Fuel Pump running with Key ON & Motor off...

[AaronWhitt82]

Hey guys I just recently replaced my Carter low pressure fuel pump. Replaced it with an Airtex, but I'm not sure of the model. I have a 350 Indmar with the Holley 4150 carb.
I notice now when I turn the key to the ON position (with the motor not running) I can hear the fuel pump running. I don't recall the old pump doing this at all. I hooked it up exactly how the old one was. So now if I forget and leave the key on for a few minutes I get alot of gas overflow out of the carb which isn't good.
I haven't got a clue why it is running with just the key on?

Also, I replaced the Fuel pump/Oil pressure safety switch that is located in the rear under the distributor that has 3 prongs on it. There is a red wire connected to it that goes to the pump, an orange wire that goes to the starter and a purple wire that I'm not sure what it hooks up to.
Well come to find out the switch I purchased at Autozone was incorrect because after I had everything all hooked up I turned the key to ON and it started smoking a bit.
There also wasn't any power to the fuel pump.
I took the switch out and put the old one back in and hooked it all up and then turned the key ON and the pump ran.
I still haven't been able to check and see if the pump runs when the motor is because of other fuel related issues I am having.
I am wondering if the new switch I had put in burned something up and did something that causes the pump to run now with key ON?

Maybe I just need to order the correct oil pressure safety switch for it?

Thanks in advance

 

[tommays]

Re: Fuel Pump running with Key ON & Motor off...

The oil pressure SHOULD be N.O.(normally open) and NOT be passing 12 volts to the pump UNTIL the motor starts and the oil pressure closes the switch


You need to use a meter and see if the switch is BAD or wired wrong
and passing 12 volts to the pump all the time


Tommays

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

OK, now that I'm thinking of it..... I might have the Orange and Purple wires mixed up on the oil pressure switch. I'll try switching them back tomorrow and see what happens. If all is OK then I'm assuming that was the problem. If not, then I'm going to use a test light and check power while cranking to the red wire on the switch and to the wire on the fuel pump. If the test light doesn't light up, then I'm going to replace the switch and check some other wires to make sure there is no short....

If it is the switch or I do have wires crossed this might explain my other post about why the boat is only running a few minutes then dies out like she is starving for fuel...

 

[180shabah]

Re: Fuel Pump running with Key ON & Motor off...

*******I don't know what indmar uses so this is just a guess********

You said the original switch had three terminals,

1 to pump
2 to starter
3 to unknown(more than likely the key switch)

leads me to believe it is a SPDT switch with the pump connected to the common(CO) terminal, the starter lead connected to the normally closed(NC) terminal and the key switch connected to the normally open(NO) terminal.

verify this with on the old switch with a meter.
hook the new switch up thesame way.
use a meter to identify the terminals(they may not be labled) DO NOT trust terminl location on the switch. They could be different.

 

[180shabah]

Re: Fuel Pump running with Key ON & Motor off...

Hey guys I just recently replaced my Carter low pressure fuel pump. Replaced it with an Airtex, but I'm not sure of the model. I have a 350 Indmar with the Holley 4150 carb.
I notice now when I turn the key to the ON position (with the motor not running) I can hear the fuel pump running. I don't recall the old pump doing this at all. I hooked it up exactly how the old one was. So now if I forget and leave the key on for a few minutes I get alot of gas overflow out of the carb which isn't good.

OK, two more things.

Is the Airtex pump USCG approved.

If you have fuel running through the carb, then either the fuel pressure is too high or you have a carb problem.

 

[wire2]

Re: Fuel Pump running with Key ON & Motor off...

The pressure switch needs 2 sources and 1 load (the fuel pump). If it's marked, it's the "common".

The 2 sources are from starter (yellow)to the normally closed (to run pump while cranking) and the normally open (purple) from ignition (will close when there's oil pressure)

 

[Don S]

Re: Fuel Pump running with Key ON & Motor off...

I know places like NAPA and many other automotive stores, sell oil pressure switctes that are 3 terminal that can be either normaly open or normally closed. You need to determine which is which.
You only need 2 terminals power in and power out on the normally open NO part of the switch.
Then you hook it up like in the diagram below.

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

I appreciate the replys guys!

OK here is a link to exactly what the switch looks like:
http://www.pegasusautoracing.com/bigpicture.asp?RecId=88

As you can see one terminal is marked with an "I" and the other one is marked with a "P" and I can't see what the middle is marked. Mine is exactly marked as that one is.

The RED wire goes to the P terminal which is the Fuel Pump hot wire.

The Purple wire (Ignition) goes to the middle terminal and the Orange wire (Battery/Starter) goes to the I terminal.

Am I correct on that or do I have the purple and orange ones mixed up?


Also the AIRTEX pump directions said not to be used for Marine or Aircraft, but I gave the parts store the Carter Marine part number and they cross referenced it directly to this and said it is "Marine Approved" so who knows.

 

[180shabah]

Re: Fuel Pump running with Key ON & Motor off...

Also the AIRTEX pump directions said not to be used for Marine or Aircraft, but I gave the parts store the Carter Marine part number and they cross referenced it directly to this and said it is "Marine Approved" so who knows.

The manufacturer knew, they said no. If it was marine approved it would have a tag permenantly affixed to it(as required). Return the pump and get the correct one before you blow yourself up.

As for your switch wiring, get out your meter and identify NO / NC / COM don't know what the markings one the switch mean.

 

[Don S]

Re: Fuel Pump running with Key ON & Motor off...

Also the AIRTEX pump directions said not to be used for Marine or Aircraft

I guess that is a good indication that it should NOT be used on your boat.
I would trust the written word in the instructions before I would take the word of any parts guy trying to sell parts.

There should have been a wiring diagram with the pressure switch, to tell you what terminals do what for what reason. I and P mean nothing.

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

I found that out today about the fuel pump not being marine approved when I was looking through the paperwork that came with it.
She's coming off and going back tomorrow so I hope they give me an exchange for the correct pump.....

I'll also test the terminals on the switch to determine common, NC, and NO
then go from there now that I understand how it all works

Thanks again for the help!
Aaron

 

[wire2]

Re: Fuel Pump running with Key ON & Motor off...

The Purple wire (Ignition) goes to the middle terminal and the Orange wire (Battery/Starter) goes to the I terminal.

Am I correct on that or do I have the purple and orange ones mixed up?

I think purple goes to "I" for Ignition. Orange will be "S" for Start.

As Don's schematic shows, the factory wiring needs only 2 terminals, Com and NO but the 3rd wire is connected directly to the pump "hot" lead.
Electrically, it's the same thing. The pump runs with the starter first, then the pressure switch takes over.

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

I think that would sound correct. I'll try that tomorrow and see what I get. I don't think it can hurt much by switching the wires around...
If it doesn't fix it then I'm going to the marina for a new oil pressure switch. Pretty simple, but just understanding the whole concept takes sum time to comprehend and figure out....

 

[capecodder116]

Re: Fuel Pump running with Key ON & Motor off...

Below is a link to a Carter Marine Electric fuel pump I purchased on Ebay. This is the same Carter pump which can be purchased thru NAPA only this is less expensive. I am converting my mechanical pump to electric and needed to purchase the pressure switch (which comes with wiring diagram) which I purchased at my local Napa store....Hope this helps.
http://cgi.ebay.com/ebaymotors/New-...010QQitemZ200156289819QQrdZ1QQsspagenameZWDVW

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

Below is a link to a Carter Marine Electric fuel pump I purchased on Ebay. This is the same Carter pump which can be purchased thru NAPA only this is less expensive. I am converting my mechanical pump to electric and needed to purchase the pressure switch (which comes with wiring diagram) which I purchased at my local Napa store....Hope this helps.
http://cgi.ebay.com/ebaymotors/New-...010QQitemZ200156289819QQrdZ1QQsspagenameZWDVW

Thanx for the link!
The Airtex pump I currently have (which I found out isn't Marine approved now) was $120 and looks the same as that.
Also, the old carter pump I pulled off the boat was the exact same as the one on e-bay. The Airtex is going back today and they better exchange it for the Carter Marine series. The funny thing is that on the bottom of the Airtex pump it says Carter on it which I'm wondering if the two companies are in together....
I should still test my old Carter pump as I still have it. I just figured it was bad or had weak pressure. Never know though cuz it might be good then I can save her for a spare!

 

[AaronWhitt82]

Re: Fuel Pump running with Key ON & Motor off...

UPDATE: I called Airtex and spoke to a tech guy and gave him the part number off my fuel pump. He said that IT IS MARINE APPROVED. I asked him why it said in the directions that it wasn't for marine or aircraft use..... He said he's not sure and maybe the wrong directions got put in there, but he is 100% sure that is Marine approved so I'm going to stick with it.

I also ordered a new oil pressure switch which will hopefully resolve my fuel pump running with key on and motor off situation.

I'll keep updated once I get new switch and install it to see how the fuel pump functions......

 

[180shabah]

Re: Fuel Pump running with Key ON & Motor off...

Get it in writing. Keep a copy on the boat and one at home for insurrance.