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97 272 Baja w/502 MAG MPI not running right. Need help pls.

T

Tom Layne

New member
I have a 97 Baja 272 With a 502Mag MPI Cool fuel SN# starts with OK17......dont know the rest sry.

Anyways i have been having some issues with it not running right latly. For the first 5 minutes or so it runs great. Then it loses all mid to high RPM Power and takes forever to get on plane from a standstill. Seems to idle fine and rev fine in neutral. But has no power above about 3500 RPMs under normal load.

I have checked all the plugs they look good to me but I am no expert. The distributor cap had some corrosion on the inside of it so I replaced it and the rotor. I put new wires on because a few looked cracked and like they have never been changed before...the boat is 15yrs old.

i checked my fuel pressure here is what i saw.

Just turning the key on, not starting= 28psi which drop'd with in a second to 20psi. It held @ 20psi for a few minutes then slowly droped to 15psi where it held.
Running at idel= 25-27psi
Running at idel with vaccume hose off of the pressure reg 30-32psi.......note: I am assuming that the circle thing on the front of the fuel rail right by the shrader valve is the fuel reg.
Running at 3k RPM= 20-22psi

My question is this. Is the Fuel Pump bad or the pressure regulator or both. Anyone know for sure?
Edit: or could i have a restriction somewhere in the fuel line?

Any help you guys can offer would be most appreciated.
 
Edit: or could i have a restriction somewhere in the fuel line?
Click to expand...

Ayuh,..... Have ya examined the contents of the fuel filter to rule out Water,..??

Water pumps, 'n holds pressures, but don't burn so good...
 
The regulator is on the fuel module the one on the fuel rail does not regulate fuel pressure. You need to remove the regulator from the top of the fuel module (fuel Cool) and check it for paint chips.

This engine should have 40 lbs of fuel pressure.
 
Docksidemarineservices said:
The regulator is on the fuel module the one on the fuel rail does not regulate fuel pressure. You need to remove the regulator from the top of the fuel module (fuel Cool) and check it for paint chips.

This engine should have 40 lbs of fuel pressure.
Click to expand...

Ok it's been a few days since i had a chance to work on the boat.

I pulled the fuel pump and tested it on my work bench pumped 60psi. So i think it is save to say that the pump is good.

I put the pump on it's fuel line, running it thru the filter BUT not thru the cool fuel or fuel rail, and checked the pressue... 60psi..safe to say no clog from fuel tank to fuel pump.<--right

I then reconnected the fuel system as it should be. and tested again at the fuel rail.....25psi. Something between the pump and the rail is lowering the pressure 35psi.....the regulator???? Today when i took the vacume line off the regulator there was only a 1-3psi jump in pressure....shouldn't it be closer to 10psi?

Any thoughts???
 
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