2001 Merc 225 EFI boggs down on take-off

[kanghee]

I recently put a new powerhead on my 2001 Mercury 225 EFI. Starts great and after a minute of idle, it will get on plane with no problems. I can run a few minutes, set down and it gets back on plane with no problems. BUT, if I have to idle through a no wake zone or any other low speed idle for a peroid of time, it boggs down when I try to blast off. I have also found that if I shut the motor down, after it boggs, wait a couple seconds with the key on, and restart, it will get on plane slowly, but it will get on plane. The only time it boggs on take-off is after an extended peroid of slow speed idle. (Fuel pump pumps to pressure in 15 seconds, has good pressure. Maybe an oil problem?)

 

[CharlieB]

Re: 2001 Merc 225 EFI boggs down on take-off

Bog or hesitation on acceleration USUALLY indicates a slightly lean fuel mixture, however, your bog only occurs after extended idling, which could indicate possibly aged spark plugs,too cold a spark plug, excessive oiling loading up the plugs.

What plugs are you running?

What do they look like?

Inspect them immediately after a high speed run then again after extended idling.

If you are adding oil to your fuel during 'break-in' in addition to the oil regulated by the oil pump then you can expect to carbon up a couple of sets of plugs.

NGK B8HS will last longer during your break in and are often cheaper than the precious metal surface gapped plugs specified for your motor under 'normal' fuel/oil operation.

If you are NOT adding additional oil to your fuel then check the oil pump linkage and adjustment per the directions in the service manual.

Repost with your findings.

 

[Mtgeorge]

Re: 2001 Merc 225 EFI boggs down on take-off

My 2000 Merc 225 EFI does the same thing. It has a new set of plugs but the mechanic said I was running the wrong ones before (when it was running fine). I hope that the spark plugs are the reason behind this. Its hard to really pinpoint what is causeing it because it doesn't do it all the time after a long idle.

 

[CharlieB]

Re: 2001 Merc 225 EFI boggs down on take-off

The factory recommended spark plugs are determined by extensive testing at or near maximum load and speed.

While many owners operate their motors that hard, there is a great number that like to 'putt around', idle extensively while trolling, etc.

While the factory recommended surface gapped plugs work very well for sustained high speed and high loads, they can have a tendency to soot up and foul with extended idling, especially on the seldom used craft that just sits and ages the fuel before getting used.

IF, and this is an IMPORTANT IF.......

If there is adequate piston clearance then a standard electrode spark plug may provide longer reliable service for the lighter loaded engines.

For these owners I often install NGK B8HS , some motors even have enough clearance to use the extended tipped NGK BPR8HS.

A much more cost effective alternative to the Precious metals which contribute to the higher cost of some of the surface gapped plugs.

You are the determining factor in the operation of your motor, for sustained operation at or near capacity, 3/4 throttle and/or heavily loaded, You should follow the factory service specs.

 

[kanghee]

Re: 2001 Merc 225 EFI boggs down on take-off

Adjusted oil linkage, but ever so slight, one rotation. Reset all throttle linkage, set crank sensor to 75mm, set throttle position sensor to .945. Installed new ngkb8hs plugs, gapped to .035. Motor barely started, thrashed and bashed for a couple minutes and would not take throttle at all without dying. Finally would not start at all. I pulled the plugs and clear oil and gas on plug tips. I installed the QL77's that the motor manual call for and it started up and run as smooth as a 225 EFI does. I am going to the lake tomorrow for a tournament test, will post results.

 

[kanghee]

Re: 2001 Merc 225 EFI boggs down on take-off

Same thing, different day. I will try to set the crank sensor and the TPS different, but within range. I have seen better results at different settings. Starting to think about the injectors or reeds. I keep getting a metallic screech from the front of the motor when idle/trolling.(My interpretation of noise, I do not know if a bad injector make a noise or not)

 

[kanghee]

Re: 2001 Merc 225 EFI boggs down on take-off

Checked cylinder pressure, ran 90 to 95 psi across the board.
Checked fuel pump pressure and it ran 34 to 38 psi. BUT, after relieving the pressure from my fuel gauge, the fuel pump did not kick back on, I thought it should, but don't really know. This is a new powerhead with maybe under 20 hours on it, should the cylinder pressure be a bit more? **** Have now borrowed my friends compression gauge and his gauge reads 85# across the board on my motor.

 

[kanghee]

Re: 2001 Merc 225 EFI boggs down on take-off

Problem solved!!! when they installed my power head and bolted the electrical "compartment" that houses the trim relays on, they pinched off two bleeder lines. I got to checking all of the bleeder lines and found three stuck check valves, one line not attached, and a couple that had split ends. Replace all lines, tie wrapped all ends, degunked all check valves and now it comes out of the hole just fine.

 

[trentster1230]

Re: 2001 Merc 225 EFI boggs down on take-off

My motor is doing the same thing. Could you tell me what bledder and check valve was pinched?