Posted this on the Gas Engines forum, and someone suggested I post it here on the Fuji forum, which at the time I didn't even know existed!

Bought a G.P. Giant Supersportster and a Fuji 32EI - first giant and first gasser. Engine ran fine right out of the box but started running rough after a few flights. I found that the screws that attach the diaphram cover plate to the carb, and the carb mounting screws were not very tight. Fixed that problem and the engine ran much better for a few flights and then turned to crap again. A whole lot of needle tweaking, carb screen cleaning, gasket inspection, etc. didn't help, so I removed the engine, tank, fuel lines, ei module, battery, and mounted them on test stand. That's where I discovered.....

PROBLEM #1: The screws that attaced the carb to the spacer block were too long! The screws extended all the way through the spacer block and bottomed out on the cylinder block. (As soon as I saw that, I remembered reading something about that on this forum.) I removed the carb and found that the spacer block was warped, probably because the carb mounting screws were trying to pull it away from the cylinder block while the spacer block mounting screws were holding it down. I honed all the mating surfaces flat and shortened the screws, put the carb back on the engine, and it ran smooth as silk. Hope is restored! I fine tuned the carb per info from this forum, mounted the engine back on the plane, and took it to the flying field. (From this point on I will voluntarily delete the expletives.) At the field, the engine wouldn't fire at all, no spark. Hopes dashed once again. The battery checked OK, so I took the plane home and tore the ignition module and battery (4.8 V, 1100mAh NiCd) out of the plane. After a little troubleshooting, I found ....

PROBLEM #2: The MPI switch harness that I used for the ignition battery was bad. (The switch harness is the one part that I didn't move to the test stand with the engine.) In the 'off' position it was OK, so the charge side of the circuit was fine, but the 'on' side of the switch was bad so I wasn't getting any juice to the ignition module. I've used these MPI harnessed before on receiver batteries and they have always worked fine. The EI module doesn't draw that much current, according the the specs anyway, so I'm thinking that engine vibration might have caused the failure since the switch is mounted up near the firewall. I replaced the MPI with a Cermark DSC harness that I read about on this forum on both the receiver and the ignition batteries. I took the plane to the field, where the engine idled, transitioned, and pulled the plane around just fine for the way I fly (2D). I'm hoping that the Cermark switch will hold up better than the MPI. Anyone have any thoughts on that?

Just an FYI, especially for the other newbie Fuji users out there.

We're glad to hear you got your difficulties solved!

Bax:

Thanks for the reply. Here's a question for you: Are there supposed to be washers on the carb mounting screws? The reason I ask is there weren't any on mine when I found that the screws were bottoming out; if there had been washers I probably wouldn't have had the problem. Actually, I didn't "shorten" the screws to fix the problem, I added washers under the screw heads.

Fred

I have the very same problem with my fuji 50ei. I had to get a new spacer & gaskets as the old spacer was cracked from the carb mounting bolts being too long. I too, put spacers under the heads rather than cutting the bolts down. Since the engine wasn't accelerating past about 3000 I did all this plus rebuild the carb (the diaphram seamed a bit dry). I've got it going to about 4000 or so but no further. Past that point & it stops cold as if it ran out of fuel or had the switch flipped. I didn't do any honing & this engine was in a nose in crash. Yea, I checked the runout on the crank & it's OK. If I open both needles up a lot it will go to full throtle but with little rpm & no power. I'm stumped! Can anyone help?--------joe

Adding a washer won't hurt a thing.

If the spacer and gasket have had to be replaced, you need to make sure they're both installed correctly. You need to make sure the impulse hole is kept open so that the carburetor's internal pump is getting pressure impulses from the crankcase. Otherwise, the engine cannot run correctly because it won't be getting enough fuel.

Also, in cases where the engine's not running well at higher throttle settings, a cleaning of the carburetor's internal fuel screen can help a lot.

Thanks for the info Bax. I will check to be shure the spacer is in correctly. I'm not sure about a transfer presure port in the spacer though. This 50 has a black tube going from the engine crankcase to a fitting on the carb & I assumed that it was providing the impulses to the carb. I'm gonna check it right now.---------joe

Well Bax, it's been quite awhile since I posted the problems about my Fuji 50ei. For a short time the acceleration problem was overcome but came back, with a vengence. Same thing. Engine started on 3rd to 5th flip but would not accelerate. I tryed doing it slow, fast & by increasing & decreasing the needle settings for high & low-nothing. Then, after much researching, I thought it might be the high speed jet. It being cloged or stuck would cause this kind of problem. I removed it from the carb (by freezing the carb), removed the litle waffer, cleaned everthing up & reasembled the jet & tested it for one way air flow. All was well. After installation, same problem. I checked air flow travel on the jet againno blockage. I've been trying to figure it out again (past two months) and am compltely stymied. The carb gets fuel, I have a spark & I'm using a spring starter. I thought-maybe old fuel. I put fresh fuel with 50:1 mix to make starting easier. Nothing. Won't even try to start. I checked the other Q & A's on Fuji's. A few problems came close to my experience but non of the solutions did. I'm hoping You've got a good idea on this one, or maybe one of your buddies? Here's hoping-joe