mike Posted November 17, 2011 Report Share Posted November 17, 2011 Ive been messing with the damn carb on my 74 620. Its about as stock as they get. Ive gone through it at least 3 times now and all the jets and orifices are clean. Ive replaced all vac hoses and intake/exhaust manifold gaskets and it still wont idle. It runs like a top and is very responsive at anything above idle... I finally checked down the throttle body and sure enough, no fuel at all once fully warm and Im not applying any throttle. I havent checked voltage yet but I can do that in the morning... My question is if anyone would know what year and model anti diesel solenoids are a direct swap (if any) for a 1974 620? What are the odds they are all the same? Quote Link to comment
motavated Posted November 17, 2011 Report Share Posted November 17, 2011 Your damn choke relay might be dead. Just some advice... Maybe you have the wires flipped? Quote Link to comment
mike Posted November 17, 2011 Author Report Share Posted November 17, 2011 Ive got the wires going blue to blue, black to black and black yellow to black yellow... pretty sure its right but Ill check the wiring diagram. As far as the choke relay, my choke works awesome, if the relay were bad wouldnt the choke be inop as well? Another thing I noticed right before I packed it in for the night is that my fuse box has gotten a bit toasty... Ill check that out tomorrow as well as well as swap it out with a nice one. I let my sister borrow the truck for a few weeks and she put over a thousand friggin miles on it... Its over 46K now. The only thing that she will tell me is that "it ran funny a couple times and then it just did this." ...Awesome. Quote Link to comment
bananahamuck Posted November 17, 2011 Report Share Posted November 17, 2011 Do you mean the hexagonal thing with a wire sticking out below choke ???I might have a few of those laying around if you think you could use them..And i have quite a few junk carbs so if you need something off one im pretty sure i have it. But knowledge about how those things work , not so much. Obviously you should get more advise on matter first.. Found this picture..on some thread http://i161.photobuc...ag/101_0100.jpg Quote Link to comment
mike Posted November 17, 2011 Author Report Share Posted November 17, 2011 One other thing, When it is running with light throttle on the primary side looking down the carb from the front, the nozle from the side has good atomization but the nozzle closer to the front (The primary small venturi according to the service manual) is just dumping/drizzling fuel not atomizing/vaporizing... everything is clean, it was/is assembled correctly and has maybe 2500 miles on a complete rebuild at which time it ran friggin awesome up until now. I have all the vac lines plugged and dont have the air cleaner installed with all the vac lines correctly routed which could (maybe???) explain the dumping. The truck is all the way across town and once I get there I wont have internet access so any help would be great. Im seriously stumped here... The truck is bone friggin stock and under 50K original miles... I keep looking at my spare weber but I cant bring myself to do it :lol: Quote Link to comment
Eagle_Adam Posted November 17, 2011 Report Share Posted November 17, 2011 I keep looking at my spare weber but I cant bring myself to do it :lol: id take a Weber over the Hitachi anyday! Quote Link to comment
mike Posted November 17, 2011 Author Report Share Posted November 17, 2011 The only thing non stock on the entire truck is the 5 speed and its got radial tires. It knocks down low 30s for MPG with the hitachi and its still got good power. It fires right up even when its well below freezing too and warms up in a couple minutes. I actually *like* the hitachi... when it works right :lol: Quote Link to comment
LenRobertson Posted November 18, 2011 Report Share Posted November 18, 2011 mike - I'm pretty sure I'm running my SX without the needle in the anti-dieseling solenoid. As an experiment, unscrew the hex body and yank the needle out. Replace the hex body and see if you get idle. My SX idle is really random - sometimes fast, sometimes slow, sometimes dies. But I think the problem is something in the linkage where it isn't coming back to the same spot on the idle cam every time. Your problem is likely different. But before I removed the needle, I couldn't get any low idle. I have a feeling the solenoids are interchangeable between Hitachis. Pull n Save should have something. If you remove your solenoid, ground the body to neg battery post, and touch the wire to pos post, it should retract the needle. If it seems to work, changing it probably won't make a difference, but who knows? If you can't find a solenoid anywhere, I probably have an extra. I don't know when I'll be in Spokane next, so probably makes more sense to mail it. Len Quote Link to comment
datzenmike Posted November 18, 2011 Report Share Posted November 18, 2011 First there should be 12 volts to the solenoid with key ON. Second there should be an audible 'CLICK' fron the solenoid when turning the key ON and OFF. Third removing the pin inside is a good way to test that the solenoid or the idle circut is plugged. Removing the pin will not harm anything but the motor may 'run on' or 'diesel' on shut off. Some solenoids are longer or shorter with longer or shorter pins inside. Quote Link to comment
mike Posted November 18, 2011 Author Report Share Posted November 18, 2011 Len, thanks for the offer but Ive got a few carbs to scavenge for parts and seriously, Im about to go to nissan and see what I can get for new solenoids and relays just for peace of mind... On your 200SX, is your choke rod touching the back of the choke housing? If so get a few of the small linkage washers and use them to shim the choke rod away from the choke housing. Even if its just touching a little it will stick occasionally/randomly. I think I may have the wrong idea about how these solenoids function... When the key is in the on position the solenoids are "popped out" and actuate something that allows fuel at zero throttle. With zero power when the key is off, the solenoid retracts and fuel flow is blocked, effectively starving the engine of fuel and not allowing it to diesel. When I had all three solenoids jumped with a constant 12 volts from the battery, it ran fine but dieseled when I shut it off. Ill try pulling the pins tomorrow and see what happens... Heres what I did today... I jumped all 3 wires (BCDD, choke and antidiesel solenoid) with a straight 12 volt and it ran like a friggin champ. Good idle, smooth accelleration, no hesitation whatsoever... I was in the process of making a semi permanent "fix" and just tying them all to a keyed 12 volt source when I noticed that the "mini harness" that connects the carb electrics to the main harness wasnt plugged in all the way and has probably been that way since I have owned the truck. I cleaned the connections, put it all back together, drove it up to the gas station (4 blocks) with no problems. I noticed that it was getting fairly hot and the heater was blowing cold and remembered that I hadnt refilled the coolant when I replaced the manifold gasket... so I turned it off. I washed the windows and when I fired it up I had no dash lights and no heater and it was doing the same thing it was before. Runs like a top... no idle. I brought it back home and replaced the fuse for the heater,it was broken off behind the cap... it still looked good but no/sporadic continuity. I had dash lights again, and they were brighter than before, but it still wouldnt idle. I checked continuity on the carb connections and I had power for the BCDD and anti diesel solenoid but the choke wire was dead, even though the choke still operates...? I jumped all 3 with 12 volts constant again and it ran like it was supposed too, I undid the jump wires, plugged them back into the harness and it was back to square one... no idle. I noticed that the BCDD solenoid didnt sound as strong as the anti diesel one so I changed it out with a spare (using the original pin) from another carb that had a more audible click... it made no difference. I hooked the jump wires back up again and now that doesnt even work... WTF??? Thats when I called it quits... I was tempted to start ripping crap apart and that never ends up well for me :lol: Hopefully by writing this I will realize either a mistake I made or narrow down whats wrong. Im hoping that I didnt cook something by jumping them but Im fairly certain that they are supposed to be constant 12 volts hot when the ignition is on... Im going to dig through the FSM and see... Tomorrow Im going to pull the solenoids and spray the crap out of the inside with carb cleaner... I dont remember if I pulled the anti diesel solenoid when I rebuilt the carb the first time, I know I cleaned the BCDD... Maybe (hopefully) something is stuck/gummed up in there... Quote Link to comment
mike Posted November 20, 2011 Author Report Share Posted November 20, 2011 Seafoam through the vacuum lines... works like a friggin champ :lol: Quote Link to comment
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