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dblott
01-09-2010, 09:43 AM
Charlie,
I’ve got a ’78 Datsun 620 Kingcab which is an extra vehicle. I’ve been driving a company pickup since ’88 so the Datsun has never been driven enough to keep the clutch disks from sticking to the flywheel, a problem it had when I got it from my grandpa’s estate for $1 back in ’92. My personal rig is a 99Yukon (fully loaded with 6” lift, Hypertech III programmer, K&N filter and 35s. My wife drives “my” 2009 G8GT. Just kidding, it’s hers, but I think I have her talked into an exhaust mod for this summer. My daily driver is a 2008 F350 4x4 (company supplied).
The original problem with the Datsun:
The main reason at the time for not driving it was it wouldn’t idle well without blipping the throttle to keep it going. I took it to a shop for a tuneup (probably in’96). He said he couldn’t get it without rebuilding the carb or a new one. Didn’t have money at the time for working on an extra car so I let it slide.
Summer 2009:
I reconditioned the disks, cleaned up the pressure plate, bought a new throwout bearing and pilot bearing and got it runnable this summer. I bought new plugs, fuel filter and pcv. I know the gas could be suspect as it had just a little above empty from pre E10 days with stabile, and added ¼ tank of new and a carb cleaner additive when I started working on it). I tweaked the carb adjustments where it would idle roughly when warm. I pulled the fuel line from the pump and it seems to pump plenty of fuel.
When I first start it, it will run for about a minute then it dies. I can’t save it with the throttle. It will not start again until I add about 2 fingers of gas to the carb. Then it will start and run good enough to move it around the driveway and will idle (roughly) on its own when warmed up. I would like to rebuild the carb, but the rebuild kit looks to be hard to find. (haven’t tried Nissan yet). I would consider new carb and realize this will probably be what it takes, but would like to try rebuild first. I think I can duplicate any gasket thicknesses I may need to make.
My questions:
From the symptoms I described, do you think there maybe something else going on also? Such as the electric choke or some other item? If the rebuild kit can’t be found, and I need a new carb, are there any aftermarket ones that will work on this pickup? I seem to remember that some aftermarket carbs don’t do well in imports.
I’m seriously thinking about thinning the herd(cars not kids), and letting kid #3 trade it in towards her own car.
Thanks for any ideas,
Dale

-Ray-
01-09-2010, 10:33 AM
Try carbs only in Calif. I'm sure you can get a carb for that truck.
2000 or 2200?

dblott
01-09-2010, 11:54 AM
Hi Ray,
Not sure about 2000 or 2200 question. It was bought by Grandpa new in Oregon if that matters.
1952cc, L20B eng.
Just found my old Haynes Manual. Lots of crap to test. Still appreciate any help though. Shows diagram for both Cal. and non-Cal. carbs.
Dale

dblott
01-09-2010, 01:06 PM
Ray,
It's a non-Cal carb. That sounds like a diet.The only differences I can see with the Cal diagram, is mine has a BCDD(Boost Controlled Decelleration Devise). Haynes shows this is"(for Canada)". Do I need this with an aftermarket carb? Owners manual explains it has to do with normal combustion during deceleration and decreasing hydrocarbon emissions. Symptom of faulty BCDD is high idle, which may have been a problem years ago. I remember I messed with the idle screw some years ago. There are a couple of other differences relating to the BCDD or lack of so a plate wouldn't convert mine to a Cal version. I'm thinking about trying to tear it down and blowing it out to clean it to see if it does any good, and expect to have to buy a new one if the cleaning doesn't work. Any brands recommended? First I still need to check auto-choke and fuel shut off systems which might be part of the dieing prob. Would a new carb come with these or would I have to use mine or get new if bad anyway?
Dale

GRRRR8
01-09-2010, 03:30 PM
It sounds like a few issues.

1. My guess is the plastic float is sinking to the bottom causing the fuel bowl level to be low.
2. Probable choke thermostat failure as well.

Most rebuilt carbs are junk I hate to say it, but I have been burned so many times its the truth.

You will need a rebuild kit and a float. Make sure the kit has a needle and seat in it as they are bad from sitting.

Finding the kit.....I would start online. You will need the # off the carb or the tag in most cases.

dblott
01-09-2010, 08:01 PM
Thank you Charlie,
That will be my plan.
Dale

-Ray-
01-10-2010, 07:02 AM
I was thinking the float was bad as well. If the float allows gas to enter it, it will sink. Float needs to be able to well, float, to keep the bowl full of gas.
I've used carbs only in Calif before. I've been driving since '68. I've never had a problem with them.