K1500 Maintainance and Efficiency Tuning Guide needed

Hi guys,

I recently inherited a 1989 K1500 with a 4.3L and about 100k miles on her, which I am using as my main vehicle, for commuting and general city runaround. My occupation is very theoretical and I've been looking forward to getting my hands dirty while learning the basics (for now) of automobile maintainance.

That said, I'm very meticulous and I've been monitoring the mileage of my new old truck and I've been getting 11 mpg (70% city, 30% highway). Its really annoying me - actually keeps me up at night! So, I went out and bought the repair manual, read the google pages on general automobile maintainance and I've been working my way through.

So far I've changed the oil, oil filter, air filter, fuel filter and I have a set of spark plugs (Platinum and a gapping tool to set them to 0.35) that I'll put in when the weather is nice (I'm in Anchorage, AK). The guys at NAPA tell me my wiring and belts are in good condition.

What I would really like is a set of directions/recommendations on what I should do next. I'm probably going to change the O2 sensor, although I'm told its a gimmicky repair and the chances of seeing any change in milage is slim. That said the vehicle would probably work better, extending its lifetime, but ideally an increase in mileage is what I'd like to see.

I await your advice in anticipation.

(I'm thinking of keeping a log of my maintainance and here; I'd appreciate the help contributing.)

What year K1500?

//2000CAYukon

Its a 1989 model. I've updated my original post.

Change the transmission fluid and filter,do not have the transmission flushed and you will regret it having problems after a flush was done down the road.

I would start with a complete tune-up.
Plugs, wires, cap and rotor, pcv valve, air filter, fuel filter, and check the timing.
Also inspect all vaccum lines and replace as needed.

See how it runs after that...:naughty:

Being in Alaska, is the truck a 4WD? They will not get the fuel milage of a 2WD. Also be sure to use AC-Delco ignition parts (plugs, wires, cap and rotor)-you'll get longer life on them than any aftermarket parts. Also realize that a vehicle with over 100,000 miles will not deliver the fuel economy of one with 40,000 miles.

@wafrederick: Your message was a bit jumbled. So, I should change the transmission fluid - fine, but I've never heard of a transmission fluid filter (which means nothing really :))

@Blt2Lst: I changed the sparkplug the other day, with some platinum Autolite ones (got them before jonnik's message). I found that one of them had cracked porcelain and several of them had widely varying gaps.

After replacing them however, I noticed some misfiring and heard sparks fly occationally. I checked the engine while running and actually saw sparks comming off one of the boots! I adjusted it somewhat, to increase the distance from the boot to the metal shield around it (where it was connecting) to block the discharge. It worked, the engine isnt sparking and running smoother with the new sparkplugs, but I'm concerned about that sparking business. Any ideas?

Also: What should I do next? Wires/cap/rotor should all be done together right? What about the PCV valve?

(I'm really getting into messing around with the engine. So much fun!)

Thanks guys,

Blake

Seeing sparks or flashes means the spark is grounding out instead of going through the spark plug, meaning fuel is going through the engine unburned. Change the wires.

Plugs, wires, cap, rotor, and ignition coil are the primary replacement parts to help with fuel economy.

The oxygen sensor can help as well as it helps the ECM regulate fuel delivery into the engine. After that, then air filter, EGR, vacuum lines and intake gaskets. Finally, check the MAP sensor.

Hope this helps!

Should I change wires, cap, rotor at the same time? I'd appreciate a sequence of repairs, that can be done in a couple of hours on the weekend since I still have to use the truck during the week.

What type/brand should I put in? Also, what kind of cost am I looking at, for the above?

Do I need any special tools for this? Please remember that I'm learning as I go, so if someone can suggest the easier things to do first, I'd appreciate it.

Thanks again!

There is a filter in the transmission by removing the pan and it pulls of real easy without the use of a tool.Put in AC Delco spark plugs incuding the cap rotor and plugwires which are AC Delco and avoid Bosch plugs.I have removed a lot of Bosch plugs out of GMs which failed including brand new ones and throw them in the garbage can which they are only good for

There is a filter in the transmission by removing the pan and it pulls of real easy without the use of a tool.Put in AC Delco spark plugs incuding the cap rotor and plugwires which are AC Delco and avoid Bosch plugs.I have removed a lot of Bosch plugs out of GMs which failed including brand new ones and throw them in the garbage can which they are only good for

Spark plugs already changed with Platinum Autolite ones. Dont think its cost effective to throw them out. I'll have a look for the transmission fluid filter - strange that it would have an effect on mileage though...

Being in Alaska, is the truck a 4WD? They will not get the fuel milage of a 2WD. Also be sure to use AC-Delco ignition parts (plugs, wires, cap and rotor)-you'll get longer life on them than any aftermarket parts. Also realize that a vehicle with over 100,000 miles will not deliver the fuel economy of one with 40,000 miles.

Yes its 4WD, but run in 2WD all the time - even in the snow without a problem. I will put it in 4WD for a couple of days a month, just to 'use it so I dont loose it' - dunno if thats really necessary.

I know this old boy is old, but as I stated, I'm also using it as a learning platform. My objective is to get 20mpg out of it, before I hand it over to my nephew, in a year and a half, when he starts driving.

Changing the differential oil if it was old/burnt, could add to MPG.