Running bad when trimmed all the way down/in.

[Muddy Paws]

Hey There!<br /><br />After purchasing a Johnson 90 (J90TLCCA) that needed a lot more work than I expected, I finally have it running well. The only problem I now have is that it runs bad (rich) and wants to die when I trim the engine all the way down. This puts the carbs at an angle and I assume this angle is causing them to flood. <br /><br />Is this normal or does it sound like the floats are adjusted too high? I did not have the correct gauge, but I followed the advice from the forum to set them parallel to the gasket surface.<br /><br />This is after a carb rebuild (OMC kits) and a new VRO pump install (4 wire conversion). Other parts replaced in the last few weeks include stator, rectifier, starter, thermostats, water pump, control cables and warning horn.<br /><br />Thanks,<br /><br />-John

 

[WillyBWright]

Re: Running bad when trimmed all the way down/in.

That's more likely from increased backpressure on the exhaust making it harder for the motor to breathe. The further the motor is in the water, the more work it has to do to blow out the exhaust.

 

[rodbolt]

Re: Running bad when trimmed all the way down/in.

remove the carbs<br /> remove the plastic fuel bowls. use a straight edge and check for bowl warpage along the aft edge of the bowl. sometime I can surface them other times its a replacement item. the reason is the warpage always occurs near the fuel transfer part of the bowl and allows fuel to leak into the bowl area bypassing the needle. the higher ya trim the better it runs and if on the muffs all the way down it will actually start foaming out the exhaust.<br /> as long as you transfer your intermediate and main jets almost any cross flow v4 v6 carb bowls will work. just find a metal set.

 

[Muddy Paws]

Re: Running bad when trimmed all the way down/in.

WillyB - This is happening on the hose in my driveway.<br /><br />Rodbolt - When I rebuilt the carbs I put a straight edge on the plastic bowls and they were warped about .030 in the worst spot, near the fuel transfer part. I did resurface them, but I had to remove quite a bit of material. <br /><br />It sounds like I need to start the search for metal bowls.<br /><br />But, if fuel was getting past the fuel transfer due to warped bowls, wouldn't it flood regardless of the trim? That's why I was questioning the float adjustment.

 

[rodbolt]

Re: Running bad when trimmed all the way down/in.

it will eventually<br /> however as the bowls tilt fwd when trimming up the fuel level at the front raises and actually tries to raise the float. but usually if left long enough it will flood. usually you will see it run out the carb throats when tilted.<br /> but almost anytime you can alter the idle signifigantly on the muffs by raising or lowering the motor you can trace it back to a leak at the bowl gasket.