1985 DT55 terrible idle, will NOT go slow without dying

[Ihatemymotor]

Ive been fighting with the idle with this motor for a long time now.
heres a short list of the current issues:
-idle is very rough. it shakes pretty bad.
-takes forever to get it started at times
- when i shift it into forward to cruise slowly, it just sputters and dies.

I have changed all the fuel lines, cleaned the fuel filter, put new spark plugs in, did a compression check (all 3 within spec), rebuilt the fuel pump, cleaned the carbs with Seafoam, tried adjusting the idle speed/trolling speed by following the Service Manuals instructions.

I cant think of anything else that might be causing my issues. It does have a problem staying primed as well. It gets firm but when I start it and run it, it gets softer and softer. Ive changed all the fuel fittings, primer ball, switched to black automotive fuel hose, and checked all the clamps. Still doesnt stay primed. Related?

The service manual did have something in it about the "reed valves". Ive never messed with them. Could they be causing my issues? Just a thought.

If anyone could shine some light on my issues i would be very grateful. Its been a never ending battle to keep this old thing running right.

[Solarman]

Do you have a Suzuki manual for this motor?
A couple of problems could be causing this. First, seafoam is good, but if the motor has blocked jets, and/or blocked pas-sages in the carbs seafoam might take years to clear this. Carbs should be soaked and cleaned properly with compressed air blowing out every fuel and air passage (all the tiny holes in carbs). All the jets should be soaked and blown out too. If the air/fuel idle mixture screws haven't been tampered with, screw each one inwards until lightly seated (write down the exact number of turns in for each carb - soak and clean each carb separately, as some carbs used different jets between top, middle, and bottom carbs by factory for balanced flows), before removal. All should be set identically by factory/manual. This should be the only adjustable jet that you need to remove. You only need to remove the fuel bowl, jets, and float needle valve w/its' seat to soak and clean, nothing else need be taken apart. The float adjustment must be made when re-assembling.

If the carbs are dirty, the engine will not run well, at idle for sure.

If the fuel pump(s) are not working properly, they may also be causing a problem? But cleaning carbs would be the first step. If the fuel pump(s) are damaged, they should be replaced (some motors have two pumps? Not sure on your motor?)

Post back on what you plan to do.

[cprice11]

Small amounts of air leaking into the fuel line connections (breaking the low vacuum to the fuel tank at idle) can cause this as it done on my motor .

[tsturm]

Cleaning carbs is for sure the first step! Replacing every thing from tank to carb ain't gonna help with white shit growing in the idle circuit & float bowl
Keep us posted.

[Ihatemymotor]

Do you have a Suzuki manual for this motor?
A couple of problems could be causing this. First, seafoam is good, but if the motor has blocked jets, and/or blocked pas-sages in the carbs seafoam might take years to clear this. Carbs should be soaked and cleaned properly with compressed air blowing out every fuel and air passage (all the tiny holes in carbs). All the jets should be soaked and blown out too. If the air/fuel idle mixture screws haven't been tampered with, screw each one inwards until lightly seated (write down the exact number of turns in for each carb - soak and clean each carb separately, as some carbs used different jets between top, middle, and bottom carbs by factory for balanced flows), before removal. All should be set identically by factory/manual. This should be the only adjustable jet that you need to remove. You only need to remove the fuel bowl, jets, and float needle valve w/its' seat to soak and clean, nothing else need be taken apart. The float adjustment must be made when re-assembling.

If the carbs are dirty, the engine will not run well, at idle for sure.

If the fuel pump(s) are not working properly, they may also be causing a problem? But cleaning carbs would be the first step. If the fuel pump(s) are damaged, they should be replaced (some motors have two pumps? Not sure on your motor?)

Post back on what you plan to do.

Yes i do have the service manual and operators manual for this motor. Also I did take the fuel pump apart and bought a rebuild kit and replaced everything. Im fixin to take the carbs apart but ive never taken a small engine carb apart before. Id be afraid to not set the float or needle properly and cause myself more problems. Should i get a rebuild kit and gasket kit for each carb? Could i reuse the old gaskets/floats?

[Ihatemymotor]

Small amounts of air leaking into the fuel line connections (breaking the low vacuum to the fuel tank at idle) can cause this as it done on my motor .

I just went and got new hose and clamps and a new primer bulb. Im gonna inspect all the fuel lines running to the carbs as well. Im putting new rollers on the trailer today so im gonna have to put the boat in the water so i may run it around a little and see if the new hose and bulb helps.

[Solarman]

The rebuild kits for fuel pumps di not include the little clear discs they used for check-valves (lower section of fuel pumps, often they crack and break apart, then get stuck on the back-side of float needle-valve seat). With such an old motor, a replacement pump would have been a better option.

If pumping the bulb causes fuel to drip anywhere (between the bulb and carb), or if the hoses are very soft and thinning out in spots when squeezing with your fingers (caused by using ethanol fuels), then, yes I would suggest replacing those sections. You may also find a black sooty material inside the carbs when cleaning if your fuel lines are deteriorating from ethanol fuel, another indication to replace the fuel lines.

Good luck, post back on what you are doing.

[Solarman]

If you plan to remove and clean carbs let us know. They are easily cleaned with soaking, and air compressor to blow-out all the tiny air/ fuel pas-sages, and jets. Re-setting floats will be needed, but not extremely hard to do. The hardest problem is know what to take apart, and look for when planning to do it. Post back if doing it first.

Good luck, post back on what you plan to do.