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  • Engine hesitation

    A while back I took my 83 Mini out for a long drive and after driving well for about 45 minutes at highway speeds (50 - 60 MPH) it started hesitating and chugging. I stopped a couple of times to check the coil connection thinking that might be the issue, but to no avail. On the way home, I decided to take some roads with a lower speed limit and found the car ran much better and the chugging seemed to go away at speeds under 40 MPH. Eventually, I had to get back on to a highway and the car seemed to still run better at 50+ MPH. A former mechanic I know, told me his instinct is to suspect the spark plug wires, not the coil, since coils rarely fail in his experience (he's not a Mini mechanic). I replace the wires and found the car chugging right away when driving it. I have since replaced the distributor cap and rotor as well, but haven't had a chance to drive it since. So not sure if the problem is still there.

    In the meantime, I have started wondering if engine timing might be the issue, which leads to the questions of whether I can take the car to anyone to do the timing provided I give them the specs from my Haynes guide, and how do I figure out exactly which engine I have since there seem to be so many variations with different specs in the Haynes guide?

    So my questions to the group:

    1- Am I on the right path with the wires/distro cap & rotor replacement? (Should I put in new plugs as well?)

    2- Is this an issue related to timing? Not sure what the symptoms of bad timing would be.

    3- Figuring out my engine type. All I can say is that it is a 1275 A+ engine with a block (12HE) made for unleaded gas. It isn't an SPI/MPI engine. The 1275 GT was for Clubman, I thought, so that doesn't seem to be it. Was there a 1275 Mini Metro? I've heard that before, but don't know what it was. The distributor is the 65DM electronic distributor, but not sure if that is relevant.

    Since I live out on the Oly Pen., I am a long way from easily taking somewhere where there is Mini mechanic experience. If anyone is coming out to the Port Townsend area and is able & willing to help, let me know.

    Thanks.

    Tim

  • #2
    This sort of thing can be caused by a slightly clogged fuel filter. It limits maximum fuel flow and causes the float bowl to empty faster than the fuel pump can fill it.

    Kelley
    If you can afford the car, you can afford the manual...

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    • #3
      Kelley,

      That makes sense. Seems like a simple fix. I am hoping this is a simple thing to replace at the local auto parts store? No special specifications?

      Thanks for the info.

      Tim

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      • #4
        As far as I know carburetted Minis did not have fuel filters from the factory. As a result all filters are aftermarket and you never know where they will be installed or if there is one at all.

        If you have a mechanical fuel pump you might want to see if you have fuel in the oil (smelling the oil works). A leaky pump diaphragm can cause fuel flow problems too. It's not a common but it's easy to check.

        Kelley
        If you can afford the car, you can afford the manual...

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        • #5
          Tim,

          I have found a mechanic that works on British cars here in Sequim. Not sure if he makes house calls. Will give phone number if needed.

          Dale

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          • #6
            Kelley,

            That probably explains why my Haynes guide only mentions fuel filters on fuel injected models. The filter on my car is above the fuel pump laying against the firewall in plain sight. It is a small clear plastic thing that looks very similar to the filter I replace on my riding lawn mower last fall. Simple enough to take off and replace. I don't know what kind of fuel pump I have. I can see where it is, but I'm not familiar with how to distinguish them (except maybe by looking for electrical wires).

            Dale - It might be handy to have that mechanics name and number handy. feel free to forward the info to me and I'll hold on to it for future use. Thanks.

            Tim

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            • #7
              PM sent

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              • #8
                If the fuel pump is attached to the back of the engine, it is mechanical. If it is on the left-hand rear subframe it is likely the original electric fuel pump. If it is in the boot it is an aftermarket electric fuel pump.

                Kelley
                If you can afford the car, you can afford the manual...

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                • #9
                  Looks like it is a mechanical pump. It is on the back of the engine. I got a new fuel filter and I will install it this weekend and give it a test to see if the symptoms go away.

                  Dale - Thanks for the number. I'll give him a call sometime soon about a couple of other issues I have. I'll let you know when I am out that way.

                  Tim

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                  • #10
                    I finally was able to get the new filter installed as well as change out a cracking fuel line. I took it out for a drive and got the same issues as before. It doesn't seem like the filter was the issue.

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                    • #11
                      OK - After a year and a half of talking with different people and getting sidetracked by numerous other issues unrelated to my mini, I replaced the rotor head with no effect. Then I started making minor carb adjustments and it got worse. I tried to undo them and it died. After trying to work out getting the car towed to someone, I decided to replace the coil with a pertronix coil it started but still ran rough. I then discovered I never changed the plugs, so I put in new NGK plugs to replace the Denso plugs and now it seems to run great. No chugging or hesitation, though it did stall once while driving, leading me to think there might be some issue with the fuel pump. But after a couple of minutes, it started up and I ran it on the highway for another 20 minutes before I got home. As a bonus, I noticed a distinct lack of exhaust/gasoline smell while driving. I had suspected an exhaust leak that was infiltrating the car, but now I'm thinking the issue (or one of the issues) was the plugs were not firing well. The plugs in cylinders 3 & 4 were pretty black compared to the one in cyl 1.

                      If the car keeps running as it is, I'm looking to drive it somewhere to get the timing and other tuning issues checked so I can use for my daily commute while I get my primary car to the shop for some long overdue maintenance. If there is anyone out there willing to do this for or with me, please let me know. It would be great if you were here on the Oly Pen, but I can get to Seattle, especially N Seattle. I could get to Gunnar's shop if he is still willing to let me bring it there. I hope this would only be a 1 day effort, but it took me a year and a half to change the coil and plugs.

                      Tim

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                      • #12
                        From the sound of things, it might have been an ignition problem rather than fuel supply. I'd check the distributor cap for corrosion on the contacts, a clean rotor, decent spark plug wires with good connection between the dist cap and coil lead. Check the spark plugs and gap, should be .025". Insure that the points, if so equipped, are clean and properly gapped (.015"). I didn't see what size engine is installed, so try a timing figure of 8-10 degrees BTDC. Additionally, if the car has been idle for a year and a half, chances are that the fuel could be contaminated with water and for lack of a better technical term, gunk. Before changing the fuel pump, have a peek at the fuel filter and put fresh gas in the tank. Good luck and keep us informed.

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                        • #13
                          Any news?

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