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Old 07-09-2020, 10:32 PM
SeaHarlequin SeaHarlequin is offline
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How to diagnose potential bad pump?

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!
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Old 07-09-2020, 11:21 PM
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Ando Ando is online now
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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.
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Old 07-10-2020, 12:48 AM
SeaHarlequin SeaHarlequin is offline
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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?
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Old 07-10-2020, 01:04 AM
sunnnnseeeker sunnnnseeeker is offline
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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
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Last edited by sunnnnseeeker; 07-10-2020 at 01:37 AM.
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Old 07-10-2020, 01:28 AM
JOHN COOKSON JOHN COOKSON is online now
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Quote:
Originally Posted by SeaHarlequin View Post
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
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Old 07-10-2020, 01:34 AM
SeaHarlequin SeaHarlequin is offline
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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!
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Old 07-10-2020, 11:33 AM
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roadnsky roadnsky is offline
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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
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  #8   IP: 70.249.170.224
Old 07-10-2020, 01:47 PM
SeaHarlequin SeaHarlequin is offline
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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.
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