Poor Gas Mileage

[natenkiki2004]

I hesitate to suggest injectors but only because they're a chunk of change and I haven't personally tried that fix yet. Once I do, I'll be sure to share info.

That said, any 24 year old fuel system is going to have problems. Especially a system that requires extreme precision like vehicles. The injectors are of an early design and with batch fire, there's a LOT of use going on in 200,000+ miles. I think it's a miracle that they still work at all. I'm going to end up replacing mine with rebuilt ones of a newer design (91 & 92 used a pintle-style, 93 & up used a 4-hole style). I don't expect it to be turned into a hot rod but I do expect an increase in mileage and am hoping to see smoother performance.

 

[2stroke]

Yes they are, and thats why I suggest accepting that 11 mpg city is normal for this vehicle, especially since old injectors probably isn't the only problem.

 

[Watchman]

Your points are both good - I still have the records of my mileage since it was my daily vehicle for over 18 years. Oil changes were probably the biggest thing that kept this engine in good shape. After the truck only had 100 miles, I switched to Kendall GT-1 racing oil and changed every 3k-4k miles or 3-4 months. It cost a little more, but I believe this is what helped it's longevity.

Nate - Please post your findings on the fuel injectors, I think this is where my fuel is getting wasted, because I can even smell the rich burning. I cleaned my injectors with carb cleaner and actuated them using a 9V battery, but as you mentioned above, their OLD. So, I'm wondering if they like O2 sensors can wear out. Could it be that the injectors don't switch off like they use to or are starting to lag ? Is this possible ? Could more fuel be injected than necessary ? Just enough to drop MPG, but not enough to cause fouling of the spark plug ? Remember, we now have ethanol (as 2stroke mentioned above -up to 15%) in the fuel which could be cleaning things up enough to do this, so that the tell tale signs are "masked or erased". What do you guys think ?

 

[natenkiki2004]

I've been thinking about injectors for the longest time, many months. I need to save up a bit and do the whole top end, gaskets, thermostat, fan clutch, rocker arms, pushrods, and injectors. One of these days I will...

 

[2stroke]

Don't we all? I've got dozens of ideas for my truck, but I always seem to be stuck on a few simple plans. Usually I give up ideas when I realize I don't make that much money in a month, and I could better spend my money on the dirt bike. I'd love to get back into racing this year.