superc_1 Posted January 11, 2008 Report Share Posted January 11, 2008 Have a Hitachi carb on my 620. I put my hand over it the other night trying to see if I had trash. It kill the truck, and when I started it back up all it would do is rev up to about 4000 rpm (fast). I took the carb off and found the fast idle cam was the problem. I tighten everything up and put her on and she runs like a million. (Problem fixed; right, well no!) Now the problem. After it warms up in the morning and I drive a mile or two she kicks into the high rev mode and I have to turn her off and pull over to the side of the road. I then pull on the accellarator cam on the carb, pull up on the automatic choke (which I guess is connected to the fast idle cam) and then she works fine for the rest of the day. (whew) MY question: Did I break something when I put my hand over the carb; which is, allowing this to happen now? Any suggestion or what to look for? Thanks in advance.:confused: Quote Link to comment
]2eDeYe Posted January 11, 2008 Report Share Posted January 11, 2008 All I can say is, stopping the car that way won't hurt anything. I was gonna say maybe your choke is out of adjustment but if it's manual.... Quote Link to comment
superc_1 Posted January 11, 2008 Author Report Share Posted January 11, 2008 redeye. the choke is automatic. Quote Link to comment
]2eDeYe Posted January 11, 2008 Report Share Posted January 11, 2008 Is it adjusted properly? Quote Link to comment
Shonuff Posted January 30, 2008 Report Share Posted January 30, 2008 it sounds like your linkage might be too tight, not allowing the fast idle cam to re-set after warm up. is all your linkage clean? it also could be the return spring for the fast idle cam has slipped off its anchor so there is no tension to force it to return. maybe its just a datsun thing but i dont understand this sentence I put my hand over it the other night trying to see if I had trash Quote Link to comment
Bleach Posted January 30, 2008 Report Share Posted January 30, 2008 I don't get the trash part either... maybe its a Datsun 'truck' thing. ;) Should be as simple as linkage adjusting or sticking. Putting your hand over the carb just gets rid of all air intake. It runs rich for 1 second at the worst. No permanant problems doing that. Quote Link to comment
datzenmike Posted January 30, 2008 Report Share Posted January 30, 2008 Clean all the linkages at the rear of the carb with brake cleaner. WD-40 also works but will leave an oily coating that will attract dust which might cause the same problem later. ENGINE OFF AND COLD, hold open the throttle half way. Check that the choke butterfly on the top of the carb closes and the linkage raises and sets the fast idle cam. When the throttle is released it should not return to idle but sit on the fast idle cam. Open throttle again, and hold. Manually open the choke butterfly, the fast idle cam should drop down and when the throttle is released it should return to idle. There should be no sticking or any tight spots in the linkage travel. Sometimes working the individual linkages back and forth many times will shine up the contact points and loosen them up. Once engine has warmed check that the choke butterfly has opened fully. Important that it is fully open! Quote Link to comment
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