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Outside workin'
67 Posts
Discussion Starter · #1 ·
I've got a 1988 Lawn Boy RT5S rear tine roto tiller, this thing is a real serious piece of equipment! It's got two 40lb (or so) weights that mount over the drive tires.

It's got the 5hp Briggs on it and it runs like a champ now that i've rebuild the carb, BUT it starts hard when cold. The choke works properly, it doesn't matter if the gas tank is full of half full or low, oil levels are perfect (freshly changed). It's got the setup where the fuel tank is mounted below the carb and the carb mounts directly to the tank with a fuel intake tube (solid) lowered into the tank. I'm guessing the problem is siphon related? as in you have to pull it 20 times to get the siphon going to suck fuel up the tube? What's the fix for this so it starts like my other briggs motors, second pull!

Thanks in advance.

1,750 Posts
I think that's probably a Pulsa-jet.
What happens is the longer tube pulls gas up out of the tank and dumps it into a little cup mounted in top of the tank, but under the carb.

Then the shorter tube is supposed to pick up fuel from that cup and take it on into the engine through the jet etc.

So...what happens is rust. Normally the tank rust's and fills the little cup with rust particals.

Or the little Cup rusts out, and the carb fill's the cup but it runs right out before the siphon can catch any of it.

I made a fix for that. You can do it yourself too.
I got a Chainsaw tank filter, on the end of a long hose and fastened it on to the carb in place of the long Siphon.

Then I took the little Cup out of the tank, made one out of Copper, and (Solder or Rivet it in place) and replace the Diaphragm in the Carb.

Honestly, in front of witness's, I put all that together dry, poured some gas in the tank, and the engine was running before I got the pull rope all the way out.

Pictures of that are on this forum somewhere. Might be called "Chain Saw fix"

Two different cups. One of aluminum which corroded, not a good idea, and the other is copper. Much easier to work with and worked without corrosion.
Tool accessory

Auto part
Fixing the fuel siphon line to the plastic nipple of what's left of the long siphon tube. The other end lays in the tank with a Chain saw filter.
That tiller is still running, I used it tonite.

Pipe Finger
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