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Author Topic: OS FP 40 Running Poorly - Stumped  (Read 3137 times)

Offline Steve Dwyer

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OS FP 40 Running Poorly - Stumped
« on: October 16, 2016, 12:52:46 PM »
My OS FP 40 had been running great on the Primary Force all summer but recently toward the end of the run it ran intermittently slow with loss power. I readjusted the NV 20-30 degrees richer than optimum as the instructions say and it still does the same. I richened it another 10 degrees and it improved some but still had the same slight loss of power toward the end of the run. Any more rich adjustment and I run into a 4 stroke cycle.  Toward the end of the tank it acts like it's running too lean and looses power almost like it's overheating. Again it didn't act this way all summer.
 
I'm plumbed the same as earlier with the muffler pressuring the bottom overflow tube and the top fill tube is tightly capped and sealed.  I've replace all the tubing and it's tight. There is a inline filter but I doubt it would run good for the first 3/4 of the tank and then become a problem if it was partially plugged, but I'm not sure on this, I have not tried bypassing the filter. I replaced the plug with an identical Fox Long plug I've been using all along.
 
This engine was an RC conversion where I installed an RSM Super Tiger needle valve and venturi and installed the added head gasket as recommended. I have read where some people have complained of the engine “running out” and was corrected by installing as many as three head gaskets to reduce compression. Is the term running out what I'm experiencing where the engine is actually going into a lean mode and possibility overheating causing it to slow down?
 
The prop is the same wood 11/4 I have used all along and the fuel is the same Sig 5%/29%. I did buy a new gallon recently and it was upped to the 29% by adding 4 oz. of Castor oil as I did to the fuel I purchased in the Spring. A companion Fox 35 on my Flite Streak has been on the same fuel without any noticeable change. Everything is tight on the FP 40.engine.

I'm stumped,

Steve
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Offline Tim Wescott

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Re: OS FP 40 Running Poorly - Stumped
« Reply #1 on: October 16, 2016, 01:19:20 PM »
When in doubt about a fuel filter problem, always replace the fuel filter and try again.  They're cheap, filter problems can mimic other things, and the only way to know is to replace.  And, when you're done, you'll have a new fuel filter.

Does the exterior of the engine show baked-on crud?  I had a FP that was displaying these symptoms.  It finally just seized up one morning and refused to run.  I did the crock pot thang (do a search here on "crock pot"), put it all back together, and it now works better than it did when I got it as a good-condition used engine.
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Offline Mark Scarborough

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Re: OS FP 40 Running Poorly - Stumped
« Reply #2 on: October 16, 2016, 01:56:05 PM »
that is a lot of oil for an FP .
Is that all castor, or is there synthyetic in the mix. I would suggest runing a tank of fuel with synthetic in it, then trying to find some 10 - 22 ( half synth half castor.) The fox 35 wants that, but the FP is a totaly different motor and needs different fuel
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Offline Tim Wescott

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Re: OS FP 40 Running Poorly - Stumped
« Reply #3 on: October 16, 2016, 02:15:37 PM »
Quote from: Mark Scarborough on October 16, 2016, 01:56:05 PM
that is a lot of oil for an FP .
Is that all castor, or is there synthyetic in the mix. I would suggest runing a tank of fuel with synthetic in it, then trying to find some 10 - 22 ( half synth half castor.) The fox 35 wants that, but the FP is a totaly different motor and needs different fuel

To complicate things, the FP is two totally different motors -- does Steve have a steel-liner FP or an ABN FP?  And what's the best oil for the steel-liner FP?  (I'm pretty sure that 11/11 synthetic/castor should be good for both, though -- I know it's good for the ABN).
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Offline RandySmith

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Re: OS FP 40 Running Poorly - Stumped
« Reply #4 on: October 16, 2016, 02:59:29 PM »
Steve
You should try 10% nitro 24 % oil 1/2 synthetic, that will  perk up the motor and let you run the motor in a rich setting, plus that is right on the  oil amount

Randy
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Offline Steve Helmick

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Re: OS FP 40 Running Poorly - Stumped
« Reply #5 on: October 16, 2016, 03:10:01 PM »
I'm quick to blame Fox glowplugs, but only because they're crap! Still, that doesn't seem like the probable cause in this case. But you never know. Glowplug seals sometimes leak with increased temperature or maybe run time. Leaky glowplug seals seem to cause lean running, which I'm neither certain of, nor understand why that would be.

I'd start by running different fuel, as proposed by Mark or Randy. And a new filter and hoses won't hurt. Clean the spraybar while you're at it. But I'm thinking that the problem is in the tank, specifically the uniflow tube may have corroded through at some point. What can you tell us about the tank? Metal? Brand? Are the tubes brass or copper?   D>K Steve
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Offline Steve Dwyer

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Re: OS FP 40 Running Poorly - Stumped
« Reply #6 on: October 16, 2016, 04:15:30 PM »
Lot of good info here thanks,

The engine is starting to crud up and I have an old crock pot, I have wondered if the varnish was building up on the sleeve. I'll have to look for a new set of gaskets I if cook the engine I think RSM carries them.

I'll replace the filter.

I thought I read the FP 40 like the 29% pure castor mix but in the long run obviously not I have both 5%Nitro/24% Castor and 10%/20% Syn/Castor blend, I'll switch over away from the heavy castor try a tank of synthetic and see how it improves the run. I don't think it's an ABN I'm pretty sure it's a steel sleeve so I have to limit the full synthetic fuel..

I had a problem with a previously tank two weeks ago, the solder on the filler tube failed and I replaced it with a brand new tank. I'll clean the spray bar. Hey I wonder if the pressure outlet on muffler could have plugged with crud also reducing pressure to the tank??

In summary could the varnish build up on the cylinder and piston wall from running the high castor softens during the run and cause to drag on the movement, yet the prop feels free after a run. Could the varnish affect the compression??

No one has commented on the added head gasket, what are your thoughts on this? This was an RC engine if it make a difference.

Steve
 

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Offline Tim Wescott

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Re: OS FP 40 Running Poorly - Stumped
« Reply #7 on: October 16, 2016, 04:34:00 PM »
I wouldn't mess with the head gasket until I'd cleaned up the motor and tank and whatnot.  Keep in mind that it had been running great, and not everyone believes that a pile of head gaskets makes that type of engine run better.
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Offline Steve Helmick

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Re: OS FP 40 Running Poorly - Stumped
« Reply #8 on: October 16, 2016, 04:46:30 PM »
Changed the tank, so I would be very suspicious of the tank and replace the filter. Lots of junk in new tanks, sometimes, even homemade with lots of TLC.  y1 Steve
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Steve Dwyer

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Re: OS FP 40 Running Poorly - Stumped
« Reply #9 on: October 16, 2016, 05:10:58 PM »
Got it thanks for the input, I'll keep you all posted on the results.

Steve
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Offline M Spencer

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Re: OS FP 40 Running Poorly - Stumped
« Reply #10 on: October 16, 2016, 07:11:19 PM »
Just to clarify ,



iron FP 40 / 1 .



a.b.c. FP 40 / 2 .

sounds like yours needs delacquering , due to All Castor .

50/50 C/Syn should do that in a few flights .

My Iron Fp is finally running o.k. ! %^@ . Couldnt give it away . Threw it in the Mewgull as its light , and has C'case Cooling , for a laugh . Inverted.

Didnt seem to like the 50/50 ( in ther MC72 ) Using 17C / 5 Syn & 15% . or other about 75/25 - 10 from blend of two .
Was leaning off on outsides , so moved the tank down .

11 x 5 Master ( the black one ) or Tornado 11 x 4 .

50 /50 Syn/C should delacquer yours , if thats the problem , in half a dozen flights or so. Saves stripping it .
Ive left Syn in TO delacquer as it goes . Sounds healthier with the higher castor.

The ABC Id go 50/50 or more Syn , but as its plain bearing , you need good oil . Over 23% wouldnt be needed .
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Offline Steve Helmick

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Re: OS FP 40 Running Poorly - Stumped
« Reply #11 on: October 17, 2016, 01:19:32 PM »
They're ABN, not ABC.

Also, if you buy one used, the early version case could have had an ABN piston/cylinder set installed. It could also have been converted from a .40FP to a .35FP, or a .35FP to a .40FP. Not real likely, but since they can be converted without machining, I thought I'd mention it. Piston/Cylinder, head, wrist pin swap. Same deal with the .20/.25FP. The interesting thing is that they run differently.  n~ Steve
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

John Leidle

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Re: OS FP 40 Running Poorly - Stumped
« Reply #12 on: October 18, 2016, 01:13:24 AM »
  Steve ,
  My Super  Magum .53 ran in a similer fasion awhile back it turned out being a POS  fuel filter.
  John
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Offline DanielGelinas

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Re: OS FP 40 Running Poorly - Stumped
« Reply #13 on: October 18, 2016, 04:35:07 PM »
Sounds like fuel is the problem. You did actually say it started to run poorly with this new fuel.
I agree with others that there is too much castor in your fuel. Try 10-22 half castor  half syn. Should run way better with all other elements the same.

Dan H^^
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