strange carb problem

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Bugabago
Posts: 15
Joined: Fri Oct 02, 2009 4:28 pm
Car: 1978 datsun 620 motorhome

Post

Hello gentlemen,

I have a 78 with the L20B engine that I have been driving semi regularily for a few years now. The last time I drove her I noticed a lack of power accelerating and climbing. I tried to take her out yesterday and she would start and idle okay, but when I pushed on the throttle, she sputtered and died. I managed to get her back into the driveway by gunning it and letting out the clutch at the same time in rapid fire. Once I got her back in the driveway, I started looking in the carb and if I held the choke mostly closed I could get her to rev up, but if I let the choke open up she would die when I operated the throttle cable. She is starving for gas. The level in the sight glass seems fine. I replaced all the loose vac lines I could find. Now today she will start, but I can't get her to idle.

Any Ideas?

Al


newnissanfanatic
Posts: 14
Joined: Mon May 10, 2010 5:02 pm
Car: 1984 Nissan 720

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I have had similiar problems with my carb, you probably have some carbon buildup in one of the cylinders. I use carb cleaner right down the throat of the carb and you will have to rev it up when you do this or it will die on you. Do it a couple of times or until the exhaust comes out clean, trust me if it is a carbon build up you will see a visible exhaust.

Bugabago
Posts: 15
Joined: Fri Oct 02, 2009 4:28 pm
Car: 1978 datsun 620 motorhome

Post

Thanks for the reply,

I think I may have solved the problem for the short term. Yesterday I was messing around with it and I tried gunning the engine once I got it started enough to not die in two seconds. I gave her full throttle in rapid fire mode until it seemed to break free. I figure that there must be either some varnish that broke off and plugged a jet or like you said, some carbon build up. I generally drive her real gently. Maybe I need to blow out the gunk more often. I absolutely will try some carb cleaner though.

Al

jdroberts720
Posts: 4
Joined: Mon Jun 20, 2011 8:27 pm
Car: 1981 Datsun 720 king cab

Post

try replacing your fuel filter, theres one on the pump and a tiny screen in the inlet on top of the float. clogged filter = lack of gas = fail


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