2001 Optimax hard starting/surging

[krgriff]

2001 Mercury Optimax serial# OT207468, engine runs fine 2000 rpm and above, but surges and hard starting. Replaced tracker valve, the air pressure at 80 psi but gage flutters fuel pressure at 90 psi gage flutters when engine running. Key on engine off, fuel pressure goes to 40 psi and within 2secs of fuel pump cutting off drops to 10 psi, pulled fuel rails back and no fuel injectors leaking. Any suggestions would be helpful.

[EuropeanAM]

Welcome to BBC!

Recommend using a DUAL PRESSURE (Liquid or Glycerin-Filled) Gauge set, and recording EXACT pressure readings (Air/Fuel) for EACH of the following:

-At idle
-Under Acceleration
-5/10/15 seconds after engine shutdown*

* Restart engine for each of these time period tests.

[krgriff]

Thanks Don for your post on car o lite sparkplugs.Just bought six iridium extreme sports that will be returned or go into the trash can.As for my Optimax idle problem my Air/Fuel readings are as follows 81/91 at idle,82/91 under acceleration,0/10 at 5 seconds,0/10 at 10 seconds, 0/10 at 15 seconds.Thanks for all your help Don and I will be buying my maintenance and repair parts from European Marine to support this site.

[M4A1]

Thanks Don for your post on car o lite sparkplugs.Just bought six iridium extreme sports that will be returned or go into the trash can.As for my Optimax idle problem my Air/Fuel readings are as follows 81/91 at idle,82/91 under acceleration,0/10 at 5 seconds,0/10 at 10 seconds, 0/10 at 15 seconds.Thanks for all your help Don and I will be buying my maintenance and repair parts from European Marine to support this site.

Are you sure on these readings? You have no air pressure at 5 seconds after shutdown?

[krgriff]

Yes those are correct readings.

[krgriff]

I have done the thermostat and housing upgrade.5600 rpm WOT ,17p Mirage Plus, 23ft Key West walkaround.Smartcraft monitor with no alarms.

[thomasfouraker]

FWIW, my 2001 225 Optimax loses air pressure as soon as I shut down. Sherm made mention that the older Optimaxs tend to dump air pressure after shutting them down in this thread:

http://www.bbcboards.net/mercury-mot...-air-leak.html

[EuropeanAM]

Thanks Don for your post on car o lite sparkplugs.Just bought six iridium extreme sports that will be returned or go into the trash can.As for my Optimax idle problem my Air/Fuel readings are as follows 81/91 at idle,82/91 under acceleration,0/10 at 5 seconds,0/10 at 10 seconds, 0/10 at 15 seconds.Thanks for all your help Don and I will be buying my maintenance and repair parts from European Marine to support this site.

Earlier (pre-2003 production) models MAY dump air pressure at shutdown, depending on the PCM calibration in use.

I would recommend a LEAK CHECK of the air side of the system, via REGULATED shop air pressure (pressurize to 80 psi, and see if it holds the pressure). This is done via the same schrader valve port (on the PORT SIDE RAIL).

If pressure leaks down RAPIDLY, listen for the leak (and locate it). Substantial leaks in the air side of the system will cause ALL of your symptoms.

[krgriff]

Pressurized port side rail to 80 psi .Took 1 minute to leak down to 63 psi.Did not pull plugs but listened to air compressor inlet and could not hear anything leaking past reeds.Could not locate leak is this an acceptable amount of leak down?

[EuropeanAM]

You've confirmed you have no significant AIR leaks. If you can- it would be a good idea to simply rule out FUEL pressure leaks as well.

REPEAT your air pressure leakage test (80 psi applied), and cycle the key ON while air pressure is up. FUEL pressure should remain at a 10 psi differential (ie: Fuel pressure = Air Pressure + 10 psi). You're simply verifying that FUEL PRESSURE follows air pressure, and remains at the 10 psi differential above current air pressure.

If all here is as it should be, I would be looking at the following items, in the following order:

-Confirm clean/fresh/properly gapped NGK: IZFR5G Spark plugs

-Compression Test

-INSPECT REEDS

-TPS Voltage Sweep Test to check for problems

-MAP Sensor (check to confirm functioning properly)

[krgriff]

Small hole in poppet valve caused all these problems.

[thomasfouraker]

A hole in the cooling system was causing pressure loss to your air and fuel rails?

[Savage]

Small hole in poppet valve caused all these problems.

Impossible!

[EuropeanAM]

I agree. Tracker valve- perhaps. But NOT the Poppet Valve.