DF140 HP pump is loud and runs constantly

[nondem]

The HP pump on these engines is supposed run for a few seconds when the key is turned on but the engine isn't started. I have twin 2004 DF140s and while one of them does just that...the other one runs constantly. Its also very loud compared to the other one.
The engine starts and idles OK..but it falters under load...kinda like its fuel starved. It will run smoothly at about 4000rpm though...once the other engine helps it get there.

Does anyone have a clue what may be going on?

[kmoose]

Bad high pressure pump. It cannot obtain pressure needed to cut pump off so it continues to run. A simple pressure test on the high side fuel bus will confirm if it has below spec pressure.

[redlowrey]

When you turn the key on the power relay is energized and the high pressure fuel pump gets battery supply and the ECU puts a ground on it. It will stay on for three seconds and if you haven't turned the key to start it will remove the earth off it and it will stop, the ECU duty cycles the earth on the fuel pump and it has nothing to do with fuel pressure switching the pump off and on. Why your pump stays on I don't know the computer is the only place it gets an earth on pin 37, but as far as the noise goes the low pressure fuel pump might not be keeping the fuel up to the vst and the pump would be noisy, pump the hand primer for a while and see if the noise disappears. The only way you can check it properly is to hook a pressure and flow meter up to it, pressure will be around 36 psi and flow wont be much because the pump is duty cycled and depends on demand.

[nondem]

Thanks and more thoughts....

I appreciate the replies and I hope to get to the bottom of it soon.

The engine with this pump is acting fuel starved as it is. The loudness of the pump would reenforce the low pressure theory but - I can not find any part of the fuel system that would sense low pressure and keep the pump running other than possibly the pump itself??? Also, as was mentioned; The computer is supposed to "blindly" turn the pump on for 3 seconds or so when the ignition is turned on and then it should stop. The other identical engine does so.
The fact that the pump is loud convinced me that no matter what - the HP pump had issues so I've got another VST in hand and will put it on if it ever stops raining.

If the ECM switches the ground to control the pump I can imagine a scenario that might explain it...Maybe the pump is getting ground through a short somewhere on it via the VST housing and that is causing it to run whenever it has + power.

[nondem]

More info....

Replaced the VST - still runs 100% of the time the key is on regardless. Also - the ECM was showing a CAM position sensor error - so I swapped it with the other engine. The other engine started showing a CAM code so that proved it was bad. The good CAM sensor from the engine w/no problems didn't fix the problem w/the HP pump on the other engine.

So at this point - it could still conceivably be the Crank sensor but it doesn't seem likely - problem with that is, there isn't anything else it could be. I already swapped ECMs between motors and it makes no difference. With the "bad" ECM installed - the "good" engine runs the VST 3 seconds as it should.
I also - with the ECM and VST unplugged - checked the wire between the ECM and the (-) side of the VST..it isn't grounded. With the Suzuki Diagnostic System(SDS) I can watch the Duty cycle of the pump while the engine is running and the ECM reports variable duty cycle %s as it appears it should...53% at idle etc....
The new VST is quieter but it made obvious another fact and possible clue - the HP filter is loud also - the fuel flowing through it produces a sound similar to a water hose with a spray nozzle....Figured it might be clogging so I have a new one on the way.
None of this could be causing the ECM to decide to run the pump more than 3 seconds without the engine running....there is nothing sensing pressure in the High Pressure fuel circuit.


What else could it possibly be? I've been able to swap or conclusively test every possible part it could be except as mentioned above - the Crank Sensor.

There is a seemingly unrelated issue that I'll mention just to be complete - The #4 fuel injector on that same engine doesn't work correctly. When using the SDS - I noticed when I turn that one injector off and on - it doesn't always come back on. It appears to be 'sticking" because if I cycle it on/off it sometimes clears up. I've ordered a new one.

I appreciate the replies and I hope to get to the bottom of it soon.

The engine with this pump is acting fuel starved as it is. The loudness of the pump would reenforce the low pressure theory but - I can not find any part of the fuel system that would sense low pressure and keep the pump running other than possibly the pump itself??? Also, as was mentioned; The computer is supposed to "blindly" turn the pump on for 3 seconds or so when the ignition is turned on and then it should stop. The other identical engine does so.
The fact that the pump is loud convinced me that no matter what - the HP pump had issues so I've got another VST in hand and will put it on if it ever stops raining.

If the ECM switches the ground to control the pump I can imagine a scenario that might explain it...Maybe the pump is getting ground through a short somewhere on it via the VST housing and that is causing it to run whenever it has + power.

[Harper]

Since you double-posted this same topic, have you bothered to look at the reply to the other post on this subject? Maybe that response will help, maybe not.

[redlowrey]

Replaced the VST - still runs 100% of the time the key is on regardless. Also - the ECM was showing a CAM position sensor error - so I swapped it with the other engine. The other engine started showing a CAM code so that proved it was bad. The good CAM sensor from the engine w/no problems didn't fix the problem w/the HP pump on the other engine.

So at this point - it could still conceivably be the Crank sensor but it doesn't seem likely - problem with that is, there isn't anything else it could be. I already swapped ECMs between motors and it makes no difference. With the "bad" ECM installed - the "good" engine runs the VST 3 seconds as it should.
I also - with the ECM and VST unplugged - checked the wire between the ECM and the (-) side of the VST..it isn't grounded. With the Suzuki Diagnostic System(SDS) I can watch the Duty cycle of the pump while the engine is running and the ECM reports variable duty cycle %s as it appears it should...53% at idle etc....
The new VST is quieter but it made obvious another fact and possible clue - the HP filter is loud also - the fuel flowing through it produces a sound similar to a water hose with a spray nozzle....Figured it might be clogging so I have a new one on the way.
None of this could be causing the ECM to decide to run the pump more than 3 seconds without the engine running....there is nothing sensing pressure in the High Pressure fuel circuit.


What else could it possibly be? I've been able to swap or conclusively test every possible part it could be except as mentioned above - the Crank Sensor.

There is a seemingly unrelated issue that I'll mention just to be complete - The #4 fuel injector on that same engine doesn't work correctly. When using the SDS - I noticed when I turn that one injector off and on - it doesn't always come back on. It appears to be 'sticking" because if I cycle it on/off it sometimes clears up. I've ordered a new one.

Mate the fuel pump can't run without an earth, so it is getting one from somewhere disconnect the battery and the ecu put an ohm meter on the earth side of the wire going to the ecu and ground it should read infinity

[nondem]

I did read the other post

I didn't reply to the other post because I've gathered more information since - and I also thought it might have seemed insulting...

If you had accurately read the original post you would have noticed I said there is nothing to sense pressure on the high pressure fuel circuit. Even if there was, the ECM runs the pump for three seconds when the ignition is energized and then stops. This is what the other engine does even if there is no fuel at all in the circuit to be pressurized.
I'll admit that everything about this screamed low fuel pressure but two things rule that out at this point:
1) as I mentioned above - there is nothing to sense fuel pressure on this outboard at all(unlike most cars). The duty cycle of the HP pump is calculated using the other inputs the ECM gets(RPM etc....)
2) At this point - I've replaced the entire VST and HP filter which are about the only things that could cause low pressure on that circuit even if that were to be the possible cause.
The pressure in that fuel circuit is controlled with a mechanical regulator with NO electric connections that keeps the circulating pressure constant and the VST has a float bowl that adds fuel to the circuit as needed.


I also checked the wiring between the VST and the ECM...with both ends disconnected there is no continuity. The ECM is giving it a ground....and that would indicate the possibility of a bad ECM. It isn't a bad ECM because I swapped the ECM with the other engine. The problem stays with the same engine. IOW: I took the ECM out of the bad engine and put it in the engine that is operating it's VST normally. With that "bad" engines VST installed, the good engine still ran the pump 3 seconds as designed. The bad engine still ran the vst all the time with the good engines ECM installed.

I don't remember if I mentioned, but I've also swapped out the cam position sensor because it had a history of codes in the ECM...that had no effect beyond ending the codes.

So, it pretty much has to be something giving the ECM bad data which is in-turn making it tell the pump to run. I've resolved all error codes and have basically run out of stuff that could be causing it. There is no code for it, but I may swap out the crank position sensor since it's about the only thing I haven't already tried....

Since you double-posted this same topic, have you bothered to look at the reply to the other post on this subject? Maybe that response will help, maybe not.

[Harper]

Well, you might think that there is nothing in the high pressure fuel system that senses pressure, but most electric high pressure fuel injection pumps that I know of (Bosch, Matsushita, Mitsubishi, Bendix, etc) all have the sensor built into the pump itself and shut off at a specific pressure. You apparently didn't think it insulting to ignore those who answered your other post. Well, that's fine. That's what happens when you double-post the same problem. Good luck solving your problem.

[CaptT3]

Was this problem ever resolved?having same issue

[tsturm]

The HP pump on these engines is supposed run for a few seconds when the key is turned on but the engine isn't started. I have twin 2004 DF140s and while one of them does just that...the other one runs constantly. Its also very loud compared to the other one.
The engine starts and idles OK..but it falters under load...kinda like its fuel starved. It will run smoothly at about 4000rpm though...once the other engine helps it get there.

Does anyone have a clue what may be going on?

Sucking air & doesn't build enough pressure to shut off.

[redlowrey]

Sucking air & doesn't build enough pressure to shut off.

Don't want to ruin your day, but the system does not run like that. The ecu controls the ground on the high pressure pump, it will apply a full ground when the key is turned on for a few seconds, or when the key turned to the start position. If the ecu receives a crank sensor signal it will keep the full ground on the circuit depending on engine temp, then it will use duty cycle depending on engine load.
All df Suzuki engines use this system, it has been around for a long time.

The reason the computer controls the output is to extend pump life, for an example if you were trolling at low rpm why would you need the pump running at maximin output.
the post above with the pump running all the time with the key on and engine not running, either has a short to ground in the fuel pump ground circuit going to the ecu or the ecu is faulty.

[tsturm]

Don't want to ruin your day, but the system does not run like that. The ecu controls the ground on the high pressure pump, it will apply a full ground when the key is turned on for a few seconds, or when the key turned to the start position. If the ecu receives a crank sensor signal it will keep the full ground on the circuit depending on engine temp, then it will use duty cycle depending on engine load.
All df Suzuki engines use this system, it has been around for a long time.

The reason the computer controls the output is to extend pump life, for an example if you were trolling at low rpm why would you need the pump running at maximin output.
the post above with the pump running all the time with the key on and engine not running, either has a short to ground in the fuel pump ground circuit going to the ecu or the ecu is faulty.

Did not do any damage to my day