www.iFourWinns.com

the initial power comes from your battery not from the alternator. if you only have 2 volts check the harness around the ignition switch. my depth finder switch was doing the same with low voltage one of the harness connections was connected but not making a good contact on one of the pins

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1989 245 vista
5.7 cobra

I don't know if you are right about the alternator running the fuel pump... I will let someone else answer that. If that is the case, then there must also be a pre-start circuit to run the pump, because it is not uncommon to have a dry carb after sitting for a long period.

I have had two experiences that contradict the alternator theory:
-- I have had a bad alternator, and the engine kept starting and running fine until the battery got low.
-- I have started the engine after having a completely dry carb (because of rebuilding it). I just crank for about 3 sec, then turn the key off, then key back on, wait a few seconds, then crank again (and pump the throttle). After 3-5 tries it started right up. I did it that way because I am thinking that the pump runs for a few seconds each time you turn the key on. I'm not sure though.

You could have a bad pump that is somewhat shorted, therefore causing the low voltage? Or it could be a problem somewhere else in the circuit? Why don't you check voltage at the pump while you have someone else turn the key off and on.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I just looked up many different schematics, and saw a lot of differences for different engines. Some did have the Oil pressure switch wired between the alternator and the pump relay.

However, most of these schematics also show a wire going from the starter coil to the pump relay so that the pump will run while the engine is being cranked.

Here is a thread about this: http://www.justanswer.com/boat/2ibdc-2001-5-0-carburated-engine-boat-when-turn.html

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I just looked up many different schematics, and saw a lot of differences for different engines. Some did have the Oil pressure switch wired between the alternator and the pump relay.

However, most of these schematics also show a wire going from the starter coil to the pump relay so that the pump will run while the engine is being cranked.

Here is a thread about this: http://www.justanswer.com/boat/2ibdc-2001-5-0-carburated-engine-boat-when-turn.html

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

That's a good point, I'll check that today. Thanks!

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

Yeah, I was kinda going out on a limb with my dry carb theory, not knowing boats much. But what you say makes sense...

I don't believe the pump itself is the problem, as it runs fine when I remove the fp relay and hardwire the power to the fp. I'd post the schematic that I have, which i am sure represents the wiring I have on my boat, but I'm thinking Seloc wouldn't like that It shows the wiring going from the back of the alternator 'Indicator Light' terminal to the relay coil positive.

Does anyone know how much voltage is required to excite the fp relay? I'm half tempted to just rewire this lead to the ignition switch, but I don't want to bypass any safety measures or have fuel pumping out the top of the carb if I forget to turn the key off!

What gets me is that the power going INTO the alternator shows 12v or better... that's why my theory of the alternator needing to spin up came into play. However it makes sense that the fp would get it's power from the battery to start with...

Something rpengr said just clicked... looks like there is a line from the starter solenoid to the fuel pump relay coil positive as well? maybe that connection is bad, and it's not switching the fp on while cranking... therefore no initial start? Once the engine is running and the starter is no longer cranking, that circuit is disabled and the voltage from the alternator takes over? I'm going to go check that line from the starter.

Thanks again, fingers crossed!

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

There's a diode in the wire between the starter relay and the fp relay. Anyone know what it's for and if it can be bypassed? I have 12v power at the starter relay but at the fp relay on the same circuit I don't have anything. Has to be the problem!

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

you could have as many as 3 wires from the solenoid to the relay . a red orange and black. check the connections from there to the relay

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1989 245 vista
5.7 cobra

the diode is it on the red wire ? check power on both sides i think that could be a fuseable link

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1989 245 vista
5.7 cobra

VICTORY!!! On the positive fp relay coil terminal there is a green (from alternator) and orange (from starter relay) wire which turns into a yellow/red stripe wire with a 'diode' at the junction (The schematic says it's a 'diode'). I think I read somewhere that it controls polarity or something.. may just act as a fuseable link... at any rate, I fortunately had my old wiring harness laying around from the old engine, so I cut out the section of wire from the fp relay to the starter relay and there was in fact the 'diode' inline on that circuit.

I'm not proud to say it, but I spliced in the section of wire outside of the harness as a work around because to pull the wiring harness out would be another 3 hours work and alot of things having to be removed... looks like hell but she runs! Maybe I'll pull it apart in the winter and do it cleaner when I have more time.

So for anyone else out there experiencing the same problem - starter relay is connected to the fp relay in order to send fuel to the carb while cranking. Then once the engine is running and you're no longer cranking, the wire from the alternator will KEEP the fuel pump running.

Also, for anyone out there with questions about the wire harness on these boats, I have one hacked apart already that I will take pics of and send to anyone wanting to know what's where without having to peel your harness apart. Let me know!

Thanks everyone for your input, really helps to have other suggestions when thinking things through.

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

good to hear you got it . did you get out today?

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1989 245 vista
5.7 cobra

No, sadly my side business takes most of my time in the summers... hopefully next weekend!

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

Glad to hear you worked it out.


A "Diode" can be described as a "one way check valve" for electrical flow. The function of this diode would be to prevent voltage from going back on that wire to the starter relay. Bypassing it would be very bad, as I think it would energize the starter relay once the alternator was producing power.

A diode can be tested with an OHM Meter. If working properly, it should show infinite ohms (or extremely high) in one direction, and only a few ohms in the reverse direction.

Ray

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

So back again 3 yrs later with the same problem... are there any electrical gurus out there that might know why I'm blowing this diode repeatedly?

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Newbie Boat Owner, Looking to Learn!
1998 Four Winns Horizon RS 180
4.3L OMC/Volvo Penta Outdrive

Could be an over voltage? Diodes have a break over voltage that will allow current to flow in only one direction. Maybe an issue with the output of the alternator?

Good luck!

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Current:
2000 Sea Ray 380 Sundancer "still Livin the Dream"

Past
2002 268 Vista 5.7 GXI "Livin' the Dream"
1996 Rinker 192 Captiva. "The Simple Life"
1999 Yamaha XLL 1200 Waverunner.
1976 Mercury Marquis tri hull 120 hp