1989 nissan pick up trouble


Old 01-11-07, 01:25 PM
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 219
1989 nissan pick up trouble

89 pick up, reg cab, 6 cylinder auto. trouble is gas milage, its only about 12 mpg. any ideas as to what will cause this.
it has good even compression on all cylinders.
159,000 miles.
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Old 01-12-07, 09:21 AM
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,779
You can go end to end and do a lot of things that would help. I don't know those are supposed to be capable of. Since it's an older pickup and automatic tranny, it won't get the best anyway.

You usually start with the easiest and cheapest. Air filter, spark plugs, plug wires, pvc valve, cap and rotor, check timing, clean fuel system, fuel filter. Then check all tire pressure and increase the tires on the front near the max stamped on the tire for loading. The front tires kill mileage because they carry the load of the cab engine, etc. all the time and you have to push those.

Change the oil and filter. If you do easy driving, using the truck like a car, go to 5W30 oil and add PFTE. The lighter oil gets better mileage and the PFTE will cut the tolerance on the rings a little and help the lubrication.

Then if you're not where you want, take a look at your ignition timing. If it's a couple of degrees off and it hasn't been adjusted for a long time, it could be an indication the timing belt/chain needs attention. Adjust the timing to specs and think about checking the valve timing.

Also have the front end aligned. Out of alignment kills mileage. Ball joints are mileage killers too.

Check your brakes to make sure they are releasing properly. Check the caliper slides on the front (assuming disc brakes) and lube them with a caliper grease to make sure they slide freely.

If you have greaseable Ujoints, grease those. If not check the play in them and replace if necessary.

That should get you about 93 miles to the gallon, if not it's a place to start.

Hope this helps,

Old 01-12-07, 01:15 PM
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 219

Hi Bob,

thanks for the reply. I am going to replace the plugs, filter and wires soon. Plugs and wires are about 2 years old.

I know it wont get the best of milage but it seems to be increasingly worse.
The tire pressure is fine, alignment is good too. had that checked.
I will do some of the other small things too, thanks for the help appreciate it.

Hope to be getting 93 mpg soon lol

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