Electronic fuel pump failing?

[TimBSmith]

I won't mix threads and update on the oil pressure sender/gauge issue here.

Starting a new thread, for a additional electronic fuel pump issue...

My electronic fuel pump has always registered between 5psi and 6psi. Sometimes the dial will oscillate in this range. Sometimes it is steady at 5psi.

Today during my pre-sail work-up, I noticed a strange rattling noise while the engine was running...

It ended before I could inspect more closely a couple of times, then finally I was able to see it first hand.

-A rattling noise, like a loose marble, originating in the electronic fuel pump coincided with a drop in fuel pump pressure from 5psi to below 3psi.

-At idle the pump would generally recover for a time only to rattle and see a pressure reduction, seemingly without any clear pattern.

-Throttle increase would keep the pressure up and I did not see pressure drop during higher rpm testing. I did not hold high rpm very long.

-This problem repeated at idle

Next steps.

-I suspect the fuel pump is dying.

1) Run briefly in gear at higher rpm for longer duration, see if the rattle occurs during higher loading.

2) Test pump jumping OPSS and seeing if drop in pressure and rattle is observed.

3) Study threads. Consider if there is any relationship between fuel pump operation and my high oil pressure readings. (I think not).

4) Seek your guidance.

Thankful. Fair winds.

[Dave Neptune]

To hear a ticking noise with an electric fuel pump is normal, the pump works by an on/off switch which operates a diaphragm to pump and a steel ball to work as a check valve. These type of pumps when operating show a variation in pressure especially at idle so expect it.

The drop in pressure and the "rattling" is the check valve, the steel ball bouncing around in the canister.. That ball is notorious for sticking and can be knocked loose if the pump stops because the ball is stuck and zero pressure would be registered.

Sounds to me like the pump is getting old and maybe in need of replacement for piece of mind.

Dave Neptune

[TimBSmith]

Dave, thank you for post. Update..

Great reality check. After I spent so much time chasing the air leak earlier this season. I really never fully attuned to the habits of my pump after leak fix.
-I had come to know the happy clicking noise over the past 2 seasons.
-I had not encountered the ball rattling noise and psi drop, or I had not heard it so pronounced before. I do wonder if my fixing the air leak has caused the pump to regulate pressure more normally at idle.
-I understand from your post that the ball valve noise adjusting pressure is a normal occurrence with these pumps.
-The fact that mine is adjusting a little noisier that usual may mean time to do some preventive replacement.

-There have been no operational symptoms, start, idle, or throttle up problems under load. Just this rattle and psi shift I had not noticed before.
-I checked the fuel hoses and retightened clamps just in case an air leak was the trouble though I doubted this because of prior work and inspection.
-No sign of gasoline anywhere it is not supposed to be.
-Will replace pump for peace-of-mind and keep functioning pump I am replacing as emergency backup.
-Noted in another thread a new to him A4 owner(maybe ndutton?) changed out pump right after buying boat just to be sure he knew what he was dealing with. Today, I would do this.
-Lastly, this is another instance where the fuel pressure gauge plumbed in and this forum have given me priceless information.

Done a lot of thread review and document review

Here is a link to the Moyer plumbing doc for the Facet

https://drive.google.com/file/d/1X_Gn51uWyEsRwVp3karGgHR-OrggIPoo/view?usp=sharing

Here is the Facet plumbing doc

https://drive.google.com/file/d/1kb-bXH2O3_ZogoCejSlLUgWUIo5CJBp8/view?usp=sharing

Next to failing pump my symptoms seem to align with air leak especially if there were accompanying starvation operating troubles (which there are not.)

Welcome further comments and reflections. Helpful threads. Until next. Fair winds.

[Al Schober]

I'm wondering if perhaps air is getting into the pump?

[TimBSmith]

Update...

I went back to all hoses to fuel filter, pump, pressure gauge, and carb.

I have not been able to hear the distinct marble rattle or pressure drop since. The fuel pressure needle has been much more stable during all operating/throttle/load profiles.

I still suspect my fuel pump is failing and I suspect potential vacuum leaks at clamps need more investigation still. The inspection and clamp relocation has created more stable pressure and the idle rattle has abated.

I will do some more work measuring connector barbs, hoses, and improving clamps for reasons below. I am monitoring pump and pressure. Buying a replacement pump to keep on hand.

I reread my "angel" PO's posts in this forum (that I stumbled upon a year after buying Oasis) a Godsend after buying the boat absent 2 PO's worth (5 years) of neglect and broken hopes, big plans, etc.

Turns out he ("angel" PO) who installed electronic fuel pump has always had an erratic fuel pressure drift toward 1psi during idle, as others point out can be an artifact of valve function and pressure balance in pump.

Turns out he had historic episodes of fuel gauge pressure needle oscillations as well. As well as some vacuum leaks due to carb barb and hose diameter mismatches.

All that is to say, Oasis comes by these fuel pressure patterns as part of her provenance. Based on evidence I am seeing, I am in a much more confident place with fuel pressure issues today. Not fully resolved, yet stable and more focused monitoring and diagnostics. On the right path. Thank you all for the help here, will keep you posted.

As a final note. I am considering moving the Facet pump off the motor ground to a better location for rapid change out and fuel sourced augmentation should conditions require it. It is the higher pressure model and that gives me confidence I can manage a short additional fuel hose run to a mounting plate as I have seen elsewhere. I may take the opportunity to have fuel pressure gauge and polishing filter better organized beside oil pressure instruments. Have seen this done here and will be studying up on this approach and if it has benefits I value.

Thankful.