I decided to take it into the shop. They have had it since saturday. They have changed the batteries and FCA with no luck. Today they swapped out the ECM for a different one. Acted up again but the WIF code didn't show up. Also when it acts up the lift pump pressure drops to 3-4 psi. Then at the same time it clears up the pressure comes back up to 17+/-. I don't understand why the fuel pressure would drop off with that mechanical pump.

What they have changed so far:

Tightened crossover tubes didn't change anything
Swapped injectors to some stock ones
Pressure relief on the rail
Fca
Cam sensor
On the second AUTOMATIC ECM just to see if it would act up. It did. Yes it's a standard

Even when the fuel pressure drops off the fuel boss seems to be working fine. The stock pump is working only puts out 4 psi and once the fuel boss reaches a certain psi it shuts the factory one off

 

have you checked the crank position sensor. does it idle rough or start hard?

 

I don't think they've checked the crank sensor. It seems to start pretty good most of the time. It idles rough when it's acting up. Would that make the fuel pressure drop off?