Engine Oil Pressure and Electronic Fuel Pump Interface

[RobertLangdirect]

I ask "All Sailors" this question hoping that from the thousands who read this, a few of you will know the answer.

I do not have all the paperwork for my Pearson P-31, but I thought that at some point, I read that the electronic fuel pump is wired through a relay that switches on only when the engine's oil pressure is positive. This was to ensure that the electric pump would not flood the carburetor or worse, if the motor was to turn off but the ignition was to remain on.

Please, do not push this back into engines. I am looking for the answer in response to a recent article in a otherwise decent boat magazine, that talked about wiring a replacement electronic pump via the ignition key. I think the article is in error and that the pressure switch is better if not required.

Thank You!

Robert

 

[Stu Jackson]

I ask "All Sailors" this question hoping that from the thousands who read this, a few of you will know the answer.

I do not have all the paperwork for my Pearson P-31, but I thought that at some point, I read that the electronic fuel pump is wired through a relay that switches on only when the engine's oil pressure is positive. This was to ensure that the electric pump would not flood the carburetor or worse, if the motor was to turn off but the ignition was to remain on.

Please, do not push this back into engines. I am looking for the answer in response to a recent article in a otherwise decent boat magazine, that talked about wiring a replacement electronic pump via the ignition key. I think the article is in error and that the pressure switch is better if not required.

Thank You!

Robert

Robert, you ask a philosophical question. Regardless of engine.

Does the pump only work until the oil pressure comes up or not.

You might be interested in this, if you’re into looong-winded explanations, again regardless of engine type.

http://c34.org/bbs/index.php/topic,5078.msg41829.html#msg41829


Good luck.

Your boat, your choice.

 

[kloudie1]

The pump should not be able to push past the float valve in the carburetor, so if the engine normally idles without flooding, the float is OK.. Not necessary to shut the pump down... I have, however, seen some systems that were wired so that the pump ran with the ign on, no oil pressure, and the starter engaged. Then when the starter is released, the pump runs through an oil pressure circuit. That way, the engine can start if the float bowl is empty, but the pump does kill when the oil pressure goes to zero. With a functioning oil pressure alarm, there is little chance of the key being on and the engine not running.. I wouldn't bother with a circuit to cut off the pump other than straight to the ignition switch.

 

[tommays]

It is a CG legal requirement on a GASOLINE Inboard

The oil pressure switch is most common BUT some Volvo's do it with diodes

http://www.bing.com/images/search?q...6A5067B0EF8785E60DECCFF776F55&selectedIndex=2

There are plenty of pictures of the various wiring diagrams

 

[RobertLangdirect]

Tommays -- THANK YOU! That explains a lot. Especially the emphasis on GASOLINE engines. The article in the boating magazine was on a diesel motor. And I see now,, that is significant.

Thanks again.

Robert