Ignition Timing on Mercruiser 5.0 EFI (TBI) 1999?

[Kuneha]

Hey guys,

I'm going to see if my ignition timing needs set as a means to cure my poor engine performance at the moment.

I know that it needs to be set at 8-BTDC. Does this engine have clear timing marks? (I ask because my boat is quite a while away from where I live so like to make sure I know and have everything I need for when I go up there).

Does the engine need to be put in some sort of timing mode? - If so how is this achieved?

Thanks.

 

[alldodge]

Without the serial number I do believe you have a TB-V distributer, MEFI-3 ECU and TBI.
Yes it needs to be placed in base timing mode by using a paper clip as shown below



Don't know for sure but being a 1999 manual 25 shows it should have the timing plate of the chain cover. If in doubt, bring an advance timing light and there will be no issues

 

[Kuneha]

Thank you friend.

I will pick up a timing gun with advance ASAP.

From what I gather, this is the steps in which I should do this:

Warm up the engine.

Turn off engine and set timing mode on.

Turn engine back on.

Use the gun and set to 0 degrees or TDC. (turn distributor)

Set the gun to 8 degrees.

Then set ignition back to 0 degree or TDC (but will be 8-BTDC because of the advance feature of the timing light). (turn distributor)

Switch engine off.

Turn timing mode off.

Switch engine on and enjoy the rest of the season.

Is this correct?

 

[alldodge]

Should work, but don't touch the distributer unless it needs to be adjusted.
Adjust the timing light to 8 BTDC degrees and see if its at 0, if it is not then and only then is the distributer touched

 

[Kuneha]

Makes perfect sense. I will get on to this ASAP. Thanks for the information, priceless.

 

[Kuneha]

Ignition timing seemed good at 8-btdc so I'm again at a loss.

Ignition base timing set.
2x new batteries.
New fuel pump.
New plugs.
New cap and rotor.
New oil pressure sensor.
New MAP sensor.
New oil filter.
New fuel filter.
New fuel.

And the boat still have low power/WOT.

Sigh..

 

[alldodge]

Need to measure the fuel pressure throughout the rpm range.
Also do a compression test

Hey, could also read the codes using a resistor LED