Dukes Fuel Pump Drip

[RMarkSampson]

I completed the fuel testing per the SID 97-3F. The hook-up to the fuel system was very straight forward - turns out I only needed one P/N MS51523-B4 swivel tee to hook up the two test gauges as I was able to attach one gauge to an existing t-connector that had one port capped off. Simply removed the cap and connected the gauge. Tie-strapped the hoses at a few points to keep them secure in the propwash. The two bleed valves make quick work of bleeding the air out of the system using the Dukes fuel pump to push the fuel.

Recorded the fuel pressures with just the boost pump on low and high setting prior to engine startup. After engine startup, brought it up to normal operating temperatures and then conducted the fuel pressure test recording per the SID. All adjustments are done with the engine shutdown - and then retest after adjustment. All told, from cowling off to cowling on, spent about 1.5 hours conducting the test. Now have full confidence that my fuel system, including the boost pump, is operating within spec.

Whether using the SID 97-3F or the M6 6-3.7.3. Fuel System Operational Check as your reference, I certainly recommend others test their fuel systems per Continental's guidance. With gauges now in hand, I plan to do it as part of my annual - to me it is as basic as an engine compression check. Expect it to take about 30 minutes of extra setup time to strap on the fuel gauges perform the test. One item of note, Continental recommends cleaning fuel injectors every 300 hours - which is one of the reasons for performing the fuel operational check post-cleaning.

[keithPTC]

Mark,

I was in the process of beginning to make my own TCM SID97-3 compliant gauge setup when I came across this excellent article on the same topic. http://bit.ly/1epTKNl I will try building mine using the digital Dwyer brand gauges as the author described. The Dwyer digital gauges are available from multiple sources including Amazon.

Keith

[RMarkSampson]

Keith,
Glad I could help. My only hindsight is the fact that the highest reading my IO-240B at full power was around 20psi so most of the 60psi gauge is not used (and the reported accuracy only at 1psi vice a half so that was my one compromise from the SID specs). But I am a private owner with only one (small) engine to consider. For a shop I'm sure the 60psi gauge is the right call.

Regards Mark

[thefoxx]

So this thread was very helpful as I had the leaky Dukes fuel pump. As per your recommendations to send to Aeromotors, my AME did such and received the pump back.

Issue is now we cannot get the aircraft started (no other changes have been done to any part of the ignition or fuel system. Pump was simply removed and reinstalled). The fuel pressure gauge reads maximum 3.5psi with the prime pump on and about half of that with just the low stage on. Seems low when the gauge has such a much higher range on it.

They have hooked other gauges directly off the fuel pump line and it shows about 4.2psi

Do these readings sound normal?

What is everyone's normal fuel pressure readings from the gauge on the aircraft with low and high speed?

[Derek]

Perhaps your engine was tuned to take account of a non functioning fuel pump. Now that the rebuilt pump is pumping well your engine may be getting too much gas and it needs to be retuned to take account of the higher fuel flow at start up. Also look at your magnetos and an internal battery that provides "shower of sparks" at start up.

[thefoxx]

Thanks. We got it. Might have just been air in the fuel line? Persistence and bleeding line seemed to make it work.

Thanks for your insight!

[thefoxx]

Well back to square one. We thought we had it. Got it running. Hot started great, but leave it over night and next day she refused to start.

Replaced shower of sparks battery
Replaced main battery with new B&C
Sent mags for 500hr check
Cleaned out excess fuel drain plugs in cylinders

Had it running yesterday after all the above completed. Hot starts were great.

Left it over might and it just turns over and can't even get any pops or any sign of wanting to start using normal starting procedure that I have used for last year, and using flood start procedure.

All pressures tested to Diamond & Dukes/aeromotors specs.

We are at a complete loss as to what it could be.

Could it be the fuel air mixture needs tuning to pump as mentioned above? Wouldn't this affect nornal engine driven pump adjustments too?

Once it was running, it seemed to perform great.

Even though specs according to Aeromotors/dukes are being achieved could it s till be a defective rebuild? Before fuel pump change I had no problems at all.. problems came immediately after pump chsnged.

Any insight is sure appreciated.

[keithPTC]

.
>>>Before fuel pump change I had no problems at all.. problems came immediately after pump chsnged<<<


Based on that statement alone, I'd suspect the overhauled pump and replace it with a new or factory authorized overhauled pump.

FWIW: a couple years ago a local flight school with a very large fleet of DA20's had issues with 3rd-party overhauled pumps. Specifically, the pumps were coming back from overhaul with idle pressures set too high. They stopped using these pumps. This info came from a friend who used to be one of the flight school's maintenance inspectors.

Other questions: 1) are you using an external fuel pressure gauge or aircraft's gauge to read fuel pressures? 2) did you remove and clean the metal-mesh finger fuel filter on the engine?

[thefoxx]

Thanks for the reply.
I certainly understand the recommendation to go with the Factory Authorized pump - and I do somewhat regret not trying that to begin with - however the recommendation to use Aeromotors came directly from this forum, and from what I consider is a respected member of this community. It certainly wasn't just a random google search choice, but I generally respect other users experiences and recommendations - especially in our small community. Going with the Diamond Authorized electric fuel pump is still forefront in my mind as the problem - but also a significant $$$ difference (Diamond $1900 CAD for o/h one) - especially when all pressures seem correct and within specs.

In regards to your questions:
1) We are using an external fuel gauge to read the pressures.
2) I am not sure about the finger fuel filter - I will check with the AME regarding that. If it was a part that would have been part of the removal and reinstallation of the pump, I am sure it would have been completed, but I cannot say for sure.

To be clear, we have got the engine successfully running (but then the next morning it will not start - not even a hint of kicking). When we have got it to running whiles still having these issues, it runs great - so that is why I am not thinking a filter would be the culprit.

Other considerations:
1) Ignition switch or shower of sparks system issues?

Thanks for your time and assistance.

[keithPTC]

If you suspect the SOS, perform a "Starting Vibrator Functional Check" as detailed in the IO-240 Engine Maintenance and Overhaul Manual (Publication M-6). This only takes 15-20 minutes.

BTW, if it turns out that the SOS is not working, before you start replacing components, be sure the retard lead on the left mag is properly connected & secured. I had one break off shortly after the 500-hour magneto IRAN. It will not start if broken off!

Regarding the finger filter, I only mentioned it since you are not sure whether it's a fuel or ignition issue. The finger filter is regularly overlooked. At a minimum, it should be checked annually. However, I've seen them clogged with years of debris inside of fuel lines with fittings that appear to have never had a wrench on them.

Lastly, when I referred to factory authorized overhauled pump, I was referring to the pump manufacturer, not Diamond. I believe Aircraft Spruce has these.

Good luck!