electric fuel pump helper....

[bob johnson]

my fuel pump has gotten tired..its on a 1995 115 ocean runner 2 stroke carbed motor. it is the OMS pump with the oil shut off...

the pump seems to have slowly gotten worse over the last two years...

last year i started to have to prime the motor on the way out of the harbor, 4-5 times....maybe every minute or 30 seconds...then after that, the motor ran fine with no fuel delivery issues, until i shut the motor down for a while...more than one hour say...and then started it again and tried to bring the boat up to speed.

this year it doesnt seem to ever get better... have to constantly re prime the bulb.


I think it is because my two gas tanks are up on the bow of my 22 ft boat...I have the lines feed a switching valve and then the lines run to my water seperator, then through an inline filter and then to my motor....it might be too much to ask of the pump to pull that much gas...

soooo i was thinking of adding an electric fuel pump with maybe 2-3 psi to HELP the gas along... so the pump( after i rebuild it) wont suffer again...

but my idea was to turn OFF the pump once the lines were all full of gas and the siphoning effect was working...( not sure if that is absolutely happening in real life...but it is my guess)


does anyone know if they make an electric pump that i can SHUT off but that still will allow gas to flow through it???


or will i have to always have the electric pump on when i have the motor running, if I expect gas to flow through the lines to the motor??

thanks


bob

 

[wilde1j]

Re: electric fuel pump helper....

If your gas lines aren't 3/8" ID, I would start there. I don't know of an electric pump that would do what you want, though I recall an electric primer pump, but can't remember what it was used on (was MANY years ago). You shouldn't need a supplemental pump if your gas plumbing is up to snuff.

 

[bob johnson]

Re: electric fuel pump helper....

If your gas lines aren't 3/8" ID, I would start there. I don't know of an electric pump that would do what you want, though I recall an electric primer pump, but can't remember what it was used on (was MANY years ago). You shouldn't need a supplemental pump if your gas plumbing is up to snuff.

I have a quality gas hose... in 3/8ths ID, and it is only two years old!!! there are a few connections and i went around and tightened them all....

you dont think the LONG pull of about 20 feet is a burden on the outboards fuel pump?

bob

 

[wilde1j]

Re: electric fuel pump helper....

My GW has fuel line runs almost that long and never had had a problem. Mine is rigged with all 3/8" fuel line. I don't think 20' should be a problem. I would check to be sure the pickup screen is clean and that the pickup tube is not cracked. I've only seen this a few times, but causes the symptoms you describe, as will any air leak into the pump suction side.

 

[bob johnson]

Re: electric fuel pump helper....

ok thanks...all components were new at the same time two years ago...but the tanks ARE PLASTIC, and i dont even know what the pick up tube entails!!! each one is a Moeller 9 gallon plastic tank. each tank has a quick disconnect fitting...so i can pull the tank to fill and or clean... and both hoses to each tank have a primer bulb installed. then there connections into the diverting valve and then the connection at the qwater seperator and then the fuel filter.. and then I have another primer bulb on the gas line right before it enteres the engine cowl, and then there is the connection to the tube going throuigh the cowl and then there is a connection on the other end of that tube...then there is a connection into the fuel compionent bracket! whew.....lots of connections that could go back and let air in........

but.... I think they are all tight!


take care

bob

 

[Chris1956]

Re: electric fuel pump helper....

That is a lot of primer bulbs. Each one has a restriction called a one-way valve. Couldn't you get away with a single one between the engine and the valve?

Does that motor have a pluse limiter on it? The larger motors of the same year do. You might check it and clean it. If it is partially cloged, it could restrict the pulses from the crankcase that pump the fuel, causing your issue.

Another idea is to rebuild the OMS pump's fuel side. You have removed the quick disconnect at the engine? if not, that is a good idea.

Was there a reason you did away with the oil injection?

 

[bob johnson]

Re: electric fuel pump helper....

That is a lot of primer bulbs. Each one has a restriction called a one-way valve. Couldn't you get away with a single one between the engine and the valve?

Does that motor have a pluse limiter on it? The larger motors of the same year do. You might check it and clean it. If it is partially cloged, it could restrict the pulses from the crankcase that pump the fuel, causing your issue.

Another idea is to rebuild the OMS pump's fuel side. You have removed the quick disconnect at the engine? if not, that is a good idea.

Was there a reason you did away with the oil injection?

the oil side was closed off when I got the motor, and I wasnt givenm an oil tank or harness... I actually now have three of the same motor 95 , a 96 and a 97!! and only one came with the tank and harness, but even it has been changed over to not use the oil side of the pump!

i do plan on rebuilding this fuel pump...but I might just use one of one of the other two motors.

i havent checked the pulse limiter...is that the blue anodized fitting on the block???

just seems to be a check valve to me( i am rebuilding one of my motors now and I had taken that valve off to look at.)


I installed a primer bulb at each tank, because I was worried about trying to pull 20 feet of gas !!!! so i figures Id PUSH 20 feet of gas and then have a helper primer at the motor to finnish it off...

in use the primer bulb is just a fat gas line one one spot...isnt it??
the motor doesnt have a quick dissconect...the gas line of hose clamped onto a plastic barb...that comes through the cowling

bob

 

[boobie]

Re: electric fuel pump helper....

The electric primer pumps were used on the old OMC V-8's. With that set up you didn't use a primer bulb 'cause the bulb could have caused a fuel restriction.

 

[kenmyfam]

Re: electric fuel pump helper....

So did we actually check the current pump output at the carbs end ??? or tried just one primer bulb in the equation ???

 

[bob johnson]

Re: electric fuel pump helper....

I am not sure i totally understand the question...I can see you are suggesting somehow checking the flow at the carbs? is that a flow meter, or a pressure guage? or just a clear section of gas line looking for air?

as for the pump remark..

are you saying that one or more of the primer bulbs may be the culprit?

what would be the test you are looking for?

hooking a gas tank up with a seperate line with no primer bulb and then checking ?

or running a whole new TEST line from a portable gas tank??

if i check the out put of the pump? how do i do that with out interupting the gas to the carbs, thus killing the motor?? has to be some kind of IN LINE test device...

I have this weekend to work on this..

i was going to just replace the fuel pump with a spare I have and see if there is any change.. as it is i have four rebuilt carbs waiting to go on the motor, so taking the pump off wont be a big deal.

bob

 

[Chris1956]

Re: electric fuel pump helper....

Gee, the simplest and cheapest test is to run a 20' piece of 3/8" fuel line from one of your tanks to the motor. It should have a single primer bulb near the motor.

If that works, remove the other two bulbs, replace the fuel line so it is one piece to the valve and retest. If that works you are good. If not swap out the valve and then the water seperator and see what combo is acceptable. All fittings provide resistance to the fuel flow, especally the primer bulbs with their cheap valves.

yes the pluse limiter is that fitting on the block behind the fuel pump, with the pulse hose on it.

 

[bob johnson]

Re: electric fuel pump helper....

actually the cheapest tes is to disconnect teh gas line that feeds into the last primer bulb, which is hanging between the motor and the floor.. then I am going to get a 2 foot hose and run it into my gas tank plumbed direct...no quick disconnect.

if the motor runs without dying then.... Ill know it is either the length of gas line or an air leak



the killer is if I prime now while the motor isnt running...I am sure i see a gas slick form on the water at the lower unit.....almost says the carb floats arent sealing(.the motor doesnt present any trouble that would suggest non sealing floats when I am running it.....
)..or gas is shooting through the pulse valve right into a cylinder and right out the exhaust
right???

 

[steelespike]

Re: electric fuel pump helper....

Disconnerct the line from pump to carb put end in a can and crank the motor over should be a strong even pulse. if it isn't then could be the pump.
Primer bulb should be near the tank.Length of the hose doesn't really matter if the right size.
I run almost 20 ft with absolutely no issues since 1987.It is a premix system but a pump is a pump.If it has a pulse line be sure it and the port are clear.

 

[Chris1956]

Re: electric fuel pump helper....

That motor likely has a vapor seperator and vapor pump. If you get raw gas in thw water, perhaps the inlet needle seat or gasket for the seperator is bad. Alternatively check the vapor pump for a diaghram leak.

 

[Sprky]

Re: electric fuel pump helper....

No such thing as a vapor pump on these motors! Fuel in the water could be flooding carb or hole in OMS pump diaphram.

Pull the VST apart and reseal the top cap. These had a habit of leaking and causing fuel delivery issues.

You can bypass the OMS pump all together and run an electric unit purchased from the auto parts store. They produce 3lbs pressure, (perfect for carbs) are sealed and are cheap.(approx$50).

 

[tx1961whaler]

Re: electric fuel pump helper....

You can bypass the OMS pump all together and run an electric unit purchased from the auto parts store. They produce 3lbs pressure, (perfect for carbs) are sealed and are cheap.(approx$50).

Not a real good idea, for many reasons already discussed to death many times.

 

[bob johnson]

Re: electric fuel pump helper....

well...an update..

I had decided to install a pump off another ocean runner I have for now..and if need be add the electric fuel pump later...

and since I had bought a set of four 115 hp carbs and throttle plates, and rebuilt them, i decided to install them now as well....kinda tricky( too many changes at once thing)

taking the old fuel pump off I discovered that the hose going from the pump to the big blue puls limiter under the the fuel compnet bracket was split almost 100%....

sooooo I dont know what the ramifications of ( basically not having that hose hooked up) that split is.....soo i am not 100% sure my fuel pump is bad yet!!

I installed the back up unit anyway..and the rebuilt carbs.....the motor is a 95 and the idle screw is supposed to be backed out 3 turns as a start. when i rebuilt my second hand purchased carbs i used that setting...but the carbs came from a 97! and earlier this week someone had asked about a 97 idel setting and I looked it up and it was 5-3/4 turns!!

I also have a 97 manual for the 97 motor I own. but I rebuilt the carbs before I had this 97 manual.....so the motor wouldnt start!! I eventually realized that might be the issue and set them at 5-1/2 turns... and it fired right up...purrs like a kitten...YEAH!!

just for a check...i check the setting on the take off carbs and found they varied from 4.5-7 turns!!..... i am wondering if those carbs had been added to that motor sometime in its life.

bob

 

[Sprky]

Re: electric fuel pump helper....

Not a real good idea, for many reasons already discussed to death many times.

Discussed to death by Mechanics or clueless wonders.....................mmmmmmmmmmmm my guess, the latter.

 

[tx1961whaler]

Re: electric fuel pump helper....

Discussed to death by Mechanics or clueless wonders.....................mmmmmmmmmmmm my guess, the latter.

Some of both.

 

[clanton]

Re: electric fuel pump helper....

Just for a heads up, the little pump on top of the VST is a vapor pump. If this engine is a 60 degree engine it has one.

The split hose you found is what operates the pump.