Need help with bogging down

[Fishhook2120]

Have a DT90 that will not plane out. Runs great in the driveway at idle and WOT, but once on the water, it won't open up. I thought this was a fuel pump problem from past experiance, but rebuilt it with new kit and still runs the same.

What am I missing ? Any ideas ?

Thanks

Fishhook2120

 

[99yam40]

Re: Need help with bogging down

A motor needs good compression and spark on all cylinders, along with the proper timing and air /fuel mix to build the proper power to push the boat.

What all have you checked?

as you said most of the time it is the fuel, but you have to check the others to be sure.

 

[Fishhook2120]

Re: Need help with bogging down

Well my issues have been long and hard. I have rebuilt the carbs, starter valve, fuel pump and the entire fuel tank/line/filter system.

I will try to keep it short as possible. I have posted a few times along the line, but about seperate issues.

The long/short:

Engine sat for over 3 years. I pulled the carbs and cleaned everything. Filled the tank with 15 gallons of non E fuel, and a bottle of Seafoam. Shot some either, and fired it up. Got it running smooth and took on the water for a test ride. Performed perfect for the hour on the lake. Took it from start to WOT several times and cruised at WOT for a while. Perfect.

Took out 3 days later and would only run at WOT. Pulled the filter when I got home and found contamination in the fuel. Lots of brown silt like particles in the fuel. I pulled the carbs, recleaned and rebuilt, pulled the fuel pump and starter valve and did the same. Bypassed my in-hull tank with a portable tank, new hose, and filter. Claened the plugs and put it all back togather. Filled the aux tank with non E fuel, and headed to the lake.

Boat fired right up, idled for 10 min and then pushed it up to plane and it was running perfect. Cruised for 5 min or so, and it bogged off plane and ran bogging only, after that. No getting back up, just gags. I did notice fuel on the water after this. (Clue ?)

So I thought the Fuel Pump diaphram was blown, so I rebuilt it and hit the water again. Idles fine, and runs on the low side of the RPM ok, but when pushed up into mid to full, it won't get up, and just boggs. Can run about 8mph and that's it. I also noticed fuel on the water again after the boat was sitting, not running for a while. (Clue?)

Hooke dit back up to the water ears last night, and started it. Starts fine, runs good, ran the RPMS up with carb only by hand at the engine, and no issues. Rehook the link, and pushed with the remote control all the way up to full and it runs perfect at all positions. (Clue?)

I hear ya on the air/compressoin/spark. I just don't know what else to do. I don't have the money to drop it off and wait for a repair bill, and I can do many things myself at home. I just don't want to replace anything else without a good reason. Everytime I come up with a theroy, one of the things it does or doesn't do, won't fit. I have read the book back and forth and can't figure out what to do next.

I do have a new set of plugs, but was trying to wait before I put them in, guess I should do that now ?

Fishhook2120

 

[waffles1]

Re: Need help with bogging down

Have you checked the fuel line for leaks? Tank venting ok? Bulb staying hard? With the fuel we have today it takes very little time for untreated gas to sit before it gets water contaminated. I had my boat sit for 2 weeks and got water in the gas. Good luck.

 

[Fishhook2120]

Re: Need help with bogging down

I replaced all fuel lines, new tank, new filter, new clamps. Gas is fresh, not a fuel issue. Has to be somewhere past the fuel line to engine. That much I know, after that I am lost at this point. The tank is venting, the bulb is staying semi hard, not colapsing, but not rock hard either. It is getting fuel at this point, but........

Thanks for the reply, anything else I can try ?

Fishhook2120