RickerTX

Ran the boat (25 Daytona w/ 502 mpi stock) all weekend and when I get ready to leave the raft-up this evening, the boat starts and then just dies and won't start again. Check fuel pressure with the little valve on the front of the motor and very little if any pressure there.

Side note: I installed a power inverter this week and ran the cables to the inverter up the driver side of the boat which happens to be where the kill switch is, so I think maybe I screwed up the wires for the kill switch. I pulled the switch out and there are only two wires connected to it and a third is about an 1/8th of inch out of the switch and no wire. Is there supposed to be three wires gong to that switch? If so that may be my problem. Does this switch cut the fuel pump or the ignition?

If it is not this switch then I need to know how to test my fuel pump. It had started and ran several times today and when I get ready to leave this happens. Luckily my friend was still close so he towed me in (how embarrassing). I've towed others in but never been towed myself.

Sorry so long. Any advice is much appreciated. Thanks.

Rick

RickerTX

No ideas huh?

Dave1972

what generation 502? Is it the cool fuel or the VST? Do you hear the pump cycle on when you turn the key to the run position without starting? If you hear the pump running and you have no fuel pressure at the schrader valve, I would assume you have a problem with your pump. The VST tank/pump has a small barrel-like pickup screen inside of it to filter the fuel before getting to the pump and to the injectors. I pulled mine and that small barrel-like pickup was completely clogged. This might be a place to start?

Did you have a fuel pressure gauge hooked up on the fuel rail?

RickerTX

It is a 2000 boat and motor (whatever generation that is). I will check this afternoon to see if I have cool fuel or not. I will check my fuel screens too. I believe the pump is running. I did just add all new gas this weekend and that could have dislodged some junk in the tank and caused a clog. I will let you know. Thanks for all the good suggestions.

I do not have a guage for the fuel rail. I hope the damn thing is just clogged.

Vinny P

The first thing to check is to make sure the pump is running. Just turn the key to ignition and listen for the pump. You should hear it run for a few seconds before it shuts iteself off. If it doesn't turn on, check for power and ground at the 2 wires for the pump. They are down low on your port side behind the motor mount.

RickerTX

I have Cool Fuel set up. I turned on the key and did NOT hear the fuel pump at all. Just a "click", no "whirrrr". I need a better description of the wires I need to test. And if I have power and ground then I guess it is the fuel pump. Hey checkmate, can you be a little more descriptive so I can test those wires? I really appreciate your help buddy!

Rick

Dave1972

Not sure if this will help but in this photo number 3 is the fuel pump. One will be positive and one will be ground. Not sure which but not sure if it will matter or not as the pump will work in either direction to test it I would "assume". If you can't make heads or tails from it take a look at Mercruiserparts.com

RickerTX

Thanks Dave1972 and Formulafastech, I have a good idea what I am looking at now. Fuel pump so small? I will post my results after I test.

Where is the best place to get a fuel pump if this one is gone? Thanks again guys!

bowtie

There is a fuse and a relay for the fuel pump. If there's no power to the pump, check the fuse first. Remember to test between the two wires for power within 10 secs of turning the key on.

RickerTX

Update on my problem.

After checking all the sensors that disable the fuel pump and checking for power at the pump, I determined it must be the fuel pump itself and replaced it. She started right up and sounded very happy.

Thanks for all of your help and especially Dave1972 for the parts diagram. That was a big help. You guys came through again!

Rick