Electric Fuel Pump Info Needed

[LuvBoating]

Boat: 1992 Celebrity 200 Cuddy Cabin w/Mercruiser 5.7L I/O

​Has a regular gas pump, but giving some thought to installing an electric fuel pump next Spring. Actually, having our Mercruiser mechanic do it. An electric fuel pump does shoot the gas up to the carb faster than a regular fuel pump does, right? During the summer, after sitting for a week or so, due to bad tide times or weather, the boat is rather hard to start. With an electric, it would be much easier.

​Wonder how many boat owners of boats that have a carb and regular gas pump, end up changing the pump to one that is electric?

 

[Scott Danforth]

but giving some thought to installing an electric fuel pump next Spring. Actually, having our Mercruiser mechanic do it. An electric fuel pump does shoot the gas up to the carb faster than a regular fuel pump does, right?

Nope, the mechanical pump is actually a higher flowing, faster pump with less problems (wont wear out as often, self-priming, quiet)

weather, the boat is rather hard to start. With an electric, it would be much easier.

​Wonder how many boat owners of boats that have a carb and regular gas pump, end up changing the pump to one that is electric?

Wont be any easier to start as hard starting may or may not be fuel delivery issues. most of the time a hard start situation is not fuel delivery. if it is because your bowls are empty, many times its because the welch plugs are leaking in your carb.

if it is due to evaporation, it is a few months before the carb bowls are empty. even as such, pump twice, crank for 5 seconds, pump twice, crank and it should be running (unless your anti-siphon valve has an issue, that is another problem all together)

I switched my boat over to electric only because the new motor does not have a mounting boss for a mechanical pump. the added complexity of adding fuel relays, diodes, oil pressure switch, etc. as well as the cost of the electric fuel pump is a pain in the butt compared to the simplicity of a mechanical fuel pump.

Not to mention the annoying whine of an electric fuel pump.

if you decide to go electric, make sure that you get a marine rated unit. Carter / Airtex makes the one that most of the OEM's use.

http://www.iboats.com/Electric-Fuel...8281911--session_id.842896145--view_id.203982

https://www.summitracing.com/parts/crt-p4389

 

[Maclin]

The low fuel level issue in a carb after sitting, sometimes called drain back, is not specifically addressed by going to an electric pump. An electric pump when installed correctly with safety measures will only run when the engine is cranking, or when the engine has started and is running. This is the same as with a mechanical pump. The only way an electric pump could help get fuel to the carb sooner is if a momentary bypass switch is installed into the circuits, allowing the operator to press it and pressurize the line to the carb ahead of turning the key to start. A carb rebuild may address a drain back issue of the carb is leaking fuel from the bowls slowly.

If you are relating the electric fuel pump(s) on a fuel injected engine, those power up and pressurize the lines as soon as the key is turned on, does not need to be cranking the starter motor. A carbed engine setup does not work like that.

 

[Maclin]

must have been typing in while Scott was... :ranger:

 

[LuvBoating]

Hummmmmm, didn't know any of this about an electric fuel pump. A friend of ours told us about it, because he told me "sounds like you might not have enough patience when starting your boat." To a point, he is right, but, when the carb bowl is dry, it does take some effort to get fuel to it. I told my wife, "if we ever (which we won't) get another boat, I sure want it to be EFI, not a carb type." Thing is, and I do know this much, when a boat has an EFI problem, it sure can be costly.

​Looks like we will give up on the idea of the electric fuel pump. And, THANKS for the info about it.

 

[Scott Danforth]

have the welch plugs in your carb looked at. common problem

 

[LuvBoating]

Actually, I thought an electric fuel pump worked the same way as EFI did..........turn the ignition key to the "on" position and the gas starts flowing to the carb. If the boat hasn't been started for awhile, and the carb bowl is dry, just leave the ignition key in the "on" position for a short time before turning the the key to "start" position/engine turning over.

 

[Scott Danforth]

Actually, I thought an electric fuel pump worked the same way as EFI did..........turn the ignition key to the "on" position and the gas starts flowing to the carb. If the boat hasn't been started for awhile, and the carb bowl is dry, just leave the ignition key in the "on" position for a short time before turning the the key to "start" position/engine turning over.

No, a proper carb setup uses a oil pressure switch to control the relay (some also use a diode from the start circuit to prime when cranking). since there is no ECM to turn off the fuel pump in event of oil starvation like the EFI systems have. so until you have oil pressure from the motor running or you have the diode, it wont run until cranking or running (just like your mechanical fuel pump)

EFI only powers the fuel pump for a short period of time to get pressure into the rail, then during cranking, it resumes. if it doesnt see oil pressure it stops

your carb should take weeks, if not months to empty the fuel bowl from simple evaporation. if it is draining down in a much lesser time, you have an issue that you need to address. look at the two welch plugs to see if they are leaking (common problem on the carbs used in mercruisers).

as mentioned in post #3. if your motor has sat for months, crank for 5 seconds, pump twice, crank as normal and the motor will start (unless you have a drain-back issue from your anti-siphon valve). if you have a leaky carb, fix the carb.

 

[Maclin]

I get that. In a Marine application it does not, or should not. You can put one in and ignore the mandated safety regs and it will run all the time. In a car that is sorta ok, because in a wreck or other bad happening, the fuel pump just dumps out onto the pavement or ground. In the Marine world, the fuel pump running on is itself a bad happening.

So fuel pumps only get power when the engine is actually running, or when the engine starter is activated during cranking. Exception is if a momentary switch has been integrated into the circuit, not recommended, and the need for that in and of itself indicates a problem that needs to be addressed at the source (carb).

Mercuiser does this by running the power through an oil pressure switch, if there is 5lbs or more of oil pressure the switch turns on.
Volvo does this by powering the pump from the alternator output, if alternator is not turning fast enough the pump does not run.
Both have a bypass wire from the starter relay to power the pump when cranking.

A boater should not bypass the CG safety regs, otherwise when it goes all bad they could be liable (survivors anyway!) for additional damages from a run-on fuel pump.

Scott has the procedure to get used to in his post. It is "free" and only takes a little adjustment in a boater's approach to the issue.

At the first of a season my carbs would almost always need some extra cranking to fill before they wanted to start usually. During a season though, even after a month layoff, the engine would start right away.

 

[Maclin]

Wow, we did it again with the posts... :tea:

 

[LuvBoating]

Our carb was new (remanufactured one) that was installed last summer. It has an electric chock, which the old carb did not. So, as far as any carb problems, I wouldn't think so.

​After reading all of the replies, I really think that my patience with starting the boat are simply too short. I think that's basically it.

​Actually, a few years ago, at a ramp, I seen this guy's boat start immediately. Turned the key to "on", then "start" and the boat started right up. Just like our Durango does. His boat had EFI, like our Durango does.

 

[Scott Danforth]

your old carb probably had a divorced choke, new one has electric.

new reman last summer does not mean its good now. it means it was good last summer. most likely it is still good

my boat is carbed, it will start as fast as any EFI motor. one pump, give it 40% throttle, turn key and motor is running, back off RPM to 1500 for 30 seconds while I pull off the dock lines and motor away. Then again, I am constantly tinkering with the carb (jets, etc) as i swap cams, etc. So I know my carb and motor inside out.

EFI is nice, however when it goes awry, its not cheap.

please describe exactly what you do when you try to start it - both when it simply sits over-night and when it sits for 2 months

 

[LuvBoating]

your old carb probably had a divorced choke, new one has electric.

new reman last summer does not mean its good now. it means it was good last summer. most likely it is still good

my boat is carbed, it will start as fast as any EFI motor. one pump, give it 40% throttle, turn key and motor is running, back off RPM to 1500 for 30 seconds while I pull off the dock lines and motor away. Then again, I am constantly tinkering with the carb (jets, etc) as i swap cams, etc. So I know my carb and motor inside out.

EFI is nice, however when it goes awry, its not cheap.

please describe exactly what you do when you try to start it - both when it simply sits over-night and when it sits for 2 months

​First, 5 year old gas drained from tank in July, then 25 gallons of new gas put in. Also, new fuel filter installed.

​Here's how I start, after sitting a week or so: While in Neutral, throttle all the way forward for a minute. Bring throttle back half way. Engine cranks, but not start yet. Throttle put all the way forward again for another minute. Bring throttle back half way again. Engine cranks and most likely start. Have to keep RPM's up some to keep running and let engine warm up some. Then, bring throttle back to Neutral and everything is fine.

​Most likely, starting the darn thing wrong.

 

[Scott Danforth]

​First, 5 year old gas drained from tank in July, then 25 gallons of new gas put in. Also, new fuel filter installed.

​Here's how I start, after sitting a week or so: While in Neutral, throttle all the way forward for a minute. Bring throttle back half way. Engine cranks, but not start yet. Throttle put all the way forward again for another minute. Bring throttle back half way again. Engine cranks and most likely start. Have to keep RPM's up some to keep running and let engine warm up some. Then, bring throttle back to Neutral and everything is fine.

​Most likely, starting the darn thing wrong.

pushing the throttle forward isnt a push and sit deal. its like pumping the gas on a 1963 pickup truck. full movement, there and back (about 2 seconds)

one push all the way forward, it sets the choke and gives it a primer shot of fuel. you may need a second shot from the accelerator pump for priming. one or two pumps is all that should be needing

try giving it two full pumps, back off to about 40% throttle, turn key

and yes, you have to keep the RPM's at about 1500 for about a minute since most marine carbs do not have a high-idle cam. this is for safety reasons so you dont put it in gear and run over swimmers. EFI will manage the RPM at idle by controlling fuel and the IAC. a carb relies on the choke and the operator to maintain higher RPM when cold for about a minute

 

[Rick Stephens]

A couple of thoughts on carbs leaking down. I have a Edelbrock marine carb on my motor and when first installed - with a properly wired electric fuel pump mind you - if I left it for a week the carb was empty and took some cranking to fill back up.

I tried quick priming the carb as a test by powering it for a bit before cranking, just to make sure I was correct that the carb was leaking down. Motor would fire right off when I primed it that way.

I ended up putting an Airtex check valve between pump and water separator filter. Solved the issue. It appears that it was leaking back down into the tank.

 

[Scott Danforth]

Rick,

that is what the anti-siphon valve in the tank should be doing

 

[LuvBoating]

pushing the throttle forward isnt a push and sit deal. its like pumping the gas on a 1963 pickup truck. full movement, there and back (about 2 seconds)

one push all the way forward, it sets the choke and gives it a primer shot of fuel. you may need a second shot from the accelerator pump for priming. one or two pumps is all that should be needing

try giving it two full pumps, back off to about 40% throttle, turn key

and yes, you have to keep the RPM's at about 1500 for about a minute since most marine carbs do not have a high-idle cam. this is for safety reasons so you dont put it in gear and run over swimmers. EFI will manage the RPM at idle by controlling fuel and the IAC. a carb relies on the choke and the operator to maintain higher RPM when cold for about a minute

​Sounds better than what I've been doing.. I'll try this next Spring.

 

[Rick Stephens]

Rick,

that is what the anti-siphon valve in the tank should be doing

Yah, agreed. I also have an outboard plumbed off the fuel filter. And I have yet to see an antisyphon valve that was a few years old that wasn't at least a little less than 100% tight. The check valve after the filter, before the pump, resolved my leak down entirely. I only mention it since the anti-syphon has to be perfect to prevent leakdown. Might help the OP.

 

[Scott Danforth]

soak the AS valve in brake cleaner, worked for me.

the OP stated he had 5 year old fuel in the tank. guarantee there is crud in the AS valve.