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Engine noise with key in accessory position

ignisuti

Member
I have a 1995 Rinker Floatilla with 4.3L Mercruiser engine. It's relatively new to me. So, I'm still learning what is and isn't normal.

I noticed that when I turn the key to the on position there is a buzzing (electric motor noise) coming from the engine bay. Other posts indicate this is likely a fuel pump, but they say it should turn off after 3 seconds. Mine does not. I just stays on. Can someone please confirm if this is or isn't normal operation?
 
Other posts indicate this is likely a fuel pump, but they say it should turn off after 3 seconds. Mine does not. I just stays on.

The fuel pump cycles only with fuel injection TBI or MPI . If you have a carb you have an electric fuel pump incorrectly wired or a bad pressure switch
 
If you have a carb you have an electric fuel pump incorrectly wired or a bad pressure switch

I have a carb. How bad is it to run the boat like this?

I have plans to be on the water all weekend starting tonight and unlikely I'll have the option to fix it before then.
 
you need to verify it is the fuel pump running when the key is ON.

Its a safety issue as the oil pressure switch should turn the pump OFF if the engine looses oil pressure...
 
Wonder if previous owner hooked up accessory terminal to prime fuel system?
Best to see what wire is attached to accessory terminal and trace it back to connection, where ever that may be, possibly at oil pressure switch.
 
there is a wire connector on the left top front of the engine just left of the thermostat housing if you re looking at it from the front. it goes to the fuel pump, unplug the onnector and see if the noise stops, if so, then s the others wrote, you need to check the wiring to see why it is running constant.
 
Thanks to everyone who is helping with suggestions. I delayed my weekend plans to try and figure this out, but still no luck.

I confirmed it was the fuel pump that was running by disconnecting it's connector and verifying that the noise stopped.
But, I'm not sure what to do next. kghost said "trace it back to connection". This sounds like a PITA! I'd have to use an ohm-meter with a really long cable attached to the ignition accessory wire and then use the other test lead to probe all the engine wires until I find a match... Is there an easier method here that I need to know?

Isufan71, I do ALSO have actual alarm going off now that I'm trying to troubleshoot, but I believe that is a different issue. I've removed the wires to the oil sender, oil switch, both temperature sensors, and the gear lube reservoir, but the alarm is still present. Did I miss anything?

Bt Doctur said I could have a bad pressure switch. What I see from the oil pressure switch wiring diagram is that it can only stop power going to the fuel pump, not send power to it...???

Just by chance I have one issue causing many others (wouldn't that be grand), I'll let everyone know that my boat now now cranks, but no spark. Today is the first time I've tried to fire it up this season. Ran great last season. Got a rumble out of the engine the first couple times I tried, like it had a spark, but then no more spark... If you think these are related (like a disablement system), please let me know. FYI: The no start issue is looking to me like a Ignition Module issue based on my troubleshooting.
 
UPDATE:
I noticed that with the Key ON, if I turn the safety lanyard OFF, then my fuel pump stops running, but all my gauges stay illuminated. This is confusing because according to my wiring diagram, the gauges should also be shut down by the safety lanyard.
 
"""""This sounds like a PITA! I'd have to use an ohm-meter with a really long cable attached to the ignition accessory wire and then use the other test lead to probe all the engine wires until I find a match... Is there an easier method here that I need to know?""""

Yes troubleshooting is a pain in the *****, Why do you think it costs so much to pay someone else to do it?

The oil pressure switch is a on/off switch. When key is in run position 12 volts is present at pressure switch. When oil pressure is reached, switch closes and passes that 12 volts to fuel pump. One side of pressure switch should have TWO wires. One of those wires goes to pump, other should go to starter solenoid to supply pump with 12 volts when cranking. With out this the pump would not run when cranking/starting engine. Once pressure is present and pressure switch closed and engine starts and key is returned to the RUN position then 12 volts to pump goes thru switch ONLY.....

There cannot be any other source for this 12 volts to pump regardless of key position.

12 Volt supply to fuel pump sources-

1. When cranking, 12 volts comes from starter solenoid ONLY which bypasses oil pressure switch to start engine ONLY.

2. Once ~5 psi of oil pressure is generated oil pressure switch closes, 12 volts now comes from Ignition on/run ONLY (Purple wire)

If your boat ran good last season before you put it away for winter, what was done to it before you attempted to restart it for the spring?

Something is fishy here...............Did you replace anything? Did you mess with any wiring? Did you install something and wire it to the wrong place/power source?






Here is a standard wire schematic for dash board wiring. This is very typical for all boats.

dash wires.jpg
 
unplug the oil pressure switch located next to the oil filter on the port side lower part of the engine. that is the switch that sends power to the fuel pump as jack mentioned. if the pump still runs, it is being fed power from another source and you need to track that down
 
Thanks again for all the info.

Jack, as mentioned in my other post, I added stereo, fish finder, and Low voltage cut-off over the winter. I feel very confident in stereo and fish find wiring. They are wired to the accessory switch power. The Low-voltage was a new electronic toy for me. So, I un-did that modification and found zero improvement.

Stang32, I did as you suggested and unplugged the oil pressure switch (one with two wires) and the fuel pump still ran.

So, it sounds like I need to trace down the fuel pump's power source.
The rain is coming back into the Midwest. So, I've got to put the cover back on the boat and I'll get back to tracking this issue down in a few days when the weather clears.

FYI: I want to say this noise was there when I ran the boat last fall, but I'm not certain now as it's still a new boat to me and I only had it out a couple times. Please help me understand if that's even possible. My understanding is that the boat will run like this, but it poses a safety concern. Is that right? If so, what is the safety concern?
 
the concern is that the fuel pump will continue to run even if the engine is not running or there is no oil pressure. so, if the engine gets shut down for a saftery issue, the pump will continue to pump fuel into the carb &/or boat. fuel is not something to take chances on .

somehow, somewhere you will find that the wire to the pump has been modified, spliced or shorted to another source. find it.
 
I looked at stang32's wiring schematic and I did not see a separate fuel pump relay that could be stuck "on".

"somewhere you will find that the wire to the pump has been modified, spliced or shorted to another source. find it." or a jumper attached (look for a wire of the wrong color in the circuit)

Ignisuti: Do you have any experience reading and following a wiring schematic? They can be confusing when the bundle of wires looks like a bird's nest. Concentrate on one wire at a time when tracing them. kghost gave you the list of how the fuel pump runs...keep that in mind when tracing wires by color code.
 
Thanks everyone!

I had a conversation with kghost. Since disconnecting the oil switch does not stop the fuel pump in the Key On position, the most likely scenario is that a previous owner may have mis-wired the other connection at the starter. I'll trace this down and confirm after I wrap-up another issue I'm having.
 
Thanks everyone!

I had a conversation with kghost. Since disconnecting the oil switch does not stop the fuel pump in the Key On position, the most likely scenario is that a previous owner may have mis-wired the other connection at the starter. I'll trace this down and confirm after I wrap-up another issue I'm having.


exactly
 
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