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Old 09-10-2019, 12:45 PM
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Where to mount electric fuel pump

In response to my possible vapor lock issue on my 68 Ford Fairlane, I'm thinking about going with an electric fuel pump.

I've mounted these on other cars but my Fairlane seems to prevent a problem. Your supposed to mount an electric pump below the tank since they push fuel.

The bottom of the tank seems to be the lowest thing on the car other than the spring shackles. I thought about mounting it on the frame rail but the tank is still lower.

This photo is horrible since the car was never undercoated but you might see the fuel tubing. This is about halfway between the tank and engine.

Could I just cut the tubing here, remove a section and mount the pump here? As long as I have flow going to the pump does the location really matter?

Or does the pump really need to be near the tank?

I realize the pump needs head pressure to work. I work at a chemical plant.
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Old 09-10-2019, 01:10 PM
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Quote:
Originally Posted by jseabolt View Post
In response to my possible vapor lock issue on my 68 Ford Fairlane, I'm thinking about going with an electric fuel pump.

I've mounted these on other cars but my Fairlane seems to prevent a problem. Your supposed to mount an electric pump below the tank since they push fuel.

The bottom of the tank seems to be the lowest thing on the car other than the spring shackles. I thought about mounting it on the frame rail but the tank is still lower.

This photo is horrible since the car was never undercoated but you might see the fuel tubing. This is about halfway between the tank and engine.

Could I just cut the tubing here, remove a section and mount the pump here? As long as I have flow going to the pump does the location really matter?

Or does the pump really need to be near the tank?

I realize the pump needs head pressure to work. I work at a chemical plant.
Wherever you put it, it will probably work fine as it has to draw some vacuum. Just make sure you don't mount it where the hoses can get easily snagged if you accidentally run over stuff and keep away from exhaust. In a street car I would mount it where it fits the best, and this is where you are describing. Mount the pump on rubber on something solid or it will be noisy. Don't forget to use a fuel pump relay, proper gauge wire, and to bypass the mechanical fuel pump.

p.s. I like old Fairlanes - in the past I had a 67 390 GT and a 69 Fairlane 500 2Dr HT pretty much just like yours.

Last edited by 2001Blazer4x4; 09-10-2019 at 01:22 PM.
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Old 09-10-2019, 03:54 PM
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If the tank sits lower then the frame your only choice is an in tank pump.

Electric fuel pumps can not "suck" fuel they must be submerged at all times to work properly.
I have had them pull fuel up to the top of a tank before, then had the line drop down. But this severely reduces the pumps life. Your better off with a in tank pump that minimizes the lifting.

If your tank is low one other option is a sump between the tank and diff. Your using the diff as protection. Then you can mount the inline pump next to the sump.

This requires dropping, drying, cutting, and welding, your tank. But the final result is something that will keep that pump fed.
A small v shaped baffle on the sump itself installed before welding will help to keep fuel in the outlet and inlet port area so during hard acceleration you do not have starvation. Ideally the sump would be mounted in the back of the tank to prevent this. But I assume it would be highly exposed there.

I have simply emptied a tank in the past, dropped it, dried it, found a double wall corner on the side without exhaust, drilled that corner as low as possible, tapped that corner, installed a male to tap/male to compression fitting to female compression fitting. Which let me snake a line against the bottom of the tank. I then ran the line to the to the pump which was located in the corner by the axle.
I tig welded around the tapped area sealing in the threaded male fitting in there. It worked.
I fed the return line to a T in the neck using that vent line(there were additional
vents) as a return line to prevent needing to tap the tank again.
I would have been better off using an in tank pump.



Your best bet here is to drop the tank and install an intank electric pump, new sending unit, and new straps. Run flexible lines off the top of the pump to the side of the frame. This allows for easier tank installation/removal as well as allows you to keep your hard lines mostly straight.

Install a regulator with return. The regulatior will maintain a set psi of fuel which depending on the size of your rail/floats should be enough to prevent starvation even when the front wheels lift. The return will circulate the fuel keeping it cool while filtering it more.

Last edited by cerial; 09-10-2019 at 04:02 PM.
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Old 09-11-2019, 12:16 AM
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Low and close. Some pumps don't self prime well, others do. For those that have priming problems you just prime them the first time and they are good to go as long as you don't run the tank dry.


Modern fuel is designed for fuel injection so it from the electric pump, which is in the tank, to the injector is under pressure. Since injection has all been sequential, port injection since 1996 and some back as far as 1986 or 87, there is scant time for vaporization which must take place in the cylinder. So modern fuel has a lower vapor point than old fashion carburetor fuels to facilitate quick vaporization. For a carb'ed engine with a mechanical pump on the engine pulling fuel the length of the vehicle this has led to significant vapor lock issues.


My preferred method on the street is to use an inline pump intended for older low pressure TBI systems choosing a version that develops 20 psi max. Then plumb this to a bypass regulator under the hood such that you furnish the carb with 5 to 6 psi while the remainder returns to the tank. A bypass prevents forcing the pump to work against a near dead head when the engine is idling which keeps pump and fuel cooler. The bypass can return to the tank by purchasing a flex length of filler pipe hose with a vent tee in it. Or tee into the feed line ahead of the pump, this gives the looped fuel a little time to cool before going back through the pump. Self bypassing pumps tend to overheat the fuel and you end up back at vapor lock. So even on a self regulating pump set it higher than the carb needs, use a bypass regulator at the proper pressure under the hood then send the difference back to the pump intake side. Arrange the regulator so the feed line to the carb is as short as reasonable. Use fuel injection hose where hose is used as it is designed for higher pressures should regulation go wrong to the high side.


Electric fuel pumps should get their power from a 3 way oil pressure switch. This switch turns on the pump when cranking then switches over to controlling the pump in the run position of the key switch as it sees oil pressure. In an accident, if oil pressure is lost because the engine stalls or is shut off for other conditions beside the turned off with the key switch, the loss of oil pressure shuts off the pump preventing fuel spillage at the carburetor.


Bogie
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Old 09-11-2019, 09:31 AM
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I had horrible luck with a Barry Grant pump mounted about even with the center of the tank, it would suck air and never recover unless the tank level was above the pump. No other changes than replacing it with a Holley "black" in the same mount and it would run (way below 1/8 on the gauge) until I'd get nervous enough to fuel up.

Russ
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Old 09-11-2019, 12:35 PM
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Until I can get on my computer, so I can elaborate more, I came up with an idea. Why not "glue" a bracket to the bottom of the tank so the pump will sit below the tank and use the drain port to feed the pump?

The drain port is a 1/8" NPT pipe plug so I'll have to feed the pump using a 5/16" fuel nipple then use a 3/8" outlet coming off the pump to feed the fuel line above the sending unit. Then just cap off the port on the sending unit.

The line coming off the mechanical pump is 5/16" anyway.

My theory is since an electric fuel pump will flow more, eventually the line will fill up with gas when the float valve is closed.

Since this is not a high performance 302 engine (2 barrel Autolite at that) I doubt fuel starvation would be an issue.

So what about this glue? I have used 3M structural adhesive, RTV and if it has not dried up I've got a tube of some 3M urethane leftover when I glued the windows into their tracks.

Just get the surfaces down to bare metal, apply it and use a sissor Jack to hold it in place until it cures . I've actually done this before.

See where my finger is pointing. This is where I want to mount the pump. Only issue is I need to be careful and not hit something and rip it off since the car is lowered.

I pulled the plug out and gas shot out like gangbusters.

Only a bit of crud came out. Not bad for a 51 year old car.

Also I took a photo of a fuel pump I mounted on my turbo Yugo if you can see around the cob webs. This car has been off the road for sometime.

Its a GM throttle body pump. More on that later. That was mentioned as a suggestion. That is a story in itself. I'll comment on that later.
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Old 09-11-2019, 12:50 PM
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This is the fuel pump I ordered.

https://rover.ebay.com/rover/0/0/0?m...2F222757644547
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Old 09-11-2019, 01:12 PM
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If I am looking at that correctly using that plug then dropping down an inch to a 2" diamiter pump is going to put that pump below the diff.

That is a no on safety in my book. Thats actually saying something. I would drive something with only one wheel to stop before running a lowered car where the fuel line could be ripped free. I have scraped tanks over speed bumps before in lowered rides. It is not something that you do twice before fixing the issue or installing protection.



Your left with raising the tank, installing a smaller tank, or installing an in tank pump.

I would go with an in tank pump here.



Panel bond is amazing stuff. My money is on the gasoline breaking it down over time though. You may get several months out of it sealing. But eventually I feel it would fail leaving you with a slow leak that would quickly turn into a larger one.


Get an in tank pump.
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Old 09-11-2019, 01:49 PM
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Quote:
Originally Posted by cerial View Post
If I am looking at that correctly using that plug then dropping down an inch to a 2" diamiter pump is going to put that pump below the diff.

That is a no on safety in my book. Thats actually saying something. I would drive something with only one wheel to stop before running a lowered car where the fuel line could be ripped free. I have scraped tanks over speed bumps before in lowered rides. It is not something that you do twice before fixing the issue or installing protection.



Your left with raising the tank, installing a smaller tank, or installing an in tank pump.

I would go with an in tank pump here.



Panel bond is amazing stuff. My money is on the gasoline breaking it down over time though. You may get several months out of it sealing. But eventually I feel it would fail leaving you with a slow leak that would quickly turn into a larger one.


Get an in tank pump.
I was talking about just using the urethane or panel bonding epoxy to secure a mount to the bottom of the tank then bolt the pump to that. Since I don't want (or can't) drill holes in the bottom of the tank to mount the pump directly to the tank. Be yeah, your right, I really don't want the pump vulnerable. Just trying to come up with ideas.

While re-thinking about it, I have another idea. The original tubing points upward runs, makes a bend, runs along the body, then down again. In other words the way the original tubing is routed that would not provide any head pressure to the pump. Since I guess the original mechanical pump "sucks".

My current idea is to still use the drain port and run a new metal line along the bottom of the tank and downwards to the frame.

Then mount the pump to the side of the frame there like most people do and connect the original tubing going to the engine to the outlet of the pump. Well this is a uni-body car but you get the idea.

As long as I have good flow to the pump, is that all that matters?

As far as using an in-take pump goes. I looked into this but so far have not found anything that doesn't cost a couple hundred dollars. Also I've been struggling to get the original sending unit out. It's rusted pretty bad. It's just like the one on my MGB using the collar.

I was going to replace it while I had the tank drained. For some reason the guage only goes to 3/4 tank but is accurate once it get's below 3/4 tank. I also thought that there was a bronze sock on the pickup that might be getting plugged but someone told me they didn't start installing these until the early 70s. Since I drained the tank and nothing came out, I don't think having a plugged pickup is the problem anyway.

My 77 MGB uses an electric fuel pump mounted below the trunk and just a supply line going to the carburetor. No return line or regulator. I have never experienced any vapor locking with that car. In fact it's one of my easier cars to start in hot weather. That's why I'm wondering if it's really necessary to run a return line back to the tank.

I hear what your saying and all. I turbocharged my Yugo and had to drop the tank about three times before getting it right. I ended up having to use the 5/16" vapor line as the new return line. I drilled a hole in the bottom of the tank and soldered a fitting for a 3/8" fuel fitting. This is what supplies the GM throttle body fuel pump. I had to use a larger return line because my regulator couldn't dump enough fuel back so I flooded the carburetor at times. The pump I used was for a GM throttle body and deadheaded at 20 PSI. There are currently no hoses connected to the sending unit.
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Old 09-14-2019, 10:26 AM
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I can't say I'm crazy about the exposed position nor the attachment method. The OEM's go to great lengths to use structure to protect the fuel lines with good reason. Especially with an electric pump that will keep on pumping till the electricity is shut off this is a big concern. Having seen a few fuel fires in my life it's not something I want to participate in, thank you very much.


Bogie
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Old 09-14-2019, 02:19 PM
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I'm just going to mount it on the side of the frame rail and hope it has enough head pressure to feed it and see what happens.
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Old 09-14-2019, 02:42 PM
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Quote:
Originally Posted by jseabolt View Post
I'm just going to mount it on the side of the frame rail and hope it has enough head pressure to feed it and see what happens.
A word of warning: Do not mount the pump directly to the frame rail. The droning of the pump will transfer all through the car and make you insane in about 10 minutes. Mount heavy molded rubber to the frame rail and mount the pump to the rubber. Ask me how I know.
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Old 09-14-2019, 05:11 PM
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I know they make fuel pump mounts. They look like miniature motor mounts.

But I've got some black rubber material about 1/4" thick I found somewhere. I was planning on cutting out of piece the size as the base and placing it between the frame rail and pump.

I did the same thing when I mounted that GM throttle body pump to the body on my Yugo. I can't tell that there is much vibration.
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Old 09-15-2019, 06:08 AM
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Quote:
Originally Posted by jseabolt View Post
I know they make fuel pump mounts. They look like miniature motor mounts.

But I've got some black rubber material about 1/4" thick I found somewhere. I was planning on cutting out of piece the size as the base and placing it between the frame rail and pump.

I did the same thing when I mounted that GM throttle body pump to the body on my Yugo. I can't tell that there is much vibration.

Some thick rubber won't do much if the bolts will transfer the vibration. The little motor mounts are the way to go. Although if you use what you have, you can help it further by making rubber washers from the material to help isolate the vibration through the bolts.

As far as the location, I'd go with your original location and a Carter pump will self prime no problem. Once the lines are full of fuel the pulling effect is sort of minimized. A Carter will do the job just fine. With the Carter the mounting is improved also, as it hangs from 3 rubber bushings and they sell an additional frame mount kit. I didn't even use the motor mount kit, but my car is a little loud.
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Old 09-15-2019, 06:42 AM
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Getting back to your original problem. I don't think a electric FP is the answer. I would look at the float and needle in the carb. Clean it up. Crank the engine with the line to the carb disconnected to see what kind of flow you are getting. Clean out the fuel lines and tank . This car ran good for years for you. Just needs attention. You won't like the E FP.
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