Question for Either TheFermanator or Spareparts or anyone else that might know.

[Destroyer]

In light of what happened to me over this past weekend, it got me to thinking... Why don't outboards use electric fuel pumps? Seems to me that it would be a lot easier than having a squeeze bulb, vacuum diaphragms, lines all over the place, etc. I'm fairly certain that the fuel pressure would have to be regulated, just like on a car, but they make fuel pressure regulators for just that reason. In fact I've used several of them over the years on cars that I've converted from mechanical pumps to electric. For that matter, why not use a mechanical pump much like what was found on cars for the longest time? They could grind a lob on a crank just like they ground a lob on a cam. Why are we using these pumps that run off the crankcase vacuum?

[RidgeRunner]

I am sure it could be done but think about the 2-stroke OB. They all use roller bearings/ball-bearings for the rotating assembly. Then, the air/fuel/oil gets distributed throughout the crankcase lubricating the bearings. A cam lobe, on the crank would be required, then you would need to find a way to lube it up the friction point to keep it from failing. I prefer the vacuum operated pump, it has been good enough for outboards since the 50's. The mechanical pump still has a diaphragm to fail. Electric on a race boat, Yes! Too complicated for the average fishin boat IMO..

[THEFERMANATOR]

Electric pumps are very doable, but why? Old school outboards were meant to be able to run without any electrical power needed short of the starter(and some have even tried to rope start the big outboards as well in an emergency). As far as running the fuel pump off the crank, that would require ALOT of added expense to build VS using a pulse type pump. Pulse pumps work fine, and are cheap and simple. Almost all lawn mowers with a pump still use a basic pulse pump, and you rarely have problems out of them. The OMC loopers though required the more complicated style pump like the VRO pumps to pump enough fuel. The OMC loopers work off of a very efficient crankcase flow pattern, and after about 3500 RPM's the crankcase stays almost pressurized constantly. this is why OMC's used teh more complicated VRO differential pump whereas other outboads stuck with a basic pulse pump. When they work they work, but unfortunately the VRO style pump does have more failures than other diaphram pulse pumps do to there design. They do though pump alot more fuel with not much crankcase differential pressure.

[Destroyer]

Originally Posted by RidgeRunner

I am sure it could be done but think about the 2-stroke OB. They all use roller bearings/ball-bearings for the rotating assembly. Then, the air/fuel/oil gets distributed throughout the crankcase lubricating the bearings. A cam lobe, on the crank would be required, then you would need to find a way to lube it up the friction point to keep it from failing. I prefer the vacuum operated pump, it has been good enough for outboards since the 50's. The mechanical pump still has a diaphragm to fail. Electric on a race boat, Yes! Too complicated for the average fishin boat IMO..

I would think that you would lube it the exact same way that the other bearings are being lubed.... like you described, the gas/oil mixture.
And that's exactly what I'm talking about Ridge...We're using 80+ year old technology. There's GOT to have been something better invented since then.

Understand, I'm not against the vacuum operated pump, I'm just curious as to why we use it and not either a mechanical or an electric one. I know I'm not the first person to ever think about this, so I'm just trying to find out what the reasoning is. I'm trying to learn.

[phatdaddy]

i used to fish with a guy who had an old omc seadrive and when his fuel pump went south, we replaced it with an electrical one. at that time we were told not to do because of grounding issues. on cars and most power equipment, you can ground through the frame. on boat not so. also most elec fuel pump applications are flooded suction situations, where as on a boat you are lifting out of a tank and pushing up to the carbs. as far as i know the elec one was still on the boat when he sold it several years later.

on all of my ditch witchs with wisconsin engines (2 & 4 cyl) i have replaced the old mech arm pumps with elec, because of the cost of wisc parts vs oreily's.

[RidgeRunner]

I know what you mean. The VRO pump bit me a while back on my 90 hp. The diaphragm started coming apart and filled the carbs with debris. Threw the VRO in the round can and went with the still avail. fuel pump only style. KISS method. keep it simple and servicable. (I changed it up a little.)
Electric pumps are a PITA. Been there too. In fact the Optimax and the EFI Merc motors have both a vacuum operated pump and a VST with an electric pump to jump up the fuel psi for injection.
In order to make the mechanical pump work they would literally need to re-invent the wheel. Due to the efficiency of the diaphram pump and its simplicity, that will never happen.

[Destroyer]

Originally Posted by THEFERMANATOR

Electric pumps are very doable, but why? Old school outboards were meant to be able to run without any electrical power needed short of the starter(and some have even tried to rope start the big outboards as well in an emergency). As far as running the fuel pump off the crank, that would require ALOT of added expense to build VS using a pulse type pump. Pulse pumps work fine, and are cheap and simple. Almost all lawn mowers with a pump still use a basic pulse pump, and you rarely have problems out of them. The OMC loopers though required the more complicated style pump like the VRO pumps to pump enough fuel. The OMC loopers work off of a very efficient crankcase flow pattern, and after about 3500 RPM's the crankcase stays almost pressurized constantly. this is why OMC's used teh more complicated VRO differential pump whereas other outboads stuck with a basic pulse pump. When they work they work, but unfortunately the VRO style pump does have more failures than other diaphram pulse pumps do to there design. They do though pump alot more fuel with not much crankcase differential pressure.

Well, my thinking was that if one could no longer obtain the proper part from the manufacturer, and they didn't want to junk the engine, then maybe an electric pump might just save the day.
As to the rest of the post, that's exactly the kind of info I was looking for Ferm... I may not like the answer, but at least I can understand some of the reasoning now. Many, many thanks.

[spareparts]

Ferm explained it pretty good. BTW some 2 stroke outboards use electric pumps, the OMC V8s had them, an electric primer pump was offered on the OMC seadrives, and the Yamaha VX76 has a stand alone electric pump that dumps extra fuel in at higher rpms thru an ecu controlled solenoid in each carb

[aussie]

look with boats cars anything its all down to dollars they look for the cheapest way and best way to make things ill be running electric water pump and fuel pump 2 reasons cheap to replace and added hp on some things

[THEFERMANATOR]

When you have an engine with a good differential pressure in the crankcase, the pulse type vacuum pumps work great. Also they draw virtually no HP from the engine since the moving parts are driven via crankcase pulses instead of a mechanical means. Also factor in that magneto type charging systems put out virtually nothing at idle, so the fuel pump running at idle will pull the battery down a good bit at idle. i know my old 140 would put out less than an amp at idle, but push 9 amps or so at 5K. The thinking was if you didn't need a better mousetrap, why re-invent the wheel.