Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

I am running this engine on two seperate 6 gal portable tanks; new hoses, new primer bulbs; the engine died on me at first at cruising speed 35MPH; started immediately after that no problem; swithed tanks to the newer tank and ran great at cruising speed until tank was half full; then engine acts as starving for fuel and "boggs down". I noticed the "plastic" tank was concave in shape; opened the filler cap and heard suction noise(venting issue or so I thought) had the cap almost off after refilling all the way and no issue until half full again and starts "bogging down" again; if this if happenening to two different tanks; I do not think I need to look at the tanks so I pulled off the fuel pump and screen was immaculate; what gives??? any ideas? your response is greatly appreciated.
Sincerely
RD1

p.s. my Dad pumped the primer bulb while it happened the last time(crusing speed) and the symptom temporarily went away....

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

If both tanks are vented properly I'd say that your pump dosen't have the suction to pull off both at the same time. Rebuild the pump or run one at a time is my opinion.

Art

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

How far away from the engine are the tanks?
Pumping the primer bulb helping the problem would indicate a pump problem, unless the tanks are to far away or to far below the engine for the pump to suck fuel.

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

Sounds like a defective pick-up tube in the tank that's giving you the problem maybe a crack half way down the tube?

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

I am only running one tank at a time, not both together; the tanks are right under the rear seats of my 15' run about; the fuel lines can't be more than 3' and the vertical seperation is 2'?(guestimate). I primed the bulb while engine was off back in my garage and discovered a slight leak/drip at connection to "upper carb" and felt it is an unsafe condition so I am going to replace the fuel lines as I found a dried cracked hose on output from pump to t section that eventually feeds carbs. This engine runs strong and does not seem to mis so I do not think I have a carb issue....do fuel pumps typically get weak with time or do they just "quit"; any opinions?? thanks again very much

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

Your pump has a diaphram inside, can crack and not pump fuel properly. Your pump is remote mounted, there is a pulse hose from the block that makes the pump work. Make sure the hose is not cracked or has any fuel in it. Gas in that hose is a sign of a cracked diaphram in the fuel pump.

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

Daviet
Thanks for your help; I just ordered a new pump; I will let you know if that cures it;
thanks again

Re: Fuel Delivery Issues---1976-85HP V-4 Johnson Outboard

I didn't suggest your pump was bad, just some things to check. Before spending money you should do some checking.