huntingdad

My Feedback: (2)

I have an FS-120 surpass pumped. The pump is leaking and I can't find anyone with parts to repair it. Hobby services suggested I try the forums, so here it goes. Anybody got parts that could help?

Gray Beard

My Feedback: (-1)

There are a couple different types depending on the series. I do have a series one under the bench, I think, with the metal pump. Parts for these haven't been around for a long time though. The newer models have a plastic pump that you have to replace when it goes bad. A photo of your engine and an idea of what parts you need would help.

huntingdad

My Feedback: (2)

I believe it's a metal pump. The engine just says FS series on the side. I think the diaphram in the pump is leaking because I get an excessive amount of fuel through the bleed hole on the pump back plate. I'll try to attach a picture. Thanks.

Gray Beard

My Feedback: (-1)

Sorry, I can't be of any help at all. I'm not real familiar with the first two pump types that OS started out with and have never had the type you have. I think? Think you have the second type tried by OS? For questions go into the glow engine forum and then into factory support and ask Bill Baxter. Bax may be of some help? This is the type I have on hand and thought maybe I could help you out with some parts but it's not going to work. OS hasn't used either type of pumps in years but someone else may have an old parts engine on hand. Only thing I use this one for are screws. It was running but I could never get it adjusted to make any power so I trashed it when I got a newer model with the new type of pump. When that pump went out I moved on to another brand of engine.

Bax

My Feedback: (11)

Your engine is an O.S. FS-120 Surpass II that is missing the pump. You have the C-13 carburetor installed, but somebody's removed the pump from the rear cover. What you are likely calling the "pump" is the regulator. That carburetor cannot operate properly without the pump. The carburetor requires a differential of at least 10:1 between pump pressure and engine demand in order for the regulator to work properly.

The regulator has not been available for years. O.S. stopped making the engine in 1996, and parts were discontinued around 2001 or so.

You will have to see if you can find a pump, which is normally part of the rear cover of the engine. You'll also likely need to locate a new carburetor, since the regulator was not sold as a separate part.

ho2zoo

My Feedback: (5)

I have the same problem. Mine still has the pump but it runs like crap. I have heard that the diaphragm in the pump will start leaking after a few years and that's why it won't run right. But, I tried bypassing the pump by connecting the tank directly to the carb. Muffler pressure to the tank just like any other glow engine. Runs a lot better! I am hoping that as long as the tank is above the carb it will work. Putting it inverted in a Top Flight Mustang, so we shall see.

Gray Beard

My Feedback: (-1)

I do question using these old obsolete engines in a nice airplane. The engine I showed didn't run correctly and nothing I did with it instilled any form of trust so it turned into a parts engine. I like pumpers and ended up with a new OS 120 III and loved that engine until the day the pump went out. I paid the big bucks to send it in for a new diaphragm first then discovered the pump required replacement so moved on instead of sticking with the OS. I went to YS and haven't had any problems in years. Once in a while I need to replace a diaphragm but they only cost $2.50 and keep spares on hand for the two different sizes I have. 1.20s and 1.10s.
At the moment with most modelers going to either gas or electric I find a lot of both brands of glow engines for sale at swap meets for next to nothing. I gave up buying new four strokes years ago, they are too easy to rebuild to bother with a new one at this time.
For about $100.00 you can also buy a new .91 SK two stroke, I have also had great luck with these engines.
I wouldn't risk a plane by using one of these old engines. They do provide me with a number of screws and sometimes help others out by using them as parts engines.
If you need a pumper then try the swap meets and pick up a YS but make sure it is an FZ model, I have a number of the older models but unless you have been taught to tune one the older models can kick your butt.
I have also found a number of like new, even some NIB OS engines without the pump that are a great deal.
There is no good reason to be fooling with these old obsolete engines and risking a nice new airplane.
One of my hobbies is rebuilding OS and YS engines and I have done a lot of them. When I have a question or problem the first thing I do is ask BAX if it's an OS or read the YS forum when needed.

huntingdad

My Feedback: (2)

Thanks for the input everyone. I guess I'll put a different engine in the plane. No need risking a new plane with an old egine.