1972 400 fan cooled, wont suck gas.

[Viking]

I have a go kart that I have a 399 kawi fan cooled from early 70s has a walbro carburetor wda-1 type. Rebuilt the top end last summer along with the carb. Has good compression and it ran good although I did not open the crankcase and replace the seals. So I got it running this spring took it on a bumpy ride and had to baby it back it wanted to stall. After I shut it off I couldn't get it started again. I rebuilt the carb again only switching the diaphragm. Put it all back together and it will not suck gas, it wont even move the gas in the clear line. The fuel was running good to the carb. Replace the pulse line that doesn't have any leaks. Does this mean I have a leaky crankcase seal. Any suggested or advice before I have to split the case?

[rminier]

 1. Could a leaking crank seal diminish the strength of the pulse to the carb?...absolutely.
 2. Is it a good idea to replace the crankcase seals if the owner is unsure of their condition?....absolutely.

 I would try unhooking the pulse line at the carb...you may have to substitute a longer hose to the crankcase fitting.
 In order to make the engine easier to spin, remove the spark plugs and leave the ignition "off".
 Hold your thumb on the end of the pulse line, and give the recoil a few pulls.
 You should be able to feel if you're getting a decent pulse at your thumb.....then the evidence points to the good, ol' finicky Walbro carb.
 You can rig up a pressure tester as described on some other posts on here to check if the seals are leaking.....not a bad idea, or just replace them. But, if the carb isn't pumping fuel properly, you will still have to deal with that issue.
 Good luck!

[rminier]

http://vintagesleds.com/bs/index.php/topic,49980.0.html

If you find you have a decent pulse from your pulse line, check out the link above....posted over on the vintagesleds site.....by one of the sharpest members over there.

Rick

[Viking]

put thumb over it and pulled seems like nothing at pulse line, I felt little to nothing.  Always, it sucked gas 12 inches in 1 or 2 pulls. Now nothing don't even move. must be bad leak. also in the rebuild kit seem there is only 1 seal why is that?

http://www.mfgsupply.com/snowmobile/snowengine/snowwinderosa/snowackawwinderosa/snowackawwinderosacomplete/711033a.html

[rminier]

 Well, that's a bummer if you can't feel much of a pulse.
 I'm baffled by the gasket set, too.
 Those engines (is yours a T1A400S1B ?) used the exact same seal at both the MAG and PTO ends.
 Mfgsupply shows the crank seals individually ( part 501302R) for $2.89 apiece. I guess you could order an extra one, although the picture of the full gasket set may have both seals stacked on top of each other??
 I can't believe a full set would have only 1 seal..

[Viking]

ok I did I test by put some soft grease in pulse line. pull plugs and pulled it over like 10 times fast. it moved grease about 1/8 inch in towards case, grease still sealed line after all that.. not enough action there? motor is TIA400SIB

[Viking]

To check for proper operation of the pulse line from the crankcase. Pull the line loose on the pump end and place some soft grease over the opening so that it completely covers the hole. Run the starter to crank over the engine, If the grease does not suck in and blow out, you do not have enough action to operate the pump.