Electric Fuel Pump 4-7psi.

[Captain Crunch]

Hi All,

I have picked up a Holly fuel pump that operates at 4-7psi.

Is this too much psi for the needle valve to handle?

Do the filters drop off some psi?

I was thinking if it is I can put in a valve to choke the psi down. Do you think this will be effective?

Ultimately I was hoping to put my electric fuel pump in as a back up on a 3 way valve in the fuel system. If my mech fuel pump drops out I can flip the valve, switch on the elec. fuel pump(series switch with the OPSS circuit) and keep going. Half baked idea?

Until I re-build my mech fuel pump I was going to run on the elec. fuel pump, im a little concerned with the psi.

Thanks in advance for the help!

CC.

[Dave Neptune]

The pressure a pump makes is the pressure it makes! Restricting the flow will actually increase the pressure a bit not lower it. It can be reduced with a "regulator". By the time you do all that the correct pressure range pump will cost less and be simpler as well as BETTER.

The carb could probably handle the pressure fine, but that just pushes it closer the the edge.

Dave Neptune

[joe_db]

Exactly plus it isn't very hard to find the correct pressure. My pump runs about 4.5 PSI and that is plenty. Actually 1 PSI seems fine too, our engines don't use much gas, it isn't like feeding a big block V8
What is wrong with your mechanical pump? Fixing that might be a better use of time and money.

[Captain Crunch]

Thanks for the reply's.

I was experiencing intermittent loss of power/rpm's, and eventually stalling. I had to get the boat back in with the dingy motor.

BTW, I highly recommend an outboard motor bracket on the transom for the dingy motor. This made getting the boat to safety a breeze...and very good piece of mind.

The engine ran great for the first two seasons I owned it. Then I started having problems that could have been from:

- dirty carb
- sticking needle valve
- failing fuel pump
- dying coil
- air leak in the fuel system
- or whatever else might cause my loss of power/rpm's and stalling while at cruising speed issues.

Any other suggestions?

I started going through everything and found lots of loose stuff, and started tearing things out, cleaning and replacing.

I decided to add a electronic fuel pump as a back up and to use while I wait for a rebuild kit for my mech fuel pump.

I will monitor the carb when I prime the system and see if it overfills.

CC.

[joe_db]

The throw everything at the wall and see what sticks system of engine diagnosis and repair can be troublesome, you'll never be sure what you fixed or what new problems you caused vs, old ones returning.

This has been a common theme for many years if not decades, the engine randomly stops and no one knows why. What you need is DATA. I have both a fuel pressure gauge and a fuel filter vacuum gauge and have solved issues that would take 100 years to find otherwise. Moyer even has a kit specifically for this issue:

https://moyermarine.com/product/the-engine-warning-and-diagnostic-system-ktas_01_564/

You certainly can plumb in a system with an electrical and mechanical fuel pump. I would not do it aircraft style with the pumps in series, if the diaphragm starts leaking into the crankcase and you hit the electric pump switch it will be bad

[Sam]

I'll say it- 4 to 7psi is two much. Surprised you don't smell gas fumes as I had in the distant past with 3 to 7 psi. If you have a long run from tank/filter to the pump [like in a friends ODay] 4psi works well. I have an electric Facet 2-4psi and the fuel pressure gauge shows a fairly steady 2.5 -2.75 and the engine runs well. I 've always been told that the A4 carb only needs 1 or 2 psi. I have gone through three electric pumps in about 40 seasons. Never thought installed backups would be a concern, but I do have one stored on board.

[Captain Crunch]

Thanks Guys.

I might not find the problem right away but from what I found when I started looking it seemed the right thing to do was replace gaskets ( Manifold, carb, water jacket, valve cover, exhaust), hoses, clamps, take things apart clean and inspect, new gauges in the cockpit(it had none), new sensors, new warning system, some new wiring(I'm an electrician), etc...

Glad I did. The engine runs well. Compression test seemed a little too good. 110-114 across all cylinders. I think I did it correctly. I will do again. I will also do a pressure test on the cooling system when I'm finished going through it. I rebuilt the HX last winter, and will acid flush when I get it running again. I pulled lots of scale out of the block and head. Everything was covered in black sludge. I did overheat this thing for a while and it ate a couple of impellers.

I planned on re-powering when I bought this boat. I felt like the boat was worth it, a well equipped Newport 30 II in pretty good shape for a steal because of the A4.

Thanks to the resources and people on this site, the availability of cheap parts at local auto parts stores, and scoring what appears to be a rebuilt(although I think it sat in the corner of someone's shop for 15 or 20 years), complete spare A4 on wheels for $500, I decided to keep the old girl and see how it goes.

I'm lucky to cruise out of Sidney,BC so I never have to motor for long, but as my kids grow up and we are able to go for longer cruises I'm hoping to get reliable range out of this A4.

Once again, thanks for the great resources compiled here and all the help so far!

CC

[ndutton]

Thanks to the resources and people on this site, the availability of cheap parts at local auto parts stores . . . . .

Consider that buying your A4 parts from Moyer Marine will guaranty you get the right parts. An example is your local parts store electric fuel pump @ 4-7 psi with which you expressed concern it might be too much pressure for the carburetor float valve. The correct electric pump Moyer offers for your boat is 2-3 psi making your concern well founded. Whatever the 4-7 psi pump cost, it is not useful on your boat.

Also, when you installed the electric pump, did you include an oil pressure safety switch in series? It is offered in the Moyer catalog too.

[edwardc]

... Ultimately I was hoping to put my electric fuel pump in as a back up on a 3 way valve in the fuel system. If my mech fuel pump drops out I can flip the valve, switch on the elec. fuel pump(series switch with the OPSS circuit) and keep going. Half baked idea?...

One of the typical ways an A4 mechanical fuel pump fails is for the diaphragm to leak. The pump is designed so that such a leak goes into the oil pan, NOT into the bilge. This is a safety factor so you don't fill your boat with gas fumes and risk going BOOM.

With gas in the oil, I don't think it would be a good idea to switch to an electric pump backup and keep on going.

[Captain Crunch]

Thanks again.

I am using a OPSS. I have not put the fuel system back together yet and I will take the advise of not running the electric fuel pump in series through the mech pump.

How about plumbing it in between the mech pump and the carb?

I have also been spending money on this site. A few hundred at this point. My issue right now is it took a month for my last order to arrive, a handful of gaskets and a overhaul manual. I believe the postal systems in both countries are experiencing Xmas like volume and delays.

I have found a good pressure regulator for the pump I have, and I have two mech pumps. I should be good. I will rebuild the one I got with the boat for piece of mind.

Thanks again!

CC

[joe_db]

We all are cheap, we're sailors That said, I am not sure my boat would be usable absent Moyer, so many of us feel compelled to give them a shout out when we can

The safe way to run two fuel pumps is this. You need to be able to cut the mechanical pump totally out of the system and you need a gauge or warning sensor to know when it needs doing.

[Surcouf]

technically, these would be the 3-ways valve, not 2-ways valve
But spot on for the proper configuration.

[joe_db]

technically, these would be the 3-ways valve, not 2-ways valve
But spot on for the proper configuration.

Oops

This is how Piper does it. It works fine, but there is a failure mode for a boat engine that would pump all the fuel into the crankcase
* Do you see the fuel line running off the page from the primer? I once found one of the primer lines broken right at the manifold, so if I had used it I would have sprayed gas all over the engine

[Captain Crunch]

Hi,

The motor started right up today.

I ran it in the slip for a while in N and screwed around with the carb. I leaned it out until i found the best RPM after i let it warm up a bit. Stopped it and started it a few more times then ran it up in the slip in gear.

It ran well, considering the minor surgery it just went through.

I put a new Pertronix EI module in and this one has a small level on the side which changes the timing to the point where I can get it to stall. What is this for?

It seems to idle too high as well now that I have run it up and really warmed it up. I tried leaning it out to reduce RPM at idle but that was inconsistent. Is there any other way to reduce RPM's at idle? If my new tach is reading correctly it is idling in N at 1100 RPM. The idle screw it backed right off. WOT in the slip in F tops out at 1900RPM. The motor accelerates very smoothly and quickly in N and sounds like its normal well running self all around.

I will take it out on Friday and burn some fuel through it, adjust the timing at cruising speed and see how it goes.

New upgrades included:

- Electric fuel pump set to 3 psi.
- Fuel lines and fittings.
- Fuel filter/water separator.
- Polishing fuel filter
- Carb teardown and clean.
- Valve cover gasket.
- Cleaned and tested Thermostat.
- Cleaned out FWC system.
- New coolant hoses.
- Water jacket cover and gasket.
- Cap, Rotor, Coil, EI module.
- Removed, cleaned up, manifold. New gasket,
- Exhaust gasket.
- Instrument panel and gauge.
- Rebuilt starter.

Thanks for all the great advise!

Coming up next is a rewire, New panel, FWC acid flush, and rebuild the mech fuel pump.

Is replacing the head gasket as a preventative maintenance task worth doing? Or is it more common to wait until they go and then replace? The motor access on the Newport is amazing and it would be easy to do.

CC

[joe_db]

You have a lot going on at once!
Let us start with one basic issue - how clean is your running gear? Do you have or can you get a vacuum gauge?