fuel pressure regulator problem?

[topaz surfer]

Ok so I have this phantom problem with my motor just cutting out with no patern other than while crusing at almost wot or surfing. Runs fine but will just randomly die. But always fires right back up. Anyone think fuel pressure regulator could be the culprit? Only thing left I haven't tuned up is cap and rotor but they looked fine so I didn't yet. Ideas??

[boatwakes]

You can put a fuel pressure tester on the rail to determine if the regulator is bad. Fuel pressure should pop up above 25psi when you turn the key to on and then SLOWLY (within 5 minutes) go back to below 10psi. When running the pressure should be around 32psi +- 4 psi. If the pressure goes higher, like climbs and doesn't stop, then the regulator is bad. Problem is, it's located on the fuel pump which is located on the starboard side engine forward motor mount in that stupid Mercruiser cool fuel plastic box. You will need the regulator kit AND the brass adapter fitting that screws in to the front of the regulator, you will not be able to remove it from the unit without breaking it.
Also, tune up : ignition sensor, coil? I've had a rash of ignition coils go out lately and Mercruiser is backordered on them until July 30th, the sierra ones have had issues so I'm just waiting for the factory ones.

[topaz surfer]

You can put a fuel pressure tester on the rail to determine if the regulator is bad. Fuel pressure should pop up above 25psi when you turn the key to on and then SLOWLY (within 5 minutes) go back to below 10psi. When running the pressure should be around 32psi +- 4 psi. If the pressure goes higher, like climbs and doesn't stop, then the regulator is bad. Problem is, it's located on the fuel pump which is located on the starboard side engine forward motor mount in that stupid Mercruiser cool fuel plastic box. You will need the regulator kit AND the brass adapter fitting that screws in to the front of the regulator, you will not be able to remove it from the unit without breaking it.
Also, tune up : ignition sensor, coil? I've had a rash of ignition coils go out lately and Mercruiser is backordered on them until July 30th, the sierra ones have had issues so I'm just waiting for the factory ones.

I will have to check the fuel pressure. Do you just stick the gauge on the shrader valve on the fuel rail? Also is the ignition sensor under the rotor? Only thing that came up on the last ecm scan was fuel pump circuit but it was also at the same hour mark as when we scanned it so they didn't think it was an issue? Also how do you know if it would be regulator, low pressure fuel pump, or high pressure fuel pump? Thanks for the help I have a big weekend trip coming and and worried about it crapping out when we are on our houseboat trip.

[boatwakes]

Ignition sensor is under the rotor in the distributor and if it's original will only have two wires, white with green and white with red. The new units have a ground wire included as well. The pressure tester connects directly to the rail at the schrader valve, yes.

[topaz surfer]

You can put a fuel pressure tester on the rail to determine if the regulator is bad. Fuel pressure should pop up above 25psi when you turn the key to on and then SLOWLY (within 5 minutes) go back to below 10psi. When running the pressure should be around 32psi +- 4 psi. If the pressure goes higher, like climbs and doesn't stop, then the regulator is bad. Problem is, it's located on the fuel pump which is located on the starboard side engine forward motor mount in that stupid Mercruiser cool fuel plastic box. You will need the regulator kit AND the brass adapter fitting that screws in to the front of the regulator, you will not be able to remove it from the unit without breaking it.
Also, tune up : ignition sensor, coil? I've had a rash of ignition coils go out lately and Mercruiser is backordered on them until July 30th, the sierra ones have had issues so I'm just waiting for the factory ones.

Ok so tonight I put a pressure gauge on it and when I first turn the key on its at 44psi while the pump is priming for a few seconds then drops to 38psi and then within 5 min it drops to 32psi. Not sure if that tells me anything but Im going to try and run the boat on the lake tomorrow night after work and watch the pressure gauge. Manual says it should be at 43psi at 3000rpm I believe.