Export thread

have an ancient Troy built rototiller that has had a 5hp briggs engine, with the pulsajet carb, put on it somewhere along the way. I'm having issues keeping it running. It'll start great the first time and runs for 3, maybe 4, minutes and then dies. After that it is a mofo to start. Seems like it is getting way too much fuel. I've been through the carb and tank. New diaphragm/ pump, new governor spring. I've cleaned the jets & passageways. Everything is clean. Triple checked the linkages. New fuel. I've tried adjusting the mixture screw in and out. Removed and cleaned behind it. I just don't understand why it's getting so much fuel and then just dies. It's a manual choke and it works as it should.

Hoping some of you gurus on here can enlighten me.....

There are 2 basic types of pulsajet carbs. The old style has an adjustable needle valve for the main jet and the newer style doesn't. The main jet is fixed and it has an adjustment for the idle mixture. Can you take a pic or give the model and type number of the engine so we know what carb you have?
When it dies have you checked for spark?
What does the spark plug look like after ut dies? Black wet? Black dry?
Does engine smoke?
Did you have fun getting to the carb mounting bolts?

There is also a couple other possibles. One is the valve clearance if it is a L-head as They near Zero cold and at Zero or less hot. Another is a weak or failing coil or plug. I just an air compressor that would run until it get hot. It would not stay running or start under air tank load. Unload the air tank and it would start up and run until the kick off pressure and die again. That one was the ignition coil but I seen plugs to do the same thing.

That is why i asked if it has spark when it dies. I doubt if it is flodding out after 15 mins of running. Something else like you said coil or valves. I am going to bet on a bad coil.

Got when checking for spark too as some plugs and coil can fire when not under compression load but not when under compression load as well as a plug that shorts under load will flash one those neon testers.

The best test on single cylinder is try a known good plug. New don't always means good.

When I think a coil is failing i use the Briggs gap style tester and not the neon type and i always put in a new plug. And since i screwed up and ordered the wrong plugs i have close to 100 RJ19LM plugs. LOL.

That is a lifetime supply for me.

Now, now, you not suppose to be making mistakes like me...I have gotten to where I triple check my ordering lately as I have ordered things in the past that I didn't intend to order as I had to put in the cart to just see the cost.

I am still working thru my software programmer's screw up of my inventory and it is now going on two years. Just ran into where my system said I had two belts but when I checked there were none. Rats just placed an order the evening before. I suspect I am still show over $5,000 in inventory that I don't have even I have increased it by $2,000 so this year.

I buy the RJ19LM, RC12YC and BPMR7A plugs by the 25 plug shop pack. I wanted 2 packs of the RC12YC and brain farted and orderd RJ19LM instead and already had 2 packs on hand. Will be a few years before i need more of the RJ19LM.

Someone say Pulsa Jet?

Where did the OP go? Dude ghosted us.

Did you remove the welch plugs and clean behind them? Most likely you will have to boil the carb to clean it out good. Old carb probably is full of varnish and grit.

I would lap the carb to block flange and use the real Briggs gasket. This gasket I speak of is roughly 1/4" thick. Chinese Amazon/Ebay carbs come with a thin 1/8" gasket.

OP here. For some reason I'm not getting notification about replies. Figured I'd check today and behold!!

I haven't checked for spark after it dies. I'll do that as soon as i get home. I haven't had a chance to mess with it any more as it's been raining for days now.

It isn't varnish. Carb was remarkably clean on the inside and I cleaned it again. I'm confident that's not the issue. Tank is clean also.

I'll take some pics and report back in a few hours

Ok. Preformed as usual. After it died I pulled the plug. It was surprisingly dry and lightly sooted. I've ran way worse before. It still had spark. Only adjustment is shown with the red arrow in the pic. Screw it all the way in and it dies. I've backed it off 1 1/2-2 turns. It runs great when it's running.

Model 130202

See pics

The screw is the idle mixture. When it dies try spraying a small amount of starting fluid into the carb and see if it fires for a few seconds. If it does you probably have a fuel pump or fuel pickup tube problem.

PROBLEM SOLVED!

Hopefully this might help somebody in the future. Ended up being the tank wasn't venting. Took off the cap and ran it under a load for a few minutes until it sloshed out and I shut it off in the name of safety. A couple well placed drill holes in the cap and it runs like a champ now! Ran it for half a tank of fuel with numerous stops. Started on the first pull every time now!

Thank you all for your 2 cents worth! These carbs are stupid simple. What clued me in was the dry plug. It WASN'T getting fuel yet the carb had plenty.

Briggs made a screen cup deal that went over the main jet fuel pickup tube. That was a huge step in the right direction. These carbs and tanks need to be spotless in order to run correctly. Can look inside the tank and think it's clean. Get some readers on and see another sloppy mess LOL.



Glad to hear you got it running.