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Discussion Starter · #1 ·
I'm new to this. Here's the short run-down:

My son was given an '84 nissan 4 x 4 p/u a couple of weeks ago for his 16th birthday--gift from grandpa. The truck apparently sat for over a year down in TX (location is now mid missouri). It's the 4cyl 2.4 liter, 5 speed manual--about 204K on it. I've installed new alternator, battery, water pump and fan clutch, thermostat, belts, and radiator hoses. Truck has new gas tank--but sending unit is bad. On order. Will get installed in a couple of days. A/C has been removed by previous owner.

So far, this thing hasn't gone over 72 miles on 15 gallons of gas--roughly 4-5 mpg. Told ya it was crappy.

Here's the kicker: It runs like a top. No smoke. No miss. No stall. Idles smooth with no "ramping" or revving. Like others, it's a little hard to start in this 7deg weather, but will start and run great. This is a carbuerated model--grandpa had a new carb put on before he gave it to my son (along with new clutch and tranny re-build). The fresh air intake and blow-by tube to the breather are completely gone. Could this be causing this severe an issue? This just seems to be too bad a problem for a fowled plug or dirty air filter. Seems to me like more of an air/fuel mix issue but I'm no mechanic. Idles at around 800rpm, but tach is a little quirky.

Has fresh oil change. Oil smells very slightly of fuel, but I can't be certain.

Haven't really had it on the highway to see how HP performs yet. I'm having the timing, choke, and vacuum advance checked tomorrow by a local mechanic, but I just feel like I could chase this thing from bumper to bumper and spend a lot of money without fixing anything. (Yes, the front hubs are unlocked:) O2 sensor? Catalytic converter? Any thoughts?

Any help given would be greatly appreciated!
 

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Discussion Starter · #3 ·
Thanks zane. I really appreciate the tips.

By carrier bearing, do you mean in the clutch? I can't hear it from inside the cab, but from outside I can hear a very light "squeal" when he depresses the clutch. Now that I think about it, from inside with clutch depressed--in gear or neutral either one--it's actually pretty quiet. But in neutral there's a bit of a "hum" when I let off the clutch.
 

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The carrier brg or the driveshaft support brg...(in the driveshaft going to the rear diff)
You said it has a new carb.. has it been adjusted at all??? the jets might be a little too big for the application, might try re-jetting. If it takes awhile to get up to speed I would look at the cat. Might also change the fluids in the diffs, might be a little thick (if you havent already) You have about 10mpgs hiding somewhere....
 

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I had those carbs on an 82 & an 85. They are great. Check the site glass, for fuel level. There is a dot where the fuel level should be. If it is above the dot, adjust you floats. I always started both adjusting screws at 1 turn open, then adjusted to the highest vacuum.
I can't remember if a 4WD 720 has a carrier bearing. It's freexing rain right now, so heck with going outside to look. Some can set me straight on this for sure. I know it has the shorty center driveshaft. I'm not trying to sound like a smart [email protected]@, but I really can't remember if it has a carrier bearing.It's been about 7 years since I replaced the U-Joints. I know my 61 Chevy has 1,you should hear that noise when it lets loose.
Good Luck
 

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new o2 sensors, remember you have two, one at the exhaust man. and one at cat. converter and a new cat converter. my 97 started getting poor gas mileage a few weeks ago. i changed both sensors and the converter and that bumped me back up to around 19 MPG.
 

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Thanks for the reply Speedo.I finally quit raining,so I snuck out and took a look this morning. I don't have a carrier bearing in the rear.So if your truck is like mine,a seperate tranny and transfer case with 3 driveshafts-maybe check the transfer case bearings. If I remember right,there was a problem with many of these transfer case bearings. That would cause you drag too-but you should also feel a vibration. A binding center drive shaft would do it also-but it should also shake the whole truck,like a wet dog.
Good Luck
 

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Discussion Starter · #10 ·
Hey, thanks to all who pitched in their advice. I had the truck in the shop. Carb was way out of adjustment, some timing issues, vacuum issues, so on. Unfortunately, Christmas nite some SOB blew a stop sign and T-boned my son in this truck.

New problems now. Any interested parties please refer to the new string I'm starting.
 

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need help on converting older 2.4L motor into 91 truck

i have a 91 2.4L and its finish. i also have 84 2.4L motor which runs great. can i use it in the 91 but use all the stuff from 91 motor to make it work? (intake, injectors and all the wiring?)
 

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the 84 and 91 have different bolt patterns for the intake and exhaust manyifolds.

the 84 is a 2 coil sysytem and the 91 is a one coil sys.

the ecm are completely different as well ..


but if you really are going to try then u need to speak to datsunmike on Ratsun Forum - Powered by vBulletin


he is one of the fore most experts on mixing and matching nissan parts..
 
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