fuel mileage

[scottybobby]

I have a 2002 gmc sierra 5.3 auto 2wd. BONE STOCK. I am getting in the neighborhood of 11 mpg and the darn think will almost never start on the 1st try. I have checked my regulator and it does NOT leak fuel running or not. Most of the time when I attempt to start it I can crank it about as long as I want and nothing, I stop cranking and try the second time it might start and it might not. 3rd time it always starts. Most of the time when it starts on the 2nd try it barely wants to run. It spits and sputters and eventually smooths out. I have tried turning the key on and waiting bout 5 secs and turning it off and repeating and that does NOT help. Any help would be greatley appreciated. BTW I happen to be very mechanically inclined just not educated on the engine in my truck.

 

[scottybobby]

I really appreciate everyones help!!! 195 veiws and not a single friggin response!!!

 

[jagtoes]

Pull your plugs and see if they are wet . Do this before you start it in the morning. Also check the fuel pressure in the fuel rail whe it is running.

 

[nikolaiak2007]

word of advice, don't complain when you get views and no replies. not a good way to ask for help. just saying.

 

[Z15]

Fuel mileage is affected by many things and a lot of them might not even be the fault of the vehicle.

Some reasons for excess fuel consumption, I know you said "bone stock" but check to make sure none of these fit your situation, especially check the axle ratio and tire size, a low axle ratio will make the engine work harder.

• Oversize, undersize tires (can change axle ratio/trans shift points)
• under inflated tires
• Aggressive tires or the wide tires (more road friction = less mpg)
• speeding
• erratic driving
• fast takes off, spinning tires, hot-rodding etc
• lots of hills
• lots of idling
• modified engine, trans
• Changing the exhaust (now driving differentially likes to hear the noise the exhaust makes)
• low rear axle ratio (higher number means lower gear<---can have a big impact
• loaded down vehicle
• carrying unnecessary weight around
• Having an oversize camper/bed topper

to name a few that come to mind. With the trend with many new owners of trucks to go for larger and meaner looking tires it can lead to dissatisfaction with the vehicle that are purely the result of using non-stock wheels and tires. These can drastically affect mileage to the tune of 5+ mpg loss not to mention that a great majority who go to different size tires also tend to hot-rod more.

 

[scottybobby]

jagtoes I will try that,and z15, I have owned the truck for going on 7 years. The tires and wheels are stock 16 inch rims and tires are stock 255/70lt16. I have original converters with dual exhaust with 24 inch glass packs. They have been on there since the first week I owned it. I would say the new hotrodding factor has wore off. I DO NOT drive fast or heavy footed. My wife says I drive like a grandpa. LOL!! The mileage seems to be getting worse and the hard to start is staying consistent. I have spoke with a mech and they suggested that it could be a injector constantly dripping but it does not miss when idling but on occasion i do get a check engine light that reads a random miss fire code. (large parts store chain)

 

[kwbudaman]

I have a 2002 gmc sierra 5.3 auto 2wd. BONE STOCK. I am getting in the neighborhood of 11 mpg and the darn think will almost never start on the 1st try. I have checked my regulator and it does NOT leak fuel running or not. Most of the time when I attempt to start it I can crank it about as long as I want and nothing, I stop cranking and try the second time it might start and it might not. 3rd time it always starts. Most of the time when it starts on the 2nd try it barely wants to run. It spits and sputters and eventually smooths out. I have tried turning the key on and waiting bout 5 secs and turning it off and repeating and that does NOT help. Any help would be greatley appreciated. BTW I happen to be very mechanically inclined just not educated on the engine in my truck.

Regarding the starting problem: a restricted/dirty fuel filter might cause that problem.

 

[Nikelliott]

5.3 issues

First I would check all the codes. And to get a better idea of where the fuel is going check fuel pressure should be 55 . If more check for restricted return. If not equipped with return check evap system for a plugged system . Pull the fuel injectors check them for leakage and flush them while there out. Also clean throttle body and air filter a good tune up wouldn't hurt. If u have tech 2 or scanner to look at the fuel trims at closed and open loop would give an idea of what your O2' are doing