05 50 Fourstroke

[Houser04lly]

Recently purchased an 05 50 Four stroke.. replaced the High Pressure fuel pump replaced both high and low filters.. replaced all fuel lines on motor.. Starts right up great every time. The problem is if you try to go WOT from idle to fast it will bog and won't go over 4k rpms but if you ease into the throttle slow it will run up nicely to around 5k but as soon as you give it more thtottle she will bog down again . Also primer bulb doesn't stay hard but there is no difference in performance when pumping the bulb hard while its bogging..Also I bypassed the fuel connection on front of the motor and hooked the fuel line from the bulb to the inlet of the low side fuel filter on the motor and no Change in performance. Could the fuel pressure regulator be causing this or injectors., maybe a voltage issue? Any help would be greatly appreciated...

[Houser04lly]

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[catacom225]

50 Fourstroke

Silly Question ! but how old is the fuel your using, Also you might check condition of the spark plugs after a run, It may give some insight to whats going on

[Houser04lly]

Fuel is brand new and sparks plugs didnt look bad a little black .. going to put new ones in

[Houser04lly]

Possibly coils ?

[catacom225]

50 four stroke

May be running a little rich, sounds like a fuel related problem, try not to use ethonal or high octaine fuel. I would do a commpression test eliminate worst case sernario

[Houser04lly]

Might have figured something out.. had the connections on thr low pressure fuel filter hooked up backwords.. put her in the water a d she ran great for about 30 mintutes or so then she started bogging again but realized the bulb was almost flat when I squeezed it.. shes sucking air from somewhere so I looked at the connections on the tank and the motor and they dont look like there getting a good enough connection so Im gonna replace those.. also could it be getting vapor locked as it warms up didnt know if that was a coincidence?

[artdf175]

The fuel bulb almost flat indicates a vacuum is being created in the fuel line

Could try running with the fuel cap slightly ajar because it sounds like either the fuel tank vent is not working or the fuel line is plugged
If the fuel line is old it can be deteriorating internally
Art

[Houser04lly]

Fuel lines are brand new just not the connection at the tank and the motor... could the low pressure fuel pump cause it to pull a vacuum if air gets in there from bad connections?

[RayBersch]

Question: Did the bulb actually collapse or just go soft when you tested at high RPM? I'm not sure from your description. As Art mentioned, a collapsed bulb means a blockage between the bulb and the tank, or blocked tank air intake. But reading over your posts I don't think that is what you mean. I THINK you meant it was soft or just not full hard.

You have eliminated the issue of a bad quick disconnect fit by bypassing it, but did you check if the bulb is actually pumping gas? (by the way, I am not sure that the F filter -"low pressure filter" is one way, but could be.) When you squeezed the bulb while experiencing the bog down did the bulb actually get hard? (by "squeeze hard" did you mean fast?) It probably should not get hard at high RPMs so if it does check for a blockage between the bulb and the high pressure pump.

If there is no change when you squeeze the bulb while the motor is bogging down it could mean 1) the bulb is not pumping fuel - an air leak in the lines between bulb and tank or the bulb is faulty or 2) the fuel that you are pumping is going somewhere that is not intended. Assuming you see no fuel leak, you may want to check the low pressure fuel pump - take it off - the diaphragm may be split and is dumping full into the oil sump - check the oil - over full? smell like gas? or 3) an open fuel injector(s) - black plugs, one worse than the other two? Clean and gap the plugs but not likely the problem.

I assume you bought the problem, thus all the new parts - Suzuki high pressure pump or after market? Same with the F filter? My time on the water is always more precious than the difference in cost, but that's just me.

And, if it were me and all the above does not find the problem, I would remove and clean the VST. Who knows how long the former owner let gas sit in that tank and the needle valve or filter screen could be clogged - normal maintenance. If the filter or needle valve is clogged you may be pumping fuel back into the crankcase via a tube in the VST when you are squeezing the bulb. And don't worry about vapor lock, not likely.


Good luck, let us know what fixes the problem.

[Houser04lly]

From the diagram of the F filter and the low pressure pump I had it hooked up wrong.. also Dr the bulb wasnt collapsed just when it would start to bog it was soft to where I could squeeze it flat . . before I realized the filter was wrong I bipassed the fuel connection on motor and hooked straight to F filter from bulb.. now as of yesterday I pulled plugs put new in fixed F Filter connections the right way. Ran great for about 30 min them started bogging again no change when bulb when I squeezed bulb hard .. but a few times the bulb would prime easy had to put fuel line directly into the tank and it would prime easy which makes me think both connections are bad . At motor and at tank.. primer bulb is brand new.. might be having a couple issues here though.. I did seem to think the oil smelt like fuel and it was slightly over filled.. im gonna check the Low pressure pump diaphragm today. Thank you for all the help everyone. I greatly appreciate it.. Ill let everyone know what I come up with

[artdf175]

Fuel in oil may be coming from the overfill hose on the high pressure pump
Usually caused by the float sticking or adjusted incorrectly
Another thing you might check if you suspect the possibility of air getting sucked in - check all the hose crimps carefully check fuel filter is seated correctly
This might seam too simple but make sure bulb facing the right direction and should be mounted vertically
Just a couple of things that get overlooked occasionally
Art

[Houser04lly]

Still havnt figured it out ive checked and checked everything stated from everyone.. . It definetly seems to do it after running the motor for a little while.. runs great at first but still after about 30 minutes or so running her good she will start to bog after you let out of it and come to an ie and try to get back in it .. you can still play with the throttle and go easy and it will run like it should but if you hammer the throttle down it will bog .. Ill let everyone know what I come up with ..

[artdf175]

could this be a spark plug timing issue?? so asking the question - have you checked the timing ?
You didn't mention how many hours are on the engine but when was the last time you checked valve clearances?
and did you have any compression and leak testing done?

Art..

[Elliot Griffin]

I agree to check compression. I had similar symptoms, see my post. Good luck!