hi everyone. its nice to see such a devoted community of isuzu enthusiasts.

my 3.1L engine is just sucking down gas as quickly as i can put more in. dont know what the problem is... it even passed smog with flying colors.

the only thing i've left to do is completely rebuild the engine, and hope it doesnt suck down gas quite as much.

do any of you have a good suggestion for where i could get an engine rebuild kit for my 92 3.1L engine?

Just about any automotive parts store should have kits......

link
shortened the link -- Randii

If it is in such dire condition to need a rebuild, it most likely would not have passed smog.

I would personally find out WHY it is consuming excessive fuel. Then I would work on fixing the problem. It will be cheaper and easier than just rebuilding the engine on a whim.

Just a suggestion, I would start with the TBI injectors and see if they are spraying properly. If they are clogged or dirty, the spray pattern can go south fast. Bad spray will equal bad combustion and poor fuel milage.

Michael

Before you do anything as drastic as rebuild the engine, let's first define how it is running right now. What kind of mileage are you experiencing right now?

Are you burning any oil? How much. If you aren't burning significant oil you probably aren't going to gain anything in terms of mileage by rebuilding the engine.

Edit

Michael and I were evidently typing at the same moment, he just got done quicker.

Mileage-related problems are most often fuel and/or ignition system problems.

thanks for all the advice so far...

mileage is around 10 mpg, though something like 8 mpg is more probable. oil isn't burning excessively fast, btw.

could such bad gas mileage be exhuast-related? the exhuast leaks here and there. could it be a bad O2 sensor?

i should elaborate...

-pcv valve clean
-somewhat new head gaskets
-spray on the injectors are OK
-no vacuum leaks (at the TBI)
-sparkplugs in good condition
-EGR all cleaned out
-leaky exhuast
-fuel lines all in good repair
-OK oil consumption
-passed smog well within limits
-timing within specs

what I don't know are the conditions of the valves, timing chain, camshaft, or if the O2 sensor is any good.

i plan on putting in a new dist. cap, and new plug wires, but could those things account for such bad mileage?

what mileage should i even expect to see out of a 3.1L?

im not sure what to do with this thing.

not real familiar with your engine, but perhaps the Throttle Position Sensor should be looked at ... I
don't know if it could make that much diff, and don't
understand how you could pass smog, but worth a test.

You really need to get in there and do some diagnosis. From your description, a rebuild is not warranted.

I would start with a manual and a multi-meter. Pull any codes out of the computer and then start checking things like the TPS to make sure they are within range.

I would highly suggest a compression test to see where you really stand mechanically. A leak-down too, if you can do that (or are willing to pay for it).

You very well may be at a point where you have a few things that are not necessarly "bad" but together they add up to your problem. A slow O2 sensor, a exhaust system that needs attention, some bad plug wires combined with a weak coil and anything else, may be enough to allow the MPG to drop like you have described. But, you won't know until you do some of the leg work.

Good Luck,
Michael

This is a very good point, Jeff. Most emmissions stations test first at idle, if that's good yer outa there. However, ailments in proper scaling of a TPS above idle can dump unnessary juice (fuel) into the engine, not uncommon above 100K miles.

i checked the TPS...no problem, and within specs. I was hoping it would be the problem, just because it would be so easy to fix. <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

are there any ways to check if an O2 sensor is crapping out?