90 hp bogs at high spped

[Eddie fogg]

Hi,

My 1990 Johnson 90 hp bogs at high speeds. I have a glass in-line fuel filter and at idle can watch the fuel drain out of it. I have changed the bulb and connection at the motor but, it?s no better. If I run from portable can the motor runs fine??.Any ideas?

Thanks,
Ed

 

[ezeke]

Re: 90 hp bogs at high spped

Could be clogged tank vent or pickup screen, bad anti-siphon valve, clogged fuel filter, fuel line too small.

I would scrap the in-line filter(s) and get a full sized water separating filter.

 

[Eddie fogg]

Re: 90 hp bogs at high spped

Thanks for the quick response.
Will check the pick up; already checked the anti-siphon valve and fuel line is correct size. I did change the fuel filter, remember the motor run?s well on a portable tank and ok at lower speeds when using the inboard tank.
Regards,

 

[emdsapmgr]

Re: 90 hp bogs at high spped

Try constantly priming the fuel hose bulb when it starts to bog. This will force extra fuel into the carb bowls. If the engine picks up and runs fine, you may have a weak fuel pump.

 

[Eddie fogg]

Re: 90 hp bogs at high spped

Thanks Illinois,
That?s exactly what happens. Once the engine starts to bogg a quick squeeze of the bulb and it picks right up again.

Eddie

 

[Eddie fogg]

Re: 90 hp bogs at high spped

Thanks Illinois,

That?s exactly what happens. Once the engine starts to bogg a quick squeeze of the bulb and the motor picks right up again. But, what am I missing? Why does the motor run fine on the portable tank?

Eddie

 

[emdsapmgr]

Re: 90 hp bogs at high spped

ezeke has given you the clues as to what the issue could be with the built-in tank. I'd pull the tank pickup out and check to make sure it is not sucking air. Also, check the antisiphon valve to make sure it does not have any grit/debris in it which will affect it's movement and ultimately the fuel flow rate. Make sure the tank vent is clear/open. I'd take a fuel sample and make sure the built in tank does not have any water in it at the bottom.

 

[Eddie fogg]

Re: 90 hp bogs at high spped

Hi,

Most things fuel had been checked to this point however, the fuel pick had not. This weekend I removed the fuel line and antisiphon valve but could not remove the pick up from the tank. It has a large nut screwed tight to the tank and once removed the thing would not move. I was afraid of cracking the tank. I pushed a few pounds of compressed air into the fuel out-let and fuel shot back out at me. I re-installed the valve and went for a run. The motor ran well for most of the day about 20miles but, started to act up again at high speeds on the way back. So???fuel pick-up seems to be my problem.

Thanks to all who responded.

Regards,

 

[James R]

Re: 90 hp bogs at high spped

There is a non return valve in the pick up fitting. By pressurizing the outlet the sudden release of the pressure sucked the fuel, that is why it shot fuel out.
Has the tank been allowed to sit with a low fuel level. Fuel tends to evaporate leaving a shelac coating on the inside of the tank. This washes into the fuel and builds up at the pick up, clogging it and the non return valve.
Good tank flush, use of Stabil in the fuel and the fitting of a big old water trap filter should solve your problems.

 

[emdsapmgr]

Re: 90 hp bogs at high spped

Possible you have a pinhole in the plastic fuel pickup or that the plastic pickup tube is starting to loosen where the top of the pickup tube attaches to the metal head. You can purchase a replacement fuel pickup at most any boat shop which has a ship's store. They sell plastic tubes with the nut which will fit in any tank. Just cut to length.

 

[ezeke]

Re: 90 hp bogs at high spped

Yourt tank vent may be partially blocked; check it at the opening, the screens are often corroded.

 

[tashasdaddy]

Re: 90 hp bogs at high spped

also could be weak fuel pump. pump does not have to work as hard on portable tank.

 

[Eddie fogg]

Re: 90 hp bogs at high spped

Any Ideas on why I can not get the pick-up out of the tank?

Iboats part number Part # 033500-24

I believe the above is what I have or at least some what representative of what I have. I loosen the nut and tried to twist left and right but it will not move, even tried to pull straight up just will not move.

Thanks,




I believe the above is some what representative of what I have. I loosen the nut and tried to twist left and right but it will not move, even tried to pull straight up just will not move.

Thanks,

 

[ezeke]

Re: 90 hp bogs at high spped

The pickup usually is threaded and fits an insert. The nut holds the insert in place. Tighten the insert nut back up and turn the pickup it should come out.

Here's links to clockwatcher's pictures: http://i363.photobucket.com/albums/oo76/harrije2/boat/Picture010.jpg

http://i363.photobucket.com/albums/oo76/harrije2/boat/Picture015.jpg