Fuel Pump Re furbishment

[Peter Rob]

Hi all My first post Wolfdad thought it would be a good idea to share this with you Turbine Freaks
WARNING NEVER RUN A PUMP DRY
With the JetCat ECU it is possible to monitor fuel pump voltages, I found that mine were rising for no apparent reason, also startups were taking longer,
I decided to have a look at the fuel pump to see if there was some thing amiss. Ran clean fuel through the fuel pump to flush it out, no difference in voltage.
Cut back heatshrink and removed 2 end plate screws,removed the sealing ring.
The plate had score marks from the gear wheels, cleared these by rubbing on a flat surface with wet and dry,checked the gear wheels they apeared to be OK
Rebuilt the pump and flushed it through with clean fuel,until clear
we found that we could adjust the tension of the 2 screws and it would change the voltage required to turn the pump
With carefull adjustment we found that the pump would work well at 0.3 volts (JetCat) Wolfdad needed 0.63 volts (Orbit and Wren I think)
With clean fuel and a loop system we ran the pump for 1/4 hour, no problems
Degreased the end plate and screws and secured the 2 screws with nail varnish/laquer (your choice of color) and put on new heatshrink
This has worked for me on 3 pumps and with 1 of Wolfdads
Peter R

[wolfdad]

Peter,
Sincerely appreciate you posting this. Fuel pumps are one of those items that, I would be willing to bet, fit in the category of "throw-away" items for a lot of folks (maybe wrong here). Very dependable item, however, definitely a "single point" failure item when it does fail. When I had the failure on the Jaka, I immediately got on the phone with Al Wert out at Starwood to order another one. During the process, Al mentioned sending the pump back....that it was definitely an item worth repairing. Up to that point, I was totally unaware that it was a "user fixable/adjustable" item. Peter, you further amplified that with several PM's we shared, so I thought, what the heck...the pump has already failed...what can I lose. In the meantime, thanks to Al's superb customer service, I had another new pump in my hands within 24 hours, so now, I really had nothing to lose by attempting a repair. Now, I have no idea why the original pump failed, however by removing the heat shrink, then removing the two screws on top and cleaning them up, then cleaning the gears of any collected gunk, I was able to re-assemble the pump and by adjusting the torque on the two mounting screws, I was able to get the pump running again and running very effectively. Jakadofsky in the instruction manual, says to (don't run the pump dry...always use a container of fuel to perform these procedures) increase the pump voltage to 1.1 (max voltage available from the ECU), then back the ECU voltage off until you get just a consistent stream of fuel from the output side (Jakadofsky says a value of about .6 volts is nominal). By adjusting the torque on the two mount screws (doesn't take much here...finger tight may be fine), you can achieve the correct operating value. A note of interest here is that loctite is NOT a viable method for keeping the screws at the correct torque. Peter was kind enough to tell me that clear nail varnish/polish will work fantastically. Since the torque on these screws to achieve a smooth operating pump is minimal, securing them at this torque is critical. I knew something different has been used when I had to run the screws through a 3mm die to clean them off. Also, replacement of the heat shrink is critical as well. The heat shrink also serves to keep the pump plate on and secure as well. The motor on these pumps is dang near "bullet-proof," so if you have a motor gone bad or the gears are stripped, then it is, indeed, time for a new pump, however it is well worth the effort to try to fix/adjust these little buggers. Now, I am even more of a happy camper, knowing I can at least try to fix or adjust them and I have a spare as well...always a "good thing." In closing, my thanks to Peter for the help/advice and also, these pumps are precision items that operate under close tolerances, but they are not magical and, in many cases, can be cleaned, adjusted and put back into service.
:D :D :D
Doc

[Heli_jack]

interesting, I wonder if that holds for the Jaka?

[chopper jockey]

most of these pumps are the same :)

[Greg Alderman]

Jack...the pump that Wolfdad rebuilt was for his Jaka....

[Heli_jack]

bigger print....sorry

[Dr.Tim]

Thats OK Jack ... :shock: I have to call my daughter in to read for me! :D LOL!!

Dr.Tim

[Heli_jack]

ya but you have nice lon hippie hair.

[wolfdad]

Dr. Tim,
Dude! I heard you on that one! Sherry and I save all our "unreadable" stuff, then take it all up to Mark to read for us. :lol: :lol: :lol:

Jack,
That was on the fuel pump for my Jaka. Model number is Orbit FP280. The pump quit working on me on a day of gorgeous weather and killed a day's flying. The above was posted, hopefully to help others avoid the same thing. Actually, had I known what I was doing (do I ever??? :? ), I could probably have adjusted the pump in the field and gone flying.
Doc

P.S. Dr. Tim....Sherry and I are both fevoriously looking for a new hat for you.

[Heli_jack]

Doc, don't cover Tim's beautiful locks..... Man most of us old farts don' t have hair anymore...lol.

I just never knew it would kill the pumpt to run dry, but I never do anyhow, wanting to keep air out of the system.
Jack

[wolfdad]

Jack,
Actually, knowing you and you knowing me the way we do (no comments, Alderman), once you pull the pump apart the first time, you will know that "limited" dry running won't hurt it. What you will find is a gear pump system and, yes, running it for extended periods without the lubrication of the fuel/oil mixture will destroy the gears (they appear to be a berilium-type metal...no sparking), however during the adjustment, you may have to "momentarily" turn them through on battery power to get the intial adjustment, then with a jar fuel of fuel/oil mix, tweak the adjustment in while watching the read-out on the ECU. I don't know this to be a fact, however I would think that a run-in period on these pumps would be a wise idea as well....least-ways, what I did with the one I repaired since, other than a minor gunk build-up, I could find no reason why the pump wouldn't run. I can see, because of the close tolerances, why these little fellows would be subject to stopping after a lot of fuel had been run through and the crud had built up.
Doc

P.S. And, by the way, we found the good Dr. a new "pimp hat." However, it will be up to him to reveal the secret. BTW, Dr. Tim's birthday is 8 March.

[Peter Rob]

Wolfdad and the rest NEVER RUN THE PUMP DRY. A brand new JetCat
pump lasted less than 30 seconds without lubrication BE WARNED, A touch of grease maybe, I started the adjustments from stop at .5 volts and released the 2 screws until the pump started working all the time the pump was connected to a fuel supply
Peter R

[wolfdad]

Peter,
I most humbly stand corrected. Thanks for that bit of information.
Doc

[Peter Rob]

Thanks Doc it was because I did not want to see someone lose a pump that could be re furbished
Peter R