Low Voltage At Fuel Pump

[Don S]

Re: Low Voltage At Fuel Pump

You can get a standard 2 wire oil pressure switch (normally open) from NAPA, get one in the 5 psi range and wire it like the merc.<br /><br />EDIT: Told you wrong, see achris's explanation below.

 

[jeffnangela]

Re: Low Voltage At Fuel Pump

Thanks Don. That sounds so much more simple than my current configuration and I'll have a little more peace of mind for those longer trips offshore (more simple design = less that can go wrong). I'll let you know how it turns out. I just hope NAPA has one in stock so I can pick it up on my way home from work and give it a try.

 

[achris]

Re: Low Voltage At Fuel Pump

Don,<br /><br />If he does that, when the oil pressure switch closes it'll also re-engage the starter. He'd need to use a diode in the Yellow/Red wire to stop current flowing back to the starter soleniod.<br /><br />Jeff,<br /><br />Check if you have an unused terminal on the back of the starter marked 'I', if you do, that's where you run the wire from. That terminal is only live when the starter is engaged and was orginally designed to feed the ignition coil with full voltage when cranking (old points type system). As the ignition systems are all electronic now, it's unused. Merc use it to run the fuel pump during cranking. So can you.<br /><br />Chris..........

 

[highaltitude]

Re: Low Voltage At Fuel Pump

have you checked for spar? start with the basics. good luck

 

[Don S]

Re: Low Voltage At Fuel Pump

Drat!, forgot about that yellow/red wire coming from the wrong terminal on the start solenoid. <br />Good catch, hope Jeff sees your instructions.<br />It needs to be hooked up like the Merc drawing I posted earlier. It shows that Purple/yellow wire coming from the I terminal on the starter solenoid. <br /><br />

 

[jeffnangela]

Re: Low Voltage At Fuel Pump

Ya'll have a good point. But, If the yellow/ red from the start solenoid is applied to the same terminal as the red (on a new pressure switch), will that also feed back from the 12 volts from the continous power that is delivered to the pressure switch from the red/ yellow wire? <br />I don't know if I'm phrasing this question right, but it seems to me that the red/ yellow wire would feed the fuel pump by way of the red wire when the oil pressure switch is tripped which is what I want, but wouldn't it also feed back up the yellow/ red wire and cause the solenoid/ starter to engage again?<br />Maybe I'm confused. I need to get out to my boat again and do some more testing with the meter, but here in Alabama we are on day 2 of rain. I hope I get this problem straightened out soon because if this rain doesn't stop I'm going to need my boat to get to work. Anyway, thanks guys!

 

[jeffnangela]

Re: Low Voltage At Fuel Pump

Okay, rain let up long enough to get back to the boat with my meter. The voltages are getting to the oil pressure switch (although they do drop during start), but the red wire going to the fuel pump is not getting a voltage anywhere near the red/ yellow or yellow/ red. I think we're on the right track with the idea of the oil pressure switch being at fault..<br />I pulled the oil pressure switch and am now trying to locate a replacement. The number on the switch is 97295. I tried NAPAonline crossreference, but had no luck. I would like to keep my current configuration if possible, so ideally I would like to go back with the same switch. Any suggestions?

 

[jeffnangela]

Re: Low Voltage At Fuel Pump

Quick update for you guys and anyone with similar problems in the future. The oil pressure switch was faulty. I ordered a new one for $12.00, replaced the harness that connects to it, turned the key, and she fired right up. Lots of troubleshooting for a $12.00 part. Thanks so much for all the valuable help guys.