MX240

My Feedback: (4)

I have a ZDZ 40RE on a TF Mustang that has given me good service this summer.
At the last it was hard too hand start at idle and stay running. Useing a electric starter to spin it over would work but still was hard to start. A couple of days ago I bought a carb kit and put a new diaphragm in both sides with a new screen. The motor "still" will not stay running after a choke. Have to reuse the starter....motor runs 6400RPM, but the idle varies slowly up and down from 1600 up to 2150 and some times almost dies unless I goose it. The high side is study and smooth with a Biela 20-8 prop.

Another questen....when installing the diaphragn on the pump side (Big screw) I put the diaphragn NEXT to the carb body and then the hard gasket then the cover. This is just the opposite of what the picture shows.....I just thought that if the pump lever was getting worn it would pump fuel better being closer?????
Jim

w8ye

My Feedback: (16)

The side with the lever is the metering valve by Walbro's definition.

Actually it is a demand regulator. Venturi vacuum on the diaphragm pulls it in and pushes on the lever which opens the needle from the seat and lets fuel into the metering champer that was pumped by the pump diaphragm on the other side of the carb.

You have the gasket on the wrong side of the diaphragm?

MX240

My Feedback: (4)

<You have the gasket on the wrong side of the diaphragm?> .....lol, yep, I know....it just seems at idle the ZDZ isn't pumping enough fuel and is unsteady. Closeing the idle needle speeds the idle up so I slow it down with transmitter trim and it starts all over again...die-ing. Then the airplane wants to slowly taxi on the hard surface runway. I took the new clean filter screen out as I have a inline screen. I thought maybe two fine screens were too much?? Jumping to high speed is ok.
I am thinking I have lost some compression and that will mean a send-in to Troy Built??
I need that to make the carb pump right???? right!

I have been in R/C since the 50's but, not that well versed on gas...

Jim

Tony Hallo

I don't know where that compression goes but it does get loose oncebroken it. I have three 80's and each one is the same, if you turn the engine over slowly, there no compression, however if you turn the engine backwards, there's plently. Must be the rotary valve leaking by. I found no lose of performance as the compression decreased. Did you loose any?
It's hardto image you put the pump daiphragm in backwards it still runs, but who knows? I've battling mine for two months with stalling symptions. About ready to throw the towel in.

MX240

My Feedback: (4)

Yes I hear you. I think I will give TBM a call tomorrow. I tried today but the engine guy (Jeff) was out.
I souldn't have to use a electric starter to get this thing to run everytime....It worked good this spring.
Jim