77 Datsun 620 Won't Stay Running

[Justyn]

Hello guys! I'm new here and just recently picked up this 77 Datsun 620.

 

I got it running for few days idling well and driving it around the block and here and there. I drained the old gas and filled it up with some fresh gas and changed all the spark plugs as well the mechanical fuel pump. Ran well for around a week and now it stopped running. 

 

If I pour some gas down the carb it will fire right up and run for few seconds until it stalls. Check the float bowl  (the eye to see the gas level on the carb) and it seems bone dry. Pulled the fuel line coming out from the fuel pump and the gas is coming when cranking the engine over. 

 

All new the Datsun world and carbs in general but I'm not sure what to check or what could be wrong. 

 

Cheers!

[datzenmike]

If it was running , why change the fuel pump?????? If you still have the old fuel pump put it back on. Original pumps are better that the newer replacement ones. Never fix what isn't broken.

 

 

[Justyn]

2 hours ago, datzenmike said:

If it was running , why change the fuel pump?????? If you still have the old fuel pump put it back on. Original pumps are better that the newer replacement ones. Never fix what isn't broken.

 

 

Pump was originally broken since the day I bought it. Changed it it ran with the new pump then after a week it stopped. Pump is still working gas is getting pumped from the tank the line.  

[]2eDeYe]

Sounds like you have Hitachi problems.

 

Did this truck sit for a long length of time?

[datzenmike]

OK

 

Look down the barrel closest the valve cover and have someone pump the gas pedal several times. If gas squirts in then carb gas gas in it and it should try to start.

 

 

 

Before going farther replace the fuel filter if you haven't. Shit in the tank is stirred up and it should be changed every 3 years. Changing the pump may have sent some crap into the carb too.

 

 

 

 

[Justyn]

1 hour ago, ]2eDeYe said:

Sounds like you have Hitachi problems.

 

Did this truck sit for a long length of time?

Yeah believe so must of been for at least 10 years if I had to guess. 

 

48 minutes ago, datzenmike said:

OK

 

Look down the barrel closest the valve cover and have someone pump the gas pedal several times. If gas squirts in then carb gas gas in it and it should try to start.

 

 

 

Before going farther replace the fuel filter if you haven't. Shit in the tank is stirred up and it should be changed every 3 years. Changing the pump may have sent some crap into the carb too.

 

 

 

 

 

Might be so, while pumping the gas pedal no gas isn't squirting inside the carb. Not a drop. 

[Crashtd420]

8 minutes ago, Justyn said:

Yeah believe so must of been for at least 10 years if I had to guess. 

 

 

Might be so, while pumping the gas pedal no gas isn't squirting inside the carb. Not a drop. 

Try removing the fuel inline, not sure on the Hitachi but there might be a screen in there... 

Second thing would probably be something with the needle and seat, possibly the float.... might be stuck closed not allowing the fuel to pass....

Could just be gummed up and sticky...

 

 

[Crashtd420]

Something you could try is spray some carburetor cleaner into the fuel inlet and see if that frees it up and allows fuel to flow.... maybe even just a low pressure blast of air.... 

If that works you need to clean the carburetor.... 

[banzai510(hainz)]

OK do this. Look like Crashed beat me to the punch while writing this

 

if gas is  is coming out the fuel pump its making it to the carb.

Now the gas line to the carb there is a banjo fitting where gas goes in.

 

I want you to tap on this and maybe the needle valve is plgged or most likely has dirt in there. Usualkly if dirt the carb floods out as the needle valve wont close and let too much gas in.

Now could be sticky since the gas has varnished up the needle or seat. But you have been running this a week. Maybe the new gas is cleaning the parts inside and its working its way to the carb.  Most time its the idle jet that plugs up.

 

change out the filter or run 2 for a time until its clean. and swap out at least every 2 years as the trucks are bad at dirt getting in the tank from the fuel hose being underneath the vehicle and hose clamp get loose and water dirt work its way in there.(check fro brake line rust and dirt build up in that area as moisture kills the brake line there)

 

I never did this but i would pull the fuel line at the carb and maybe shoot carb cleaner up in there. Otherwise you got to look at the needle valve as gas is not getting into the the BOWL

Edited January 8, 2021 by banzai510(hainz)

[Justyn]

On 1/7/2021 at 8:51 AM, banzai510(hainz) said:

OK do this. Look like Crashed beat me to the punch while writing this

 

if gas is  is coming out the fuel pump its making it to the carb.

Now the gas line to the carb there is a banjo fitting where gas goes in.

 

I want you to tap on this and maybe the needle valve is plgged or most likely has dirt in there. Usualkly if dirt the carb floods out as the needle valve wont close and let too much gas in.

Now could be sticky since the gas has varnished up the needle or seat. But you have been running this a week. Maybe the new gas is cleaning the parts inside and its working its way to the carb.  Most time its the idle jet that plugs up.

 

change out the filter or run 2 for a time until its clean. and swap out at least every 2 years as the trucks are bad at dirt getting in the tank from the fuel hose being underneath the vehicle and hose clamp get loose and water dirt work its way in there.(check fro brake line rust and dirt build up in that area as moisture kills the brake line there)

 

I never did this but i would pull the fuel line at the carb and maybe shoot carb cleaner up in there. Otherwise you got to look at the needle valve as gas is not getting into the the BOWL

Turns out you are right! Thanks guys! 

 

Took apart the bowl section and it was so dirty. Cleaned it up well and got a new seal and she fired right up!. Think it's good for now also running two filters just to make sure no junk gets there again for time being. 

[banzai510(hainz)]

when one divides it up these motors are simple. just trace it out.

 

you can go back to 1 filter but on my truck I run 2. the 2econd one I run a clear one so I can see whats getting past the first one

[klam07]

I had pretty much the same issues on my truck when I first got around to running it.

Echoing banzai's last post, I learned that these trucks are pretty straight forward - for fuel you literally trace the fuel until the point where it stops flowing then start working at that, then repeat. Even wiring was the same from nose to tail, just follow the wires until you find the break.

 

For my carb I believe it ended up being one of the jets that was clogged/stuck, because tapping it would make it run for a bit. I had a rebuild kit but only replaced like 2 items.That and, having the air cleaner and all the vacuum lines hooked back up helped alot.