mrfishy34

i have a 99 silverado 4x4 with the 5.3 v8 in it. i just picked it up from my brother. he was getting like 17 to 18 mpg on average. i got it and drove it i am getting around 12 to 14 with it. i did have to put a fuel regulator in it since the pickup would start hard, that fixed the problem since the vaccume line to regulator was sucking up gas, and overloading engine. but it didnt increase my fuel mileage as to most of the time i am clocking it at 12 mpg. (i check by filling up setting trip and then refilling and checking mileage aginst gallons used) most of my miles are highway about 20 miles one way to work. pickup runs good, no check engine codes come up, only thing is that sometimes, more often than not it dont start one first crank. but second time it fires right up. fuel pump was new a year or 2 ago and new air cleaner and plugs and wires not to long ago either. any ideas? like i said before pickup runs good down the road and no engine codes so i am lost to were to check.. thanks

cleveland63b

I'd start with checking fuel pressure and filter.

also what do you mean by "start hard"

country_09

Was he checkin it like you are when he had it? These trucks generally don't get 17-18. More so 13-15. How's your drivin style compared to his?

oldchevy

I have a similar starting problem with my 99. Changed the filter, fuel injectors and fuel pressure regulator. The truck runs great after starting. Great idling also. I am now thinking that it is the check valve within the fuel pump assembly. I am trying to decide on changing the fuel pump or adding a check valve in the fuel line.

basilkies

Your brother sounds like a buddy of mine, he is more or less truthful, he just doesn't tell you all the truth. 17 to 18 mpg is highway mileage around town it's under 12 mpg. It's amazing to me that all things said and done these trucks don't do any better than trucks in the 1970's. It tells me that mileage today is gained by aerodynamics (and I bet that's minimal) and shedding weight. It seems Detroit still can't do a lot to improve engine mileage!

oldchevy

I don't know about your truck, but mine gets around 17 mpg around town and over 20 highway.

mrfishy34

cleveland63, By starting hard i mean i go to start it and it dont fire, if i jus sit and crank on it, it will start the first try but funny thing is if i jus try it and quite right away and try it the second time it fires right up. but if i crank and crank the first round it takes a bit for it to start. and it dont do it all the time. more than not tho. first bet is my fuel filter but i have a feeling that aint my problem. secondly my brother checked fuel mileage same way i do, and he drove some town and highway also, he said hed get better than 12mpg pulling his boat. i use to get 14 with my 1997 chevy 5.7 4x4. i sold that one when i bought my 06 dodge cummins and im gettin 17 to 19 with that town/highway mix. bought this pickup to drive to work and to save miles on my diesel and figured i should get close to same with gas. my buddy has a 02 gmc half ton 5.3 and he says hes always gettin 17 with it. only reason i am thinkin something is up with it is the starting problem. if it started right up every time on first crank like my old chevy did i wouldnt think twice about it. some pickups jus dont get good mileage.

Thanks for your imput guys

cleveland63b

yea I'd say your seeing the start of a fuel delivery issue