Fuel problem

[ziggy2]

2003 Mercury 90 hp 2 stroke engine. Engine does not appear to be getting fuel. Engine starts in idle and will accelerate and then appear to be starved for fuel. Squeezing bulb makes engine run OK. I rebuilt the fuel pump and when ran it seemed OK for the first 5 minutes, idled OK and ran at 5000 rpm OK but then seemed to lose power, pumping the bulb made it run normal. Need help to trouble shoot this problem.

 

[racerone]

How did the motor run for you last season.------The fuel pump is driven by crankcase PRESSURE.----There may be an issue there.------Post cylinder compression values.-----That is separate , but may offer a clue.-----What serial # for your engine and what rebuild kit did you use ?

 

[ziggy2]

I wonder why crankcase pressure would change after about 10 minutes of running. Never noticed any engine problems other than lack of fuel to keep engine running.

 

[ziggy2]

How did the motor run for you last season.------The fuel pump is driven by crankcase PRESSURE.----There may be an issue there.------Post cylinder compression values.-----That is separate , but may offer a clue.-----What serial # for your engine and what rebuild kit did you use ?

One other item I am curious about, it seems when the engine is cold it runs fine and after running a short period and engine warms up is when the failure starts and I must keep compressing the bulb to keep running.

 

[racerone]

You have an issue with fuel supply.-----It should be easy to figure out.-----Sorry , I can be of no help to you because I can not , see , hear or touch your motor.

 

[dingbat]

I suspect either your fuel pump rebuild didn’t go so well, you have a leak in the fuel delivery system (hose) or you have a bad crank seal.

My money is on the fuel pump rebuild.

 

[ziggy2]

How did the motor run for you last season.------The fuel pump is driven by crankcase PRESSURE.----There may be an issue there.------Post cylinder compression values.-----That is separate , but may offer a clue.-----What serial # for your engine and what rebuild kit did you use ?

Thank you for reply. Motor ran fine last year and Serial number is 0T646239 and fuel pump rebuild kit was Quicksilver 21-857005A 1

 

[racerone]

Test run with another fuel tank and hose.----If that fails the test.----Replace check valves in the fuel pump.------Test for crankcase compression.

 

[QBhoy]

Either fuel pump or the primer bulb and fuel like from tank are connected the wrong direction for flow…

 

[Sea Rider]

Yep, test with a different fuel tank and fuel hose or with current fuel tank and a new fuel hose, current hose's connectors may already be dried, worn, hardened, o'rings letting air in and motor missing specially at high rpm...

Happy Boating​

 

[ziggy2]

Test run with another fuel tank and hose.----If that fails the test.----Replace check valves in the fuel pump.------Test for crankcase compression.

I found the problem to be a leak in the fuel supply hose connection at the fuel tank. Problem solved with the help of all who responded to my request for assistance. Thank you for your help.