dt 55 bogging down after minute of wot

[jcole83]

i have a 1989 dt 55 . bogging down after min or so of wot . gets up and goes just fine , idles fine, will also bogg after going over big chop or boat wake occasionally, have replaced fuel pump, lines and carbs seem ok , could the fuel filter be causing such an issue, as i have not replaced it but had a buddy tell me it could be the problem, it doesnt appear to be dirty. and like i said runs great idle and low speed just anything more than half throttle will bog down after few minute or more. any help would be greatly appreciated.......

[Moonlighter]

Yes, replace the fuel filter, that is most likely the problem. In any case, a relatively cheap and simple thing to do and even if it is not the problem, certainly will not hurt to do it.

Hope you have a good external style filter like a Racor. Dont just rely on the engine fuel filters under the cowl. Dirty fuel is your enemy!

If you have replaced all fuel lines that is good, but if not any that are old would be worth doing. Also, check that the tank vent is not blocked or obstructed in any way.

Finally check the anti-syphon valve on the fuel tank. If it has one you could remove it as it isnt necessary and is just another potential source of problems.

[jcole83]

Ok. I will replace filter today and as far as tank vent goes i am new to boating and did not know the vent on the cap on tank was suppose to be open. If that could cause that sort of problem that may be it. Let me know about that a little more if possible. And i do appreciate the suggestions. Thanks

[Moonlighter]

If the tank is a portable one then yes, the little vent on the top/cap must definitely be open. Need to let air into the tank as fuel goes out. Could definitely be the problem if that is the case.

[jcole83]

Ok *** yea i have had the vent cap closed completely everytime i have taken it out. Will replace filter and open cap all the way this weekend. Much appreciated and will keep ya updated. And yes is a portable 12 gallon tank

[Moonlighter]

I will put money on the vent being closed as the issue now that you have fessed up to it being closed all the time!!!

Just want to be sure: the little vent screw is what we are talking about here, not the actual filler cap. On most 5 gallon plastic tanks, it is a small black screw looking thing about 3/8 inch across in the middle of the filler cap. Should be something similar on your tank.

When you open it you will probably hear a hiss as the pressure equalizes. It will either suck air into the tank or let it out. I have seen plastic tanks get sucked out of shape when the vent has been left closed with the engine running at high speed!

Nevertheless it certainly wont hurt to replace the fuel filter as well. You don't know how long the previous owner had it on there and its a good idea to replace them every year anyway.