Couple weeks ago I was getting onto the highway and hit 40mph and the truck just lost power then came back 3sec later. I checked for codes later on and nothing showed. Anyway, two days ago it started again but almost every time under hard acceleration? I took it to my local shop for diagnostics and two days of running tests, the techs can't find the issue. Fuel and rail pressure are normal and they say the injectors are ok. There's 216k miles on it and the tranny was done at 166k and injectors done at 100k. It starts and idles fine and cruises at highway speeds fine, just under moderate/hard acceleration it loses power for a few seconds?? Any ideas what it could be....something in the motor internally? I'm at a loss and appreciate all comments!

 

Could be the APPS starting to act up. Did you change the fuel filter? It is also possible that you have a lift pump on the way out. Do you have a fuel pressure gauge?

 

ck air filter

 

I agree with Spooler!

 

I had the dead pedal awhile ago and put in a Timbo APPS so I dont think its that. I'll change the fuel filter when I get the truck back Monday. The guys at the shop said my lift pump was fine and fuel pressure was good.

 

A dirty fuel filter will allow the fuel pressure to look normal until you get hard on the throttle then because of the dirty filter, fuel flow is restricted and the motor falls on it's face.

Unless you have a fuel pressure gauge installed so you can see the pressure drop under WOT, you won't see the problem. It could be something else but I have seen this too many times not to suggest trying it

 

I'll change the fuel filter when I get the truck. Funny I thought about that before taking it in and thought that was to simple and couldn't cause this problem. Hopefully thats the problem. I had a quadzilla fuel/rail pressure gauge once but it never read right....guess its time to get another fuel pressure gauge.

 

The very first change I made was to install gauges and of the 3, the feed fuel pressure at the high pressure pump inlet is the most important. Once you determine what is normal through use, unusual changes are readily detectable well before trouble arrives.

 

A clogged air filter caused these exact same symptoms for me.

It only had a few thousand miles on it, but I had been doing a lot of off-roading in very dusty conditions, and it got clogged.

 

Pull the tank because the pickup screen in the tank is plugged up. Fuel pressure will show good, they need to run a 10 second fuel volume test, that will show below spec's