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Author Topic:   2006 Mercury OptiMax 150 Electric Fuel Pump
jawsinak posted 06-13-2009 10:34 PM ET (US)   Profile for jawsinak   Send Email to jawsinak  
The [electrical] fuel pump on my [2006 Mercury OptiMax] 150 is not pumping fuel. I tested the pump and it is fine. There is no power to the pump when I turn the key. Is there a relay or sensor that may have gone bad? And, where is it? I live on a remote island and there is no dealer or mechanic; Optihaving the dealer plug it in is not an option.
jimh posted 06-14-2009 08:20 AM ET (US)     Profile for jimh  Send Email to jimh     
The two electrical fuel pumps on a Mercury OptiMax are protected against over current by a fuse. The fuse is located in a small fuse holder that contains four fuses. The fuel pump fuse is an SFE 20 AMP. If you orient the fuse holder so the cover tang is on the bottom, the fuel system fuse will be on the bottom row on the left. The fuse holder assembly is located in the wiring harness adjacent to one of the fuel rails.

Power to the fuse block comes from the main power relay. The main power relay is fed from the battery positive terminal at the starter solenoid.

Since you live on a remote island, I assume you have the service manual for the motor. The electrical schematic shows all the details of the fuel pump circuit.

jawsinak posted 06-14-2009 06:13 PM ET (US)     Profile for jawsinak  Send Email to jawsinak     
Thanks for the response Jimh. I should have mentioned I did check the fuse and it is fine. So, I will try to work back from there and see where the power is interrupted. I have the operations manual but not a service or repair manual and am having problems finding one. I am contacting mercury marine and see if they will send me one. I was wrong on the year it is a 2007. Interesting enough I am also having trouble with the alternator. When unhooked from the post, the alternator is putting out 24 volts, however, when I hook it back up, it is not charging. All terminals are clean and I even replaced the battery. Any ideas on that? thanks for your help
jimh posted 06-15-2009 08:52 PM ET (US)     Profile for jimh  Send Email to jimh     
I can help only in the most basic sense of electrical troubleshooting, which I have been doing for over 40 years. My assessment is as follows:

--the fuel pump is not defective; it fails to work because there is no voltage or current supplied;

--the circuit feeding the fuel pump is protected by a fuse, but the fuse is not blown;

When we expect voltage in a circuit and find none, we begin to trace the circuit back toward the source, looking for the voltage and the point at which it is lost. The next element in this fuel pump circuit is the main power relay. Follow the wiring back to the main power relay and check for voltage. Does the relay energize?

MontanaWhaler posted 06-16-2009 06:09 PM ET (US)     Profile for MontanaWhaler  Send Email to MontanaWhaler     
I would double check all of your electrical connections, especially the grounds. On my 2005 150 Optimax I had intermittent situations where the starter would not energize when I turned the key. I found a loose ground on the starter and tightening it fixed the problem for a year. Then it happened again with nearly identical symptoms and it turned out to be a loose connection on one of the solenoids.

It appears to me that the factory went to great lengths to make all the connections corrosion resistant and trouble free but perhaps in my case with all the trailering I do (about 20,000 miles in the last 2 years) the vibration may have loosened some things up.

Good luck,


jawsinak posted 06-21-2009 08:31 PM ET (US)     Profile for jawsinak  Send Email to jawsinak     
Again thanks for your help. So, I cleaned all posts and grounds. I checked the main power relays and even switched them around to see if it was bad. I can hear the relay energize. I am getting power to the fuse just no power to the pump. I guess it's about to the point of crating it up and shipping it off to a dealer. I am at a loss. Unfortunately Mercury doesn't help with shipping and they won't cover the work under warranty if I send it to anyone but the dealer. Ouch.

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