Posting for my brother. Trucks a 2000 4.8, anyhow we just replaced fuel pump and fuelfilter. Truck is backfiring/popping noise when accelerated hard. What's weird is when I'n neutral or park u can rev it all u want n won't do it. Any ideas Mayb clogged injector. ??

 

How many miles? Had a tune up recently? Did the problem only appear after the pump change? Any codes?

 

Sounds like its leaning out on the topend.
Check fuel pressure while driving to make sure the new pump isnt bad and losing pressure at high rpms
Possible the new pump is weak

 

145k ,probably due for plugs believe they were changed at 70k.. Truck was running normal before pump when out.

 

Thanks, will ck pressure later.. It was an aftermarket pump from oreillys.. Which I heard ain't all that great

 

Hey. I'm going to agree with the fact that your new pump may be bad. The pump you got, is it an airtex? Those pumps are cheap for a reason. The pressures it creates are min. For daily use and have a life span of just over a year. Enough to get out of its warranty. If I were you. Go back to oreilly. Buy the delco pump and tell them the airtex isn't working up enough pressure. They have to warranty it. I got my delco pump from napa for 300 pre tax. I also have a school acct. Lol

 

it was an AirTex

 

might wanna double check that the fuel filter isnt backwards