Help with plumbing please

[andrew wise 2]

Hi. I am just having a go with my first  4stroke model, but I need a bit of help with the plumbing. The engine is a SC52 my problem is the fuel inlet is on the top of the card the throat facing down. The fuel tank outlet is about level with the carb barrel, the fuel pipe to the carb has rather a large loop in it to get to the inlet which seems to cause an airlock as I cant get the engine to prime. If I raise the tank the card floods. What an I doing wrong? Thanks

[Doug Ireland]

Hi Andrew,

 

I've got a similar set-up on one of my models. The only thing I can think of is you may have a leak in your plumbing somewhere if it is air-locking like that. I'll admit I didn't like the big loop in the tubing either.

[Steve Hargreaves - Moderator]

Andrew, 4 strokes normally draw fuel up pretty well...even through a loop of tube....as Doug suggests I suspect you might have a leak or a split tube somewhere....check the fuel tube where it goes over the fuel tank tube & also onto the carb...also check the clunk tube inside the tank as this can split or hole where it slides over the brass tube. Another good one is to check that the clunk isn't touching the back of the tank & restricting fuel flow that way......

 

You have opened the needle valve 1.5-2 turns?? What happens if you open the throttle, choke the carb & turn the prop...?? Does it suck fuel up to the carb??

Try to keep the tank to engine runs as short as possible but a small loop shouldn't cause you any problems.......