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Nos Fuel Pumps Vs Ethanol

Discussion in 'Early CJ5 and CJ6 Tech' started by oldtime, Dec 17, 2021.

  1. Dec 17, 2021
    oldtime

    oldtime oldtime

    St. Charles,...
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    How many of you are installing NOS or NORS fuel pumps into your old Jeeps ?
    Have they been rebuilt with ethanol resistant diaphragms or not ?
    What sorta fuel do you run through the pump ?
    What service life are you getting from them ?

    I have exclusively been installing OEM NOS pumps during the past 20 or more years.
    These are new old pumps were all built way back pre 1960’s.
    Fact is that all fuel pumps built after 1963 were no longer designed for rebuilding.
    I get 3 months to 1 year of service life from the pumps if I use 10% ethanol fuels.
    The same old pump can operate for many years if I switch strictly to ethanol free fuel.
    Problem being scarcity of unleaded fuels in my region.
    I have to drive 40 miles to source the non ethanol fuel.

    So who on here has been running the rebuildable AC 4827 (pre 1964) on their Dauntless ?
    Where can you find a good ethanol rated rebuild kit for it ?
     
    Walt Couch likes this.
  2. Dec 17, 2021
    Norcal69

    Norcal69 Out of the box thinker 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Northern California
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    California gas is by far the poorest quality in the country. I ran a mechanical pump for 6 years and 20k miles. Never had an issue. I’d be happy to send it to you. It came on my Jeep in 2014.
     
  3. Dec 17, 2021
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member

    Tantallon, Nova...
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    Have you considered setting up a separator system to remove the ethanol from your gas? Looks like a bit of a PITA to do but you may find it worthwhile.
     
  4. Dec 18, 2021
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Run non-ethanol fuel. A little more expensive but problem solved.
     
  5. Dec 18, 2021
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    I agree with this, I run non-ethanol gas and the Jeep likes it better, but oldtime mentioned he's far from a source of "pure" gas.
    My concern with a NOS pump would be the 60 year old rubber diaphragm.
     
  6. Dec 18, 2021
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
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    For many of us the issue is getting to a source of non ethanol fuel. I have to drive quite a bit out of my way to get to a station that carries it.
     
    Lockman likes this.
  7. Dec 18, 2021
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

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    I guess I am lucky to live around so much water. Because there are a lot of boats here non-ethanol gasoline is available at just about every place that has gas pumps. I use it in my Jeeps, tractors, boats, and other small engine equipment.
     
  8. Dec 18, 2021
    oldtime

    oldtime oldtime

    St. Charles,...
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    So what kinda service life are you all getting using old pumps an ethanol ?
    The cheapest ethanol pump kits I found cost $75 which is notably more than the cost of an OEM NOS pump.
     
  9. Dec 18, 2021
    timsresort

    timsresort Member 2022 Sponsor 2021 Sponsor

    South Lake Tahoe CA
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    I have 4 V6 Jeeps all running newish (5-10 year old) fuel pumps and 100 percent crappy CA gas. Never had a problem. Maybe I missed it, what is the point of running NOS fuel pumps?
     
    Norcal69 and dnb5853 like this.
  10. Dec 18, 2021
    oldtime

    oldtime oldtime

    St. Charles,...
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    I run NOS for a couple reasons.
    All pre 1964 pumps like the AC4827 were rebuildable.
    And a only a very few of the post 1963 pumps were rebuildable . Like the AC 40001 some are and some are not rebuildable.
    If I run the pumps with 3-1/4” diameter diapragms then I can add a glass fuel bowl like this:
    [​IMG]
     
  11. Dec 20, 2021
    Wmi68CJ5

    Wmi68CJ5 Let the Sun Shine! 2020 Sponsor

    Twin Lake MI
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    Are the rebuild kits pre’63 also ie NOS also?
     
  12. Dec 20, 2021
    oldtime

    oldtime oldtime

    St. Charles,...
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    Just depends.
    You can certainly find a few oem nos kits listed on eBay. But anything modern manufacture should be
    ethanol rated.
    The cheapest ethanol safe kit I found so far for a Dauntless fuel pump is about &80.
    The NOS AC pumps generally are much cheaper than that.
     
  13. May 25, 2022
    Eric

    Eric Member

    CA
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    I have been trying to find some quantifiable data on ethanol's reaction with the materials used in fuel pumps, hoses, etc. While there are huge numbers comments on ethanol's affinity for water, none of what I have found describes that ethanol degrades rubber. Sure, the water will affect metals (tanks, carbs, etc.) and the alcohol will degrade some greases and oils, but how does it affect rubber? Many of the posts (most not on ECJ5) suggest other problems with ethanol, but many attribute the fuel pump issue to simply age of the rubber, regardless of ethanol. They state, in general, that an older fuel pump will fail due to age and agin rubber, not to ethanol. That makes sense to me. One of my eariler projects (now living in Germany), a 1944 MB, had not been introduced to ethanol in its life and most of the rubber was cracked and/or brittle. Where am I going? I am wondering if rebuild kits just need to be of quality materials and not "ethanol resistant" materials? When a vendor suggests that their product will withstand modern fuels, does that mean it is simply a better rubber than a cheap knock-off?

    Sorry for all the wind... hope someone won't mind adding to myt understanding. Thanks all.
     
  14. May 25, 2022
    nickmil

    nickmil In mothballs.

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    I can’t give you quantifiable data based on any studies but I can give you personal experience as an automotive tech when the Portland, Oregon area switched to using ethanol. Immediately we were seeing a huge uptick in vehicles coming in for carburetor, fuel injector, fuel pump, fuel filter, and rubber fuel lines being degraded. Some from age or foreign material but many were newer vehicles that were otherwise in very good condition mechanically. We were finding all kinds of rubber particles plugging up injectors and filters. Fuel socks were falling apart or melting. Ethanol is corrosive and will attack rubber. Those who race using ethanol or alcohol use only special fuel lines rated for that use. Modern vehicles use plastic fuel tanks and lines and hoses that are resistant to alcohol for a reason.
    My recommendation is to use products meant for ethanol.
     
    Eric likes this.
  15. May 25, 2022
    oldtime

    oldtime oldtime

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    I agree from what I have observed.
    I have a recent rebuilt Jeep with near 100% OEM NoS parts. The fuel pump is an AC 4693 that was mfg back in late 50’s or early 60’s. The Jeep currently runs and operates perfectly normal on ethanol free gasoline. I go out well of my way to find ethanol free gasoline because of the OEM fuel pump. I will not run ethanol gas through it. I have installed these old original AC 4693 pumps on Hurricane engines before and see them only last six months or so when using ethanol gasoline. Seems to me that the diaphragms get soft and loose their ability to pump.
    [​IMG]
     
    Last edited: May 25, 2022
    timsresort and Eric like this.
  16. May 25, 2022
    Eric

    Eric Member

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    Thanks. I am trying to reduce the amount of rubber anywhere in the fuel system. I took Oldpappy's advice and replaced the fuel line so there is no rubber anywhere between tank and carburetor, installed a ceramic filter just ahead of the pump, and short of the pump diaphragm and valves, there should be no contact with any rubber and the fuel. It is an older metal tank I have in place. Your experience is valuable input, for sure. I have managed to find one fuel company near property I own up north that sells ethanol-free gas, so I will investigate that. They do not fill vehicles but will fill portable tanks... It is inconvenient, but perhaps worth the effort.

    May I ask a follow-up question? Do you think most the problems you described in the "huge uptick" were due to rubber products along the route, and not so much the fuel pump? (I realize that is an opinion question, but worth noting.) Thanks again!
     
  17. May 25, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2022 Sponsor 2021 Sponsor 2020 Sponsor

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    Do you think most the problems you described in the "huge uptick" were due to rubber products along the route, and not so much the fuel pump?


    I still am running the same fuel pump that was in my '56 F-head when I bought it twenty years ago. It could be much older.

    Use regular pump gas, 10% ethanol. No problems. (Pre-chinese rubber?)

    I DO use small amounts of Seafoam on a regular basis, in all my engines large or small.
     
    Eric likes this.
  18. May 25, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    I attribute most of the fuel pump issues to the fuel sock's melting and filling the pump with debris and the corrosive/solvent properties of ethanol to cleaning debris from the inside of the tank and running it through the fuel system.
    The debris in the fuel injectors, carburetors, filters, etc. was some from the same source but also any rubber in the systems. You need some flexibility in the system, primarily between engine/body. There are fuel hoses readily available that are ethanol rated.
     
    Eric likes this.
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