Another fuel pump issue.

[95 Lowbuck]

Got a 1998 Trophy with the Merc. 4.3 carb engine.
Had not been started for awhile and tried to start it last week.
Not getting gas to the carb, and not getting any power to the pump or e-choke.
Splashed gas down the carb and it will run.
Bench tested the pump, works fine.
Followed the power wire that goes back to the starter, looks good.
Is there a oil pressure switch in this circuit?
I get 40 lbs on the gauge just off the starter btw.
Any ideas?

 

[wellcraft-classic210]

Is 12 volts present at the starter lug via a dc volt meter check ? If so it could be a fuse or connections

 

[alldodge]

Got a 1998 Trophy with the Merc. 4.3 carb engine.
Had not been started for awhile and tried to start it last week.
Not getting gas to the carb, and not getting any power to the pump or e-choke.
Splashed gas down the carb and it will run.
Bench tested the pump, works fine.
Followed the power wire that goes back to the starter, looks good.
Is there a oil pressure switch in this circuit?
I get 40 lbs on the gauge just off the starter btw.
Any ideas?

The 40 psi is way to high for a carb

Check you kill switch

 

[95 Lowbuck]

The 40 psi is way to high for a carb

Check you kill switch

I was referring to oil pressure, I don't get any fuel pressure but it will
run if I splash some fuel down the carb.

 

[alldodge]

don't get any fuel pressure

My guess is you need a fuel pump but first;
Pull the filter and see if its full, if not go to the tank.
Remove the antisiphon valve and see if the ball and spring move easy

If filter is full then its the pump

 

[bman440440]

possibly the oil pressure switch P/N 805024 circled in red in the attached wiring diagram... also use it to check your wiring completely

 

[95 Lowbuck]

My guess is you need a fuel pump but first;
Pull the filter and see if its full, if not go to the tank.
Remove the antisiphon valve and see if the ball and spring move easy

If filter is full then its the pump

I think my problem is electrical.
I don't get any power to the pump, bench tested the pump and it works.

 

[95 Lowbuck]

possibly the oil pressure switch P/N 805024 circled in red in the attached wiring diagram... also use it to check your wiring completely

Thanks for the tip.
Any idea where the oil pressure switch is located?

 

[alldodge]

You have an EFI motor and the oil pressure switch does not make a connection for power to the fuel pump. The switch sends a ground to the ECM telling it that there is a loss in oil pressure. The ECM supplies the ground to the fuel pump to turn it ON/OFF

Don't know if you have a MEFI 1 or 3 but here is the MEFI 1 with Alpha

 

[95 Lowbuck]

You have an EFI motor and the oil pressure switch does not make a connection for power to the fuel pump. The switch sends a ground to the ECM telling it that there is a loss in oil pressure. The ECM supplies the ground to the fuel pump to turn it ON/OFF

Don't know if you have a MEFI 1 or 3 but here is the MEFI 1 with Alpha

Thanks but I have a carb motor.

 

[alldodge]

Dang, did it again :facepalm:

The oil pressure switch should be port side down next to oil filter or remote connection, or behind the distributor. It will have two wires going to it

bman was correct

 

[Scott Danforth]

Also, sitting probably has caused the carb float to stick. Sitting so long you may have to do a carb rebuild

 

[95 Lowbuck]

Also, sitting probably has caused the carb float to stick. Sitting so long you may have to do a carb rebuild

I thought of this too.
Loosened fitting on the carb and still no gas or noise coming from the pump.

 

[95 Lowbuck]

Dang, did it again :facepalm:

The oil pressure switch should be port side down next to oil filter or remote connection, or behind the distributor. It will have two wires going to it

bman was correct

Thank you, I will check it.

 

[Scott Danforth]

I thought of this too.
Loosened fitting on the carb and still no gas or noise coming from the pump.

also check the anti-siphon valve at the tank. when you pulled the fuel filter and replaced it and checked the contents, what was in the filter

 

[Maclin]

The pump should get 12v while cranking. That may be hard to verify by yourself with a meter, but it should hum when the engine is getting cranked. That should be enough time to get some fuel into the carb. Many times the when the oil pressure switch is not working the symptom is the engine will start but not run very long.

Once you find the oil pressure switch, it has two terminals, and jumping across those should give it 12v any time the key is on.

Is this the first time you have tried to start it after a recent purchase?

 

[95 Lowbuck]

So it turned out to be the oil pressure switch, and fuel pump.
Hot wired the pressure switch and could hear the fuel pump,
but still no fuel pressure.
$400.00 later and the boat runs again!

 

[alldodge]

Thanks for the update, hope you have an uneventful boating season