1988 70 hp Johnson bogging down

[Bill3434]

Re: 1988 70 hp Johnson bogging down

Okay not sure what to think now. Went fishing yesterday and boat was fine all day. When I started the boat there was more smoke than usuall and after that no problems. I'm not sure how the fuel pump works but think that it works off the vacuum from the engine. Is it possible there was a restriction that went through? The other difference was that I put too much gas in the tank and closed the vent a bit. Is it possible to have too much venting? Please advise.

I was going to say is your vent open. Never heard of to much venting.

 

[mauryc]

Re: 1988 70 hp Johnson bogging down

Too much venting? Your motor should suck gas out of an open bucket. THe fuel pump rebuild should treat you well.

 

[dctaz37]

Re: 1988 70 hp Johnson bogging down

the vent was definately open when I was having the problem and I have gone as far as opening the cap. I just closed the vent because of too much gas in the tank but that could be completely a coincidence. Also when I started the motor there was an abnormal amount of smoke. but trolled for a few hours and went full power a few times with no problems.

 

[Bill3434]

Re: 1988 70 hp Johnson bogging down

I wonder if your engine needs an overhaul.

 

[Sea-Bear]

Re: 1988 70 hp Johnson bogging down

If your vent was closed, the motor won't run. The fuel pump runs off a vacuum impulse & is not strong enough to suck fuel from a not vented tank.

 

[Bill3434]

Re: 1988 70 hp Johnson bogging down

If your vent was closed, the motor won't run. The fuel pump runs off a vacuum impulse & is not strong enough to suck fuel from a not vented tank.

That would depend on what kind of seal you get from your vents and how strong your pump is. Mine motor decently until 3/4 power before it started to run like crap or shutdown. Opened up the vent and she ran just fine.

 

[dctaz37]

Re: 1988 70 hp Johnson bogging down

It was vented. I was out today and ran fine had it 3 minutes 3/4 plus then trolled for 4 hours and ran back at high speed with no problem. This was on a different tank. I picked up the fuel pump kit on my way back from fishing. The fuel pump works on vacuum so how does the motor create this? Not sure if I should install the gasket kit and play it by ear.

 

[Bill3434]

Re: 1988 70 hp Johnson bogging down

It was vented. I was out today and ran fine had it 3 minutes 3/4 plus then trolled for 4 hours and ran back at high speed with no problem. This was on a different tank. I picked up the fuel pump kit on my way back from fishing. The fuel pump works on vacuum so how does the motor create this? Not sure if I should install the gasket kit and play it by ear.

I'd see what it does on the tank you just ran off of. If that solves the problem you got a spare fuel pump, save that project when you got time, I'd rather be fishing.

 

[Home Cookin']

Re: 1988 70 hp Johnson bogging down

sometimes the bulbs go bad, too.

 

[dctaz37]

Re: 1988 70 hp Johnson bogging down

Okay was out again on the weekend with no problems. Should I just wait for the fuel pump rebuild? if it happens again are there some additional trouble shooting I should do?

 

[Bill3434]

Re: 1988 70 hp Johnson bogging down

Okay was out again on the weekend with no problems. Should I just wait for the fuel pump rebuild? if it happens again are there some additional trouble shooting I should do?

I'd wait, it is running good now so you might want to leave it alone. Save the fuel pump for a rainy day when you can't be out on the water or until it breaks.

 

[phillnjack2]

Re: 1988 70 hp Johnson bogging down

when you have time on your hands do the fuel pump rebuild.
this will then be preventative maintainance and that is the best thing you can do.
the old stuff in the pump although working will now be getting tired and worn a fair bit.
i would take out the old stuff and re-new it all when i have time,especially if you already have the kit just sitting around.
The pump could do with a clean out anyway to make sure its all good, and if taking it apart it realy needs the new gaskets.

or leave it till it fails , and i bet it will be when you have no tools and your a long way out in rough weather and need to
get back in fast.
they never break down in the garden on the trailer.

phill