Engine only runs with choke

[RPDBRADY]

Hi, I have an 18hp Briggs V twin in my Max IV. The engine sat for a while without being started, I'm guessing a few years, from the previous owner. I had to clean out the fuel pump and the fuel line that goes from the fuel pump to the carb to get it to start orginally. The engine ran great after that. As I was driving the Max around the engine just sputtered out and died on me. I've put on about three hours of run time on the engine and now it will only start and run with full choke. Any suggestions?

[ji240z]

You need to take the carb off and clean it or rebuild it depending on the condition you see when you open it. The problem is a main or idle jet is clogged and needs to be cleaned

Hope this helps

John

[RPDBRADY]

Thanks John, appreciate the advice!

[racerone3]

you also might need to replace all the rubber fuel line and filter. fuel line that's a few years old (before all the ethanol was in our gas) doesn't seem to hold up to the newest fuels. the line can suck shut and starve the engine for fuel. the newest fuel also seems to be causing varnish in the carb at an alarming rate. i've seen a few carbs this year where the fuel was only 4-6 month old that looked like they had been in a barn for 20+ years with stale gas in them

[LarryW]

Hey RPDBRADY,
Before you tear the carb down, which might not be a bad Idea anyways but.... Sometimes you can rev it up high with the air cleaner off. Cover the carb with your hand and let the engine choke out to near stall. Keep the throttle wide open when doing that. When it almost chokes out release your hand and let it clear out. Do it a couple times. This creates a vacuum that sometimes can clear debri/gunk out of the carb. If it still does it after a few tries then you have no choice but to tear the carb down. Good luck!

[RPDBRADY]

Thanks again for the response. I bought new fuel line when I picked up the Max but I never replaced it with the old, guess now is the time... I already started takeing apart the carb and it looked clean, just a little crud, hope I didn't miss anything. If its not the fuel line or carb the only other thing I think it might be is the fuel pump. I could be way off on that. I still need to put the carb back on and replace the fuel line first and try that. Thanks!

[Roger S]

You may need to do more to the carb. The older models have a perforated emulsion tube pressed in the top, newer models have it screwed into the carb body(I think). Some of the tiny holes need the head of a small needle pushed through them to make sure they're open, along with carb cleaner sprayed through everything. Also take out the idle mixture needle screw on the side of the carb and spray. Then compressed air blown through everything.

The idle mixture screw, pull the plastic cap off, and count the turns as you screw it in. Prolly around 1.25. Thats your starting point when you assy it

[RPDBRADY]

Thanks Roger for the tip, mine is pressed in the top. It is definitely the carb causing the problems... Taking a closer look at it John (ji240z), you were absolutely right the main jet is clogged. Hope to have it up and running soon!

[chiefmoose]

Torch tip cleaners work great for cleaning out the jets. Use plenty of carb cleaner too. Clean all jets and passageways while you have it apart.

[RPDBRADY]

Just wanted to say thanks to all of you for the tips! I got the carb back on, after a good cleaning, and it started right up and runs perfect! I went ahead and replaced the fuel line too and while I had the chance I cleaned the rust off the fly wheel... I swear this motor has more than 18 HP... lol, Thanks agian.