2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please help

[hall832]

2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why?
1. I checked the High Pressure Fuel Pump, its coming on with key.
2. I ran 12 volts to the low pressure fuel pump it works.
3. I am getting spark
4. It appears both pumps run off the same relay. but i have no voltage going to LP FP.

not sure what to check.
Please help

 

[Watermann]

Re: 2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please h

You can try testing the relay's power output with a multimeter. The relay is getting power since one of the pumps is coming on so there must be something going on, maybe even low voltage coming out.

 

[hall832]

Re: 2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please h

i checked the plug supplying the hpfp 12 volts. and nothing at lpfp plug. I know its not like an optimax, do both pumps feed of the same relay.

 

[hall832]

Re: 2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please h

so relay is working it is turning on the ECM. when key is switched on. HP FP is coming on. And no voltage at LP FP checked plug with a meter.

 

[Watermann]

Re: 2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please h

Wish I could help you out on your problem. Most of the outboard guru's I'm familiar with here at the iboats forum are Johnson & Rude mechanics. I think you may have to take your boat to a merc mechanic to have the motor hooked up to see if there are any fault codes showing. Sometimes the ecm will shut down the fuel pumps when they get a fault code.

 

[Faztbullet]

Re: 2004 Mercury 225 four-stroke EFI no power to Low Pressure fuel pump. Why please h

The low pressure(lp) pump only comes on after starting and will run for about 3 minutes after that it pulses 10 seconds on 20 sec off below 1200 rpm, above 1200 rpm it operates all the time. Check all the harness connections and ground to ECM. Check to see if you have output on pin A19 as thats the fuel pump driver for lp pump, if no output ECM maybe defective.