Thread: fuel consumption - where did I read this!?!?

there are ton of things that could change mpg's on a older car. dirty injectors,dirty fuel filter, dirty fuel sock on pump, worn fuel pump, worn fpr, old spark plugs and wires, O2 sensor being worn, maf sensor being dirty, dirty intake manifold, dirty egr valve and tubing, low compression, poor spark due to other worn ignition parts. This should cover the motor.

I ran 4+ bar on stock p11 fuel pump for over 150k miles. Stock 259cc injectors too. Not sure if p11 pump stronger.

Where is everybody buying there 91-94 B13 255 walbro's these days? I might be in the business for one this summer.



^This is true for me in my personal experiences. Some people say different, but whatever lol.

You're talking about the base pressure? So you ran 4-bar base pressure and on top of that ran around 7 psi?

you could also have a dirty fuel strainer on the fuel pump itsself, this could cause some issues, but without modification to the ecu imo you arent going to see greater mpg than what the stock ecu will allow even with all new fuel parts, like fuel pump,fuel filter,fuel injectors,regulator,spark plugs,wires,maf ect ect ect i really just dont see the car making anything more than stock mpg

My old engine got terrible mileage. When I replace that one with my 10:1 I immediately got significantly better mileage. I went from 18-22 up to 27/32. I'm now boosted on top of that and get 30+ on the highway. I'm not trying to brag about getting great mileage either. There are a lot of things that I need to fix on my car, I just don't have the money for right now.

So likely a large part of the mileage problems are in the engine itself and not before the engine.

Try running seafoam through your engine and fuel tank. It made a big difference on my car.

An alignment, check tire preassure, brakes, wheel bearings, etc. Full tune up. Check anything and everything between the engine and the ground. As a last resort, pull the fuel pump and clean the "sock" filter on the pump or replace it.

I've heard that the IACV can be a culprit. The water temp sensors (I know I need to replace mine.) The MAF can cause poor fuel consumption. There are a lot of factors that can affect fuel efficiency.

But the original post and question poses a good theory. Though those parts brand new are expensive, and most of the cost is in the injectors.

Lance

If you get them cleaned at a reputable place like RC Engineering (who have done it for as long as I can remember), the do spray pattern and bench flow testing. They also supply you with a performance printout of each injector before/after.

They're pretty thorough, I would bet money that the cleaned injectors will perform as good as new.

http://www.rceng.com/

I have a local shop rebuild my injectors for pretty cheap ~$25 per. RC is very good too.

Running 4 bar will theoretically net you better mileage but 26-28mpg is low. Something is off. I always got mid 30s from NA SE-Rs. Awhile back I had my B13 setup with 370s@3-bar and netted 34mpg on a trip from Portland to Seattle and back. It was regular 75mph driving with some traffic.

Ya, when's the last time you've done a tune up?

i changed spark plugs, rotor/distributer, wires about 4 or 5 months ago.. no change.. i used all OE nissan stuff, copper plugs..