MY 98 blazer 4x4 is geting bad MPG city 10mpg and freeway 13-15 mpg. its got a new tune up on it. fresh oil change new ball joints and a new wheel bearing on right side. trans fluid recently changed along with rear diff fluid. i have a flowmaster 40 on it with stock exhaust. well my tires in rear are about shot. and my aglinment is lil off. can this cause bad mpg. my fuel sending unit went bad so i dont know how much fuel is in the tank. what can i look into to get my mpg back up. msrp says 15 in city and 20-25 freeway.

 

Well, a good start would be to take care of the alignment. If it's bad it could be worth a couple MPGs. Plus theres the cost of replacing tires more often. Having the least rolling resistance possible will help. Also, if you have anything but stock tires the calculated MPG will be off. If you bring the truck to autozone or a similar place they can hook it up to a scanner and see if there's any codes. Sometimes there's intermittent codes that cause problems but won't set off the check engine light. There's numerous issues that could cause poor MPG on an older vehicle like leaking injectors, vacuum leak, plugged catalytic converter, bad O2 sensor, and a scanner might give you some hints.

Keeping up on maintenance items like spark plugs, air filter can restore MPG as well. A bone stock 4x4 blazer should be capable of 20 mpg with mostly highway driving keeping it around 65, 15-20mpg with mixed driving is realistic.

 

thanks. i put a tune up on it back in feb 2011 when i first got it. but how can you tell if it has a leaking injector or fuel pressure regulator.>>????

 

You would need to do a fuel pressure leak down test. A quick search of the site should turn you in the right direction.

 

well i found out i have a intake gasket going out. can this cause bad mpg plus im leaking oil and burning coolant a little not badyet?>??

 

We redid the gasket sets before installing another 119K mile 1998 motor in our 1998 S10 and just replaced the fuel regulator and spider while it was on the engine stand.

Search for Delphi FJ10565 Fuel Injector on Amazon. It comes with a new fuel pressure regulator and gives the real injector upgrade set that became standard around 2003.

On Amazon.com the new upgraded spider runs around $180.

If one waits until raw gas is dumping into the crankcase it can lead to rod/crank bearing damage resulting in low oil pressure or spent bearings.