Electric fuel pump issues

[Galvez83]

Folks question regarding electric fuel pump not working when cranking. 1993 Sea Ray 7.4 bravo i have to crank the engine about five time before i hear the pump starting. I replaced the relay with a waterproof one due to some rust on the connections thinking it might solve the issue but no luck. Could you guys advise on how to get the pump to start when cranking.

 

[achris]

There should be a purple/yellow wire coming from the starter motor solenoid post. Make sure that is being powered while cranking.

Have a read through this thread. I know it's long and often takes tracks that may not be helpful in your case, but the ful description of how the fuel pump circuit works is in there.

4.3 Mercruiser cold start issues

I seem to be having a hard time starting my boat after it sits for a day or more. The boat starts right up if it been running. I pump the throttle between a half a dozen to a dozen times but it still takes a while to start. Towards the end of last year I even had to start using starter fluid to...

forums.iboats.com

Chris.....

 

[alldodge]

What's the serial number?
I'm seeing the 1993 7.4 coming with a mechanical pump

 

[Galvez83]

What's the serial number?
I'm seeing the 1993 7.4 coming with a mechanical pump

When i bought it it had the electric conversion which was working fine and still does after 4 or 5 cranks. Attached is the pic.

 

[Galvez83]

There should be a purple/yellow wire coming from the starter motor solenoid post. Make sure that is being powered while cranking.

Have a read through this thread. I know it's long and often takes tracks that may not be helpful in your case, but the ful description of how the fuel pump circuit works is in there.

4.3 Mercruiser cold start issues

I seem to be having a hard time starting my boat after it sits for a day or more. The boat starts right up if it been running. I pump the throttle between a half a dozen to a dozen times but it still takes a while to start. Towards the end of last year I even had to start using starter fluid to...

forums.iboats.com

Chris.....

Thanks Chris, i will look now to see where i am at with the pump wiring.

 

[alldodge]

The serial number 0L036613 0r 0L038613 comes up as 1998 3.0

If the motor coming with a mechanical pump and it was changed over to electric, it may not have the purple/yellow wire. Look on the solenoid to see where the wire would be and if there is even a terminal there

This is how Merc would setup an electric fuel pump option




If terminal is not there, then setup the pump like this

 

[Galvez83]

The serial number 0L036613 0r 0L038613 comes up as 1998 3.0

If the motor coming with a mechanical pump and it was changed over to electric, it may not have the purple/yellow wire. Look on the solenoid to see where the wire would be and if there is even a terminal there

This is how Merc would setup an electric fuel pump option

View attachment 337824


If terminal is not there, then setup the pump like this

View attachment 337825

Apologies i must have submitted the wrong serial #, the correct one is F006526. Also there is currently a relay controlling the oil pressure switch and the pump. What would be the proper connection to start the pump while cranking untill it builds up pressure?

 

[nola mike]

Depending on your starter--you may have a terminal off it that supplies 12v while cranking. If so, you can use that to supply the NC terminal off the OP switch. If not, you can run it off of the slave solenoid. See AD's post above. The common terminal off the switch is going to trigger the relay, either terminal 85 or 86 (the other is ground).

 

[alldodge]

Thanks for the SN, the starter (Gen V 92 to 94) should have the extra terminal. So it could be wired up as in the first pic

Would need to understand how yours is wired and what might be the best way to change.

 

[nola mike]

Thanks for the SN, the starter (Gen V 92 to 94) should have the extra terminal. So it could be wired up as in the first pic

Neither of those pics has a relay. This is pretty close to what you'd need:

https://static.summitracing.com/global/images/eventimages/april_99_wiring/600/techecma99_fuelpump.jpg

 

[alldodge]

Neither of those pics has a relay. This is pretty close to what you'd need:

https://static.summitracing.com/global/images/eventimages/april_99_wiring/600/techecma99_fuelpump.jpg

Not the point I was making. The starter should have the extra post on the starter so could just wire it up without a relay and only use a oil pressure switch

Saying it could, not saying it would

 

[nola mike]

Not the point I was making. The starter should have the extra post on the starter so could just wire it up without a relay and only use a oil pressure switch

Gotcha, but he already has a relay. Imo better to run it with the relay, though I realize merc didn't use one.

 

[Bt Doctur]

I install a priming button either on helm or engine compartment. Aids in refilling the fuel filters

 

[Galvez83]

Here is what the relay and connections look like, to be honest this is a mess but then again it works fine after a little cranking. The starter does have a connection which the purple wire should connect to but the purple wire only reaches the ignition coil. Here is how the relay is currently wired. Blue wire to pump positive, white is ground, black to oil switch, Red wire from relay to battery pos and spliced to oil switch and them from switch to yellow red starter. All the diagrams i see state different connection point.

 

[alldodge]

That pump is not marine rated (ignition protected), its illegal to use on a boat.

Does the motor have a belt driven raw water pump, and if so does it have a place for the fuel pump?

To fix what you have, suggest connect one side of the switch to the purple wire coming from the (+) side of the coil.
The other side of the switch goes to the pump
Run a new wire from the outside terminal on the starter to the fuel pump side of the oil pressure switch.

Remove everything else

 

[Galvez83]

That pump is not marine rated (ignition protected), its illegal to use on a boat.

Does the motor have a belt driven raw water pump, and if so does it have a place for the fuel pump?

To fix what you have, suggest connect one side of the switch to the purple wire coming from the (+) side of the coil.
The other side of the switch goes to the pump
Run a new wire from the outside terminal on the starter to the fuel pump side of the oil pressure switch.

Remove everything else

Yep the raw water pump has a spot on top for the fuel pump