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Old 09-17-2002, 09:09 PM   #1 (permalink)
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Electric fuel pump SBC350

I am considering running an electric fuel pump on my YJ, that has a 350 in it. I was wondering what I would, or should do about the return line for the gas tank. Most pumps have one line in, and one line out. What should I do with the return line?

This is really a two part issue. I am considering the electric fuel pump so I can route my lines away from the exhaust underneath. Right now, the lines are running right next to the exhaust, and I think this is causing serious vapor lock. At least this is what I have been told. Here is the problem. After running the Jeep for a while, and letting it sit for 20 minutes or so, it runs terrible for about 5 minutes once I restart it. I don't mean that it runs a little bit bad, I mean it will just stall out if I even give it a little gas. Now, if I start it up and immediately floor it for about 5 seconds, it is fine.

I am lost here. The engine has the Holley Truck Avenger carb on it, if that makes any difference. It is a 350, .030 over. Stock heads and a mild cam.
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Old 09-18-2002, 05:54 AM   #2 (permalink)
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So basically, you're running a carb'd 350 and you want an electric pump? Have you thought about how to shut the pump off when the engine isn't running, but the key is in the run position? Any reason why a good old fashioned mechanical won't work for you?

Bryan
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Old 09-18-2002, 06:17 AM   #3 (permalink)
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I think you're better off just putting some insulation tape around that line where it comes close to your exhaust system. Thermoshield 3000 works awesome for this (and it sticks like a demon) but it's kinda expensive...
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Old 09-18-2002, 06:33 AM   #4 (permalink)
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Quote:
Originally posted by Oxjockey
So basically, you're running a carb'd 350 and you want an electric pump? Have you thought about how to shut the pump off when the engine isn't running, but the key is in the run position? Any reason why a good old fashioned mechanical won't work for you?

Bryan
Hooking the pump up correctly is the least of my problems. My main question was concerning the return line. The mechanical pump is working, I was just inquiring as to whether or not the electric pump was something I should try.
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Old 09-18-2002, 06:56 AM   #5 (permalink)
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There should be two hookups on the tank, one for feed, one for return (right from the factory). Oddly, I'd consider that the least of your worries because it's already there.

You can use an oil pressure switch for the pump relay so it won't pump if you don't have oil pressure. Some what important if you're in an accident.

And I'm not sure why you think this will let you route the hoses differently? Maybe the best bet is to wrap it. I had to take two LARGE hose clamps and clamp a piece of galvanized sheetmetal around my frame for my peace of mind.

Bryan
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Old 09-18-2002, 08:53 AM   #6 (permalink)
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Quote:
Originally posted by Oxjockey
There should be two hookups on the tank, one for feed, one for return (right from the factory). Oddly, I'd consider that the least of your worries because it's already there.

You can use an oil pressure switch for the pump relay so it won't pump if you don't have oil pressure. Some what important if you're in an accident.

And I'm not sure why you think this will let you route the hoses differently? Maybe the best bet is to wrap it. I had to take two LARGE hose clamps and clamp a piece of galvanized sheetmetal around my frame for my peace of mind.

Bryan
I'm not sure what my plan is either. My question is this: since the electric pump has one line in and one line out, I am left with the return line that has no where to be hooked up. Mabe I am missing something here. Right now, my mechanical pump has a line in, a line out and the return line all hooked into it. At any rate, I may just make a heat shield for it and be done with it.
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Old 09-18-2002, 08:57 AM   #7 (permalink)
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I gotcha now. You mean the origin of the return line. No idea.
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Old 09-18-2002, 09:37 AM   #8 (permalink)
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You guys touched on something here that I would like to stress the importance of, having an electric fuel pump that will shut off with the key on. A friend of mine scored a '62 Willy's for $50 and we got it running one afternoon, the fuel pump wa shot so we wired up an electirc we had laying around, well, after a short joyride we turned around and the Buick V6 back fired, casuing the whole front clip to go up in flames, with the electric fuel pump still chugging away feeding the fire until the battery melted enough to break the circut. If you'er going to run an electric pump, make sure you wire it in such a manner that it will stop puping when the engine stops running.
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Old 09-18-2002, 02:05 PM   #9 (permalink)
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I may be wrong here, but I believe you do not need a return line for an electric fuel pump on a carb'ed engine. The return line is primarily used in FI setups to maintain constant pressure on the fuel rail while still providing adequate flow. On the carb your float will maintain the fuel level in the bowl and shutoff flow from the fuel pump if the bowl is too full. If you are concerned about fuel pressure you can (and probably should) install a pressure regulator in the line. You can get one from Summit for around 50 bucks.
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Old 09-18-2002, 10:03 PM   #10 (permalink)
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Quote:
Originally posted by sothpaw
I may be wrong here, but I believe you do not need a return line for an electric fuel pump on a carb'ed engine. The return line is primarily used in FI setups to maintain constant pressure on the fuel rail while still providing adequate flow. On the carb your float will maintain the fuel level in the bowl and shutoff flow from the fuel pump if the bowl is too full. If you are concerned about fuel pressure you can (and probably should) install a pressure regulator in the line. You can get one from Summit for around 50 bucks.
Ok, I can see that. Now, do I just plug the return line from the tank?
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Old 09-18-2002, 10:28 PM   #11 (permalink)
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fuel return line

The job of a fuel return line is to retturn unused fuel to the tank,helpping stop vapor lock.Electric pumps need fuel flow to cool.It is posible that you have a carb floodding prob. not a vapor lock prob.
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Old 09-18-2002, 11:31 PM   #12 (permalink)
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Re: fuel return line

Quote:
Originally posted by michael orlandi
The job of a fuel return line is to retturn unused fuel to the tank,helpping stop vapor lock.Electric pumps need fuel flow to cool.It is posible that you have a carb floodding prob. not a vapor lock prob.
I imagine it could be a flooding problem. Any ideas what might cause it to flood just by it sitting there? I have asked many people on many forums, and no one has been able to come up with the magic bullet yet. I have adjusted the float levels many times. I have jetted, and re-jetted, and nothing seems to help. One school of thought was fuel percolating in the float bowl. I added a wood spacer and routed the fuel lines as far from any sources of heat that I could...and nothing helped. I am just fresh out of ideas.
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Old 09-19-2002, 06:28 AM   #13 (permalink)
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Quote:
Originally posted by Brackneyc


Ok, I can see that. Now, do I just plug the return line from the tank?
If you aren't using it, then yes.

With regards to the other comment above about the pumps needing fuel flow to cool them (unless I misread it), most electric pumps mounted outside the fuel tank are air cooled, not liquid, so the amount of flow through the pumps would have no effect on cooling.
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Old 09-19-2002, 06:35 AM   #14 (permalink)
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Re: Re: fuel return line

Quote:
Originally posted by Brackneyc


I imagine it could be a flooding problem. Any ideas what might cause it to flood just by it sitting there? I have asked many people on many forums, and no one has been able to come up with the magic bullet yet. I have adjusted the float levels many times. I have jetted, and re-jetted, and nothing seems to help. One school of thought was fuel percolating in the float bowl. I added a wood spacer and routed the fuel lines as far from any sources of heat that I could...and nothing helped. I am just fresh out of ideas.
Have you checked the throat of the carb at idle to see if fuel is overflowing from the bowl? That would indicate that either there is an issue with the way you adjusted the float or the float itself is bad. If you are running a high pressure/volume fuel pump it could also cause similar issues.

Don't know how many miles are on this carb, but you may also want to consider looking at the accelerator pump and power valve.

Lastly, does it have a manual or electric choke on it and how do you have it adjusted? If it is adjusted improperly the engine will run poorly until it warms up.
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