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.
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).
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.
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 http://www.ford-trucks.com/forums/me...fab-39511.html