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Discussion Starter · #1 ·
Hi everyone, before bothering anyone with this question, I looked for some of my old post re. this subject matter but couldn't find what I wanted. So, I'll explain again. The electric fuel pump on my gasser had been shutting off for reasons I didn't know. I tried a few suggestions which appeared to have worked. The car was good for the longest time. Today, I went out for a ride in it and about 1/8 mile from home, at a busy intersection with buses wanting to go through, the car died. Had to wait about 10 minutes and it worked again. Drove it home and put it away. The only suggestion that I didn't do back then, was put in a relay switch. This is the only thing left to do other then buy another fuel pump. My question is: where and how do you plumb this into the line? My fuel pump works from the ignition switch, to a toggle switch and then to the fuel pump. It's a Holley pump and they wanted it hooked directly to the ignition switch. It would go on/off with the switch. I didn't want it this way because in case I had the ignition switch on for some reason, I wanted to control the pump also. So, I've never done a relay before and could use a little guidance. Thank you very much, Carmine.
 

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What a relay does is use your switch to activate the coil on the relay rather than powering your electrical load directly, in this case your fuel pump.

So you run the wire that used to go to your pump to the coil terminal on the relay. This doesn't take much electrical power so you don't need big wires. Then the power contacts on the relay are controlled by the coil. You run a wire from the battery to one power contact on the relay and from the other power contact on the relay to the pump. This should be big enough wire to carry the full electrical load of the pump.

If your battery and your pump are at the rear of the car, you only have a short distance from the battery to the pump when you use a relay. The wires that run to and from your switches at the front of the car don't carry a significant load.
 

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Hey Carmine, I'm afraid that installing a relay wont fix your issue (IMHO). A relay is definitely the correct way to do it, but not having one will not give the symptoms you are describing.
First of all, intermittent problems are a bear to figure out. But if you can catch it in the failure mode, go back with a meter (or test light) and see if you have voltage. I bet you will. If you do, it's your pump.
If you don't then yes, wiring and relay.
I dont know why if it is a wiring issue, it would just start working after a time out.
A bad pump can do that however.
Catch it in the act, then you will know for sure.
I really wish you luck with this one.
 

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also make sure you have a large enough wire going to the pump. I always use 12 gauge. 14 gauge for efi intank pumps.
 

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What a relay does is use your switch to activate the coil on the relay rather than powering your electrical load directly, in this case your fuel pump.

So you run the wire that used to go to your pump to the coil terminal on the relay. This doesn't take much electrical power so you don't need big wires. Then the power contacts on the relay are controlled by the coil. You run a wire from the battery to one power contact on the relay and from the other power contact on the relay to the pump. This should be big enough wire to carry the full electrical load of the pump.

If your battery and your pump are at the rear of the car, you only have a short distance from the battery to the pump when you use a relay. The wires that run to and from your switches at the front of the car don't carry a significant load.
Great explanation Rick :tu
 

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Discussion Starter · #7 ·
Hey Carmine, I'm afraid that installing a relay wont fix your issue (IMHO). A relay is definitely the correct way to do it, but not having one will not give the symptoms you are describing.
First of all, intermittent problems are a bear to figure out. But if you can catch it in the failure mode, go back with a meter (or test light) and see if you have voltage. I bet you will. If you do, it's your pump.
If you don't then yes, wiring and relay.
I dont know why if it is a wiring issue, it would just start working after a time out.
A bad pump can do that however.
Catch it in the act, then you will know for sure.
I really wish you luck with this one.
When the pump is operating, I can not only hear it but also feel it inside the car. I don't mind this and kind of expected it. When it stops working, you don't hear or feel it at all. Nothing. My illuminated toggle switch tells me juice is still going to it but the pump isn't responding. It takes about 8-10 minutes or so before it will work again (cool down??). It acts like it shuts itself off automatically because of an internal problem; perhaps overheating?? After it does recover, I'm either home or close to home, so I don't challenge it anymore to see how long it will last between episodes. I've had it on shorter rides before, 10 miles or so, with no problems. This ride was about 20-25 continuous miles, never shutting it off. The pump is mounted real close to the tank and below it for a gravity feed. The wire from the fuse panel is designated for the electric fuel pump. Not sure of the gauge but looks heavy enough. And, that's all I know.
 

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Yep that's what I'm thinking......internal pump problem.
The only thing we are really testing now is the wire between the swtch and the pump. Since your switch has an indicator lamp, we know we have power at least to there.
If you really want to have some "fun", you could run a temporary wire that is connected to your pump (along with the one that is already there), run it inside the cab, connect it to a light or better, a volt gauge (or multimeter) and connect the other side of light or gauge to a ground.
Then just take it for a drive.
When the pump quits working, check the temporary light or guage. I predict it will be showing that you have full voltage.

Then once it cools down, or whatever, fire it up and head to your local "Fuel Pumps-R-Us".

You can get a relay while you are there. :)

Good luck
 

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an internal problem could be atributed to to small a wire therefore not enough voltage under load and the motor on the pump overheting and shutting off.
 

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Discussion Starter · #11 ·
Thank you everyone for your time and responses. I sincerely appreciate it.
Funny thing, I thought I had a relay switch, which I bought and didn't use last time, and I found it. I tried some other, easier remedies first, which I thought cured it, but it didn't. So I have a new relay switch and some good ideas, thanx from you kind folks, to work on. Will probably fool with this over the weekend and report back. Again, many thanx, Carmine.
 

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Carmine....What does the relay look like? Can you post a pic of the bottom, where the terminals are?
 

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Back when it first happened I would have left the ignition on and gone to the trunk and wrapped on the fuel pump with a small hammer or anything I could find to smack it with. If it starts pumping, replace the pump. Well actually I may have checked to see if it has voltage first. You can get a cheap test light for that. If it has voltage it's the pump, if it doesn't, it's the wiring. Pretty simple really.
 

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Discussion Starter · #14 ·
Carmine....What does the relay look like? Can you post a pic of the bottom, where the terminals are?
David, I wish I could, but I can't do it at this time. I'm sorry. I can tell you I bought it at Jegs and it's a Jegs brand. I do believe there are 4 different color wires involved. It also came with an instruction sheet. The hook up looks to be simple enough. I'm just not sure what I am going to do first.
 

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Discussion Starter · #15 ·
Back when it first happened I would have left the ignition on and gone to the trunk and wrapped on the fuel pump with a small hammer or anything I could find to smack it with. If it starts pumping, replace the pump. Well actually I may have checked to see if it has voltage first. You can get a cheap test light for that. If it has voltage it's the pump, if it doesn't, it's the wiring. Pretty simple really.
My gasser has a pretty decent rake to it and the pump would be hard to get to without jacking it up. The illuminated toggle switch remains lit even when the pump takes a break. This tells me that juice is flowing at least to this switch and I'm assuming (bad word to use) to the pump itself. I do agree that if it does have juice to it even after stopping, it's the pump.
 
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