This is cross posted from the facebook group - figured I'd widen the exposure, plus make a record that was searchable for once this gets solved. 1994 Carry, 2wd, lift/dump. As you can hear explained in the video, truck develops a bad idle when under electrical load. Fresh spark plugs, wires, cap and rotor - no change from old parts to new parts. The only other issue this truck has is a weird backfire - which sounds like a sneeze, and isn't noticeable with how it runs/drives other than being able to hear it. Usually off throttle, but happens under steady throttle application/cruising too. Doubt its related though. I haven't hooked up a multimeter to the battery yet, but that's on my list. What else should i consider with troubleshooting? My hunch is alternator or battery, but open to suggestions. Video too large to upload, found here -> . Thanks!
Seems pretty normal to me. At higher revs, the kinetic energy seems to smooth it out while at lower revs, the gap between power strokes is so much more noticeable. Idle time is usually quite less than higher rev time. Personally, I would not be concerned about it, but if it does bother you, you might bring up the idle speed a bit so it wouldn't be so noticeable when you do sit with it idling. The reason 6 & 8 cylinder engine seem so smooth is that the power strokes overlap, and the 4s have their power strokes just about meeting while there is a gap in 1, 2, & 3 cyls. Fred
My Hijet has a kick up solenoid which increases the throttle when the air conditioner is on, or the voltage drops. That kicks it up so the electric loads don’t bog the engine down. You might try setting your idle up a bit. My truck likes it at about 950-rpm, and 1300 to 1400 cold. On the back fire: It sounds you’re getting lean out as you come off throttle, and the throttle blade closes down. That can cause a backfire. Some carbs have dashpots to retard the closing. Some carbs have solenoids to keep them open for a moment, and some have a vacuum diaphragm which keeps the throttle open for a moment. Look at the carb and see what you can figure out.
So, mine will kick up the idle when the A/C is turned on, however, when I turn on the headlights it drops down in rpm to the point of almost stalling. It never kicks up the idle for the headlights. Are there two separate idle up mechanisms for the two systems, ie, A/C and other various electric circuits?
I’m running a Hijet, so I don't have any specific knowledge on what the Carrys have. Just a pretty good working knowledge of what the options are. On the Hijet, the idle kick up is run through a vacuum circuit.
Borrowed this diagram from gdw4078. Good diagram. Depends if you have a 3+2 or 2+3 but I think more importantly, we should look at the white vacuum circuit as a starting point to figure out why we aren't getting the rise in rpms when loaded.
Did you replace every vacuum line in existence yet? That may cure some of this. As mentioned there are relays and solenoids that activate via vacuum so its important to have zero vacuum leaks.
I have read that too. It is absolutely pointless to even start tinkering with the carb until you are certain there are no vacuum leaks. Have also read that a vacuum line can look good but actually the wall have become porous from degradation. Just got my new silicone vacuum line in yesterday. Once it warms up outside, that's the plan. Brrrr....
On my 1995 carry there us 2 diaphragms/vac solenoids (round metallic with vac lines going in) around the carburetor. 1 is for when truck is going through its warmup high idle it kicks down the idle once warm. The other one will kick up the idle when lights are flipped in or any other draw such as heater fan. Both of these diaphragm vacuum solenoids are run off if vacuum. One of mine had a clogged in line filter or timing valve that is on the vacuum line connected to the soenoid/diaphragm. It is a round blue/white valve looking doohicky. Check your vac lines to these solenoids/diaphragms and also your vacuum timing valves that are inline. My 2 cents...
Mine is similar. For AC on it kicks up fine but for heater fan or lights on it doesn't and it should. I drive around it for now but I suspect its like @Nebuniram says and I have a dookicky thats just not doing its vacuum job right or I don't have the other idle up diaphram adjusted right. I know my AC idle up was misadjusted to could be.
I totally missed all the activity here - thanks for all the responses. I will look into the vacuum lines - good call on those. Guessing its something like that as there was a definite change - this truck used to idle perfect with lights/heater on full blast, its only been a more recent change that it struggles a little bit. Does anyone sell a vacuum line 'kit', or is it best to just go and buy a roll of vac hose and cut to length? I haven't stuck my head in there yet to know if there is anything special about the lines for these.
I got mine from from Summit, you will need 20-30 feet of it to do all of em. https://www.summitracing.com/parts/tbs-ts-hv0303-be
Solved mine. Mother in law needed a jump start and my carry was the easiest to get to the battery. Put the cables on it and low and behold, the negative turned with ease. Not tightened. Found out that they remove the negative for shipping. It wasn't retightened after shipping. Works perfect now. Hope this helps someone else. Still doesn't kick up when lights are turned on but also doesn't drop idle much at all either after the proper tightening of the ground.
I finally got a volt meter out last weekend to check, with lights on it drops from 14.4 to 13.6. Still plenty of juice to keep it charged, so likely not the battery or alternator. My guess is vacuum leaks as suggested above, I'm going to buy a roll of hose and replace them all this spring.
I finally got around to replacing all the vacuum hoses about a month ago and that seems to have fixed the issue. In the process I broke the end of one of the AC idle up vacuum switches - but when I cover the switch it idles properly. Definitely had a leak somewhere
Hey Jigs, is there any pics of this circuit or diagram, i think my a/c kickup isn't working properly, thanks, Bob
Anyone have a IDLE UP CONTROL "VSV,IDLE UP" 18117-50F00 ? i ordered '95160-70B00-00' which is the switch next to the VSV.
I can't really see why you couldn't use any generic vacuum solenoid from the auto parts store. https://www.autozone.com/engine-man...elco-egr-vacuum-solenoid-55566051/1255975_0_0 Has anyone ever had the electrical half of the idle up circuit fail? I got a carry rebuilt recently with a new carb and sometimes it will idle up with the headlights or fan, and sometimes it doesn't. When it's not working like it should, I don't measure anything as far as voltage on the connector. I've yet to find a wiring diagram, not that I've looked that hard yet...
Found the adjustment for the idle up, now its perfect, idle with or without the a/c is identical thanks for the help.
