Johnson 70 fuel problem

J

jolly tar

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Jul 5, 2002
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5
At full throttle the primer bulb goes flat and engine loses power. I've tried two new fuel lines and a new tank and I still have the same problem ... and yes the vent was open.<br />The motor was just serviced and the carbs rebuilt ... help!!
 
oldboat1

oldboat1

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Apr 3, 2002
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9,612
Re: Johnson 70 fuel problem

It sounds like you are thinking in the right direction -- frustrating problem. If the bulb is sucked flat, my guess is that everything on the motor side up to (and maybe through) the bulb is OK. I would try new tank lines and a new bulb, with new connectors, if you haven't done that already with the new tank. You also might consider loosening the cap a little, as well as insuring the vent is open.
 
D

DJ

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Re: Johnson 70 fuel problem

Jolly Tar,<br /><br />If your tank is of the built in type, the anti siphon valve may be sticking.
 
J

jolly tar

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Re: Johnson 70 fuel problem

The tank to fuel line connector is the only thing I haven't replaced ... So I'll try that.<br />I have 3 tempo 6.5 gal tanks (one brand new) and have tried 2 tempo fuel lines, no additional filters. Is it worth trying OMC original, or another brand?<br />It's a 1984 Johnson 70 VRO ... appears to use about 4 gals (50-1 mix) per hour on 2/3 throttle on a 16ft boston whaler ... is that about right?
 
J

jolly tar

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Jul 5, 2002
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Re: Johnson 70 fuel problem

Got a new tank connector and still the bulb went flat ... I've replaced it all now. <br />Is it possible the motor is drawing to much fuel?<br />That's the only thing I can think of now, unless I got 2 bad fuel lines ...<br />I did notice the Johnson tank connector is smaller than merc or yamaha.<br />Could I use a merc connector at the tank end?<br />would that cause other problems?
 
J

jolly tar

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Re: Johnson 70 fuel problem

I'm going to try one more fuel line ... if that doesn't work then it's check book time again!!!<br />I would like to know if 4 gals per hour is normal though?<br /> :confused:
 
J

jolly tar

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Re: Johnson 70 fuel problem

3rd time lucky.<br />The 3rd fuel line works like a dream.<br />TEMPO fuel lines, my experience so far 2 out of 3 don't work. And the first new fuel tank, also made by TEMPO, leaked!!!<br />I wonder if I'll buy anything else made by TEMPO again ... hmmmmmm :rolleyes:
 
M

mwesty1

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Jul 15, 2009
Messages
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Re: Johnson 70 fuel problem

I have a 50 hp johnson year 2000, i am having fuel issues also. i can run my pontoon for up to 4 days without a issue, and sometimes when i am out on the lake we putter around and then stop in the shallows for a little dip. say about a hour and when i go to start motor, it will not. no fuel, so i have to disconnect the fuel fitting from motor and then prime fuel line by pumping bulb and opening end of fitting for motor to pump fuel that far, and reconnect and pump bulb and it will start. hmmmmm it could do this 2 to 3 times a day and then all of a sudden it will run good for a week. any help out there, please
 
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