xHighOctanex Posted April 13, 2016 Report Share Posted April 13, 2016 So I have my black 720, 84 kc 4x4 regasketed the motor (from an 84 rwd, had to find all power steering brackets) ran ok for a while, still runs perfectly fine minus the fact it doesn't idle on it's own. It's a new carb I'm pretty sure vacuum lines are right, I just used my old 720 as a reference. It used to be bad and we found a bad vacuum leak underneath the carb like the base gasket, so I bought the "upper gasket" which is just that thin metal plate with a little gasket material on the top. Couldn't find anywhere that had the real gaskets so I had to make my own with gasket material which didn't make me happy but I figured it would work. Well everything's back was hoping it would idle now. Wrong, it's even worse, truck literally doesn't idle at all anymore, only time it'll idle is when I just get mad at it and hold it at 5000-6000 and can only hope it'll blow, after a few seconds and realizing I need to have something to drive I let off and it'll idle at around 1800 for a little, just until I actually drive it again, once I hit the brakes it just drops back down and goes back to it's same thing having to start the truck back up everytime I stop. Would like to fix this it's driving me insane, help please Quote Link to comment
banzai510(hainz) Posted April 13, 2016 Report Share Posted April 13, 2016 adjust the mixture screw and idle then the timming? also the newer Nissan had a idle cut off on the stock carb. Does this carb have it also? I assume it will and you have a 12volt wire to this Quote Link to comment
xHighOctanex Posted April 14, 2016 Author Report Share Posted April 14, 2016 Have tried adjusting mixture and idle best I could, should have added that lol. If I get it to idle anywhere near normal you pump the gas once it revs up then instantly dies. Only idle I can get it to do is really high, and about the cutoff I'm not sure I just connected in the only 3 wires on this carb. It's not a CA legal one which is why I saved the stock one for smog Quote Link to comment
datzenmike Posted April 14, 2016 Report Share Posted April 14, 2016 I assume this has a single wing nut holding the air filter on? Two wing nuts is a fuel injection set up used in the late '85s and totally different to trouble shoot. Listen near the carb and have an assistant turn the ignition on and off 4 or 5 times. Not START, just on and off. What you should hear is a soft clicking sound from the carb. Does it? 1 Quote Link to comment
xHighOctanex Posted April 15, 2016 Author Report Share Posted April 15, 2016 We got it to idle, rebuilt the stock carb and tool the eBay one off, accelerator pump didn't even work on it. New one though is grounding out somewhere. The plug on the back of the carb is getting power but the second it touches the carb anywhere it's grounded out and yes that means wired together plugged into choke etc. It just grounds somewhere (no power no ticking), but for now the truck runs n drives nicer than it has since it's been put together. Going to see if I can find out what's wrong this weekend. Quote Link to comment
banzai510(hainz) Posted April 15, 2016 Report Share Posted April 15, 2016 forgot to mention sometime the idle jet gets plugged. Most like not it but I have found this often in my 521 as the tank is dirty and rusty. Oten I cut open the fuel filter to give me a indication of what the tank is like Quote Link to comment
datzenmike Posted April 16, 2016 Report Share Posted April 16, 2016 We got it to idle, rebuilt the stock carb and tool the eBay one off, accelerator pump didn't even work on it. New one though is grounding out somewhere. The plug on the back of the carb is getting power but the second it touches the carb anywhere it's grounded out and yes that means wired together plugged into choke etc. It just grounds somewhere (no power no ticking), but for now the truck runs n drives nicer than it has since it's been put together. Going to see if I can find out what's wrong this weekend. Yes the carb grounds the choke and the idle cut solenoid. They both have a single wire. Not sure what your saying. Do they blow a fuse? Quote Link to comment
xHighOctanex Posted April 19, 2016 Author Report Share Posted April 19, 2016 With a test light the wires are hot, once they touch any wires coming from the carb the test light shows no power. For example, wire for choke is hot on test light, I plug it to the choke where it goes and now the light shows no power. Same with the idle wire. Is that normal? I honestly haven't checked to see if the choke is opening since noticing that and changing the carb, I kind of figured something was screwed up and taking the power or grounding it before it got to where it needs to go making it not work. I'll double check at lunch today. Quote Link to comment
datzenmike Posted April 20, 2016 Report Share Posted April 20, 2016 If no fuses blow then things are presumed to be ok. Turn ignition on and see if the choke opens in about 5 min. Does the idle cut make a clicking sound when connected? Quote Link to comment
xHighOctanex Posted April 20, 2016 Author Report Share Posted April 20, 2016 No sound, but I also just realized when I had the eBay carb on I had to splice the old connector in and went to only using 2 wires and I had this buzzing relay under my dash, originally thought it was fuel pump, but I took it out and the truck ran fine, realized now that was electric choke so I should probably put that back in Quote Link to comment
datzenmike Posted April 20, 2016 Report Share Posted April 20, 2016 You need power to the idle cut and the choke for them to work. No idle cut and there's no gas to the idle circuit. 1 Quote Link to comment
xHighOctanex Posted April 20, 2016 Author Report Share Posted April 20, 2016 The idle is fixed, we rebuilt the stock carb and everything but now my choke doesn't open and there is no clicking. Quote Link to comment
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