Need an in-tank fuel pump help please
 

I need an in-tank fuel pump for a 1968 Mustang gas tank I put into a 1952 frame per the instructions on this site. I have a 429 cu in motor that I can not fit a mechanical fuel pump on as the motor sits in the engine bay. Not enough room for the pump. I have had 3 in line fuel pumps that just quit after about 5 minutes of running and I have to wait for a while before the fuel pumps will start again. They were name brand pumps. I have cleaned out the tank, changed the filters many times, and I have filters before and after the pump. The pressure in the line at the carb when the engine failed went from 6-7 pounds to 0-2 pounds and stayed there. Luckily I got the truck home on 1-2 pounds of pressure every time this happens. I need an in-tank fuel pump but do not know what kind or where to get one. Can someone help?

Something must be wrong with your system. External pumps have been the mainstays of hot rodders for decades. Is the tank new, or from a boneyard? First thing I'd suspect is rust/dirt cratering the pump. Did you have a quality inlet filter on the pump? If your fuel pressure gauge has glycerin in it (liquid filled) drain the glycerin out or use a different one. What pumps and regulator were you using?

I agree that high quality external pumps should not be giving you these problems, they should run for years. Ross has already questioned dirt in the system, Here's an obvious but often overlooked possible culprit: a fuel filler cap that is not vented or the vent failed. This can prevent the pump from getting fuel from the tank after driving for a while. An electric pump, in line or in tank depends on fuel running thru it to keep it cool. If it starves for fuel the pump will fail. This can be a problem with the Mustang tanks installed under the bed if an aftermarket thru the bed fuel filler is used. Try replacing the cap with a new vented cap, or if you have an available bung in the top of the tank, try putting in a check ball type vent.
Another issue I have seen in the past is someone mounting the pump far from the tank. Electric pumps are pushers, not pullers, they need to be mounted as close to the tank as possible. If you have room for a filter before the pump, then you may have the pump mounted too far from the tank. Ross mentioned an inlet filter. This is a good idea, and is usually accomplished by using a "sock" or "teabag" filter on the end of the inlet inside the tank, the purpose being to prevent any trash in the tank from being sucked into the pump. A standard inline filter should go on the pressure side of the electric pump.
Do you have the pump wired to an "ignition hot" power lead so it runs only when the engine is running? On the same vein, a rubber fuel hose before the pump could be collapsing preventing the fuel from reaching the pump. Use only hard line from the tank to the engine bay.
I assume that if the pumps are failing soon after installation that they are being replaced by the manufacturer? Have you contacted their customer service/support people for help?
There are a couple companies making in tank fuel pumps for carbed engines, such as Holley, Carter and Aeromotive. Some are designed to shut themself off when there is sufficient pressure in the line, others use an external pressure regulator with a return line port that returns excess fuel back to the tank. None are cheap!

My first thought was same as Ax, a vent problem. This is what I would check first. The other he said is they are pushers, true, but as they are pushers, one should not create enough vacuum to collapse a good quality fuel hose to the inlet side. It also helps if they can be safely mounted below the fuel tank to assist with feed by gravity.

With the problems you are having, fix your issue first, if you put an in-tank pump with a vacuum/vent issue you will have the same problem with an in-tank pump and what kind of pain in the a$$ do think that will be to replace.

plus in tank units are 250.00 up.
With today's E-gas rubber fuel hoses are rotting from inside out.

1965/68 Mustang tank same, but I don't know of any source that offers an in-tank fuel pump for it. It wasn't until the 1980's when EFI was introduced, that in-tank pumps were installed.

So...to solve the problem, install an electric fuel pump adjacent to the tank on the frame rail or cross member. It's a pusher, so it has to be close to the tank to be efficient.

Buy a fuel pump block-off plate from any autoparts store and be done with it.

Plate is the same (bolt holes at 3 & 9 o'clock) for all 1952/90's FoMoCo OHV V8 engines except 351C/351M/400 (bolt holes at 12 & 6 o'clock).

As long as the pump is at or below the bottom of the tank, I would use a large metal-cased filter ahead of the pump. Put another ahead of the regulator and use whatever carb inlet filter your carb comes with. My electric pump clearly states in big letters on it, warranty void if inlet filter is not used. It comes with an inlet filter on it. I would also not start out with anything but brand new SS or coated steel fuel lines.

On my O/T car, which has EFI but uses an external Bosch roller-vane pump and a filter sock in the plastic tank, I lost a 2-week-old $175 pump to some grit that got thru the sock. I installed a metal filter in the suction line and have had 15,000 trouble-free miles since. (BTW, taking the tank out to flush is a 15+ hour job, and the filter socks cost $40 each, whereas the external filter cost $10 and installed in 10 minutes).

D1AZ-9A011-A .. Plastic Meshed Filter Screen aka 'sock filter' / 3/8" I.D. slips over the end of the fuel sending unit's pickup tube / Available from Ford/autoparts stores.

All 1957/79 FoMoCo vehicles except trucks with in-cab fuel tanks and Maverick/Comet/Pinto/Bobcat (use D1FZ-9A011-A 5/16" I.D.)

Great answers thanks. I took most of Saturday and tore the system apart. Then taking your suggestions built the system up again and here is what I now have:
(BTW-I removed my gas cap before testing and had it off for all tests, just in case. Also, already had a check ball vent in tank before first installation.)

1. tank was new, and before installing, made sure tank was clean.
2. Because tank is under frame, it is quite hard to get the fuel pump level or below the bottom of the tank, any suggestions will be greatly taken. Pump is a good 12 inches higher from bottom of tank to mounting on frame. (going up hill)
3. Have SS fuel line all thru system.
4. Have outlet from Mustang tank connected to 30 inches of 3/8 inch SS line with 3 inches of rubber fuel hose to metal fuel filter .
From first fuel filter I connected to electric Holley Red Fuel pump then again to a second metal fuel filter. From second fuel filter I have SS line run to firewall and connected to pressure gauge. From the pressure gauge I went to carb with SS line. The line from carb to fuel filter is insulated with 2000 deg covering to combat heat. All connections are with 3 inches of rubber fuel line. There is no fuel pressure regulator in the system cause Holley tech said no need to have one with the carb and the pump I installed. The carb will take 8 pounds or more of pressure and the pump is rated at 6-8 pounds of pushing force.
5. I rewired the pump electrical connections to go thru a switch instead of directly from the ignition. I used 14 gauge wire for the 12 volt lead from the battery to the pump therefore eliminating the problem of overheating that electrical system.

Okay, now I tested my new installation. Again, when truck first starts, pressure is about 5 pounds. While watching the pressure gauge, I can see the pressure going down slowly. It took about 10 minutes to get to 1-2 pounds. At this point I got under the truck and felt the pump. The bottom of the pump was cool to the touch but the top was very hot. I could not keep my fingers on it. I turned the truck off. Only thing I have not done yet is drain tank and inspect the inlet filter. I will do that today.

What else may I have not done or missed? p.s. talked to Holley tech and he is sending out new pump.

From the Holley installation sheet for the Red pump: "PUMP MOUNTING AND INSTALLATION:
The pump MUST be located below and as close to the tank as possible. This is necessary to allow for an adequate fuel supply.
The pump is designed to push fuel and not designed to pull fuel out of the tank. "

I agree with Ross, 36" away is not as close as possible to tank, 12" above bottom is not below. You can probably fudge one or the other a bit, but in this case both are excessive. From the symptoms it sounds like the pump is starving and cavitating.
I would build a mount for the pump that hangs in front (or behind depending where the outlet is located) of the tank that mounts the pump as low as possible, but just not so low that it is the lowest item under the truck. Is the prefilter the coarse mesh one Holly recommends? Are you using the lowest flow model Holly? If all else fails, you might consider an inline regulator with a return line so the fuel keeps circulating while the pump is running.

got it, I will see what I can do to fab a fuel pump mounting that can be safely installed below the tank outlet.

Yes the prefilter is a universal course mesh metal silver can type 3/8" in and out.

Need to keep you informed when I get things fabbed. Will take pics and show you what I got.

Thanks, I will not give up.

I might look at fabbing a mount out of 3/4" square tubing to mount and protect the pump.

Finally I might have completed, (except for paint), a mounting bracket for my Holley Red fuel pump. Here are some pictures showing what it looks like and I am open for suggestions as always. This starts from the fuel filler tube that comes from the drivers rear fender, thru the bottom of the bed and to the filler hole in the Mustang tank.
The tank was hung pretty much as described from the write-up from this forum. because of the way I installed the filler tube, the tank had to be mounted from the
bottom of the frame so it hangs down about 2 inches more than if you mounted it above the frame. I fabbed the bracket for the fuel pump out of 3/4" angle iron to mount the
box to the tank frame and used 12 gauge steel to build the mounting box. p.s. better pics can be seen at
https://www.ford-trucks.com/forums/m...fab-39511.html
https://www.ford-trucks.com/forums/p...119613&thumb=1

https://www.ford-trucks.com/forums/p...119613&thumb=1

https://www.ford-trucks.com/forums/p...119483&thumb=1

https://www.ford-trucks.com/forums/p...119387&thumb=1

https://www.ford-trucks.com/forums/p...119387&thumb=1

https://www.ford-trucks.com/forums/p...119387&thumb=1

Dennis,
I think you got a set up that will work. It's protected, it's low for the gravity feed. It should last, good job.

It will also serve as a heat shield when you get the exhaust in.

I recently came across this fuel line; it is all I'll use in the future:
http://www.gates.com/downloads/BarricadeBrochure.pdf

I came across it in a thread on a forum for riceburners, where there was a discussion to the effect that the decomposition of "regular" rubber hoses is accelerated when they have been wetted with gas, then opened to atmosphere. Gates recommends plugging all rubber fuel lines any time they are exposed to atmosphere.

Thanks to Ross and Dave for sticken with me and pushing me to do the better setup.
One last quick question, do I need a return line after the pump back to the tank for better flow? I have never done this before except on fuel injected vehicles and was skeptical about installing one. Will it not drop the pressure to the carb?

Ross, funny you mentioned the fuel line. I just bought some and will use it in my final install. Got it from corner store. expensive though. Should be worth it in the long run.

On an engine that uses as much gas as a 460, a return may not be needed, but I am a real fan of them. There has to be some restriction in the return tho, or the carb may starve at full demand. The return should also be from downstream of the regulator, this really helps them maintain set pressures at low flows. I'm looking for a filter with an integral return connection with orifice in it to put right in front of the carb, like the one below, but for plain hose connections.

PS have you tried out the new setup yet?

Totally agree with Ross, returned fuel is cooler and cleaner as it runs through the the filter again on its way from the tank. But as said you may need to move your regulator to the return line, or a limiting orfice, so that the carb always had pressure. All pressure is is resistance to flow.

Note that the most common regulators won't work in the return line; that is a different type. Most EFI systems use that type, it is called a back-pressure regulator. I don't know of any that control down to 4 - 5 psi.

Both Carter and Aeromotive make adjustable inline regulators for carb pressure with return line provision. I'd recommend using one You can then increase the pump pressure to provide adequate return flow for cooling pump.

Ross, I just got the rest of the connections complete and have NOT tried it yet. In fact, after reading the above from the 3 of you, (thanks) I will need to place an adjustable inline regulator that has a return in it so I can do what you all say to do for the best results. Well back to the store or web......Thanks for the heads up AX about the regulators.

I will have it all together, take more pics and show what I have done as soon as I can.

Where did you put the filter(s)?

I placed the first one between the tank and the pump:

https://www.ford-trucks.com/user_gal...256267&width=1

https://www.ford-trucks.com/user_gal...256269&width=1

And the second with the fuel pressure gauge just before the carb in the engine bay.

https://www.ford-trucks.com/user_gal...256266&width=1

https://www.ford-trucks.com/user_gal...256268&width=1

I am still struggling with the return system cause my Mustang tank has no return tube in it any where and I will have to install one
before I complete the total install of the fuel system. My pickups in the tank and the SW sender do not have tubes in them either.

Does the tank have a threaded bung on the top someplace?

Not at all AX. Before installing the tank, I had to drill and solder a 5/16" nipple in the top for a vent tube. The nipple is attached to a rubber tube that runs up from the tank thru the rear most passenger stake pocket to a check valve inside the pocket. This vents the tank.

I'm using a 73 blazer tank and sending unit, gm has a charcoal canister that was vented back to the tank. I removed the the piece and soldered a tube to it and directed it away from the pickup tube. Works fine.

Well, you could use a vented cap and use you vent line for a return, or install a T. If you use a T I'd restrict the vent line down to a fairly small diameter (air doesn't require much area to pass) so the pump doesn't push gas out the vent. Don't crank the pump pressure up too high, you don't need to return a lot of volume, just enough so there is gas circulating thru the pump when the carb float shut off, maybe a couple #s higher than the regulator.

Very likely a later model Mustang sending unit will fit your tank, and have a return fitting already on it. Otherwise add one to your sending unit, route to near the bottom of tank. I'm thinking of adding a tube to my filler tube, if you have a steel section you could too.

Thanks AX, that was another ? of how much needs to come back to the tank. John, this is a 1970 Mustang tank....it has nothing for usage except a filler hole and a sending unit hole. Plane Jane. Ross, I do have a steel section in my filler tube. Great place to put a return connection for the tank. In my installation that would be easier than the tank connection. I will try to do that instead of blowing myself up futzen with the tank. I will be back.

I wouldn't return just to the filler, tho, have the tube extend inside the filler down to near the bottom of the tank.

I agree with Ross, if you return to a tube installed in the filler neck run it down into the tank, but not too close to the bottom or directed at the pickup so it doesn't foam the fuel in the tank. gas conducts heat better than water so you don't need a lot of flow. It the stopping of the flow by the carb float causing back pressure that causes the pump to heat up, it's basically trying to push fuel thru a plugged line. think about what it might be like to be blowing liquid or even air thru an open hose then have someone suddenly repeatedly plug and release the end of the line while you keep blowing with the same effort.

An old main jet is the perfect orifice, and obviously adjustable (by replacing with a different size), if you can figure out how to incorporate one in the return line. I know guys on the HAMB have done just that, but usually that requires machining a custom fitting. The restrictor for a bypass oil filter, on the other hand, is a simple .060" orifice built into a pipe fitting, NPT threaded:
Orifice / restrictor fitting

BTW, you don't want too small a flow in the return, or it will just vaporize on its way to the tank.

Yes, a soft steady stream would be about ideal kinda like it's p*$$ing back into the tank. }>

:-X04 HA,HA,HE,HE got the picture AX. All depends how old one is.....as to how much flow there is......:D. I will try to get more pics for you as I complete the steps to try and get this done.

Had some honey do's today so I could not touch it but tomorrow is another day.

Ok here is what I had to do to get fuel to flow constantly.
This is a pic of the 5/16" filter with a 1/4" return line that was purchased from AZ and installed to get the return gas back to the tank. Also I still placed a pressure gauge and a clear filter in the pressure line. BTW the pump only puts 5-7 pounds of pressure into the system.

https://www.ford-trucks.com/forums/p...ctureid=139547


Another pic of the filter w/ a return line already built in.
https://www.ford-trucks.com/forums/p...ctureid=139546


This is a pic of my fab work to install a 1/4" bung and port into my filler tube. What you can't see is that the return line is fed thru the bung and put into the tank on the inside of the filler tube.
https://www.ford-trucks.com/forums/p...ctureid=139548

I ditched the Holley Red Pump cause I received very bad technical support from Holley. They couldn't answer my questions and satisfy my curiosity. I told the tech about my heat problem with the motor of the pump and he suggested to run a return line to help the pump not work so hard. That's why I did all this work in the first place. I received a replacement pump and it did the same thing. I returned them both for my money and purchased a Carter 4600HP and it works perfectly. So, as of right now my fuel pump and fuel line problems are solved until something else happens. Thanks to all for the great advise.

Picture of new fuel pump and filter.
https://www.ford-trucks.com/forums/p...ctureid=139550

Carter makes good stuff, and I like that it says straight out that it's good on gasohol. New layout looks good! Is there an orifice in the 1/4" connection on the filter?

No I did not put one in. I just tested the system before putting it back together and the flow to the tank seemed slow and steady enough that the pressure would stay. I ran the truck 15 minutes after it was together and the pressure on the gauge never went below 5 pounds while the flow was still running the same to the tank from the return line on the return filter. BTW was this filter with the return line in it what you might have been looking for? I could have fabbed a connection to place an orifice in the line, but after testing, it didn't look like I needed one. Also, sorry to hear about your heads.

Most of those filters already have an orifice in the return connection. If you look up the connection, you can see a little disc with hole that is pressed in. Do you have a P/N for it?

Alls well that ends well.