DF175 Fuel Pump Troubleshoot

[Zuki175]

2007 DF175 with 900 hours.

Prior to starting the motor with the key turned to the accessory mode (first click), I use to hear the fuel pump make a electrical wheeze sound and the sound of gurgling fuel for about 3 to 5 seconds. I'm assuming that's the fuel pump priming prior the the motor starting up. Around 775 hours, I stopped hearing that sound. Now it's completely silent when I turn the key in the accessory mode. Is this a precursor that the fuel pump needs replacement? I know the high pressure fuel pump is scheduled to be replaced around 900 hours so wondering if that's my issue or if it might be something else that is en route to fail.


Motor starts up at first crank every time. Even when boat has sat for over a month. Motor is well taken care of and all maintenance done on schedule. Engine is reaching 900 hours and still running like new. Is this something I should not worry about or is it time to replace a part to bring that fuel pump priming sound back for preventative maintenance?

[Harper]

I've never heard any gurgling sound from the high pressure pump pressurizing the fuel rail, and would be a bit alarmed if I did. Gurgling would suggest to me the presence of air in the fuel rail, or very low fuel level in the VST. All I ever hear is the high pitched hum. In any case, if you can't hear the hum of the high pressure pump at key on, it probably means didn't need to come on due to the pressure in the rail being adequate. I would not assume that it portends any trouble, unless you are experiencing a long crank time before it'll fire.

[redlowrey]

I've never heard any gurgling sound from the high pressure pump pressurizing the fuel rail, and would be a bit alarmed if I did. Gurgling would suggest to me the presence of air in the fuel rail, or very low fuel level in the VST. All I ever hear is the high pitched hum. In any case, if you can't hear the hum of the high pressure pump at key on, it probably means didn't need to come on due to the pressure in the rail being adequate. I would not assume that it portends any trouble, unless you are experiencing a long crank time before it'll fire.

Don't want to ruin your day harper, but your wrong, when you turn the key on the fuel pump will get a 100% duty cycle command from the ecu for about five seconds. If the fuel pressure was already high, it will just blow off excess through the pressure reg dumping it inside the vst.

[Zuki175]

I think the gurgling, hissing and electrical whining sound stopped after I had replaced several cam shaft shims and replacing the intake manifold. I had also drained the VST which had no presence of water. Is it possible that the above repairs may have caused the noises to go away? I've had this noise at every start up since the motor was new.

I have a older Chevy SUV that makes a loud electrical whining sound when I turn the key to accessory mode. That's the fuel pump priming before the engine starts up. When that noise sounds weak or silent, it's a indicator the fuel pump is about to fail.

So I'm curious if this basic troubleshoot also applies to my situation. How do I test the fuel pump if it's failing? Is there something else I should inspect on the engine? The good news is the engine fires up without hesitation on the first crank whether it's cold or warmed up.

[Murray]

Measure the fuel pressure and compare results with spec.?

[Harper]

Don't want to ruin your day harper, but your wrong, when you turn the key on the fuel pump will get a 100% duty cycle command from the ecu for about five seconds. If the fuel pressure was already high, it will just blow off excess through the pressure reg dumping it inside the vst.

LOL. That's okay red.....you haven't ruined my day. I'm not always right, ya know. But that's my first mistake this year.

[artdf175]

k

Don't want to ruin your day harper, but your wrong, when you turn the key on the fuel pump will get a 100% duty cycle command from the ecu for about five seconds. If the fuel pressure was already high, it will just blow off excess through the pressure reg dumping it inside the vst.

well you both were wrong, according to the 175 manual
fuel pressure, adjusted by the regulator, ....
By-pass fuel is returned to the fuel vapor separator chamber. quote-unquote

[artdf175]

oops Red sorry
I read your reply wrong
you were correct
Art

[Moonlighter]

Lol! Nice work guys!!

Yes the pump always cycles at key turn, but I have never heard noises that could be described as gurgling!!

Anyway OP can simply check for normal operation by taking the cowl off, standing close by, and get someone to turn the key on and listen for the pump humming for a few seconds.

[Zuki175]

Update,

The gurgling noise is still present when key is turned to accessory mode but can only be heard within a few inches from the cowling. Ran the boat recently accruing 15 hours. Motor ran great with no issues. Not sure why after nearing 800 hours of use, the noise has toned down dramatically. Will update if anything fails related to this concern.

Thanks again for all the feed back.

[artdf175]

take a look at the fuel filter at the engine.. Any presence of air? should be full and the fuel bulb should be hard when you try to pump it.

Reason for asking
I had a fuel bulb just go bad
Took a bit to figure out why engine was not running correctly. checked all the wiring and usual stuff and then noticed that filter was only half full
pump it back up and the air kept coming
changed the water/fuel filter same
in replacing the bulb, the manufactured crimp holding the nippled end in-place was loose.
now mind you it gets almost zero usage.
replaced it and that solved the problem
However, to your gurgling point-- for the first time ever when there was air in the system the high pressure pump on start up was noisy trying to get a good flow of fuel.
back to normal now
Art