Datsun Gas Tank Baffles

I have a 1978 Datsun 620 King Cab

If i’m not mistaken this old truck doesn’t have any gas tank baffles. So when i come to a quick stop, all of the gas runs to the front of the car, and kills the engine. (since the fuel pump is in the rear of the tank)

I’m a pour college student, and onl uses this truck to haul my installments around town. If there a in expensive way to deal with this?

I did go to a welding university so metal fab is not problem.

I’d recommend you do NO modifications to your gas tank. Does it do this regardless of how full the tank is? If so, it’s not the tank.

I think you are mistaken about many things here…

First off, gas tanks for the most part don’t have baffles. The sloshing around only becomes an issue when you are very low on gas, so if that were the issue keeping the tank topped off is the solution.

Secondly, this truck is carbureted and does not have an in-tank fuel pump. The fuel pump is either a mechanical one that’s attached to the engine block or an electric in-line pump that’s probably on the frame somewhere.

Okay, thirdly what your problem is. Assuming you’re not just driving around with almost no gas in true college student style, the issue is likely the float level in the carburetor. The carburetor has a “bowl” which is like a little reservoir of fuel. The level of fuel in the bowl is controlled by a little float valve which is sort of like the one in your toilet-- there’s a little (probably plastic) float that when the level is high enough it cuts off the supply valve. When the level goes down, it sinks and opens the valve up. If the adjustment is too low, the level of fuel in the bowl is too low and when you go around corners or, apparently in your case, come to a stop the fuel sloshes away from the venturi and… sputter sputter.

Depending on what your level of confidence/plans for the trucks are, you can try to take the carb apart and adjust it yourself. You’ll definitely need a service manual. Realistically though, on a 30 year old truck it would probably be a good idea to rebuild or replace the whole carb. You can buy a rebuild kit for pretty cheap, or you can just do an exchange for a rebuilt one, or if you really like the truck (and are exempt from any smog tests) you can look into a Weber aftermarket carb for it which will make it run about 10 times better.

I seriously doubt that gas tank baffles, or the lack thereof, have anything to do with this problem.

It’s more than likely related to a carburetor float level problem, idle circuit problem in the carburetor, or an emission control device problem. (possibly a BCDD (boost controlled deceleration device) problem, which is not a rare thing to happen.

From memory here, I think this truck has a sight glass on the side of the carburetor with a dot in the middle. With the engine idling, eyeball the fuel level in that sight glass. It MUST be at the dot and even a shade over won’t hurt.

Checking this should be the first step. If it turns out to be an idle circuit or BCDD problem then that will require more diagnosis.

And i bow to your knowledge! thanks so much man. Yeah all of the information i listed came from an “old datsun guy” Who also recommended non detergent oil… so i should of realized the crazy in him right away ha ha.

Thank for the info,

Look around the base of the carb for the “idle mixture needle” Sometimes they have been hidden but hopefully yours will be exposed. Open the needle 1/2 turn and see if that improves things…