[Public-List] A4 Engine puzzler

[Glenn]

Years ago, driving through the Yukon in January at 50 below we couldnt get the motor to run over 35mph, barely more than fast idle down hill and barely enuf to go up hill. Sometimes just died, then start run, die... Over and over for hundreds of miles.  We finally made Whitehorse where the Chevron Mechanic tore the whole fuel system down, part by part over three days, trying to solve the fuel starvation problems.  After many test drives, and replacing every part new, he finally pulled the gas tank and blew it out with compressed air.  A small piece of electrical tape came out!  it apparently had nearly the same specific gravity as gasoline and would swirl around inside the tank until getting repeatedly  sucked up into the intake tube where it would partially,  some times completely, choke off fuel flow and eventually kill the engine.  No rhyme or reason to timing, but each time it did allow enough fuel to enter the carb and run the engine.  After the tape was gone, the car ran like a top.

You mentioned your tank is a new poly tank.  I wonder if some plastic shaving or debris is floating around in the fuel and getting sucked up against or into the suction tube - just like my old friends dodge dart? Maybe a piece of silicon tape or similar...  Once the engine dies, suction stops and fuel  flows back into the tank to clear the obstruction, just like a bilge pump.  

Also I like your idea about a weak fuel pump and head pressure from the raised tank. Certainly worth replacing if old, even if not the problem.

Good luck!

Glenn B
Dolce 318

Sent from my iPad

On Aug 18, 2013, at 12:38 PM, Gordon Laco <mainstay at csolve.net> wrote:

> The filler cap was new with the tank, but I'll check it.
> 
> 
> On 18/08/13 2:35 PM, "Chris Martin" <notcmartin at yahoo.com> wrote:
> 
>> Good advice to check the lines and any fitting for corrosion or blockage. Also
>> a good idea to drain and check the tank, especially the bottom if you can.
>> Also check the bad tank for a blocked vent. If the tanks are the same switch
>> filler caps from good to bad, that assumes the cap is a vent. 
>> 
>> Good luck
>> 
>> 
>> ________________________________
>> From: Gordon Laco <mainstay at csolve.net>
>> To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
>> Sent: Sunday, August 18, 2013 1:28 PM
>> Subject: [Public-List] A4 Engine puzzler
>> 
>> 
>> Hi Gang,
>> 
>> I hope you’re all out sailing.... I stole Friday afternoon and yesterday to
>> do a quick overnighter up the coast.  Had a wonderful trip.
>> 
>> This afternoon I’ve been making a determined assault on the annoying issue
>> SURPRISE’s engine has;  namely it’s dislike of running while the fuel
>> selector is set to Tank 2.
>> 
>> It runs fine on Tank 1, but when the selector is set to 2 it runs for only a
>> few minutes then cuts out and won’t restart.   When I put the selector back
>> to Tank 1, it starts again after a lot of cranking...but at first only with
>> the choke on (it gets over that quickly).
>> 
>> When it stalls while running on tank 2, here’s fuel in the fuel filter, so I
>> think it’s getting gas.   If the carb were getting blocked, it wouldn’t
>> start again on either tank without a carb cleaning job, but it doesn’t need
>> that.
>> 
>> When the problem first manifested, it was stalling on either tank, but after
>> I’d followed Don Moyer’s advice and retightened all fuel line hose clamps,
>> the problem was resolved with regard to 1, but the issue still exists with
>> 2.
>> 
>> It’s occurred to me that there could be water in the fuel in 2; so I’ve been
>> putting fuel line antifreeze in to absorb it.... But it occurs to me that if
>> contaminated fuel were the issue, I’d have to clean the carb before it would
>> run again and so long as I switch to 2 that doesn’t happen.
>> 
>> The weird thing is it ran quite happily on either for many years before this
>> started happening last season.
>> 
>> Does anyone have any suggestions?
>> 
>> Gord #426 Surprise
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> 
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