Ellison Throttle Body

Looking for help from anyone with an Ellison Throttle body injector on Lycoming engine. I am having some power loss and misfires on my 0-36 and have checked the usual suspects like plugs and fuel filter etc. I think the problem is in my Ellison TBI (4-5). I believe it is in need of an overhaul but it appears that Ellison Fluid Systems is out of business. Does anyone know of an repair facility that will service these?

Thanks,
Zem

I had one of those on a -6 I purchased. Excellent in the air, spooky on the ground.

Did NOT like getting hot and protested loudly when provoked. Found a source for the diaphragm and “rebuilt” it myself. Very simple to do BUT did not help much. Towards the end, the fuel flow started meandering.

Best thing I ever did was get rid of it.

Best of luck.

Pitts

PittsS1Spilot said:

I had one of those on a -6 I purchased. Excellent in the air, spooky on the ground.

Did NOT like getting hot and protested loudly when provoked. Found a source for the diaphragm and “rebuilt” it myself. Very simple to do BUT did not help much. Towards the end, the fuel flow started meandering.

Best thing I ever did was get rid of it.

Best of luck.

Pitts

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I was able to mitigate poor hot ground performance by adding an orificed vapor vent line to the Ellison fuel inlet.

ZemsRV4 said:

Looking for help from anyone with an Ellison Throttle body injector on Lycoming engine. I am having some power loss and misfires on my 0-36 and have checked the usual suspects like plugs and fuel filter etc. I think the problem is in my Ellison TBI (4-5). I believe it is in need of an overhaul but it appears that Ellison Fluid Systems is out of business. Does anyone know of an repair facility that will service these?

Thanks,
Zem

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Before writing it off I would check carefully and make sure you don't have an intake leak at your intake tubes top or bottom including the tubes coming out of the sump.

I am with Pitts on this one. We had an Ellison on a Pitts S1C and it was flat out goofy and ponderous on the ground. Very non-conventional mixture operation and hard to adjust. With a 5-way partnership in the aircraft this non-conventional operation with a good chance of engine stoppage made for a dangerous combination. If I ever bought another airplane that had an Ellison Throttle Body Injector the first thing I would do is remove it and throw it in the nearest trash bin. By the way the product name "Throttle Body Injector" was a fancy way to market what was really a cheese ball Posa slide carburetor. The motorcycle guys in the 1970's described these slide carburetors as an "inefficient controlled fuel leak". Once you understood they are a controlled fuel leak the weirdness starts to make sense. There is a reason that Ellison and Posa are no longer around.

ZemsRV4 said:

Looking for help from anyone with an Ellison Throttle body injector on Lycoming engine. I am having some power loss and misfires on my 0-36 and have checked the usual suspects like plugs and fuel filter etc. I think the problem is in my Ellison TBI (4-5). I believe it is in need of an overhaul but it appears that Ellison Fluid Systems is out of business. Does anyone know of an repair facility that will service these?

Thanks,
Zem

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Don't trash it yet! I have a friend who is running one on his -6 and maybe his more recently built -3 as well. He has done a lot of cool things to keep them going, especially with Ellison going out of business. He is a whiz on the metal lathe! I'll see if he would be interested in talking with you.

Mine has been near flawless for almost thirty years. Rebuilt when the airplane was redone in 2015. I’ll try to find out who did the work.
They are butt simple mechanisms. I have not had any idle issues, hot or cold, and hot starts are as easy as they come.

I've made Rotec TBI's work well. Takes some engineering work to do. The reward is a 2gph reduction in fuel consumption, smooth running, and even EGTs.

My contacts didn’t pan out. The person who rebuilt mine in 2015 evidently isn’t around anymore.
Have another contact working on it and he will share if he finds any useful information.
Sorry

When I said don't write it off I should have mentioned that I had one on my RV4 for 1100 hrs that worked perfectly and have one now on an RV3 that I fly. I would hardly consider them junk. You didn't mention if this power loss was a new symptom or something that has been there since the Ellison was installed. If its something new I would be looking for other answers. In my experience the Ellison's are very responsive and fuel efficient. They sometimes have some quirks at full throttle but that is usually caused by airflow to the TBI.

PM sent for contact information

I was just informed the guy who rebuilt mine retired.
If anyone has a spare they wish to donate, I will commit to tearing it apart and seeing if we can catalog the various seals and other unique parts. We might be able to rebuild these without a lot of fuss. Their beauty is in their simplicity. That should work to our advantage.

I posted a new thread in an effort to find a donor unit.

I will add some more later just saw your thread and figured I might save you some time.

I fly behind one. Bought did not build. Currently 300ish hrs on it. Not on a RV but none the less. Done a fair amount of looking into and researching these. Also spent some time talking to Rotec at OSH about theirs which is derived from the Ellison.

First some research on rebuilding/ parts from my notes.


I will add some more later just saw your thread and figured I might save you some time.


Mike

swampyclark said:

I will add some more later just saw your thread and figured I might save you some time.

I fly behind one. Bought did not build. Currently 300ish hrs on it. Not on a RV but none the less. Done a fair amount of looking into and researching these. Also spent some time talking to Rotec at OSH about theirs which is derived from the Ellison.

First some research on rebuilding/ parts from my notes.

http://www.n56ml.com/fuel/

https://www.miravim.org/4RE/AviationThrottleBodyInjectionEllisonRotec.pdf

I will add some more later just saw your thread and figured I might save you some time.


Mike

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Thanks Mike - what a wonderful resource. Just trying to be proactive as mine is running fine and always has. Also, trying to help others but it is obvious that the hard work has already been done by you.
Great write up and article. Really comprehensive.

Not by me, just found by me.

swampyclark said:

Not by me, just found by me.

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I see that now. Coincidently, one of the authors is John Hickman, a friend, and well known in the Bucker community. The Ellison is on my Bucker. Pretty common for Buckers. At one time airbox kits were available along with mounts and cowlings for Lycoming conversions.

It’s never ceases to amaze me how much I think I know compared to how little I really do know.

JonJay said:

I posted a new thread in an effort to find a donor unit.

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Have you had any luck with getting a core for tear down ? I have a problem with my 4-5 -- Engine wont start unless I keep it running on multiple primer shots until i get enough RPM to make the TBI open up the fuel flow ... I want to replace the Diaphragm and see if that helps. Let me know how the search is going

GaryStofer said:

Have you had any luck with getting a core for tear down ? I have a problem with my 4-5 -- Engine wont start unless I keep it running on multiple primer shots until i get enough RPM to make the TBI open up the fuel flow ... I want to replace the Diaphragm and see if that helps. Let me know how the search is going

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Fwiw and you may have already but I would look at the idle “jet” circuit (not really a jet in the carb sense). for blockage and adjustment. That single hole is always on and is responsible for most of your idle gas. It’s the first hole or 2 opposite the end where your mixture and throttle connects on the center spray bar If it runs at speed i doubt your diaphragm has failed but could be wrong. I was told the rotec diaphragm fits but needs a slight trim. Not changed mine so not 100%
Hope it helps and good luck.

GaryStofer said:

Have you had any luck with getting a core for tear down ? I have a problem with my 4-5 -- Engine wont start unless I keep it running on multiple primer shots until i get enough RPM to make the TBI open up the fuel flow ... I want to replace the Diaphragm and see if that helps. Let me know how the search is going

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I have not had anyone volunteer a core.

I would check the small tube on the back of the unit. It’s a short tube that makes a bend. If this gets clogged it won’t start.
I had some problems years ago with fuel dye drying in the tube and clogging it. Blow out/replaced the tube and all good.

JonJay said:

I have not had anyone volunteer a core.

I would check the small tube on the back of the unit. It’s a short tube that makes a bend. If this gets clogged it won’t start.
I had some problems years ago with fuel dye drying in the tube and clogging it. Blow out/replaced the tube and all good.

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I found that the pressure sense tube, the little brass tube with the three small holes was full of dried up blue dye. I removed the yellow plastic tube from the diaphragm port and attached a long section of tube to it so I could suck on it. I was able to pull some avgas out of the dry side of the diaphragm ! I conclude that the diaphragm is compromised and that fuel leaks through it and evaporates in the brass pressure sense port. Cleaned out the port and line and the engine started up as expected. Needless to say a new diaphragm is on order for a Vertex or Tillosten HD series carb. It woulsd not be a good day if that leak in the diapragm would get big enough for the airpressure not to open the valves anymore....

swampyclark said:

Fwiw and you may have already but I would look at the idle “jet” circuit (not really a jet in the carb sense). for blockage and adjustment. That single hole is always on and is responsible for most of your idle gas. It’s the first hole or 2 opposite the end where your mixture and throttle connects on the center spray bar If it runs at speed i doubt your diaphragm has failed but could be wrong. I was told the rotec diaphragm fits but needs a slight trim. Not changed mine so not 100%
Hope it helps and good luck.

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Thanks -- see reply below -- Leak in the diaphragm and subsequent blue dye gunk in the airflow sense tube casued the difficult starts --- 20 years on the same diaphragm is not bad, but it could have gotten bad if not detected early -- Ordered a couple of them from Ebay sellers . Tillosten HD series -- Hope they fit .

Ebay search:

Tillotson HD Diaphragm and Gasket Set​

Label has the following : Vertex Engine parts -- DG1HD HD Carburetor rebuild kit -- United States -- 451402 --

Yes they fit.

Glad you made some progress, please post an update when you can. If the diaphragm comes out whole, would be curious to know if it failed due to old age ie hardening and cracked from normal use or was or eaten by the gas. Its on my careful watch list but have not preemptivly serviced it but just might. Been in service since around 2012. Could you see any die markings looking into the throat of the TBI at the exit of the sense tube? Also curious is you had any evidence of blue stains coming out the static vent hole on the diaphragm cover since you said you had fuel on the air side and if a slow leak would be noticeable from that? I have a -3a and its a little different from its bigger brothers so you might not have that port based of my study of the patent diagrams. Thanks

swampyclark said:

Glad you made some progress, please post an update when you can. If the diaphragm comes out whole, would be curious to know if it failed due to old age ie hardening and cracked from normal use or was or eaten by the gas. Its on my careful watch list but have not preemptivly serviced it but just might. Been in service since around 2012. Could you see any die markings looking into the throat of the TBI at the exit of the sense tube? Also curious is you had any evidence of blue stains coming out the static vent hole on the diaphragm cover since you said you had fuel on the air side and if a slow leak would be noticeable from that? I have a -3a and its a little different from its bigger brothers so you might not have that port based of my study of the patent diagrams. Thanks

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The only blue fuel stain I saw was at the throat probe end of the yellow tube. Because of the yellow color of the tube it actually looked green and at first I discounted it as a stain from the brass tube -- like copper green etc. There was a little blue discoloring at the pickup end of the probe, but no obvious stains around there. The diaphragm came off clean. The air side was about half way full with gas. There is no obvious hole or crack that I can see, even under the microscope, and when I put some alcohol on the wet site and support it on a glass I don't see any obvious leaking to the other side before the alcohol evaporates. I figure that there is a slow leak, maybe at the center rivet, where I cant see properly. The material is harder than the new one from Vertex and the new one has a pronounced bellows, whereas the old one is flat all around. One thing I noticed on both the old and the new is that the metal disc is mounted to the rubber with the punch burrs facing the diaphragm rather than away from it. On the old one you can see how these burrs have chafed at the membrane, but not to the point to see an aberration on the other side. I filed and sanded the burrs off very carefully, not to distort that thin disc. -- The 4-5 does not have any vent holes that I know off.

This is the discoloration in the sense line :

I got to hand it to you guys. You're much more intelligent and stubborn than I was. I had an Ellison throttle body on a Pitts S-1. And I could never get it to work properly or logically. In my experience it was a real Achilles heel with the airframe. Getting out of that Ellison alone was a cause for celebration after I finally sold the Pitts. I seriously have nothing good to say about it. It was worse than the ancient Excello fuel injection system found on small Continentals in the 1940's. I had that goofy Excello monstrosity on my Rose Parrakeet. But I think I would go with that before the crazy-assed Ellison. More power to youse guys.

GaryStofer said:

The only blue fuel stain I saw was at the throat probe end of the yellow tube. Because of the yellow color of the tube it actually looked green and at first I discounted it as a stain from the brass tube -- like copper green etc. There was a little blue discoloring at the pickup end of the probe, but no obvious stains around there. The diaphragm came off clean. The air side was about half way full with gas. There is no obvious hole or crack that I can see, even under the microscope, and when I put some alcohol on the wet site and support it on a glass I don't see any obvious leaking to the other side before the alcohol evaporates. I figure that there is a slow leak, maybe at the center rivet, where I cant see properly. The material is harder than the new one from Vertex and the new one has a pronounced bellows, whereas the old one is flat all around. One thing I noticed on both the old and the new is that the metal disc is mounted to the rubber with the punch burrs facing the diaphragm rather than away from it. On the old one you can see how these burrs have chafed at the membrane, but not to the point to see an aberration on the other side. I filed and sanded the burrs off very carefully, not to distort that thin disc. -- The 4-5 does not have any vent holes that I know off.

This is the discoloration in the sense line :Was the tube clear?

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As I mentioned, if it’s clogged, it won’t start. Was the tube clear?

Hello,

I have been flying my Ellison TBI on myO-320 RV-4 for over 20 years now.
The actual flying time of 320 hours is rather low.
The Ellison has been a reliable partner along the way.
Starting and flying (inverted) has never presented any problems.
However, about two years ago, I noticed bad acceleration of the engine and some trouble to run at full power. This was detected during run up on the ground.
I found the “sense tube” to be partly clogged with “green stuff”. I had noticed the greenish discoloration at the bottom the yellow hose for quite some time. It looks exactly like the one shown in the picture above. The sense tube was blown through with gasoline using a syringe connected to upper end of the hose. The engine ran fine after that.

Last week and for the first time, it would not start at all. I checked the sense tube and it seemed clogged again. I dismounted the Ellison TBI to properly clean / inspect it.
This time, the sense tube was completely clogged with the green stuff and it appeared to be extremely sticky. It took me more than an hour and a drill bit to re-open all the holes. The entire tube was filled up with green gunk.

Where does the blue/green stuff come from and what is it?

Function:
My understanding is, the venturi pressure-drop inside the Ellison and therefore in the metering tube causes the diaphragm to move inward.
The center-rivet of the diaphragm pushes a spring loaded lever against the fuel valve, opening it as soon as enough air flows through the Ellison.
Consequently the sense tube acts like a vent-hole that was placed inside the “filtered air” instead of just pointing outside.
If it is clogged, the diaphragm will not move and the fuel-valve will stay closed.

The diaphragm on my Ellison TBI is old (never changed it) but it looks ok. There is no visible sign of leaking. I am replacing it now using a Tillotson carburetor rebuild kit.

regards

Thomas