3.0 Litrer Oil pressure switch

I have a 1984 18 ft Imperial with a GM 3.0 liter 140 hp 4 cyl. I am changing the mecanical fuel to electric. I was wondering if any one had a part number and location of a place where I can buy an oil pressure cut-off switch. I read using one of these is the best way to go.<br />Thank you..

Re: 3.0 Litrer Oil pressure switch

You need a NO (Normally Open) oil pressure switch that closes at about 5 to 7 psi. Most auto parts stores have them, or you can get one from a Merc dealer, PN 87-864252A01 for about 24 bucks.<br />Here is a wiring diagram of how to install one. The diagram is from a V8, but the pricipal is the same. Item 5 is the pressure switch, and #6 is a picture of the fuel pump used on the V6 and V8 engines.<br /><br />

Re: 3.0 Litrer Oil pressure switch

Burt _to_Mullet <br />Can you E-mail me what your doing to install the electric pump? I would like to replace my mech. one.<br />Thanks,

Re: 3.0 Litrer Oil pressure switch

I would suggest a oil pressure warning system to alert you instead.<br /><br />You really want your engine to die with out warning, could cost you your life.<br /><br />What if you approching a bridge down stream in a swift current river? What if your approching a tanker in a narrow channel? What if your in a sea with breaking swells?<br /><br />Do you really want your motor to shut off and not restart then hit the bridge, be run over by the tanker or capsize in the sea.<br /><br />Personaly I would rather burn a bearing at low speed than loose my boat family and life at a danerous time to have no power.<br /><br />Alert me of low oil pressure and I will decide if it safe to shut the engine off. After all at idle engine will run a long time with very little or no dammage even with no oil.<br /><br />I know a drunk who stopped at a bar and ran over a concreat parking curb. It ripped the oil plug out of the bottom of the pan and all the oil ran out. He had a drink then drove it home over 40 miles at 55 miles per hour. I help him repair the pan and put in a new plug. He keep the car for 5 years after that and it ran good with good. It was late at night and winter but I could not belive it made it that far with no noticeable damage but it did. He was not useing any kind of Special oil either.

Re: 3.0 Litrer Oil pressure switch

I would rather ya but the boat back together as designed, its cheap, easy and works well.<br /> however the USCG says if you go electric it must have a fuel pump shut off in case the engine stalls due to a fuel leak. much more probable than ever loseing oil pressure.<br />the fuel pump must also be UL and USCG rated for marine use and there are some other requirements on fuel lines on the pressure side of the pump. all designed to keep joe backyard from blowing himself up.

Re: 3.0 Litrer Oil pressure switch

Originally posted by rodbolt:<br /> I would rather ya but the boat back together as designed, its cheap, easy and works well.<br /> however the USCG says if you go electric it must have a fuel pump shut off in case the engine stalls due to a fuel leak. much more probable than ever loseing oil pressure.<br />the fuel pump must also be UL and USCG rated for marine use and there are some other requirements on fuel lines on the pressure side of the pump. all designed to keep joe backyard from blowing himself up.

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Ya think,.... On that subject do marine fuel injected engines run high pressure fuel rails?

Re: 3.0 Litrer Oil pressure switch

On that subject do marine fuel injected engines run high pressure fuel rails?

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Yes, and they run typically between 35 and 60 psi.<br />The USCG certification has to do with fire and heat resistance, not leaks or system pressures.

Re: 3.0 Litrer Oil pressure switch

most MPI runs about 35-40 PSI, HPDI runs a medium pressure at 50 PSI and the smaller ones the injector rail is about 750 PSI the z250 and 300 run 1100 PSI on the rail pressure.<br /> however they dont use standard hoses and clamps.<br /> they use rubber compounds and components designed to take the heat and vibration as well as direct flame resistance.<br /> they also have systems that detect engine run and shut the fuel pumps down if it stops running.<br /> just in case a leak was the reason it quit running and to prevent pump overheat from running stalled.