[DML] Re: Strange acceleration problem
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[DML] Re: Strange acceleration problem

I can understand and agree with this logic up to a point. In my
experience with many other kinds of cars with fuel injection the
general symptoms of a dirty fuel filter are not of idle problems
though. A typical symptom of a dirty fuel filter is at speed (over
30-40 MPH) the car starts to buck and feel like it is holding back.
When you let off the accelerator it seems to go normally again. I can
certainly agree with changing the filter, especially if you don't know
how long it has been in the car. One bad tank of gas can plug up the
filter anyway but if after changing the filter and the symptom still
is present then you will have to go looking for the "real" problem. I
like to look inside the gas tank. If I see water in a bubble on the
bottom or the hose is soft or there is a lot of dirt in the tank that
is where you should start. My philosopy is that most fuel problems
begin in the fuel tank. If it is dirty in there all that dirt will
wind up in the filter so you might as well clean the tank out BEFORE
you put that new filter in! On the subject of the accumulator, I
thought a good visual test was to remove the rubber "relief" hose and
see if the diaphram is bad because the accumulater would leak out back
to the tank. This is NOT a good test. On one car I did this and the
accumulater did not leak so I figured it HAD to be good. A pressure
gauge said no. After replacing the check valve and the "O" rings in
the regulator I still wasn't holding rest pressure. I replaced the
accumulator and it worked. After cutting open the accumulater the
drain port was CLOGGED with rubber bits from the diaphram. The "moral"
here is the accumulator is the chief cause of failure to hold rest
pressure. Replace it first unless you KNOW it has been replaced in the
recent past. If it is still origional and it is working you can expect
it to fail soon. Just figure on replacing it every 20 years or so
"just because", sort of like changing the fuel filter every 20,000 miles.
David Teitelbaum
vin 10757

--- In dmcnews@xxxxxxxxxxxxxxx, "pjgrady2000" <rob@xxxx> wrote:
> --- In dmcnews@xxxxxxxxxxxxxxx, doctorDHD@xxxx wrote
> Dave,
> I thuoght I already had explaned it but here goes so read carefully! 
> When a B28 engine is cold is when it's thirstiest for fuel and the 
> Lamda (enrichment) curcuit is in a fixed rich mode. It therefore 
> calls for IMHO more fuel than a partially clogged fuel filter can 
> deliver in this short peak demand period. Does that make any sense?
> Rob Grady,
> P.J.Grady Inc.
> >  
> >  
> > Can someone explain to me how a bad fuel filter can cause 
> hesitation and  
> > back firing only when the engine is cold? 
> > 
> > 
> >  
> > Thanks,
> >  
> > D² & 6530
> > 
> > Dan,
> > 
> > Before you try to trouble shoot the fuel injection I would  
> suggest changing
> > the fuel filter. That corrects the symptoms you describe  more 
> than half of
> > the time. Do you know when it was last changed? A bad CPR  won't 
> allow you to
> > accelerate at all for a few minutes with a cold engine so  I doubt 
> it's that.
> > 
> > Here is something ponder over. When I start my car  after sitting 
> for
> > the night it starts up fine. When I give it gas to get out  of my
> > driveway and up the street, I notice I lose acceleration. I then  
> here
> > a slight backfire in about 3-4 quicks pops. After this the car  
> runs
> > fine and I don't get it again until the next day after  sitting
> > overnight. Any thoughts on the cause of this?  Thanks!

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