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Discussion Starter · #1 ·
I'm going to put a 2.3 in my 89 RS and although I COULD just install the stock carb, I think I'd like to go with a Weber or some other carb that would be simpler. My goal here is fuel mileage. I'm thinking I'll put 16" wheels and tires and PROBABLY keep the 4:77's at least for now unless it becomes a problem. Advice on a carb please. Thanks guys.
 

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I really like my weber. I believe Jerry prefers an excellent condition stock carb.. No idea regarding mileage with the 4:77s. I get low 20s with my stock gears 4:55 and 31 inch tires as opposed to 17 mpg when my trooper was f/i. I understand the weber 38 as opposed to my 32/36 gives a bit more ooph though weber advises against it unless you have a bit of cam, larger exhaust, etc. I have read where folks like the larger weber (38mm) though they have no other mods. I really like my 32/36. If you go weber, you'll want an electric fuel pump, pressure regulator and set it between 2-3 1/2 lbs. pressure. It has been stated that the mechanical action of the manual fuel pump is detrimental to both the operation and performance of the weber, holley, etc. Reckon that's all I can think of at the moment. In closing, I would go with a stock carb if you can locate an excellent condition/rebuild. The weber, adapter, fuel pump, and regulator would add up in price quickly as compared to a very good condition stock carb. If you get the stock carb, make sure you get the FEDERAL version and not the CALIFORNIA version. Also make sure you get the little heater plate which is sandwiched between the carb base and intake.
 

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Discussion Starter · #3 ·
Thanks Shooter, I didn't realize there were any stock carb advocates.. I have a REALLY nice and clean stock carb, looks like it may be new old stock. It came in a box in the back of an '86 I bought a while back. I think maybe I'll bolt the stock carb on and see how that goes since it's a lot cheaper for the time being. I'm surprised to hear about your fuel mileage with those tires. Everything I've read says mileage goes way down when you get tires that big. I want to use 16" wheels because I can't get 10 ply tires in 15" and I'm so tired of changing tires... I change tires as often as most people change the toilet paper roll... Also, I figured a 16" tire should be close to the same as what came on the RS stock so hopefully the performance would stay in the acceptable range, especially considering I'm going from 2.6 to 2.3. Planning to have the head machined a bit to hopefully help get a little more punch out of it. I'm not trying to build a hot rod, just a very reliable non-problematic, low cost to operate daily driver.
 

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You're welcome buddy. I'd definitely go with the stock carb and see what you think. Yep, I was pleasantly surprised with the mileage myself. Even more so was it kept the same level of performance (through all rpm bands) as the f/i. Do these little motors have rpm bands? :lol:
 

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********** said:
I'm surprised to hear about your fuel mileage with those tires. Everything I've read says mileage goes way down when you get tires that big.
I believe you'll get better mileage out of 31's than out of 235/75/15's.

But go bigger than that, and your mileage begins to drop again.
 

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Selador AKA Tat said:
********** said:
I'm surprised to hear about your fuel mileage with those tires. Everything I've read says mileage goes way down when you get tires that big.
I believe you'll get better mileage out of 31's than out of 235/75/15's.

But go bigger than that, and your mileage begins to drop again.
I agree....I was barely getting 19 with the stock sized 225-75/15's....and swapped the 31/10.50/15's on and my mileage went to 21-22, but 90% of my driving is at 55-65 mph.

Also....my little 2.3 STILL has the stock carb, and I do not believe it has ever been removed......just abused religiously!!!

My 90 only gives me 17-18 mpg.....but that is with a leaky fuel tank (hint hint **********!!!).
 

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i had a weber 32/36 on a couple troopers , they are great , very easy to install and work on , there are many jets you can buy to tune it , all you would need is a weber manual which on ebay costs about 8$.

my 2c
 

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Discussion Starter · #8 ·
Thanks for all the response... Also, keep in mind this truck has 4:77's and came stock with 31's.... My initial plan is to run 16" wheels, but I may change out the differentials at some point.
 

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Discussion Starter · #9 ·
Also, I have an '89 automatic that I've been putting a lot of miles on lately and I'm getting 21-22 MPG in it, and it's EFI'd and on 235/75r15's. I've never gotten mileage like that in any other Trooper, I've been wondering if it's the auto trans???
 

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********** said:
Also, I have an '89 automatic that I've been putting a lot of miles on lately and I'm getting 21-22 MPG in it, and it's EFI'd and on 235/75r15's. I've never gotten mileage like that in any other Trooper, I've been wondering if it's the auto trans???
Probably all the sensors, etc are functioning well, etc to maximize the mpg.
 

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shooter said:
Probably all the sensors, etc are functioning well, etc to maximize the mpg.
Exactly what I was thinking.

I've wondered for years, just what makes one vehicle out of so many identical ones, get so much better gas mileage than the rest of them. (Same thing as one being an absolute lemon, even though it is identical to the rest, and you can't put your finger on exactly what is wrong.)

The only consistant thing I have ever found, amounts to exactly what you said.

All sensors, and parts are getting full ground, full voltage, are in good shape, and everything is operating the way it is supposed to.
 

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Discussion Starter · #12 ·
Although I recognize that theory, I have changed the entire top end on this Trooper including head, compllete intake throttle body, etc. The only thing on this Trooper that hasn't been changed is the short block, transmission and ECM.... When I first got it running I put an AMC head on it so I attributed the amazing gas mileage to that, but I pulled that head a while back and replaced it with a stock head, and the mileage didn't change. Due to some other problems I was having I installed a different intake that I had completely disassembled, cleaned, cherry picked parts from other Troopers, etc. and although it fixed my erratic idle and stalling problem, the fuel mileage stayed 21-22... So... either something's been done to the motor, or the auto trans gets better fuel mileage for some reason. I went to the federal EPA fuel mileage website and it shows the automoatic getting 1 MPG more than the 5 speed which I thought was pretty unusual, usually it's the other way around, but I've owned several 5 speeds and they've never gotten anyewhere near the kind of mileage this automatic gets.... I dunno
 

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********** said:
The only thing on this Trooper that hasn't been changed is the short block, transmission and ECM....
Clue ???

We can hope so.

:D
 

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********** said:
Although I recognize that theory, I have changed the entire top end on this Trooper including head, compllete intake throttle body, etc. The only thing on this Trooper that hasn't been changed is the short block, transmission and ECM.... When I first got it running I put an AMC head on it so I attributed the amazing gas mileage to that, but I pulled that head a while back and replaced it with a stock head, and the mileage didn't change. Due to some other problems I was having I installed a different intake that I had completely disassembled, cleaned, cherry picked parts from other Troopers, etc. and although it fixed my erratic idle and stalling problem, the fuel mileage stayed 21-22... So... either something's been done to the motor, or the auto trans gets better fuel mileage for some reason. I went to the federal EPA fuel mileage website and it shows the automoatic getting 1 MPG more than the 5 speed which I thought was pretty unusual, usually it's the other way around, but I've owned several 5 speeds and they've never gotten anyewhere near the kind of mileage this automatic gets.... I dunno
ONE OF THE MAIN REASON THE AUTO GETS BETTER MPG UNDER THE SAME OPERATING CONDITIONS , IN 4TH GEAR WITH THE CONVERTOR LOCKED THE AUTO HAS A 30 % OVERDRIVE

WHERE THE MANUAL HAS ABOUT 18%, SO THE AUTO WOULD BE TURNING APPROX, 10% LESS ENG RPM AT ANY GIVEN SPD SO THEORETICALLY IT SHOULD GET A BIT BETTER MPG
 

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JLEMOND said:
ONE OF THE MAIN REASON THE AUTO GETS BETTER MPG UNDER THE SAME OPERATING CONDITIONS , IN 4TH GEAR WITH THE CONVERTOR LOCKED THE AUTO HAS A 30 % OVERDRIVE

WHERE THE MANUAL HAS ABOUT 18%, SO THE AUTO WOULD BE TURNING APPROX, 10% LESS ENG RPM AT ANY GIVEN SPD SO THEORETICALLY IT SHOULD GET A BIT BETTER MPG
The 89 automatic had torque convertor lockup ?
 

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all the trooper auto tranys are O\D 4sp with a locking converter 88 to 91
all 4wd Isuzu's pre 88 are manual trans ONLY, none are auto.
in the USA that is.....

with 31" tires and 4.55s
a MUA manual should be around 2,350
an auto should be around 2,070 @ 60
for 235/75/15 tires add 200/250ish rpms

the only autos to get an auto trans pre 88 are 2WD and yes there 3sp with no locking converter
 
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