Register now to get rid of these ads!

Electric v. Mechanical fuel pump

Discussion in 'The Hokey Ass Message Board' started by Big Nick, Aug 30, 2011.

  1. Big Nick
    Joined: Sep 7, 2005
    Posts: 847

    Big Nick
    Member

    I did a search and didnt really find an answer. I have an electic pump in my 52 now but its ready to shit the bed. Before I replace it I wanted to know the pros and cons. I was going to put a mechanical one back on and had a few people say stick with the electric but couldnt give me a real reason why. Any help is appreciated.
     
  2. 57JoeFoMoPar
    Joined: Sep 14, 2004
    Posts: 4,838

    57JoeFoMoPar
    Member

    It's a debate that has gone on for a long time on here with strong feelings on both sides. Personally, I've used mechanical and electric with success, though recently electrics have been giving me some fits.

    Mechanical pumps tend to be more reliable than their electric counterparts. However, if your engine is in tight in the engine bay, or is in close proximity to a frame member, mechanical pumps can pose packaging issues that are easily remedied with an electric pump, which can be mounted anywhere. They often can cause a harder start after the car sits, since fuel will drain back to the tank and need to be pumped up to carb.

    The problem with electric pumps is that they are loud, can be more vulnerable to rust or debris in the tank, so it's imperative to have a good filter before the pump. The electric pump should be near the tank, since they like to push fuel as opposed to pulling it. I actually like the noise from the electric pump since I can hear whether it's working or not. They also don't have the hard starting issues that the mechanical pumps have. It's key hot, so let the pump prime the system prior to hitting the start, and it has full fuel pressure immediately. The electric pumps are also easier to change on the side of the road should you have an issue out there.

    I've been running a Carter rotary vane pump in my 57 now for about a year, it has worked well.
     
  3. vegas
    Joined: Feb 6, 2008
    Posts: 269

    vegas
    Member

    I used a mechanical pump on my coupe just for the simplicity of it, and I like the looks of a mechanical pump. I do agree if the car sits for a couple weeks, it is harder to start, but other than that I have no complaints about it. They worked for decades for OEM applications, so why not?
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 47,940

    squirrel
    Member

    If you can use a mechanical pump, you should.
     

  5. Well-either one can be reliable-All new vehicles use electric fuel pumps.
    Some will argue the mechanicals "look" better on a traditionally styled motor.
    Some of your decision depends on your fuel setup-carb or fuel injection.
    If you are running a carb-just make sure whatever style pump you use-you have the fuel pressure matched to the capability of the carb.You may need a pressure regulator to control it.
    Also a good idea if you are running an electric pump to have it wired through an oil pressure switch so it shuts off when there is no oil pressure. If you are in an accident-it wont keep pumping fuel if the engine dies and the ignition is still on.
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 47,940

    squirrel
    Member

    They do so because they have to, it's the only way to get EFI to work.

    After replacing a few $300 electric pumps on my wife's late model crap, I really like $20 mechanical pumps. Quiet, reliable, cheap, aesthetically pleasing, etc.
     
  7. 4dFord/SC
    Joined: Sep 12, 2004
    Posts: 837

    4dFord/SC
    Member

    I have both, but use the electric only for priming when the car hasn't been driven for awhile, and for backup in case the mechanical gets weak or dies.
     
  8. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    It really all boils down to "I like steak, you like seafood." Who is right? I've used both and really see no difference, but do prefer the immediate priming an electric pump provides, and I can turn the key, look at the pressure gauge, and know I have fuel to the carb(s). I have also never had vapor lock with an electric pump, but have with a mechanical one.

    Same can be said for electric fans vs mechanical fans. I like electric better in most applications because I like the ability to control them at red lights and feel they are more efficient. But I will probably use a mechanical fan on my current project because I want the car to look like it has been around for a long time.

    I don't think there is ever only one right way to do anything.

    Don
     
  9. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    I've had just as many mechanicals fail on me as electrics. I have had a lot of electrical pumps over the years and one thing that I have come to like is being able to fill the carb with fuel before starting. This seems to be a newer problem with the new fuels. Turn the key, wait for the clicking to stop, pump the gas once and it starts instantly on my hobby cars that can sit for weeks sometimes. I hate cranking and cranking an engine for any reason...just a personal hang up.

    Electrics are very traditional going back to the Hurst mounts for Chevy engines.

    Every parts store in the country has an electric that can be connected with a few feet of hose, some wire and some crimp connectors. Which incidentally will get you home if your antique mechanical pump gives out too.

    That being said my Stude and my 56 Ford are both mechanicals. I did rebuild my Stude pump a year ago (it quit after unknown amount of years) and the Ford is an NORS unit.
     
  10. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    Oh, one other thing that always scared me about mechanical pumps is that certain ones will dump gas into the oil pan if the diaphram fails. I forget if it was on a sbc or other engine I owned one time where that happened and luckily I caught it because the oil level was getting very high and the oil smelled of gasoline.

    I bet it really cleaned all the sludge out of the engine though. :eek::D

    Don
     
  11. It happenned to me with a 223 ford six popper and about any diaphram-type pump is subject to this potential problem.
    I can't make a decision which electric pump to use on my project...Pontiac engine with a Hurst mount up front...or whether to use 2 in tandem in case one fails. Engine will have 2 afb carbs, another reason I'd rather use electric pumps.
     
  12. Bob Dobolina
    Joined: Jul 27, 2006
    Posts: 332

    Bob Dobolina
    Member

    Got a carter P4070 on the 46. No worries. It was a packging issue with me. The ford short drive kit has no provision for a mechanical pump. As stated above, a good filter before the pump is manditory. I may have done overkill on mine, but it runs thru a adjustable bypass style regulator. One thing i have discovered, electric pumps do NOT like ethanol. Little bit of stabil each tank.. just to make sure.
     
  13. mustangsix
    Joined: Mar 7, 2005
    Posts: 1,297

    mustangsix
    Member

    I have a couple of cars that sit for periods of time. The car with the electric pump usually starts on the key, but the one with the mech pump has to crank a bit to refill the fuel bowl.
     
  14. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    I've always used the Holley red pumps, but have recently gone to the Carter brand. I find it much quieter and the pressure is a little lower too. I'm not even running a regulator on my 27 (2 Edelbrock 600 cfms) and am getting about 6 psi to the carbs. I've had some Holley pumps that were louder than others..........people kept asking me if the one on my Jeep truck was an air compresor running ! :eek: The Carter still makes a little sound to let you know it is working, but very quiet by comparison.

    Don
     
  15. dontlifttoshift
    Joined: Sep 17, 2005
    Posts: 652

    dontlifttoshift
    Member

    That there is a heavy dose of truth..

    All new vehicles use an electric pump mounted IN the fuel tank to keep it cool and quiet, but mostly cool. That's why you shouldn't run your late models on "E" all the time. Another reason for mounting the tank in the pump is that it is more effecient to push fuel than pull it. If you must run an external electric pump mounting it as close to the tank (and below fuel level) will help immensely with life expectancy.
     
  16. Big Nick
    Joined: Sep 7, 2005
    Posts: 847

    Big Nick
    Member

    There is a Holley on the truck now, under the cab, it makes a lot of noise. This is what I love this board for, great responses! Thanks! I tend to stick with mechanics, only because I have gone all out of bikes with fully eltronic this or that and to have it fail on me out on the road with no way to fix it. I went back to points on my panhead and actually just put a points ignition in a 2004 Night train because the owner was tired of the fuel injection problems! We went back to a carb and points!

    So I was leaning towards the mechanical pump, now here is the next question, the truck has a 350 currently with a single 4 barrel carb, in the future I want to switch over to dual 4s. What pump should I be running? Will I need to switch up adding another carb? Im still in the learning process here with a lot of the car stuff. The two extra wheels came with a lot of baggage:D
     
  17. Big Nick
    Joined: Sep 7, 2005
    Posts: 847

    Big Nick
    Member

    Oh and I had the pleasure of changing the in tank pump on the Tahoe with a full tank of gas, I cut a hole in the floor and made a trap door for next time.
     
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 47,940

    squirrel
    Member

    I don't have the priming problem with my one car with the electric pump, but that's probably because it has a couple Holley double pumpers on it. They seem to hold fuel forever.

    I have the electric pump wired thru an oil pressure switch, so it won't turn on when the key is on and the engine is off. It will turn on the pump while cranking, since it's a 3 terminal oil pressure switch.

    With dual 4bbl carbs, it kind of depends on how much power the engine makes, which determines how many Gallons Per Hour you need. A high flow mechanical should get the job done.
     
  19. jcmarz
    Joined: Jan 10, 2010
    Posts: 4,633

    jcmarz
    Member
    from Chino, Ca

    When I was building my Nomad back in the late 70s, I decided to try a electric fuel pump and man, it was nothing but a headache. After a week of dealing with the crap, I threw it in the trash and installed a nice chromed mechanical fuel pump. Never had any problems after that.
     
  20. x2

    I switched to a mechanical for looks, reliability, and I hated the noise that Carter 4070 made. Now I run the mechanical, and can use my Carter for backup if needed with a simple and fast fuel hose change.

    If you do a search on this topic you can find lots of info on the do's and don'ts of electric pumps and the safety systems that should be installed if an electric pump is your choice.

    Good luck.
     
  21. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,426

    Von Rigg Fink
    Member
    from Garage

    Mechanical

    period
     
  22. Cost of buying a rebuild kit for mine (as well as the desire for 12 volts) has made me opt for the Electric over the mechanical. I am thinking about fitting one of the Brittish SU style 12 volt units to my straight 8.
     
  23. cherokee_64
    Joined: Apr 8, 2006
    Posts: 88

    cherokee_64
    Member

    Definately mechanical. Remember K.I.S.S... Keep It Simple Stupid... There is so much less to go wrong.

    However, if you don't have the room, like I didn't in a '47 Chevy I once had, then you have to run electric.

    Electrical pumps don't have to be problematic. Most of the time the problems come from the way they're installed. There are a few things that you have to consider to keep your electric pump running reliable and safe.

    Here is an article I wrote about the right way to install an electric fuel pump:

    http://www.how-to-build-hotrods.com/electric-fuel-pump.html

    I hope this helps...
     
  24. 39 All Ford
    Joined: Sep 15, 2008
    Posts: 1,531

    39 All Ford
    Member
    from Benton AR

    I really like mechanical pumps, but after repeated attempts at trying to make my failed stocker work on my 55 Lincoln, I broke down and bought a Carter electric and mounted it on a fabricated block off plate/mount in the stock location. On first glance it looks like it is supposed to be there.

    I stopped short of buying the material to make a new diaphragm, but I pretty much exhausted all the resources I could find for trying to get a RELIABLE solution good enough for a daily driver and just went with the electric.

    [​IMG]
     
  25. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,572

    Sheep Dip
    Member
    from Central Ca

    I use this 2 pump method on my OT 46 CJ2A jeep. Way back about 1973 I lost a mechanical fuel pump way out in the Ariz. desert, it was a long walk until I came across a couple of tribal members who were kind enough to get me to the nearest NAPA and haul me back to my jeep with a new fuel pump! Great guy's. Long story short every since then I have run a mechanical with a electric back up on that little devil. I do know a few who do this on their hot rods. I just carry a spare if I am going any distance to a show or such:D
     
  26. harley rider
    Joined: Aug 11, 2010
    Posts: 527

    harley rider
    Member

    I am puting a new motor in our 39 was debating electric or mechanical .it now has a pump in the tank to run a TPI set up. going to carbed motor.my engine builder says electric but I say mechanical.for cost and simplicity.
     
  27. No matter which one you use, you need a return line...

    I prefer the mechanical. I have two 3/8" fuel lines from the tank feeding the pump.. The Quadrajet on my 462 is always full..

    I'm installing a sumped 15 gallon fuel cell this winter...
     
  28. harley rider
    Joined: Aug 11, 2010
    Posts: 527

    harley rider
    Member

    ive run holley carbs and mechanical pumps for a long time with no return line.return lines are only needed for high presure pumps.
     
  29. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    Depends on what the intent of the car is. Mellow daily driver, mech. simple, less noise, more reliable. More than that, Holley blue with a bypass. If it needs bigger than a 3/8 line, two blues.
     
  30. I run a stock volume mechanical pump to feed two Carter 600's on my low profile intake, no problems at all.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.