Good deal. Ordered clear line from amazon. Got work again tonight and tomorrow so back at it Saturday morning. Thanks again for the help. I love fuel injection, accept when it's from the mid 90's.

Doug.

I didn't see anywhere in this thread mentioned ignition timing being checked...

No regulator in VST.
Genuine Mercury & Mercruiser parts. VAPOR SEPARATOR TANK, SN & Up (See Note)

Timing was a thought, but there is a known fuel issue needing corrected at this time, if the problem persists, other systems will be looked at.

This is a classic fuel issue, specifically lack of it at higher rpms. In my case it was a bad injector. Nearly identical symptoms you have. Compression and leak down might be a good idea to see if there is any residual damage from earlier operation.

Trash, you had declining fuel pressure as load increased? I'm stuck on injectors also because the low and high pressure pump have been replaced for reliability purposes. The regulator, injectors and lines have not been replaced. Mechanical fuel pumps last for decades, not hours. There shouldn't be any issue with source fuel. The pickup looks very clean and anti siphon is new.

I was under the assumption you had cleaned and flow tested the injectors. Cleaning out the injector filter baskets is not enough. The injectors must have a solvent run through them, cleaned and flow tested / balanced (i.e. all injectors flow within .X% of each other).


I had one injector working very poorly and another not far behind but didn't find out until it was too late. Symptoms were motor fell flat on it's face above 4000 rpm and an occasional miss at cruise. This miss could not be heard but I could feel it in the seat of my pants. Problem is I let it go on too long and #1 leaned out enough to command an exhaust valve seat separation. The motor disassembled itself at the most inopportune time.

Fuel pressure was not an issue in my case. From now on if any of my EFI motors are down on power I check the injectors. There is not feed back loop to the driver that an injector is going bad unless you have dual wide band at a minimum. Preferably 8 channel wide band but that is virtually non-existent on the water.

Big moves today, found a cracked o ring atop the high pressure fuel pump causing a hemerage. Fixed that. Now I have mega fuel pressure. 50-60 psi. 70 if I deadhead the pump. Drivability issues still exist. The boat gets out of the water much better, but still will not climb over 4K. I'm thinking I have injector issues also. Clogged/not functioning properly. Going to pull them and have cleaned this week.

Injectors have been dropped of for service. My logic is this, even if it doesn't fix my rpm/power issue, I can now be confident fuel distribution is proper and I won't melt any engine parts. Stay tuned.

Never hurts to have 8 known-good injectors...