How to diagnose potential bad pump?

[SeaHarlequin]

Hi - I'm trying to determine whether I have a bad fuel pump.

I have a late model Atomic 4 engine. The engine has an electronic fuel pump (Facet pump). There is a fuel pressure gauge just after the in-line fuel filter (after the fuel pump) and just before the carb.

I'm getting intermittent shutdowns, both from idle and while in gear. I've observed that these shutdowns are related to lack of fuel pressure -- the PSI will drop to 0 and the engine will run happily until it exhausts the gasoline in the carb.

I've attached a multimeter and can measure current going to the pump when attempting to start the engine (at least 5 amps which should be sufficient, right?). A few times during today's session, the pump apparently behaved and fuel pressure registered for a bit. There was no discernible pattern to the length of time of runs -- sometimes it'd run for 15 minutes before stopping, other times 3-5 minutes. The last few tries, it has not responded to these attempted starts.

I've tried uncapping the gas tank to let air in to rule out a clogged intake tube.

Since the fuel pump is a relatively significant resource sink (both in terms of cost and crawling in there to install a new one), I'm trying to rule out other possibilities before doing so. Are there other steps I can check to rule out other culprits which could result in fuel not making it to the pressure gauge (and carb)?

I'm not sure if this is related: I thought I could short across the OPSS switch to activate the pump but the multimeter showed no reading unless I tried to start the engine. If needed, I can bring a DC power supply and supply power directly to the pump but I was hoping there was an easier way to test the pump.

Thanks!

[Ando]

Would it help you if you disconnect the fuel line at the carb and place it in a transparent water jug and see if the fuel pumps into the jug? If its pumping out gas normally, maybe its a clog in the carb.

[SeaHarlequin]

Thank you for the suggestion. I can give that a try.

How do I get the pump to work after disconnecting the hose at the carb and routing it to the container? I tried shorting across the OPSS switch but that didn't register on the multimeter -- do I need to hold down the starter button or is there a better route?

[sunnnnseeeker]

fuel pump

Check the 5A fuse, if has one, in wire from coil to oil pressure safety switch. Run a bypass wire from the hot lead on coil to fuel pump. This bypasses the wire with fuse and the oil pressure safety switch. With ignition switch on and power to the fuel pump you will hear it working, if it works, without engine running. Can also take fuel line off to make sure its pumping fuel.

If working properly the fuel pump draw less than 2A. I wouldn't worry about measuring the current. I looked at your pictures of the fuel pump and I am not seeing that it has a ground wire, which should be connected to the mounting bolt of the pump.

I just had similar problem and turned out fuel pump was going bad and it finally blew the fuse. Replaced fuel pump and fuse and its running great now. It stopped on me once last year and twice this year before I decided to change everything; electronic ignition, plugs, wires, coil, fuel pump and oil pressure safety switch.

Nathan
1975 C&C 30

[JOHN COOKSON]

Hi - I'm trying to determine whether I have a bad fuel pump.
I'm not sure if this is related: I thought I could short across the OPSS switch to activate the pump but the multimeter showed no reading unless I tried to start the engine. If needed, I can bring a DC power supply and supply power directly to the pump but I was hoping there was an easier way to test the pump.
Thanks!

Run wire from the battery to the fuel pump. This the easiest way to for sure bypass the boat's wiring and the OPSS. You will find out whether the fuel pump has a problem or not.

ex TRUE GRIT

[SeaHarlequin]

Thanks -- I appreciate the great suggestions. I've got a good idea of what to do next time I'm on the boat now.

@sunnnnseeeker - that's a beautiful engine and compartment. I'm jealous of the space you have in there! Nice boat!

[roadnsky]

If none of the above suggestions solve your issue, you may want to look into the "STUCK BALL" possibility. Read Ed's post about it HERE

[SeaHarlequin]

Nice suggestion! That should be a quick diagnosis check and if it is indeed a stuck ball, it sounds like the fix is easy, albeit temporary.

[tritonyawl2]

Would it help you if you disconnect the fuel line at the carb and place it in a transparent water jug and see if the fuel pumps into the jug? If its pumping out gas normally, maybe its a clog in the carb.

Just don't use a plastic cup like I did. Gasoline melts the plastic and then runs all over.

[Zig Zag]

Had similar issues but turned out to be a sensor

I just took my (only had this boat since December) Morgan 30 w Atomic 4 Gas engine on a long run, and had to motor the whole way. Part way through the trip my engine would stop running, but I could start it back up right away. After allot of testing and removal of carb, pump and fuel filters, there is an oil sensor that CLOSES once the oil pressure goes above 3 psi and when it closes it turns on the fuel pump. The 12 volts would come from the distributor to the sensor then back out to the fuel pump. This senor's job it to stop the fuel pump when the engine is not running. After allot of consideration and research I bypassed this sensor (connected the distributor wire directly to the fuel pump wire) and the engine never stalled again, ran for 1 1/2 days till we arrived at the next dock home, and the fuel pump only ran when the key was in the on position. Before this long run the engine would just die unexpectedly usually at idle about 10 times in a month, I believe this sensor might have been failing for a while. Don't know if this helped.

[sastanley]

Just don't use a plastic cup like I did. Gasoline melts the plastic and then runs all over.

Good point. I have found that Gatorade bottles are stout enough to store fuel for an extended period.