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I just bought a 79 4x4, and I'm in the process of fixing it up... just got the valves adjusted and a new exhaust on it today. I can't seem to get the carb adjusted very well (stock hitachi) it idles rough, smokes, and idles really high or not at all. sometimes it seems to idle a lot higher than others. I just noticed today... sometimes when I pull up to a stop after being on the highway for a while, it idles really high until I take it out of fourth gear. as soon as I pop it out of gear, idle drops. (with clutch in) if I put it in third or fourth, the idle will instantly kick back up again. if I put it in first or second, no change. I find this extremely strange. it doesn't really bug me, I'm replacing the hitachi with a weber next week anyhow but I'm curious if anyone has ever seen this before or has any idea what might cause it?

final note is I also discovered that at some point someone had a DANA aftermarket cruise control module in this thing. it's still there, with all the switches and wires and stuff, but the control cable and a few wires are disconnected or cut. I have no idea if this might somehow contribute to the high idle behavior. it doesn't seem to change it if it's on or off though.

That's the curse of buying a used truck - you just don't know what creative engineering you'll find...lol

Congrats on your truck and welcome to the site!

BTW...the weber is definitely the right choice. Those Hitachi carbs are an absolute POS. You can pick up a used weber and a rebuild kit on ebay cheap. You also might wanna talk to Mokadeth about picking up one of his genuine new Offy intakes before they are all gone while you are at it. That darn stock Isuzu intake is a poorly made worthless POS too.

There's lots you can do to get more testicular fortitude outa these little old trucks, and you definitely came to the right place for any and all info on that! Some folks here have done some amazing stuff with/to their Luvs.

Enjoy your truck!

I had a van that had a Vacuum leak that did something like that. But it did have a computer on it. Fixed the vacuum leak and that fixed it.

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

im agreeing that vac leaks can do some interesting things. Also im thinking it might be the coasting richer thingy. I dont know anything about it as my truck has never had the emmisions stuff hooked up. But my gut says if that thing whent bad it could send extra fuel in there cause higher idle. I dont know just throwing that out for those who know more about stock LUVs to think over...

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1980 LUV 4x4, going under re-construction...

Ding Ding Ding, we have a winner.

Yes it is the coasting rich system working doing this. I suspect your clutch switch is miss adjusted thus allowing it to work when the clutch is in. Sounds as if your truck is running lean.

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Certified pilots, looking down on people since 1903.

well, I got the weber kit on tonight - I almost fell over when I started it up and heard it run the first time! it just... idled! perfectly, quietly, and smooth as cream! amazing... totally worth it in headache savings.


after removing the hitachi, I discovered that one of the bolts (the one that's right next to the thermostat housing) was probably really loose. that might have caused that vacuum leak... of course fixing that leak probably wouldn't have fixed the other problems I was having with the choke and who knows what else. also still can't figure out the high idle in gear thing.

The high idle in 3rd and 4th is most definitely from the coasting richer valve on the stock carb. There is a switch on the trans for 3rd/4th, a switch on the gas pedal for not pushed, and a switch on the clutch for not pressed. If all three of those conditions are met, the valve on the carb opens to allow a small amount of extra fuel in. Your clutch switch is probably not hooked up or not adjusted as mentioned above so you are noticing it. It was an attempt to get less emissions when the truck was coasting at speed.

Most weber carbs don't have the valve so your problem should have gone away with the hitachi carb.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

What he said, I was incorrect about the switch on the clutch, it is on the gas pedal. That is why we keep 800 around, so he can fix our misstakes, thanks for fixing that 800.

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Certified pilots, looking down on people since 1903.

Luvrv8: Actually you weren't wrong, there is a clutch switch and one on the gas pedal both. On a 79 there should be two switches on the clutch, one for starter lock out and one for this coasting richer business.

My 77 the switch on the pedal is touchy enough you can feel the slight dip in coasting speed as you touch the pedal. The whole system is for emissions, and never made a lot of sense to me. I think they figured out high RPMs with no fuel created NO2 emissions or something like that.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Like I said, I was right

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Certified pilots, looking down on people since 1903.