Zenaoh ,cutting out

marc wrote:

If you really want to keep the quick fill, plug it onto the second line in the gas bag. Use it for filling and burping. Take it off the line going to the carb. Only thing in this line should be a fuel filter. (and the T if you use one).

Dubro make large plugs for fuel/water lines. I maching my own out of aluminum. Doesn't have to be fancy, just something fuel proof to stick in the end of the line to plug it.

A quick plug can be made from a wood screw with the proper sized shank , just take a cut off wheel or grinder and remove the threaded portion.

Those quick fill gizwhiz's that seem so neat will open and loose fuel suction at certain frequency vibrations , I wiped out a museum scale 1/3 size model of a full size Pitts Special biplane because of one of them opening up and letting air into the line. As Marc said the only place to use one of them is on a dedicated fill line.

think ,im going the T then ,
quick fill seems not worth the hassle ,put my isolator on a peice of glass and on side that goes to engine ,:ohmy: talk about not flat ,like a swing rocks back and fro ,im going to buy a ali one with teflon seals now ,my engine is still new ,what caused this to buckle fast is it because its a modded engine more heat ?? ,, i will get rid of these 2 suspect problems and post again soon after trials ,,,

Most frequent problem for the warped isolator block is over-tightening. That was most likely your problem right there.

have been reading about fuel dots and tees in planes (as this is your suggested install method )and it seems guys are clamping the line to carby when refueling so engine dosent flood or get fuel is this nesesary or will fuel take easy path to tank ??

Not necessary with gas carbs. That was probably for nitro engines.

I run a new OMEN engine as well and experience similar "out of the blue" engine cutting issues.
I also seem to have erratic drop in power under full bore. Some of this I attribute to O-ring problems discussed in another thread here but I am starting to suspect that the engine does not like the coil mounted in its original position on the crank case. The guys over at quickdraw suggest strongly to mount the coil on the rails due to excessive vibrations on the engine itself.

I do however note problems with clunks in tanks, I am currenty using a Dubro with a clunk. I have also noticed that the shorter the fuel supply line the better the result; mounting a IV Bag next to the engine close or on the CG might help further.

Having said all that, I am sure all this has nothing to do with OMEN who I believe to a very good proting job on their engines.

cheers
Andre

I have NEVER owned a Zenoah that required having the coil mounted remotely due to vibration. If such is the case with your engine, have someone look into it. Typically very badly vibrating engines are due to a twisted crank or someone "trying" to balance the flywheel...been there done that...makes them worse than if you simply leave them alone.

Hi

This is my first post as I only joined the forum today. And what a great forum this is!

With my first Zen powered boat I had exactly the same issue with it running perfectly for a few minutes before cutting out. These symptoms appeared after only after 10 hours of running my boat with no problems and they got progressively worse.

I found two issues both causing fuel starvation. Firstly my original hard tank had a vent in the filler cap which when tested had become blocked. Secondly the same tank had a non serviceable fibre filter fitted at the clunk end of the pick up pipe. That filter had upon inspection and testing become very clogged and resistant to flow through it.

I fixed the issue by using a Dubaro hard tank. The vent pipe is now routed to the deck via a small inverted U tube with a fine hole in it. My fuel filter is an in line one that is easily accessible for cleaning and the tank pick up consists of just a heavy unfiltered clunk.

Fingers crossed this issue has now been solved for me.

Pic hopefully included shows my vent pipe.

Cheers
Craig

Hi Craig,

Welcome to MGB. That setup should work for you. Just some friendly advice though if I may. You can use a clunk, but sometimes when fuel is running low the can take in air causing missing issues. I know some guys use clunks that actually absorbs some of the gas to "make up" for when the clunk isn't actually in fuel. Most guys however will just run the brass tube inside the tank to the rear/port side for best optimal fuel pickup. When using hard tanks that's what I do also.

As for the vent, I know you've already done it now, but for future builds, I would recommend routing it out the side of the boat. With movement and vibration while the boat is running, some fuel is bound to escape via the vent...this just prevents getting fuel all over the top of your boat.

Hi Marc

Thank you for your welcome to me.

I like the suggestion of replacing the flexible inner tube with a brass one pointed to the bottom of the tank as it sounds simple and effective.

The vent I pictured does in fact have a secondary brass tube soldered inside the exterior pipe leading to a very small opening. However as you rightly said it does still allow a little spillage when the the tank is full.

I appreciate your advice.

Regards
Craig