[Zmagnette] What should I check first???

Fletcher Millmore gofanu at cust.usachoice.net
Wed Nov 13 17:21:51 MST 2013


Water in the carbs can cause this. A slug of water lies in the fuel 
transfer passages in the carb - when it gets sucked up to the metering 
needle, it blocks the jet, as water will not go through the same small 
hole as gas will. When the engine stops sucking so hard, the water falls 
down, letting gas through. If you get the demand high enough, the needle 
is high enough that fuel flows around the water, but it still leaves the 
water in the bottom.  (on HS carbs with clear transfer tubes, you can 
actually see this happen) Easiest thing is to dump a double dose of 
DriGas or fuel system cleaner in it - the cans are usually for 20 gal, 
so a whole can is about right. The cleaner may also remove varnish etc 
on float and metering needles.
Your comment that the filter is of unknown age but is OK is wishful 
guesswork - change it. And when you remove it, bang it on something with 
the inlet end downwards - see if any water comes out. Water does not go 
through good filters easily, but it can under some conditions, and it 
only takes about a half cc to block the jet as described.
(banging the filter like this can get you home when water blocks the 
filter too. In winter, a little water will freeze over a filter very 
easily, making for a very cold walk home. This was standard procedure on 
the big truck, as diesel is often contaminated; I finally started using 
filters with drain plugs, which I checked regularly for water.)

FRM

On 11/13/2013 5:52 PM, John Perkins wrote:
> Arch:
>     I once spent a winter evening in my MGB-GT with the battery cover 
> off of the car so I could tap the fuel pump with the lug wrench every 
> 10 miles for 130 miles to keep enough fuel flowing to get me home.  SU 
> Fuel pumps don't really die, they become zombies that need to be 
> resurrected.
>     I had a similar problem to yours that turned out to be worn 
> needles and seats in the carbs.  The seats were worn to a point that 
> the needles would stick.  Sometimes the rattle from the last gasp of 
> the engine would shake them loose, other times a quick rap from the 
> handle end of a screwdriver would shake them loose.  Real Grose jets 
> cured the issue.
>     Perkins
>
> On 11/13/2013 4:38 PM, Arch Boston wrote:
>> Jeff, I have had fuel pumps die, but, reserection???  I always 
>> thought when they died they were dead.
>>
>> Sent from my iPad
>>
>> On Nov 13, 2013, at 4:34 PM, JEFF ROMANS <jromans55 at msn.com 
>> <mailto:jromans55 at msn.com>> wrote:
>>
>>>
>>> /order your fuel pump now...then ready for final failure.../ on a 
>>> 100 degree day mine layed down 1 mile from home in parking lot 
>>> ,after a 100 mile trip. once the car cooled down, started right up 
>>> and drove home. next time wouldnt start. FUEL PUMP TIME.
>>>  Jeff Romans
>>>  1958 Magnette ZB
>>> > From: arch.boston at twc.com <mailto:arch.boston at twc.com>
>>> > Date: Wed, 13 Nov 2013 16:20:03 -0500
>>> > To: zmagnette at autox.team.net <mailto:zmagnette at autox.team.net>
>>> > Subject: [Zmagnette] What should I check first???
>>> >
>>> > My car has developed a problem..... The last few times I have 
>>> driven the car it does the same thing. It will be running just fine 
>>> and then it will start to act as if it is running out of gas. 
>>> Stumbling and trying to die.... After I bleep the throttle a few 
>>> times thinking it is truly "AAA time" the car will run just fine. 
>>> There is a fuel filter between the gas tank and fuel pump. The 
>>> filter doesn't look freshly installed, however, it is not needing 
>>> replacement. The fuel pump is an electronic unit not SU. Should I 
>>> suspect the fuel pump? In the past when I needed to replace a pump 
>>> it was dead --- not working part of the time and fine later. What 
>>> should I check first??? Arch
>>> >
>>> > Sent from my iPad
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>>
>>
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