I have a 1996 mercury 150 efi on my bass boat It was sitting for exactly 3 years I drained all the old gas , I bought 3 new batteries, I also bought a brand new 3 bank charger, put on new fuel/water separating filter (mercury) New inline plastic gas filter The problem is my fuel pump doesn’t come on When I jump it from the negative post to a ground the fuel pump does come on, but not with the key. I found the connector to the ecu doesn’t seem to want to tighten up even though the pins all look good Any advice I sure need help with this. I don’t no how to post pictures Thank in advance Signed desperate in Nevada
Last edited by go hawker; 05/18/2006:30 AM. Reason: Trying for a clearer picture
I have no clue what you are trying to say with "When I jump it from the negative post to a ground ...." The negative post of a battery IS the Ground in the system. So you jump "it" from a ground to a ground? Not likely, so I can't tell what you've done. What exactly is the "it"?.
You need a voltmeter and someone who has the knowledge to troubleshoot electrical issues. It's next to impossible to do that via forum message. There's a +12V lead (often red) going into the key switch. You need to confirm that's there and live with 12V on it. There's a +12V output on the key switch, most often purple. You need to confirm that's there as well. One of those is probably NOT acting as it should, and that will be what needs to be corrected. A wire may not be connected at the battery, or a fuse could be blown. Don't make matters worse with that ECU connector until you figure out the key switch issue - since there may not be an ECU issue if you get the basic problem resolved.
Next time you might consider not buying EVERYTHING before you get the outboard running again. You could be a while getting it running...
No I run a single jumper from the negative post of the fuel pump not the battery, to a good ground and I can hear the fuel pump running But not when I try with the key in my ignition Thank you
where is the "good ground" you are using successfully? (This will help in understanding a bit about where a GND disconnect must be located.) The key switch isn't going to switch GND on and off - at least not that I have ever seen. It switches power on and off. Is the key switch on when you do the GND jumper and get the fuel pump to run? I'm curious what prompted you to try jumping the fuel pump GND of the myriad of choices available?
You should start tracing the wire that's on the fuel pump. If it doesn't have a good Ground as you suggest, then tracing it will eventually bring you to a dead end point that is your problem.
1. Do you have continuity between the ground side of the pump and the negative battery terminal? 2. With the ignition switch in the run position, do you have 12V between the hot side of the pump and the negative battery terminal?
the computer could be the problem if you can direct wire it an it will run but not thru the ignition switch.
An ECM needs power, and it doesn't care if that power comes through an ignition switch or not, as long as there's a good (low resistance circuit). I can't imagine anyone "hot wiring" an ECM to be always on as a "fix" for an issue. That's a great way to run a battery down for sure. As someone else said, he may have a defective ignition switch. I'm still puzzled why connecting an alternate GND to the fuel pump makes it work - but he didn't really say if it would crank, just that the fuel pump runs.
Update: I ran a jumper wire direct from the negative side of the fuel pump to a ground on the block. It started rt up and ran good So I still can’t find out why it won’t run with the key on! And as stated in the manual as long as the battery is hooked up the positive side of the fuel pump is always hot, even if the key is off. I also found out that the ignition switch doesn’t have anything to do with the negative ground side of the fuel pump. So I just left a authorized mercury repair boat shop in Henderson Nevada, The own of this place called mercury direct, I heard the conversation There advice was to run a permanent wire from the negative side of the fuel pump to a manual on/off switch! I use a multi meter every day in my line of work as I’m a union electrician, The voltage has got good numbers in all the locations I check.
Is there a fuel pump relay? Since the fuel pump is hot full time, there has to be a way to shut it off when the key is turned off. Maybe a relay that is activated by the ket switch completes the ground for the pump to run. But for the life of me I don't understand why Mercury would have current to the fuel pump full time.
Transgenders: God made them, the devil changed their minds.
Bill, Just the positive side of the fuel pump is hot all the time, The ecu send a ground signal to the negative side of the fuel pump when the key is turned on. After I talk with a mercury technician in the morning I have decided to disconnect and cap off both wires Going to my fuel pump and I’m going to run it they my ignition by jumping off the purple wire to positive side of the fuel pump pump and negative side to a good ground. And I will run It thru a fuel pump rely.
in a efi system when you turn the key on the fuel pump only runs 4 to 10 seconds. when the motor is started and running the ecu sends a signal to the pump to run. this is the way efi has always worked.
Bill, Just the positive side of the fuel pump is hot all the time, The ecu send a ground signal to the negative side of the fuel pump when the key is turned on. After I talk with a mercury technician in the morning I have decided to disconnect and cap off both wires Going to my fuel pump and I’m going to run it they my ignition by jumping off the purple wire to positive side of the fuel pump pump and negative side to a good ground. And I will run It thru a fuel pump rely.