GAMI Fuel Injectors

[Aspen2013]

Anyone change the stock TCM fuel injectors to GAMI on TSIO 550 on a TN model? If so have you had an issue where the engine likes to die when you turn? Doesn't matter if you turn left or right but I will be taxing along straight and then when I turn the engine stumbles and if you do not catch it quick with some throttle it will completely quit. Doesn't matter full rich or leaned for ground ops. 

[GeeBee]

Have you checked for both fuel leaks and leaks on the upper deck pressure manifold, in particular where it seals to the injector screens?

[Niko182]

Maybe the mixture of the engine at idle needs to be adjusted. If leaning doesnt work, I'd guess that means you need to add some fuel. By the way, this isn't the mixture you haveat your hand, but the screw under the cowling. Most mechanics with big bore TCMs will be able to help you.

[Brandt]

41 minutes ago, Aspen2013 said:

Anyone change the stock TCM fuel injectors to GAMI on TSIO 550 on a TN model? If so have you had an issue where the engine likes to die when you turn? Doesn't matter if you turn left or right but I will be taxing along straight and then when I turn the engine stumbles and if you do not catch it quick with some throttle it will completely quit. Doesn't matter full rich or leaned for ground ops. 

My Acclaim doesn’t die, but it stumbles when you turn.  I have a hard time believing it has anything to do with the GAMI’s.  Always assumed it was a fuel sloshing around in the tank issue.  It’s not an idle problem.  

[LANCECASPER]

4 minutes ago, Brandt said:

My Acclaim doesn’t die, but it stumbles when you turn.  I have a hard time believing it has anything to do with the GAMI’s.  Always assumed it was a fuel sloshing around in the tank issue.  It’s not an idle problem.  

I would hope it's not a "fuel sloshing around in the tank issue". Look at where the fuel pickup is - that would mean you are down to unusable fuel in the tank. No way should it stumble in a turn under any circumstances. Does turning on the boost pump make the stumble go away?

[Brandt]

8 minutes ago, LANCECASPER said:

I would hope it's not a "fuel sloshing around in the tank issue". Look at where the fuel pickup is - that would mean you are down to unusable fuel in the tank. No way should it stumble in a turn under any circumstances. Does turning on the boost pump make the stumble go away?

Thought it might relate to the port.  But must admit I haven’t looked into it.  Will try the boost next time I fly and let you know.  

[Guest]

1 hour ago, Aspen2013 said:

Anyone change the stock TCM fuel injectors to GAMI on TSIO 550 on a TN model? If so have you had an issue where the engine likes to die when you turn? Doesn't matter if you turn left or right but I will be taxing along straight and then when I turn the engine stumbles and if you do not catch it quick with some throttle it will completely quit. Doesn't matter full rich or leaned for ground ops. 

Was the engine fuel system set per Continental M-O chapter 6 or the old SID97-3G when the GAMI nozzles were installed?  

[Aspen2013]

Just installed the injectors on Sept 2. Did not adjust fuel settings at all per GAMI's instructions. Have not had fuel pressures checked since I have owned it. But fuel flows seem to be in the proper range for various power settings. I did try with boost pump but shortly after turning on the pump I saw the fuel flow go up and the engine seemed to run too rich and rough.

[Aspen2013]

The only change made to the engine that day was JUST injectors. The engine did not do that before the swap was made. I fly LOP and if any of you out there find that even though TCM has tuned injectors they are not fine tuned. The second problem is they do not have a program to swap out injectors. GAMI takes the inflight lean test data and sends new injectors until we get .5 gph difference from richest to leanest cylinder. That is why I made the switch. Everything else seems to work like any other flight. I have also noticed it only happens when engine is hot. From cold engine to start to warm up and then taxi I have no issues. Landing after flying for any amount of time and as soon as you turn off runway and subsequent turns the engine stumbles.

[GeeBee]

Have you tried running the pump and leaning to prevent over rich? May be vapor issues. Pressure will suppress that.

 

 

[Aspen2013]

That is an idea worth testing out, thanks. Increase the pressure and then counter that with the red knob. Still baffled as to what the connection is to the plane turning?

Edited September 6, 2022 by Aspen2013
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[carusoam]

Had experienced this early on with the O1…

Unfortunately, can't report what it was or what fixed it…

It would occur just after start-up…. The brief taxi had two 90° angles…

 

One thing for sure… the fuel pick ups are no where near the air bubble at the top of thanks…

Getting air to the pick up would require several Gs of lateral force…

Seemed like it didn’t like the small Coriolis forces it was going through…

 

Today… different engine and different parking place… nothing to compare to…

Best regards,

-a-

[Schllc]

On 9/5/2022 at 6:48 PM, Aspen2013 said:

Just installed the injectors on Sept 2. Did not adjust fuel settings at all per GAMI's instructions. Have not had fuel pressures checked since I have owned it. But fuel flows seem to be in the proper range for various power settings. I did try with boost pump but shortly after turning on the pump I saw the fuel flow go up and the engine seemed to run too rich and rough.

This is a known issue with some acclaims. I had it on two of mine. No one has been able to explain it or fix it. It was really only a problem at really low rpm’s, so I got into the habit of just boosting the rpm’s a little as I turned. 
One of them had gami’s and the other did not. 
 

[LANCECASPER]

On 9/5/2022 at 9:51 PM, Aspen2013 said:

That is an idea worth testing out, thanks. Increase the pressure and then counter that with the red knob. Still baffled as to what the connection is to the plane turning?

Could it be an intake leak? Turning would disrupt the air pressure on one side of the engine maybe?

[231MJ]

I had this same problem in my TSIO360-MB.  I would land, turn off the runway and the engine would stumble and if I didn't add throttle quickly it would kill and then I had to do a hot start.  I never figured out what the problem was but after getting new (not rebuilt) mags the problem seems to have gone away.  No adjustments to the fuel system were made. I know it makes no sense that this was a magneto problem and I'm not suggesting it is, but so far so good.  I think any improvement to the ignition like new mags, fine wire plugs and even the SlickSTART booster for a hotter spark during starting has helped.  Plus learning how to do a hot start has reduced my anxiety level after fueling.

I don't know what causes the problem but I'm glad to know it's not just me or my engine. 

[Shadrach]

What a weird issue. If it is repeatedly and verifiably caused by turning, it wold be worth fully investigating the cause. I would find an airport with a large, empty apron where you can taxi in circles. Then determine if the stubble is caused by the initial turn or if it remains constant once established in a constant rate turn. Certainly not a fuel tank pick up issue, more likely something weird is happening within the servo.

[A64Pilot]

Only thing I can come up with is the prop is a big gyroscope, and a gyro resists turning so it will rob if you will energy from the engine when you do, if the engine is close to stumbling anyway the force required to turn that gyro may be the straw that breaks the Camels back.

There is a slight flow difference between the injector sets, that the point, that slight flow difference may have lowered your idle just enough. Turn your idle up slightly and see if your problem goes away.

[N231BN]

It absolutely is caused by gyroscopic forces, that is why it only happens when turning.

The reason it dies is related to the fuel injection system. Your idle rpm may be set too low but most likely your unmetered fuel pressure is dropping too low at idle with a hot engine. Another possibility is your idle mixture could be set too rich and as the rpm drops you are running out of air.

As Clarence said, you need to perform a setup per Continental guidelines.

[Will.iam]

13 hours ago, N231BN said:

It absolutely is caused by gyroscopic forces, that is why it only happens when turning.

The reason it dies is related to the fuel injection system. Your idle rpm may be set too low but most likely your unmetered fuel pressure is dropping too low at idle with a hot engine. Another possibility is your idle mixture could be set too rich and as the rpm drops you are running out of air.

As Clarence said, you need to perform a setup per Continental guidelines.

I think that is my problem now. I got my fuel pump throttle body and spider overhauled and tested all together on the bench at the shop. When we installed it back on to my airplane i have this new problem of dying in the turn. So it’s going back into the shop next week and they are going to put a pressure meter on it to see what my idle pressure is set at. Will report what he finds. Also today did an inflight induction leak test and noticed 6# cylinder had the lowest change in egt from  32” down to 20” map. The other 5 cylinders dropped 165 to 200 degrees while #6 dropped only 140 degrees. So will do the soapy bubbles check around cylinder #6 and hopefully find some bubbles. 

[Aspen2013]

Usually lean pretty good for taxi. We are going to check unmetered fuel pressure. I believe that the test to run the low boost pump and adjust mixture leaner may be a good test to see if we need a little more fuel pressure. Then make adjustments for such. I think N231BN may have the best explanation so far.

Thank you

[Will.iam]

11 hours ago, Aspen2013 said:

Usually lean pretty good for taxi. We are going to check unmetered fuel pressure. I believe that the test to run the low boost pump and adjust mixture leaner may be a good test to see if we need a little more fuel pressure. Then make adjustments for such. I think N231BN may have the best explanation so far.

Thank you

Well the low boost pump at idle doesn’t work for me in that i have to pul the mixture knob almost to idle cutoff to lean the engine enough to keep it from dying from an overly rich mixture and the range from that point to cutoff is very small so i could not get the mixture to peak egt before it would just cutoff and engine would die. The ff jumps from 1.6 to 2.8 when the pump is turned on. Ymmv. 

[Niko182]

1 hour ago, Will.iam said:

Well the low boost pump at idle doesn’t work for me in that i have to pul the mixture knob almost to idle cutoff to lean the engine enough to keep it from dying from an overly rich mixture and the range from that point to cutoff is very small so i could not get the mixture to peak egt before it would just cutoff and engine would die. The ff jumps from 1.6 to 2.8 when the pump is turned on. Ymmv. 

What rpm is the engine at 1.6gph?

[Will.iam]

800 rpm. 650 if i pull on the throttle cable.  

[A64Pilot]

150 RPM drop from pulling the throttle seems to indicate the screw isn’t against the idle stop and you may be running out of cable length prior to hitting the stop. Easy to check. You should have “cushion” at both ends meaning you hit stops prior to hitting the end of the cable

That could cause an idle drop maybe in a turn

[Will.iam]

On 9/9/2022 at 11:05 PM, Will.iam said:

I think that is my problem now. I got my fuel pump throttle body and spider overhauled and tested all together on the bench at the shop. When we installed it back on to my airplane i have this new problem of dying in the turn. So it’s going back into the shop next week and they are going to put a pressure meter on it to see what my idle pressure is set at. Will report what he finds. Also today did an inflight induction leak test and noticed 6# cylinder had the lowest change in egt from  32” down to 20” map. The other 5 cylinders dropped 165 to 200 degrees while #6 dropped only 140 degrees. So will do the soapy bubbles check around cylinder #6 and hopefully find some bubbles. 

Ok reporting on my visit with the A&P we hooked up his pressure regulator and at 600 RPM the pressure was supposed to be 6.1 psi. It was 3.1!  I was also showing 2.2 gph FF. He adjusted the low circuit pressure to 6.1 and the ff went to 4.2 and i could not believe the engine was even running as it was so rich. We did an rpm rise to cutoff from 600 rpm the engine rose to 1190 rpm before dropping to cutoff. He adjusted the air mixture on low circuit and walla! Very smooth idling at 600 with a 50 rpm rise. Then we tested full power and it was at 24.7 perfect. Put the cowl back on and flew it home. It ran great and landing was night and day different as i can now have the engine idling at 600 rpm and not pulling me down the runway. Only problem now is when i did the idle cutoff the rpm only rose 10 rpm before lowering to cutoff. It’s running so great i hate to touch it. How important is it to get the 50 rpm rise?  I think it changed due to the cowling being out back on and now the air goes through the naca vent on side of cowl instead of when the engine was running with it off.