KEVINBARK

Greetings folks. Yes I know i know, no such thing as a stupid question right... haha. I have recently built a Phoenix models Diabolo and installed an ASP 120FS. I started running the engine in with absolutely no problems. I was using a fuel tank out of a previous victim, after a while I noticed that it had a small leak. I replaced it with a new tank, rechecked all the plumbing, and tried once more to start it. NOTHING. I then found that I cannot get the engine to draw fuel into the carb when i prime it. The throttle is open, the choke is open, the plumbing is correct, yet I cannot get ti to suck fuel. What gives. Im sure im just missing something tiny...adice pleeeeeaaase. The model has been RTF since thursday, however im stumped by this engine.

Thanks in advance

bubbagates

My Feedback: (32)

Are you sure the clunk is on the end of the line in the tank. Was the stopper on the new tank tightened properly (air leak)

I know you said you checked all the connection but I gotta ask, are they on correctly, vent to muffler, pickup to carb/needle valve

shag555

I've had this happen to me before and it turned out to be a cut silicone line. Better pull the tank (carefully) and go through everything again. TAKE YOUR TIME. I mashed a Mini Funtana after changing out the elevator and rudder servos, and did not check the surfaces prior to flying. Turned out that the elevator servo was reversed from what I had previously set up!

MPB

KEVINBARK

Yup, the clunk and the plumbing is fine, i can suck fuel out of the tank , so its not a problem getting out, just as if the engine is not sucking enough to pull it form the tank. Glowplug is tight, so are all head screws, exhaust too, i just dont know...and yet the compression feels fine. Im totally mystified

Don M.

My Feedback: (5)

Do this, leave the pressure line hooked to the muffler, remove the line from your carb, put a finger over the muffler outlet and turn the prop, fuel should come out of the carb line with no problem. If it does you have a fuel draw problem with the engine, if it does not you have a leak / blockage somewhere in the fuel system.

bubbagates

My Feedback: (32)

Are you sure both needle valves is are open enough? Is the o ring on the needle valve still there. Do you feel suction against your finger if you try to prime the engine by holding your finger over the carb and closing the needle valve the whole way


IS the tank right behind the firewall or is it way back?

fredscz

My Feedback: (47)

If you can fill the tank and then suck it back out the same line then check and make sure that the idle and high speed needles are open and not turned in all the way closed. I've seen it happen several times and the owners had no idea as to how but it happened anyway.
FredB

bbbair

This would suggest to me that you picked up some gunk from the first fuel tank and it is now lodged somewhere in the fuel lines or carb.
Disassemble and clean carefully would be my recommendation.

Ispitfire

I second that, I had an engine that wouldnt give for ages, i couldnt figure it out at all. Someone suggested a blockage to me but I dismissed it cos I had a fuel filter in the plumbing. It turned out that I had while reassembling plumbing put the fuel filter back in the wrong way (d'oh!), the sebsequent blockage stopped me from flying for about 2 weeks!!

KEVINBARK

Thanks for all the informative answers....the problem turned out to be the nipple onto the carb had been broken off inside the threaded part of its hole, yet was still standing perfectly in place, after replacing the nipple, she fired up fine.

Thanks again.
k

Rcpilot

My Feedback: (78)

I had this same problem once.

The low speed needle fell out of the engine. Couldn't get it to suck any fuel with a big hole in the side of the carb where the low speed needle was missing.