240z running rough

[rosaaen89]

before i bought the car and made the 30min drive home i was with the previous owner and he did blow into that line and i did hear bubbling in the gas tank. i still probably should drain the tank and try to get it cleaned out.  Previous owner told me he had the tank cleaned out and sealed so no rust issues would occur with the tank. but it’s probably best for me to make sure of it myself. if the tank is indeed filled with gunk what’s the best way to clean it all out ? 

[siteunseen]

It's a PITA if you ask me. Don't do it if he said it's been sealed. Try and find a borescope and look. I guess I would suggest a Fram G-2 clear plastic filter right out of the tank and see if you get debri. That would be the easiest. The 240s have a bunch of vent hoses that go to an evaporation tank on the passenger's rear side of the hatch. That makes for a real jobby job.

Here's a Fram G-3 install for the 280s, same concept but I've found the smaller fuel lines on the 240s fit better to the Fram G-2. They're like a 5/16" where the G-3s are 3/8".

https://www.atlanticz.ca/zclub/techtips/fuel/g3filter/index.htm

[rosaaen89]

the other day when i was blowing from the line to get fuel to get it started i did catch some fuel inside of a water bottle and it was a little darker orangish color. maybe it’s just year old fuel or maybe it’s from crud? when i get home later i’ll upload some pictures to give you better idea what i’m talking about as well

[Patcon]

I would get a small container that is suitable. Fill it with fuel and feed the carbs out of that. That will help isolate the problem. If it goes away, it's in the tank or supply lines. If it doesn't it's mostly from the fuel filter forward. We'll use a gatorade bottle with some holes in the lid for fuel line. Don't leave fuel in it long term. Some plastics will melt!

[7tooZ]

Try Patcons idea. Fresh fuel is always better

Couple of other things you can do

Drain the tank, I use 5 gal buckets 3 at the most. That will give you a good idea what might be in the tank. 
take that $4 filter and cut it open to see what’s inside. You can usually see what settles after a while. 

[rosaaen89]

i did run the car off fuel by manually filling the carb bowls. it does run off that then dies but still has the sputtering issue running at like 60-70%. can i drain the tank without dropping it ?

 

sorry i know these are probably dumb questions but i’m fairly new to the datsun and thank you for all of your help. 

[Patcon]

19 minutes ago, rosaaen89 said:

i did run the car off fuel by manually filling the carb bowls. it does run off that then dies but still has the sputtering issue running at like 60-70%. can i drain the tank without dropping it ?

 

sorry i know these are probably dumb questions but i’m fairly new to the datsun and thank you for all of your help. 

I dont like doing that because you can over fill or underfill the bowls. If you add the baby bottle before the fuel pump it checks the whole system at once

[siteunseen]

Yes! Patcon has the easy way to bypass the tank. A 2 gallon gas jug will fit in between the radiator and the grill. Run a hose from the suction side of the pump into the jug. I drove mine around like that with it bungee corded down before I dropped the tank.

 

[7tooZ]

36 minutes ago, rosaaen89 said:

i did run the car off fuel by manually filling the carb bowls. it does run off that then dies but still has the sputtering issue running at like 60-70%. can i drain the tank without dropping it ?

Yes there is a drain plug in center of the tank. 

[rosaaen89]

17 minutes ago, Patcon said:

I dont like doing that because you can over fill or underfill the bowls. If you add the baby bottle before the fuel pump it checks the whole system at once

sounds good i’ll try this out and see what happens 

[rosaaen89]

2 minutes ago, 7tooZ said:

Yes there is a drain plug in center of the tank. 

awesome i’ll get that done as well and check for any crud in the tank 

[Patcon]

My first concern isn't crud in the tank if it's been coated. My first concern is you have a stopped up fuel or return line or the tank pick up is clogged with tank sealer