Help Unmodding 1999 Mariner 225 Supermag

[tux974]

X2 with Bobby. Yes, 5400 is way off and it can actually hurt that motor, need to get them up to 6500ish.
Once you get fuel pressure and temp squared away may want to check TPI setting, that may also make you run rich which equal burning more fuel.
If the the little screen is dirty I suggest to open VST and clean it as well. Heck it may not be a bad idea to do that anyway since that has a screen on the bottom of pump.
PS, why not put the spin on filter back if you plan on running stock fuel system. Personally the ideal fuel system setup for me (if stock) is with the spin on filter on the motor then run from fuel tank to primer bulb to pulse pump on the motor period.

Pic below you can see fuel routing and popet dump, hope it helps.

[Merc 2.5]

To the op. I would definitely listen to the 2 fellers trying help u.tux and tex. 2 gud guys and will steer in right direction. I also agree that there's been sum mods that didnt need b done to cooling , fuel system needs a good plug ,piston read. Also gotta get rpm up another 1k rpm atleast but then again if the motor is that fat it will kill rpm on top

[Bullet1961]

I finally got a poppet assembly in and installed, and everything plumbed like the pic. Finally getting some temp in the heads but they're erratic. At idle, the top starboard head temp is 145* and the two below are 130-135*. The port side cylinders are all 120-130*. Is this a normal range? Good news is that its not smoking like it was.

Also, tux hit the nail on the head. I took the regulator apart and the filter looked bad (see before and after pics). The VST was clean. Somebody must have already done that. My fuel pressure gauge quit so i wasn't able to check it after cleaning but its gotta be better. Are there filters on each of the injectors that should be cleaned? Could this cause the erratic temps?

[Bullet1961]

Oh, and thanks for the advice on the fuel filter. I have everything on order to reinstall it.

[tux974]

Glad to help, Im sure your pressure will be back to normal now 35-39lbs after looking at that screen.
Yes, every injector has a small basket type screen unless they were removed at last injector service/cleaning. Some do remove them but I do not recommend it for pleasure use.
I would suggest to get injectors serviced even if they check out good and clean after service.
This is a very good and important thing to do especially if you do not know the full history of the engine, last confirmed service or you will find out they were dirty/semi-clogged/clogged when you damage a cylinder.

[Bullet1961]

I finally had a chance to try it out; I have been preoccupied with a new grandbaby then an ice storm. After cleaning all the filters, it runs much better including the idle which is now normal RPMs. However, it is the gift that keeps on giving... while replacing the fuel filter i found that the high pressure fuel pump had been rewired to run directly off the battery rather than through the ECU. When I checked the ECU, the fuel pump circuit was bad. I found a place that said they could repair it for $625... simonpertech.com. Does anyone know anything about this company?

[tux974]

Run it the way it is currently wired, it will be fine. My suggestion if you like to change or repair your ECU is to keep your eyes open for a good used one they come up for sale $350-$450 from time to time.....MPO.

[Bullet1961]

Thanks for the advice. I'll leave it for the time being. Tomorrow, I'm finally getting a chance to take it to a lake big enough to really run it.