Fuel Pump Failure - Vintage Mustang Forums
 
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post #1 of 5 (permalink) Old 05-22-2019, 10:06 AM Thread Starter
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Fuel Pump Failure

I run an electric fuel pump on my 67 - stock fuel tank and the pump is mounted just in front of the tank, down low, bolted to the trunk pan.

My problem is that the pumps are only lasting a few years before they give up and die. I ran Carter pumps for the first 2 or 3, then I went to a Holley Black pump that I thought would last - it did for about 3 years! Everything seems to be fine for awhile, but I mostly drive to the track, thrash the car for the weekend (road racing, not drag) and then drive home. I'm wondering if it could be the heat from the pumpkin. I am using a relay with a good connection to power, but the ground is to the body, so perhaps it's electrical and causing the pump to work harder.

Any thoughts on what the problem might be? At this point I'm considering going back to a mechanical pump, but would prefer to keep the electric if at all possible.
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post #2 of 5 (permalink) Old 05-23-2019, 10:29 AM
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Iíve run a few different pumps and fuel line designs using carbs, Iím currently running FAST fuel injection. What I came to know in making the transition is that a return line adds life to the pump by allowing it circulate the fuel (keeping the pump cooler) rather than having the pump working into what is almost a dead end. So thatís number one, cooler pump by recycling with a return line. Barry Grant used to have information on this on his web site, not sure if itís still there, in fact Iím not sure if Barry Grant is still in business. BG also has the fuel log for the return line, youíd also need to change to a different regulator, simple huh? Lol. So there are a few things to do, but your pumps will live a longer healthier life.

Another thing I came to realize in the conversion is that, a pump is happier in the fuel cell and using the fuel itself to help cool the pump. Plus it does away with mounting issues. If your using a fuel cell that requires bladder replacement every three or five years like mine (mine is 5), you might consider converting to an in tank pump with the next replacement. You can order direct from Fuel Safe and they will do everything, all youíll have to do is connect lines and power.

There are also several manufacturers making in tank pumps that you simply drill a big hole in the top of the tank and screw down their pump. This assumes you donít have a FIA bladder style design. Thatís a Simple way to solve the issue as well, I canít recall if they are dead end pumps or return line designs. Just an idea.

Good luck,

Darrell George
'66 Fastback
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post #3 of 5 (permalink) Old 05-23-2019, 11:05 AM
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The return style regulators will help with heat soak and vapor lock issues as well as using an in tank pump will aid in pump life. I'm using an Aeromotive in tank pump as well as an Aeromotive return style regulator mounted on the firewall. This insures the coolest fuel possible going to the carb. Higher pressure EFI can use a regulator mounted at the tank because the higher pressures aren't as prone to vapor lock as the low pressure carbs are.
Be sure you have a fuel pump safety switch wired in to cut the fuel pump in the event of an accident.

John

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Last edited by j persons; 05-23-2019 at 11:15 AM.
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post #4 of 5 (permalink) Old 05-23-2019, 01:21 PM
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Quote:
Originally Posted by j persons View Post
The return style regulators will help with heat soak and vapor lock issues as well as using an in tank pump will aid in pump life. I'm using an Aeromotive in tank pump as well as an Aeromotive return style regulator mounted on the firewall. This insures the coolest fuel possible going to the carb. Higher pressure EFI can use a regulator mounted at the tank because the higher pressures aren't as prone to vapor lock as the low pressure carbs are.
Be sure you have a fuel pump safety switch wired in to cut the fuel pump in the event of an accident.
Not that Iím the expert, but Iíd suggest the regulator is best positioned when itís closest to the carb or injector fuel rail: Mounted to the firewall as youíve done yours for example. This allows the return to be a low pressure flow rather than if the regulator was in the back which would require the pump to pressurize both the supply line from the tank and nearly all the return. Iíve not seen anyone mount the regulator in the back and mention it only because you commented that it was ok. Iíd suggest regardless of pressure, itís best under the hood and on the firewall or fender depending on space and a bad design if back at the tank/cell.

A discrete kill switch can double as a theft deterrent, and as you mentioned itís important.

Below is a Barry Grant design, this one has two carbs and an external pump, but the idea is there for someone who wants to see/understand a return system.
https://images.app.goo.gl/Ddip1rtzNURxpE5K6

Summit has this Barry Grant fuel log that can also be used to build a simple return system, just add the return regulator.
https://www.summitracing.com/parts/pfs-10416/overview/

One last thought, the pump in the fuel causes the fuel to be warmer than if the pump were external to the tank. Pumps generate heat, no way around that. Pumps in tanks with low fuel levels generate significant heat. So itís not actually the coolest fuel as you commented, itís the coolest pump when inside the tank. Life is a trade off, we have to accept either warmer fuel or potential pump failure from heat. The coolest fuel would likely have an external pump with its own cooling mechanism, maybe a fan or something more exotic.

Anyway, not calling you out on this stuff, just commenting based on my experiences and reading.

Darrell George
'66 Fastback
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post #5 of 5 (permalink) Old 05-23-2019, 01:52 PM
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It's been noted on OEM stuff for years that people in the habit of running around close to empty tend to need their in-tank fuel pumps replaced. Versus folks in the habit of never letting the fuel go below a 1/4 tank. Their pumps tend to last the life of the car. Everyone's finger points to them running cooler and lasting longer with more fuel.

Short version is that, yes, the cooler you can keep the pump running the longer it will live. And differentials run hot enough that some racers run coolers on THEM. So moving it away from the rear end wouldn't hurt.
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