High fuel pressure and warning light

[FloridaMan]

I just had my engine overhauled and have put over 50 hours on it since installation; I have an issue with my JPI EDM-900 and I hope someone can advise me as to the best way to get this resolved as I believe it creates a flight safety risk. The indicated fuel pressure is 27-28 psi except momentarily when pulling the power to idle, such as on short final, the pressure fluctuates to 31psi and the "ENGINE" warning light on my panel blinks red, requiring that I either divert my attention to my engine monitor on short final, or that I ignore a blinking red "ENGINE" warning light. Neither of which are desirable. 

According to this thread, a slight fluctuation to 30psi is normal: https://mooneyspace.com/topic/16970-high-fuel-pressure-with-new-fuel-pump/ and our engines are certified for up to 45 psi, and that this is an issue that is the result of how our airframes that had a high pressure fuel line that ran through our firewalls and into the back of the analog panel-mounted instrument were originally marked. The only options that I have are to ignore/address the red light each time, figure out how to convince JPI or Mooney to change the limits, or to purchase and replace fuel pumps until I get one that has slightly lower pressure that doesn't trigger the warning. I do not believe it to be due to high crankcase pressure as the engine's oil consumption and contamination over time is very good. 

I believe the correct solution is to get the limits changed, which either requires convincing JPI that the data is engine data and that the airframe markings should not apply or to convince Mooney to allow the variance somehow. 

Any ideas of how to sweet talk either party into helping me out? 

[ArtVandelay]

I believe the certified EMs must use manufacturer recommendations for limits, they may have lower user limits, but there is no way to have higher limits, unless your hangar elf know the secret method of changing the setup parms.

[N201MKTurbo]

Where are your fuel pressure sensors mounted? Do you have a snubber in between the sensor and the servo/carb?

[carusoam]

Looks like the mechanical systems are a bit slow to react...

By pulling the throttle quickly, the fuel is being delivered at too high of a rate...causing an actual high pressure for a moment...

Try pulling the throttle out at a much slower rate to see if the fuel controller can keep up with you better...

Put this in the category of a transition event.  Not like a continuous event...

I get the feeling, that once the alarm is tripped, it takes getting acknowledged to go away.  It doesn't go away on its own, when the pressure spike is gone?

PP thoughts only, not a mechanic or instrument guru...

Best regards,

-a-

[jlunseth]

At least some of the JPI dealers/mechanics are authorized to go in and change settings.  The MSC at Willmar was before it became the new MSC at Willmar, I don't know if they still are.  Check your POH.  Is there a fuel pressure redline?  I do not have one in my POH.  There is a section for Powerplant Limitation Markings, and no redline for fuel flow, either high or low.  JPI nevertheless sets one in the 930.  I am not entirely sure what the lower fuel flow "redline" is that they set, somewhere around 5 GPH, I do see it every flight because fuel flow at idle, while taxiing, is down around 2-3 GPH.  I haven't done anything about the lower limit GPH because if I were at cruise and had low fuel flow I would like to know about it.  Since there is no upper limit, you should be able to prove that to JPI with your POH, and get either JPI or an authorized dealer to adjust the setting, it is in the software.  The problem is that JPI's customer service is, shall we say, not very flexible.  If it is a redline in your POH, then JPI has no choice, they must use that setting or your aircraft would not be airworthy, the powerplant limitation marking would be wrong.

[jlunseth]

PS there are instructions in your JPI manual for adjusting some of the settings.  I frankly don't know if fuel flow is one, but it is worth a look through the manual.  As I recall there are some combinations of buttons that need to be pressed to get in and even see what settings can be adjusted.

[M20JFlyer]

Antares, thanks for sharing your concern.

I installed a LYCOMING factory OH engine May of 2017.

My fuel pressure is also at the extreme of 30lbs from the moment of start-up, and stays pegged at 30-31 irregardless of RPM.

my mechanic shared this with MOONEY at install and Mooney sez 30 is unique but at top of allowed spec.

we even cross-checked with test equipment to assure the OEM and my JPI 830 Reading were the same.

OEM JPI and test epuipment were same ( the same being less than 2 lbs variance )

then i enjoyed a ho hum response from Lycoming " "....Lycoming offered no comment other than complying with POH / manufacturers range"  I pursued with lycoming that the last two IO-360's with same Set up that I owned operated in 16 lbs range...{{{more importantly most other injected lycoming powered planes I experienced...fuel pressure was closer to 14-18..what explanation could they offer for a 2X pressure for a fresh OH IN year 2017.}

Next conversation with BENDIX RSA. The servo  techs seemed reluctant to debate lycoming..but offered a ho hum response was not sufficient..as servo diaphragms and injection nozels performance could be  affected by extremes and lack of RPM fluctuations in pressure ..both could also be a concern in the long term.

reading the prior posts on a method to remedy the high pressure...the options to cure the high pressure are expensive and extreme ..does anyone else share MY concern that RPM and some fuel pressure fluctuations  is something necessary and some parameters could be established.

further comments will be appreciated 

[Hillard]

I have just fitted a factory overhauled A3B6 engine to my 1995 J model and have the same fuel pressure issue - the gauge is hard up against the right hand stop.  My A&P has not signed off the install because the pressure exceeds the limit that mooney set in the service manual.  This appears to be due to lycoming having this year changed the pump that they supply and it puts out 30-35 psi rather than the 25 of the previous unit.  So far we have had no response from either mooney or lycoming.

[jetdriven]

Keep calling daily until you get the response needed to sign off the install.

[Jim Peace]

Test flew my 64 C for the first time today since the JPI 900.

My fuel pressure limit is 6.0 and the fuel pressure was fine for all of the flight until going in to land.  Power reduced as you can see in the picture but the fuel pressure went over the 6.0 limit and caused the waring.  happened several times during the descent.  Sorry for the blurry picture....

[carusoam]

Check the POH...

See if the FP limit is 6.0 or just 6    ...

leaving off the decimal point in the limitation may allow for the use of 7 as the alarm point....

With the decimal point, 6.1 is probably the intended alarm range.

An interesting note, both the fuel pressure on the O360 and IO360 seem to alarm when removing power....

One uses 6psi the other is more like 30psi...

PP thoughts only...

Best regards,

-a-

[Hank]

Never paid close attention to mine in the pattern. But when running the fuel pump before cranking the engine, it will often go a little past 6. A project for my next flight . . . .

[Oscar Avalle]

Test flew my 64 C for the first time today since the JPI 900.

My fuel pressure limit is 6.0 and the fuel pressure was fine for all of the flight until going in to land.  Power reduced as you can see in the picture but the fuel pressure went over the 6.0 limit and caused the waring.  happened several times during the descent.  Sorry for the blurry picture....

I had the same issue. When I reduced power or I idled the engine fuel pressure on my JPI 900 went to 6.1 or 6.5 and caused the warning light to blink and made my non or pilot passenger quite nervous...

 

I had the same thought process about the limit and called JPI to ask them to adjust it to 7.0. don’t even try the answer is no, the limits are set according to the POH.

 

So I decided to address the underlying issue of what gets the FP to rise over 6.0. In some instances I got even close to 6.0 during cruise.

 

The first step was to check if there was any obstruction in the fuel system. The answer was no. All filters were clear. Then we looked at the fuel hoses and all connections. We discovered that some of the hoses had a smaller diameter than the one required. So we changed the hoses,trying also to avoid as many twists as possible. Finally we discovered that a small aluminium tube that goes from the fuel pump to the firewall had a small dent, which restricted the fuel flow and got the FP up...changed that too. I have flown the plane now for about 16 hours since all this work and fuel pressure is lower and fuel flow is now higher too. So the JPI was pointing in my case at least to a real problem.

 

I am not saying that this is what causes your FP problem, but you may want to look into this.

 

Oscar

 

 

Sent from my iPad using Tapatalk Pro

[Jim Peace]

Thanks to all....my mechanic looked into it with lycoming..JPI etc.....its a common problem and I am going to try to leave it be for the time being......plane flys great though...wish I put that JPI in years ago....

 

[Jim Peace]

11 hours ago, Oscar Avalle said:

The first step was to check if there was any obstruction in the fuel system. The answer was no. All filters were clear. Then we looked at the fuel hoses and all connections. We discovered that some of the hoses had a smaller diameter than the one required. So we changed the hoses,trying also to avoid as many twists as possible. Finally we discovered that a small aluminium tube that goes from the fuel pump to the firewall had a small dent, which restricted the fuel flow and got the FP up...changed that too. I have flown the plane now for about 16 hours since all this work and fuel pressure is lower and fuel flow is now higher too. So the JPI was pointing in my case at least to a real problem.

 

sounds like a lot of work.....

[carusoam]

Jim,

You guys have much in common...

Oscar has been putting a lot of work into his C for a while now as well... 

His long flights have been more North/South than your East/West... 

Tremendous panels with lots of details on both M20Cs...

MS has an M20C in Europe that is also a forever plane that gets nice treatment as well.  See @Urs_Wildermuth

David in the Carolinas? Somewhere around here, going this direction as well... 

Fuzzy memories, my apologies if I mixed them up...

Best regards,

-a-

 

 

 

[Andy95W]

1 hour ago, Jim Peace said:

Thanks to all....my mechanic looked into it with lycoming..JPI etc.....its a common problem and I am going to try to leave it be for the time being......plane flys great though...wish I put that JPI in years ago....

 

It seems to be a problem when we try to digitally monitor systems that were meant to be analog- and designed 60 years ago, at that. 

[Oscar Avalle]

Jim,
You guys have much in common...
Oscar has been putting a lot of work into his C for a while now as well... 
His long flights have been more North/South than your East/West... 
Tremendous panels with lots of details on both M20Cs...
MS has an M20C in Europe that is also a forever plane that gets nice treatment as well.  See [mention=7530]Urs_Wildermuth[/mention]
David in the Carolinas? Somewhere around here, going this direction as well... 
Fuzzy memories, my apologies if I mixed them up...
Best regards,
-a-
 
 
 

Jajaja, I like the concept of a forever plane... indeed unless I run into a serious problem, I don’t plan on selling my plane... actually my son Fausto (7 years old) talks about “his Mooney” and how he is going to fly me...

Jim you flew your M20C to Europe? That is on my bucket list!!! What route did you take??? How long did it take you?

My flights are basically Central America and Caribbean...




Sent from my iPhone using Tapatalk Pro

[carusoam]

Oscar,

I believe, Jim’s Mooney went NJ to CA and back... His work plane seems to travel the really long distances.

 

For the Europe trip...

That’s a bucket list trip for many.  Many Mooneys don’t even need a turtlePac to make the flight legs...

Piloto has provided a lot of firsthand detail on how this can be / was done...

 

Waiting for the day 201er Check’s In from Iceland....  

 

We probably average one or two really long flights announced on MS each year.  Some flights get watched by MSers live through FlightAware...

 

Best regards,

-a-

[Jim Peace]

39 minutes ago, Oscar Avalle said:

Jim you flew your M20C to Europe? That is on my bucket list!!! What route did you take??? How long did it take you?

Have not flown it to Europe.  crossed the country a few times in it and many others and lots of north south.  I did fly a 210 across the pond once when I was young and dumb.

But right now I have a bigger project/problem.  I will be moving to Spruce Creek FL.  Committing to a hangar home lifestyle for a bit.  Flew my C to SPG today for lunch.

[Oscar Avalle]

It seems to be a problem when we try to digitally monitor systems that were meant to be analog- and designed 60 years ago, at that. 

I agree, in my case my fuel flow was also not optimal at take off. I was only getting 15 .3 gal/hr at max power. With all the work I got up to 16.3


Sent from my iPhone using Tapatalk Pro

[J0nathan225]

Is there any legal issue with continuing to fly the plane? Since ownership my mooney, with an O/H'd engine installed in 2016, stays pegged in flight at 31-34psi. Fuel flow on take off is 17.8 to 18.5 typically and I have seen no issue during operation LoP or RoP. This is all with the boost pump off, turning it on yields no change to psi during flight, but at start before cranking with the boost pump on for 5 sec psi builds to 28-30. 

[carusoam]

Technical legal issue...

Exceeding a red line is not part of normal flight...

The Picture is a nice HD image. Click on it and zoom in to see the redline...

Follow up with Lycoming and your OHer on how best to handle it....?

Stuff I have learned by reading MS...

Best regards,

-a-

[Marauder]

Is there any legal issue with continuing to fly the plane? Since ownership my mooney, with an O/H'd engine installed in 2016, stays pegged in flight at 31-34psi. Fuel flow on take off is 17.8 to 18.5 typically and I have seen no issue during operation LoP or RoP. This is all with the boost pump off, turning it on yields no change to psi during flight, but at start before cranking with the boost pump on for 5 sec psi builds to 28-30. 

My boost pump when run by itself will not take my fuel pressure above 27. It sounds like your gauge is reading high. The max pressure is 30 psi. Is this a factory gauge? I have two fuel pressure indicators driven by two separate fuel pressure transducers and both read within a pound of each other and the normal fuel pressure on the engine pump is around 24-25.


Sent from my iPad using Tapatalk Pro

[Marauder]

Just looked at your pictures. What are the gizmos to the far right?


Sent from my iPad using Tapatalk Pro