jetjockey

My Feedback: (8)

Hey Ed,

Guess I spoke too soon about my slow ramp to Jet A being solved. Right after I cleaned the EGT probe, I got three pretty fast ramps - back to normal, that is (or so I thought). This past weekend we flew on Sat (5 flights), and Sunday (4 flights). Every start was very slow as before. The cockpit indicator light glows steady almost immediately after the propane lights off (which is very fast - looks like the regulator is working just right), but the engine takes up to 30 seconds for the pump to start running, even though the cockpit indicator lights glow steady indicating the combustion chamber is hot enough for the Jet A. As soon as the pump starts, the engine ramps up normally. I did try a couple of starts with a different propane regulator that allowed me to put more propane into the engine after light off to see if maybe I wasn't getting enough propane to really heat the combustion chamber, although the cockpit display said it was hot enough. Evidently I put too much propane into the engine after light off, because a couple of seconds after it lit off, I opened the valve for lots more propane, the starter motor stopped running and the engine loped along on just the propane, until I shut it off - I guess the ECU thought the engine was ramping and stopped the starter motor. It did the same thing three times, so then I went back to the standard regulator, and it started normally, except for the slow ramping to Jet A.

Is there a temperature probe inside the combustion chamber that may be coated with carbon? The engine acts like it isn't getting hot enough for the ECU to start the pump until a long while after the propane lights off even though all three cockpit indicator lights glow steady while it is running on propane and the starter motor is spinning the engine waiting for the ramp.

Also, I noticed on all my flights this weekend, after I landed and was taxying back, the engine seemed to be on a high idle with lots of residual thrust. I had to ride the brakes to keep it slowed down - not very comfortable. On taxy out, the engine seemed to idle normally and I had to add power to get the airplane started moving, and then it would roll to a stop with little or no brakes when I was getting ready for takeoff (which is normal). On landing, I felt like I had several clicks of throttle, and especially on taxy back - I really had to ride the brakes to slow it down - weird - didn't do that before.

Other than that, the engine performed great and had a great time flying both days.

Anyway, hoping for some answers.

Thanks, Les Morrow

jetjockey

My Feedback: (8)

Hey Ed, still looking for answers. Got any?

Thanks, Les

rcav8tr

Hi Les

My apologies. Got distracted with some other things. I'll have to touch base with Kevin. I'll get back to you tomorrow.

Ed

jetjockey

My Feedback: (8)

OK. Ed, I also had a suggestion that I might need a new pump?? Thoughts about that?

Thanks, Les

rcav8tr

Hi Les

that's the way I'm leaning as well, but I wanted to see if Kevin had any different ideas. Will let you know as soon as get wrod from him.

Ed

rcav8tr

Hi Les

I assume you have checked for restrictions in the fuel lines and plugged filters. The only other option is that your pump needs to be replaced. Do you not have a spare pump on hand? If so, please try it in place of the current one to see if there is any affect.

Sincerely,
Ed

jetjockey

My Feedback: (8)

Ed, yes, I checked everything and didn't find any problems - it has all new filters and lines on the installation. Once the engine ramps up on Jet A, it runs and responds normally from that point on until I shut it down - it will go full throttle with the green light flashing on the cockpit indicator, and responds to the throttle stick. I don't seem to have a lack of power or accelaration once it is running. How much is a new pump, and do you have one in stock? I don't have a spare, but looks like I need to buy one.

Thanks, Les

rcav8tr

Hi Les

We thought you had a spare. I'm sourcing pumps right now. The prices I have been getting so far are in the $130 range. SimJet doesn't have any so I'm trying other sources and the OEM manufacturer.

I'll let you know when I have them sourced.

Ed

jetjockey

My Feedback: (8)

Ed, any new info on the fuel pump source. We've got our T-38 Jet meet coming up in two weeks here, and I'd sure like to fly my Rookie in it. I will try with the old pump, but if the engine doesn't ramp to Jet A, I may not be able to. Let me know if you find anything. Price and delivery would be nice.

Thanks, Les