470 Fuel issues

[randy4140]

Help ! I am having some issues with my 470...I have filled the tank and on two occasions in the last week I run down about 10 gallons and the engine starts to seemingly starve for fuel, will run at idle or slightly above, but no more, filled it and "worked out the stumbles" and then ran fine for a while then same thing again. I am thinking the problem is in the tank draw line?? just a bung in tank with a barb fitting for the line. Dont know whats in the tank, any ideas for me. Could be fuel pump but dont think so... Any Ideas??

 

[Bondo]

I am thinking the problem is in the tank draw line?? just a bung in tank with a barb fitting for the line. Dont know whats in the tank, any ideas for me

Ayuh,.... Generally speakin', as all tanks are not the same, if ya unscrew the elbow outa the top of the tank, the dip-tube should be soldered to the elbow,....

If by chance, yer tank has the dip-tube as a part of the tank, drill out the bottom of the elbow to fit a piece of 3/8" copper tubin', 'n solder it in,....
Hopefully, it'll slide down through the tank dip-tube, 'n get ya runnin' again,....

 

[randy4140]

Many thanks Bondo for the advice, will try and get the elbow fitting out of the tank later when it may cool off...whew is 90 here today....see what we have then eh ?

 

[randy4140]

Barring finding a "dip tube " issue. What is the recommended fuel pump pressure on a 470?

 

[Bondo]

Ayuh,.... 4 to 6 psi for any carbed motor,....

 

[randy4140]

I pulled out the dip tube, it was an aluminum tube straight down into the tank, no "sock" on the end. blocked and pressurized the tube, no leaks...that's not it.
Pulled off fuel pump, looks like original, was lots of varnish in bowl but stone filter looked good. cleaned it out, pulled pump apart and found diaphragm looking "iffy"
at best. Lots o "wear and tear" in there over the years. will replace pump and then check fuel pressure ect. Thinking that will fix it...30 yrs old, probably past expectancy !!