Diagnosing Engine Problem

[CharlieWaffles]

Today we had the first start of my stock YIO-540-D4A5 with slick mags. The start was delayed as the Andair electronic pump appears to have a problem like described here http://www.vansairforce.com/communit...ghlight=andair But we decided we could worry about that later.

We got the engine started using just the mechanical pump but the engine seemed to develop power for a short period of time and then loose power, stutter like the mixture was being pulled (which it wasn't) and come close to dying as if ICO and then recover shortly. After a few times it stabilized for a minute and then stuttered and died.

I suspect a fuel pressure issue. There are no leaks and the stock injector is at the full mixture setting - we tried a small amount of leaning to make sure, but it had no affect. Oil Pressure/temp is good.

I uploaded my data to SavvyAnalysis and graphed RPM and MAP (top chart) and RPM And Fuel Pressure (bottom chart).

Is this a fuel pressure issue and could the bad electrical pump be causing this? Perhaps if the internal works are restricting the flow or something else? The pump info says there is a check valve (doesn't give much info on it) but could the checkvalve be cracking open and allowing the air into the line and that is causing the pressure fluctuations?

[Mike S]

Originally Posted by CharlieWaffles

Today we had the first start of my stock YIO-540-D4A5 with slick mags.

And another milestone is passed--------

[SportAvServ]

Take your injectors out and clean them, put some rags under the lines and run the pump for a couple of seconds if you can get it to run at all. I have started a couple of new injected engines and all of them had a little **** in the injectors, even the one that was pre-run at the factory. I have also had a mag drop on one mag and other than that the engine ran fine, it was a tiny bit of something in one injector.

Congratulations!!

RT

[DanH]

Stop and take a deep breath.

You're diagnosing a run problem because you did an engine start knowing full well a critical support component was inoperative or defective.

Perhaps that's not a good mindset?

[Pat Stewart]

I would not run again until I corrected the electric fuel pump and then did a flow check in a bucket. You don't have the electric pump turned around backwards right?

[Pat Stewart]

Also have you checked both tanks for any vent issue.

[CharlieWaffles]

Originally Posted by DanH

Stop and take a deep breath.

You're diagnosing a run problem because you did an engine start knowing full well a critical support component was inoperative or defective.

Perhaps that's not a good mindset?

Understand what you are saying Dan. Our thought was that the boost pump was an auxiliary pump that we should still be able to continue our other tests since the boost pump is only used to prime the engine before start. It wasn't until we started and found the fuel pressure issue that we suspected the pump could be a contributing factor.

Being new to FWF side of things, I was "diagnosing" the issue to see if there are other issues I could be checking into.

[CharlieWaffles]

Originally Posted by Pat Stewart

I would not run again until I corrected the electric fuel pump and then did a flow check in a bucket. You don't have the electric pump turned around backwards right?

Pump orientation was verified (giant label on the top of the Andair) and pump is unidirectional.

[Mike S]

Originally Posted by CharlieWaffles

since the boost pump is only used to prime the engine before start.

I think you may need to adjust your concept of the boost pump.

Standard practice is to run the boost pump anytime that a failure of the engine driven pump might ruin your day.

Takeoff.

Landing pattern.

Also, if engine gets quiet in flight, first thing to do is switch tanks and put boost pump on.

[N427EF]

Congratulation on your mile stone!
Can you load up some more data to Savvyanalysis?

EGT info would tell us about possible fuel flow problems to individual cylinders