2000 Mercury Sport Jet 240 has no power to high pressure fuel pump

[Crazy685]

Hi all!

Boat ran great now suddenly nothing. Boat just turns over. Tested spark so I knew it was fuel related.

Had the injectors serviced and cleaned, new plugs, still nothing... then started tracing the power. I wasn’t getting any power off the high pressure fuel pump.

When I add 12 volts of power directly to the high pressure fuel pump from alligator clips, boat will start and idle.

When i check the relay point by the manual fuel pump/filter I’m getting 12.58 volts. Dips to 8.5 when i start motor.

I’ve replaced the relay switch. Fuse (3A) on the power line connected to that relay is good as well.

When i check the high pressure pump I’m still getting 0.0 with key on. Nada.

I’ve now replaced the ECU with a working unit from another Mercury 240. It still won’t work.

Next step is swapping the fuel pump itself mainly because I’m already here and the current fuel pump has tons of corrosion on the top.

Any ideas? Is there a fuse I’m missing? I’m so confused. When I replaced ECU i thought for sure that had to be it.

 

[Tim75]

Hi all!

Boat ran great now suddenly nothing. Boat just turns over. Tested spark so I knew it was fuel related.

Had the injectors serviced and cleaned, new plugs, still nothing... then started tracing the power. I wasn’t getting any power off the high pressure fuel pump.

When I add 12 volts of power directly to the high pressure fuel pump from alligator clips, boat will start and idle.

When i check the relay point by the manual fuel pump/filter I’m getting 12.58 volts. Dips to 8.5 when i start motor.

I’ve replaced the relay switch. Fuse (3A) on the power line connected to that relay is good as well.

When i check the high pressure pump I’m still getting 0.0 with key on. Nada.

I’ve now replaced the ECU with a working unit from another Mercury 240. It still won’t work.

Next step is swapping the fuel pump itself mainly because I’m already here and the current fuel pump has tons of corrosion on the top.

Any ideas? Is there a fuse I’m missing? I’m so confused. When I replaced ECU i thought for sure that had to be it.

If you have a good battery, your voltage should not drop below 10 while cranking. Assuming you have good battery, there is a clue. Check all your ground wires. There are at least 3. Just because the screw is tight, that is not a guarantee of a good connection. No green connections. Check the ends of the wires. They have been known to break right at the end where the wire meets the crimp. Only the insulation or heat shrink holding the end together.

On these engines, the electronics are pretty robust and don't fail often. Usually mechanical or wires.

 

[tkalb22]

Hi all!

Boat ran great now suddenly nothing. Boat just turns over. Tested spark so I knew it was fuel related.

Had the injectors serviced and cleaned, new plugs, still nothing... then started tracing the power. I wasn’t getting any power off the high pressure fuel pump.

When I add 12 volts of power directly to the high pressure fuel pump from alligator clips, boat will start and idle.

When i check the relay point by the manual fuel pump/filter I’m getting 12.58 volts. Dips to 8.5 when i start motor.

I’ve replaced the relay switch. Fuse (3A) on the power line connected to that relay is good as well.

When i check the high pressure pump I’m still getting 0.0 with key on. Nada.

I’ve now replaced the ECU with a working unit from another Mercury 240. It still won’t work.

Next step is swapping the fuel pump itself mainly because I’m already here and the current fuel pump has tons of corrosion on the top.

Any ideas? Is there a fuse I’m missing? I’m so confused. When I replaced ECU i thought for sure that had to be it.

im not sure exactly what the problem is I am having the same problem but was unaware of there being two full pumps?

 

[tkalb22]

im not sure exactly what the problem is I am having the same problem but was unaware of there being two full pumps?

if you are knowledgeable about these engines I could use some assistance

 

[Crazy685]

There is a high pressure fuel pump and a regular manual fuel pump.

I did find a ground wire that’s about a foot long, medium sized bolt holes and on the main engine ground, not connected to anything from the main engine ground. Otherwise I have cleaned the grounds completely and there are 4 cables.

My batteries are putting out 700 CCA each per my load tester. I realize they are supposed to be 900-1000 CCA so that may be something, but wouldn’t I be getting some sort of power?

I’m getting flat out ZERO power leading me to believe there must be a blown fuse or.. a wire fell off?

Would the kill switch control fuel or spark? I’m trying to narrow down what would completely cut power out from the HPFP.

For another side piece of info - if i walk away for a day and come back, it fires and immediately dies. Then no firing whatsoever. Only if it’s not been started for a long time, and it’ll only fire for a hot second.

 

[tkalb22]

that would lead me to believe it has something to do with your battery do you have a jump box that puts out 70+ amps ism so gook that up and see if it changes the reading to the pump it is odd that its reading flat 0 making me think it has to be a faulty wire or ground

 

[Tim75]

im not sure exactly what the problem is I am having the same problem but was unaware of there being two full pumps?

There are actually 3 fuel pumps.

 

[brevard2002]

using the electrical wiring diagram, pull apart connector to ECM and check ohms from gnd pin on connector ( not the half of the connector that goes to ECM) on to engine block gnd

 

[brevard2002]

the ECM grounds one side of pump to turn it on. You should see 12v on pump terminal any time key is on.