Which electric fuel pump to use for priming my 98 200 HP carbed Mercury outboard

[sbklf]

I will install an electric fuel pump to overcome my priming issue. I have a 1998 200 HP Mercury carbureted motor.

Will this work and will the floats shut off with a 3 to 5 psi pump?

Any suggestions on which pump to purchase? Thanks, Kevin

[j_martin]

I will install an electric fuel pump to overcome my priming issue. I have a 1998 200 HP Mercury carbureted motor.

Will this work and will the floats shut off with a 3 to 5 psi pump?

Any suggestions on which pump to purchase? Thanks, Kevin

You need 6 psi max pressure, 5 preferred, and about 30 gph delivery.

If you use an electric pump, bypass the mechanical pump and plug off the vacuum pulse port.

There are several pumps that will work. You should use a marine pump for safety reasons.

hope it helps
John

[Silvertip]

Does the word "kaboom" mean anything to you? Yes -- electric fuel pumps are used on outboards and I/O engines. The caviat however is that the fuel and electrical system is designed for it. Here is what most people will attempt to do. 1) Install the pump and 2) wire it to the ignition switch. So it operates like this: Turn key to start and pump does not run. Why? Because the start position does not energize the "A" (accessory) terminal. So they then set the key to RUN for a bit, ahhh that's good as the carbs fill with fuel. Now hit start and away you go. Sounds good right? Well consider this. Let's assume you have one carb that has a stuck open float or even worse, there is a leaky fuel line. You are blasting across the lake and all at once you see smoke and fire as the leak ignites. While the engine may quit, the fuel pump continues to run pumping more fuel on the fire because you forgot or did not have a chance to turn the key off before you bailed out of the boat. The lesson here is that the fuel pump MUST have a safety circuit that kills the pump when the engine is not running. Without it you run the risk of filling the engine fully with fuel and causing an explosion. On carbed outboards, there typically is no such circuit. About the only way to add one would be to include a pressure switch in the water jacket and wire the pump through that. Then you would also need a bypass circuit off the start terminal of the switch to activate the pump until the engine started.

[j_martin]

Or keep it decently tuned and set up right.

V6 mercs are set up with electric fuel pumps all the time. When I was a kid, the only way we could get our hot rods to run was with electric fuel pumps. The stock lever pumps just wouldn't put out enough for 3 quads. It ran off the ignition circuit, not the auxiliary circuit, and even then we knew enough to use a relay to take the stress off the dashboard wiring.

my 02
John

[Silvertip]

Running off the ignition circuit on a two stroke won't work. This is a magneto system. And what you did was still not safe in a car either.

[Dukedog]

Or keep it decently tuned and set up right.

V6 mercs are set up with electric fuel pumps all the time. John

Factory HiPerf. Merc/Mariners...............

Pretty simple. Just like a hot rod. Relay for tha pump, aux (purple wire) operated. "2" kill switches or "1" single throw, milti pole contact switch. N/O and N/C (my choice). 1 laynard. But ya gotta use tha lanyard ..............

[j_martin]

Running off the ignition circuit on a two stroke won't work. This is a magneto system. And what you did was still not safe in a car either.

I'm sorry, but you don't have any idea what you're talking about.

There is a circuit that is hot any time the key is not off, including the start position. It's used for engine type devices, like the oiling system for instance. There is also an auxiliary circuit that drops out by design during cranking. Neither involves the ignition in this engine. There is a third circuit for that whose only function is to ground the kill circuit when the key is off.

The guys with fast boats use electric fuel pumps. They replace the lanyard kill switch with a 2 throw switch, rigged in one of many ways to kill the fuel pump when the engine is killed with the lanyard. It's no more dangerous than a mechanical fuel pump, assuming the operator isn't going to turn on the key and walk away from it.

The only caveat, other than the safety hookup to the kill switch, is to use a marine pump whose seal vents go overboard, eliminating the bilge fume problem.

I sincerely hope it helps
John

[sschefer]

There are a couple of ways to use an electric fuel pump. If your just trying to get rid of the squeeze bulb, Merc recommends using a 2lb electric fuel pump and retaining the pulse pump. This method works well and you can retain your oil injection system.

For those of us that have removed our oilers and run pre-mix, Holley makes a marine grade USCG approved fuel pump in either the Red or Black version. I run the Red and pump 4-5 lbs at the engine after the lift up from the fuel/water separater. I then remove my pulse fuel pump and use a block off plate to cover the pump vent and remove and plug the pulse fitting.

Here's what mine looks like:



If you're scared about what Silvertip say's, his concerns seem valid but apparently Merc and Evinrude don't think so because most of them run electric fuel pumps now.

I suppose if you are really paranoid you could set up a circuit that got a reference signal from the rotational sensor next to your oil pump.

Personally, if I smell smoke or see fire in my engine, I'm turning it off at the keyswitch and that will instantly kill the fuel pump. It's not the raw fuel that's going to go ka boom, it's the fumes. A small leak under the cowl is far more dangerous that a big one.

[j_martin]

Here's what happens when a connecting rod ventilates the block and goes through the high pressure fuel rail at WOT.

P-whistler boat extinguisher didn't do much, but race safety had the fire out within 2 minutes. Needed a new powerhead, of course, and the cowling took a beating going 50 feet in the air.

[Dukedog]

Like he says, tha Holley red is a good pump but I would add a regulator just in case. Sometimes tha pump will vary from spec. Sometimes tha carbs may not be exactly right. Plus you can screw it down ta 2 or 3 lbs and keep tha pluse and oiler. If ya decide ta lose tha oiler later ya got it covered. Tha Mercs still use tha pulse and electric on tha efi's and tha only thing that will kill tha electric pump is turnin' tha key off or tha motor dies. Tha pump will only run a few secounds if tha motor isn't runnin'. As for safety, use a relay and a kill switch like I described above.............At least a relay ta take tha load (amperage) of tha pump.............

[sschefer]

Thanks Dukedog, I forgot to mention the relay. Definitely use one or you'll burn up your key switch. The pumps draw about 2 amps and that's more than a toggle or key switch can handle for any length of time. Jeggs has there own brand name kit that's about 1/2 the price of the Holley and aint no different. A bonus is that it uses the same realy as the newer Merc trim/tilt relays so you always have a handy spare you can use in an emergency.

The pressure regulator is also a good idea. The pumps can vary from 5-7 lbs and you should try to keep it around 5 if you can. I have one but don't need it with this engine.