Primer Bulb/Fuel Problem!

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Quats54

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Joined
Mar 18, 2006
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Location
Sandwich/Pembroke. MASS
I have been experiencing a pretty nagging issue lately with my "new to me" 1995 18' with a 1995 115 JOHNSON.

When I begin to start the motor the primer bulb is difficult to get hard, if I can get it hard at all. The motor will start fine no problems, and run at head speed fine. Then when I give it throttle it will bog down and sometimes stall. However, when this begins to happen I have a friend simply sit on the jump seat and pump the bulb about 5 times while I am at WOT , then the boat will run great until I shut it off for a long periods of time. So far I have replaced it with 2 new OEM primer bulbs so I know this is not the issue. I replaced my racor and have drained them regularly, no problems. I have also replaced the fuel filter on the motor itself.

I find that when my boat sits on the trailer for a couple of days I do not have the problem until I have been on the water for an hour or so.

This problem began shortly after the introduction of E10 to my state, Massachussetts. My own assumption is that there is a lot of crud in the fuel tank and when I am on the water it agitates it. I am not sure but can only assume that the boat has a pick up screen and it is getting clogged. If so how do I clean it.

I am not sure if this is the answer but I am ready to hear any suggestions fellow owners may have.

Also, If i do have to take out the fuel pick up, what is the best way to go about it.

Thanks
 
Couple things here, so bear with me.

QUATS54":8d6ezi6s said:
When I begin to start the motor the primer bulb is difficult to get hard, if I can get it hard at all.
Those OMC/Bomb primer bulbs are THE best in the industry, to the point where even my local Merc dealer installs and recommendeds his customers use that primer bulb.

That said, there is a check valve in them and in order to fill best/fastest, you want the OB end of the line after the bulb higher than the other part of the line. This allows the check valve to be assisted by gravity.

Also, for your starting sequence, try this. Prime bulb as above 'til firm, then put in key, turn to ON but not CRANK,and push in on the key (primes the carbs) and count to 8 slowly. Go back and check the primer bulb and if needed, pump 'til firm again. On cold days or if she wants to start but immediately stalls, try the count of 8 twice, priming the bulb in between. On any OB, if you flood her, open her up to full throttle-in-neutral and that'll clear it out and start it, just be quick to back down on the throttle.

Then when I give it throttle it will bog down and sometimes stall. However, when this begins to happen I have a friend simply sit on the jump seat and pump the bulb about 5 times while I am at WOT , then the boat will run great ...
Sounds to me like water in the fuel tank and you're forcing more fuel into the motor, but also see below about your fuel pick-up. "Usually" pumping a primer bulb to keep her running is indicative of a fuel pump issue, but ... that would happen ALL the time @ speed.

I replaced my racor and ... I have also replaced the fuel filter on the motor itself.
I recommend you REMOVE that other in-line filter ... it is made redundant by the Racor and now only serves as a potential fuel restriction. Just put a Tempo in-line hose-mender fitting sized for your fuel line.

My own assumption is that there is a lot of crud in the fuel tank and when I am on the water it agitates it. I am not sure but can only assume that the boat has a pick up screen and it is getting clogged. If so how do I clean it. Also, if I do have to take out the fuel pick up, what is the best way to go about it.
Simple, look on the top of the tank, you'll see the fuel line go to a fitting that's screwed into a roughly square block that is on top of the tank. Remove fuel line from that end. Get two wrenches sized to fit that block and hold them 180 degrees apart. Apply equal torque and remove that square block. It is attached to the fuel pick-up. Check it, and if it has a screen ... remove it. Now also check to see if their is an anti-siphon valve on that block, as there can crud up too.

It may be that their is a restriction somewhere that is intermittant and I did have that in one of my old boats as stuff looking like "naval lint" built up in the tank and onto the pick-up screen. By pumping the primer bulb you might be forcing fuel around/thru the crap. I'd use Permatex #2A on the fittings to reattach. Teflon tape can be used by can 'cold creep' and get into your fuel system.
 
QUATS54":2vxfkyfz said:
I find that when my boat sits on the trailer for a couple of days I do not have the problem until I have been on the water for an hour or so.

Check the fuel flow items that Dale suggested, but also take a look at your fuel vent screen to see if it is restricted. It almost sounds like you are pulling a vaccum on your tank as you draw fuel out.

If you have the OEM Perko vent on the outside of the hull, unscrew the plastic cap and take a look at the screen inside. Clean or replace it as needed.

Finally, go back and look at that fuel primer bulb... Is the outlet side of the bulb (the hose that goes to the motor) higher than the inlet side? In other words, is the bulb vertical with the inlet low and the outlet high?
 
Thanks again for all your help guys. This little problem was not to fun chasing tuna, running and gunning all day today.
I plan to stay off the water tomorrow and solve this problem. I know that the fuel vent is ok and clean and no vacuum is being created. I am going to move the primer bulb to a vertical position as you both stated, I also plan on inspecting the check valve on the tank and the pick up screen.
Lastly, I am going to run the boat on a pond tomorrow with my pony tank that I usually use for SeaFoam decarbing to see if this is a motor issue or a fuel flow problem. I will let everybody know how things go!
 
Just to update, I checked everything that all of you had mentioned, inverted the bulb, checked the pick up screen , all were fine and in working order.

On to the next step of diagnoses, I dunked the boat with my Dad with a three gallon pony tank with fresh gas, and sure enough same problem, still bogging down as I open her up. The problem has slowly worsened and yesterday it had become so bad that my Dad had to pump the bulb all the way back to the dock. Therefore it is a motor issue. Got home and out came my OMC and Seloc manuels, I am now pretty positive it is a fuel pump issue and will be installing a new one this week. To be on the safe side did a compression check just in case the VRO wasnt pumping oil but all 4 cylinders are the same as before, thank goodness!

Thanks for help guys, I truly appreciate it!
 
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