TOPIC:

Does your boat have trouble re-starting when fully warmed up (this problem is generally associated with engines not equipped with cool fuel modules).

Symptom: Near zero fuel pressure readings due to vaporized gas in pump suction results in starting failure.

Cause: Heat in the engine compartment is transferred to the fuel lines and filter causing gas bubbles to form and migrate to the pump suction.

Solutions: Venting the engine compartment and/or insulating lines/filter with non-flammable insulation.

This problem can be confirmed with an inexpensive diagnostic scan. Diagnostic Scan Offer

I have a challenge for you:

Port Engine, 1997 Mercruiser 7.4L MPI. Idles perfect, runs perfect. Try to throttle up slightly from idle to troll and she shoots to 1000 - 1200 RPM. Can bring her down to 900-950 at best, but she surges 100-200 RPM at that point. It is impossible to be between 700-900 RPM. She does not surge in any other RPM range, just around 1000, but to emphasize 700-900 is not possible.

What I have done:
Replaced:
IAC
TPS
Plugs
Wires,
Cap
Rotor
Coil

I have cleaned the throttle body to perfection, checked for vac leaks (cant find any), swapped map sensor with starboard engine. No improvement.

Engine is smooth, highly responsive and otherwise perfect.

Feel free to call me if you have any ideas as this is becoming a thorn in my side. (219) 682-5575

A dirty IAC muffler/filter can cause problems transitioning away from idle conditions.

I do not believe my engine has an IAC muffler / filter. Perhaps you can confim. Mercruiser SN: 0K189296

Confirmed. Service Manual for a 1997 374F4S9KT 7.4L/8.2L MPI (MIE) GEN VI does not indicate an IAC filter.

ok - so any other ideas?

A scan will show you what the ECM is seeing from all those "new" sensors/controls.

Lets do it. Feel free to call me when you have a chance. (219) 682-5575.

Jeff