'73 620 with fuel problems

[kugelbake]

I'm trying to resurrect a '73 PL620. Southern Georgia truck with very little rust and an automatic transmission. Parked for about 10 years. Had fuel problems when it was parked. The carburetor was taken to bits and left in a box.

 

Then my friend inherited it and set about fixing it. He bought and installed a remanufactured Hitachi carburetor, then "Kreemed" the gas tank with sealer. At that point a family crisis caused him to move out of state. He generously gave the truck to me to fix up for my daughters.

 

But when I got it, the brand-new carburetor was filled with an awful white corrosion. And all the rubber bits were like jello. It looked exactly like a race-car carb that has been left to sit with a bowl full of methanol. Was it the MEK from the "Kreem?" I rebuilt the newly-rebuilt carb. But I may have missed a few details; the thing is very difficult to start and won't run for long. It behaves as if it isn't getting enough fuel.

 

Question #1: The float bowl cover can go on one of two ways. The little glass window can be offset to the top or the bottom. Which is correct? I set the float according to the directions in the manual, but the fuel level is barely high enough to be seen in the window with the cover installed 'window up.'

 

Question #2: The fuel pump puts out very little fuel. Perhaps a teaspoon-full with every squirt, perhaps less. The miniature pump on my Honda GL1000 puts out considerably more. Is it worth replacing it or should I buy an electric pump? It seems the Datsun design is lacking: The pump is mounted so high it always has to "pull" the fuel. An electric job could be mounted low and plumbed to "push" the fuel instead. Is this a common modification for the 620?

 

Thanks,

 

Kugelbake

[datzenmike]

Bull's eye sight glass up. Fuel level more or less in the middle on the dot. Not the end of the world if a bit off.

 

The Datsun pump is more than enough and works very well. If poor output expect the line to be full of crap. Check the fuel filter... what ever is in it will be in the lines too. No sense burning out an electric pump. Maybe drain the tank and look at the contents... maybe replace it and clean the lines out. Make sure the tank and lines are clean and you will find the stock pump adequate.

[kugelbake]

Thanks Datzen Mike!

 

I got a new filter on it this morning and the fuel pump is doing its thing now. I raised the fuel level to the center of the bullseye. It starts easier.

 

But the accelerator pump isn't working.

 

This was one of the most corroded areas on the carb when I rebuilt it. Of course it has a new piston and all that, but I could never really clean the ball-valve seat in the bottom of the accelerator well. I did bench test it and got a shot of fuel out of it, but now there is nothing. I think the ball valve isn't seating. Is there a way to cut a new seat? Or should I start shopping for a carburetor?

[datzenmike]

At least you can work on that with it on the truck. There should be a thin spring between the plunger and the ball bearing. Lift the ball out with a magnetic screwdriver. Maybe a piece of Scotch-Bright? it's a sort of abrasive pad for scowering, on a screwdriver? Replace the ball and tap gently to seat it, then make sure it's loose and not stuck and finish re-assembling the pump.

[kugelbake]

Datzen,

 

You are the Zen Master!

 

"Replace the ball and tap gently to seat it, then make sure it's loose and not stuck and finish re-assembling the pump."

 

It works perfectly now.

 

Thanks,

Kugelbake

[datzenmike]

Ha! Good to hear, glad it works.

[kugelbake]

Rats! Just when everything was going forward smoothly...

 

The fuel supply pipe that comes out of the tank (the one that is welded into the tank) was progressively flowing less and less fuel. So I dropped the tank and tried to clean the thing. I ran a wire into the pipe and dislodged a bunch of rust/mud. Then I got to a place just a couple of inches from the end where everything stopped up cold. Now NOTHING will go through the clog.

 

I soaked the pipe overnight with "Lime-Away." Didn't seem to help.

 

Any ideas?

[banzai510(hainz)]

dont let all that dirt hit the carb as it will glog the idle jets then no idle!!!!!!!!

 

 

http://www.olddatsuns.com/620tech.htm

[kugelbake]

Finally cleared the clogged fuel pipe with an "IV Drip" of Muriatic acid. I slipped a couple of feet of 1/4" clear vinyl tubing on the fuel outlet, then used a couple of bricks to hold the tubing up. Filled the tube with a few teaspoons full of acid, then went for a long walk on the beach.