351 Windsor - Mechanical Fuel Pump versus Electric Fuel Pump?

DriftingCloud · #1 (**permalink**) 10-16-2015, 03:13 PM

My Holley Red Fuel Pump just died. I did actually make it home, however, so no complaints. It was 11 years and 9,800 miles old.

In thinking about replacing it, I actually like the idea of a mechanical fuel pump better than another electric fuel pump. I was hoping to solicit some comments from people who are running mechanical fuel pumps on their 351 Windsors.

My main area of concern is I'm using the front oil cooler and the two oil lines leaving the block would seem to interfere with where the mechanical fuel pump would mount. They are lower, but not by much (see image).

Thanks for any advice...

madmaxx · #2 (**permalink**) 10-16-2015, 05:03 PM

If at all possible go with mechanical. Electrical SUX. They are noisy, at times loose their prime, I loathe electrical ones so NOISEY!!!!

DriftingCloud · #3 (**permalink**) 10-16-2015, 05:39 PM

You've clearly described my Holley Red... LOUD!

Aside from that, I just think the mechanical ones are simpler and safer. No engine, no fuel flow.

cycleguy55 · #4 (**permalink**) 04-26-2016, 03:50 PM

Quote:

Originally Posted by madmaxx

If at all possible go with mechanical. Electrical SUX. They are noisy, at times loose their prime, I loathe electrical ones so NOISEY!!!!

I have an electric pump - I only hear it when the engine isn't running.

The only time an electric pump would lose its prime is if it's installed above the fuel tank. Keep it low and it s/b reliable.

joyridin' · #5 (**permalink**) 04-27-2016, 04:30 AM

Quote:

Originally Posted by madmaxx

If at all possible go with mechanical. Electrical SUX. They are noisy, at times loose their prime, I loathe electrical ones so NOISEY!!!!

You can sit in my car with the engine off and never hear it run. It never loses its prime either.

Dwight · #6 (**permalink**) 04-27-2016, 06:19 AM

DriftingCloud
did you remove the bottom of your fuel pump and clean out the screen?
I have a electric fuel pump that I use to pump gas out of tanks, etc. I have clogged the screen up and locked the motor up several times, in one day. I just remove the bottom plate and clean it out. I've beat and miss-used this pump for years but it still works.

I would not put it on a car but it does run.

No much to an electric fuel pump, motor, four vanes and a screen.

Dwight · #7 (**permalink**) 04-27-2016, 06:21 AM

I had a Holley high pressure pump on my Lone Star. 42,000 miles and 13 years, it was still working.

it had a bypass and was mounted low on the frame, passenger side, rubber mounts between frame and pump. I could only hear it running when the engine was not running.

Sydney · #8 (**permalink**) 10-16-2015, 06:15 PM

I have the same Canton adapter that your picture shows. I had to turn it 90 degrees toward the ground and put 90 degree fittings on the hoses. That gave enough clearance for the hoses to run under the fuel pump.

DriftingCloud · #9 (**permalink**) 10-16-2015, 06:28 PM

Excellent. Thanks! Did you build it that way or convert it from an electric fuel pump? Any chance I could see pictures of your setup?

Pete Munroe · #10 (**permalink**) 10-16-2015, 06:34 PM

You said you were able to nurse the car home...I assume there was some flow of gas?

Have you taken off the plate on the bottom? There is a filter screen that can get plugged up if some garbage gets into the fuel. You can carefully slip it out and clean it without tearing it up.

The pump impeller vanes are replaceable...also there is a pressure relief valve that perhaps is stuck open. Pretty sure Holley sells a basic rebuild kit that includes new impeller vanes.

When you take it apart, proceed slowly and the gasket is reusable...also you will see it gets imprinted with the fuel passages, so it should go back on the same way it came off.

They maybe noisy, but fixing the electric one that is already installed is probably easier than plumbing in a new mechanical pump.

If the electric motor is dead or groaning and turning slowly (worn out brushes?) probably out of luck.

DriftingCloud · #11 (**permalink**) 10-16-2015, 06:58 PM

Yes, there was some flow of gas, but my fuel pressure gauge was reading close to zero. Normally, it's about 6-ish psi. Occasionally, the fuel supply was obviously zero (even without the gauge) as I'd quietly coast to dead stop. I'd turn everything off, sit for few minutes, and try again. Four bouts of that finally got me home (I was only about 10 miles away).

The overall pre fuel pump filter is relatively new. I did remove the bottom plate of the Holley Red. There was nothing obvious going on in there. The fuel pump is making a worse than usual noise. Groaning and a little variable is the best description.

I agree about the replumbing task being more difficult than just replacing the electric fuel pump, but the failure got me thinking. Sometimes my mind is just happier with one philosophical approach over another. I keep leaning towards the simplicity and safety of the mechanical fuel pump, so I was just curious how others have solved the Canton adapter and oil lines being in the way.

wkooiman · #12 (**permalink**) 10-16-2015, 07:32 PM

I prefer mechanical too. I hate the whirring of the electric. The only way I'll go back is if I do EFI, and then I'll try for an in-tank pump. That would be on a non-Cobra, though. My Cobra will always have carbs.

DriftingCloud · #13 (**permalink**) 10-17-2015, 07:10 AM

Quote:

Originally Posted by wkooiman

My Cobra will always have carbs.

Ha ha... Yes. Back to my mind is just always happier with one philosophical approach over others. I understand all the advantages of EFI over carbs, but to me, carbs are right on a Cobra. If I wanted all the conveniences of a modern car, I wouldn't have my Cobra.

lippy · #14 (**permalink**) 10-16-2015, 07:49 PM

If a mechanical can provide enough flow, it's simpler, cheaper, and more reliable. I'd say below 550 HP or so mechanical should be fine. One advantage of an electric though is quicker starting because you can fill the bowl before starting the engine.

Sydney · #15 (**permalink**) 10-16-2015, 08:00 PM

Quote:

Excellent. Thanks! Did you build it that way or convert it from an electric fuel pump? Any chance I could see pictures of your setup?

I built it that way. I did just replace my 10 year old Napa pump with an Edelbrock 1725 unit a couple of months ago. Hard to tell in the pic, but the oil lines are right under the fuel pump.

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DriftingCloud · #16 (**permalink**) 10-17-2015, 07:02 AM

Quote:

Originally Posted by Sydney

I built it that way. I did just replace my 10 year old Napa pump with an Edelbrock 1725 unit a couple of months ago. Hard to tell in the pic, but the oil lines are right under the fuel pump.

Thanks! That helps.

Tommy · #17 (**permalink**) 10-17-2015, 04:30 AM

I'm old enough to have driven many miles in daily drivers with mechanical fuel pumps. I don't recall ever having one fail. That said, I went with an electric fuel pump in my Cobra for two reasons. First, when the weather gets cold, it may sit for a month or more between starts. I like knowing the float bowl is full before I press the start button so I don't work the starter and spin a dry engine too much. Second, my engine has a racing modified carburetor with no choke system. It needs a full shot of fuel to compensate for the large volume of cold air at start.

My electric pump is noisy, but then so is everything else in this car. The Red Holley has an internal fuel pressure relief valve that limits the flow of fuel to the carburetor by redirecting some of the pumped fuel back to the intake side of the pump. That means when the engine is not demanding a lot of fuel, the pump is repumping the same fuel over and over. So, instead of taking heat from the pump away to the engine, the fuel will allow the pump to run hotter. Putting a fuel pressure regulator (with a return line to the tank) downstream from the pump will solve that problem and likely allow the pump to last longer. If you do that you'll either need to use a pump without an internal pressure regulator or one that allows a pressure setting higher than the one on the external fuel pressure regulator.

DriftingCloud · #18 (**permalink**) 10-17-2015, 07:24 AM

Quote:

Originally Posted by Tommy

First, when the weather gets cold, it may sit for a month or more between starts. I like knowing the float bowl is full before I press the start button so I don't work the starter and spin a dry engine too much.

Lippy made this point, too. I hadn't thought about that much yet. Mine can sit for a while as well. I am running an electric choke on my Holley Double Pumper, but it still needs fuel to start. The faster that's received the less wear and tear on the engine during a relatively dry crank.

Quote:

Originally Posted by Tommy

My electric pump is noisy, but then so is everything else in this car.

Fair point, and I'm still laughing at the simplicity of this. There's no subtly to a Cobra. I guess my issue is with noises I like versus noises I don't. Ha ha...

Quote:

Originally Posted by Tommy

The Red Holley has an internal fuel pressure relief valve that limits the flow of fuel to the carburetor by redirecting some of the pumped fuel back to the intake side of the pump. That means when the engine is not demanding a lot of fuel, the pump is repumping the same fuel over and over. So, instead of taking heat from the pump away to the engine, the fuel will allow the pump to run hotter. Putting a fuel pressure regulator (with a return line to the tank) downstream from the pump will solve that problem and likely allow the pump to last longer. If you do that you'll either need to use a pump without an internal pressure regulator or one that allows a pressure setting higher than the one on the external fuel pressure regulator.

I didn't know that about the redirection. No wonder they don't last very long absent a fuel pressure regulator and tank return line. Heat build-up in a fuel pump seems like a fairly bad idea.

bkozlow · #19 (**permalink**) 10-17-2015, 06:43 AM

Replace the electric pump. Add the mechanical, problem I see is that the engine may have not been setup for a mechanical pump. Pull off the pump cover and see if you have the pump cam on the crank. If not then a bigger job of pulling the front of the engine off and adding one. A lot of engines are built without the fuel pump cam these days with everyone going to all electric pumps. Electric-mechanical gives you an extra layer of protection on pump failure and provides a constant fuel supply to the mechanical in high RPM situations.

Bill K

DriftingCloud · #20 (**permalink**) 10-17-2015, 07:27 AM

Quote:

Originally Posted by bkozlow

Problem I see is that the engine may have not been setup for a mechanical pump. Pull off the pump cover and see if you have the pump cam on the crank. If not then a bigger job of pulling the front of the engine off and adding one. A lot of engines are built without the fuel pump cam these days with everyone going to all electric pumps.
Bill K

Thanks! I just assumed there would be a pump cam. I now have a project for today...