3400 Fuel System

KV Bruce

Member
Background: 1970 3400 200 hours since piston replacement, it has been running fine. Moving logs, got the nose low in a ditch, started to sputter like it was out of gas. Got it to roll back level, put 5 gals of gas in, let it set a minute, started up but would not hold RPM, sputtered and died. Limped it back to the shop, checked for flow out of the carburetor drain, just a trickle. Removed line from shut off valve at tank, check for flow, full pipe nice and steady. Checked flow at inlet to sediment bowel, just a trickle. Because it is easy, I removed the carburetor, inlet filter not plugged, float checked just right at 1". So, am I correct to suspect the fuel pump and its filter? The pump has never been changed, for $40 it might be best to replace it?? Original Holley carb and always heard the Zenith was so much better. There are two listed on this site, one for $220 and one for $404. Are they really that much better?? Any thoughts would be appreciated. Bruce
 
I know when mine ran empty the pump didn't want to prime, sitting for 3 days didn't prime it. Turned out the petcock screen plugged up. I was afraid it was that pump inlet screen but lucked out
 
One can only imagine my delight when I took the fuel pump cover off (one small bolt) and found it completely full of sand and $hit. Cleaned the screen and cavity out. The gasket was destroyed when I removed the cover, so I used an o ring from my HF kit. Started up and seemed to run fine. After 5 minutes it started sputtering again. Completely drained the tank and verified the shut off valve screen good. Now when I check the carb drain, nothing. 102 deg now, so I'll swing at it again in the morning. Maybe the pump needs to be primed. To be continued, Bruce
 
$220 "Zenith STYLE" (AKA large east Asian country copy), $404 genuine Zenith made in USA.
 

Does your 3400 have the glass sediment bowl in line next to the carb.
My brothers 3400 had a brass filter inside that sediment bowl that was stopped up, I unscrewed that filter and took it out, tractors run fine ever since.
Follow the fuel lines from the tank to the carb, clean every screen or filter you find until you get good fuel flow thru the carb drain.
 

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