PARADOX

Any one know where is the electrical fuel pump relay? And what is the part no? (525 EFI)
Thx
P

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iTrader: (9)

Peter give me engine serial # and year, then I can look up for the proper part # and position. Somethings changed on the 525 thru the years just as they do with all engines.

PARADOX

Motors are built on 2007, installed in 2008. Not sure what Merc would call them, 08 or 07. I have to do a little bilge diving but I will look up the info.
Thx
P

BUP

iTrader: (9)

Ok got it but going off the top of my head here is what I remember without looking up your exact configuration per engine serial number build by merc racing.

On the backside of intake area inbetween the intake itself and the mounting bracket that the PCM & connections are mounted to. If I recall correctly there should be 2 relays inbetween mounted (inside of Bracket) as the PCM & connections mounted outside of bracket facing the stern. Anyways - those relays are for the main power called 1 & 2. ( fuel pump main relay and the other main relay is the trim limit)

More info to test and wire codes so hopefully this helps you.

The relay itself - for testing the relay use a volt meter set on ohms scale - The trim limit and the fuel pump are deenergized to connect terminals 87a and 30 and energized to connect terminal 87 and 30. The ohms resistance across terminals 85 and 86 should be 75 to 95 ohms - if that spec is not showing replace the relay. The color code wires connections to term 85 - Yellow / BLK - term 86 Red / Blue - term 87 Red / BLK - term 87a no wires and term 30 Red - that's for the fuel pump relay.

NEXT there is fuse packs as well that are for varies circuits like IAC and fuel injectors, relay power and so on as there is more.

There is a fuse for the fuel pump as well - I would check that first before anything - that fuel pump fuse is a 30 amp and should be located at position 2. The wires color code to it should be Red / Black and Red / Pink. again a blade style fuse 30 amps for the fuel pump. Hopefully I remember correctly for your year model. Good luck but I want to ask you are NOT showing no power / voltage at the fuel pump connections while testing ?

PARADOX

THe pump works just fine. It won't shut off once I shut off the engine, only if I turn off the battery power. I can hear it "buzzing" when the engine is off. I just replace it.
The Ser. no. is OM 955397

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iTrader: (9)

Your relay might be mounted on the side of the bracket - the bracket still should be mounted on the backside of the throttle body.

The script that I wrote above was the set up location for the HP 525 that engine serial #'s up to OM953619.

The next lot of engine serial # ranges (yours) I THINK moved them to the side of the bracket. The trim limit relay on one side and the fuel pump relay on the other side of the bracket. I am going off the top of my head here but wanted to give you heads up. I thought maybe I had my HP 525 service manuals at the house. I do not.

Again I can not say how important engine serial # is so important when working on these marine apps plus ordering parts plus proper service procedures thru out . Things change from year to year all the time, hence why engine serial # will dictate all of that. Good luck with it.

Donzi Dude

Thats the ECM
Been there done that
Send mine to Whipple and had it rebuilt
A lot cheaper than buying one
If you have twins swap them I bet the problem follows the ECM

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iTrader: (9)

I should have read his post more completely. ^^^^^^ You are 100 % correct for the possibility for the fuel pump running continuously. This is not just HP 525 specific either. Not a everyday problem but I have had this happen on ECM / PCM 555 from black Mercruiser V-6 thru HP 525 apps that was a bad and or shorted driver in the ECM.

Make sure you have all good grounds and no shorted connections, change relay or swap relay from good known motor to see what happens. Have also seen the J connection wires to the ECM shorted causing stupid problems for sporadic running fuel pumps. Not saying this is your problem but check everything out first before ruling on the ECM only.