[DeTomaso] Three steps forward, three steps back....

[MikeLDrew at aol.com]

In a message dated 4/3/08 22 33 7, garth_rodericks at yahoo.com writes:


> 1. Is the "standard filter" the old one that's had the debris tapped out 
> onto the bench, or a new one? 
> 
>>>It's a high-zoot Earl's filter with a removable, cleanable mesh (not 
paper) element.

>  2. And is it between the pump and the mongo-sized fuel filter, or between 
> the mongo-sized fuel filter and the carb?
> 
>>>Between the new mongo filter and the carb.   

>  3. Can you rev the engine when you got the 0-psi reading on the fuel 
> pressure gauge?
> 
>>>Yes, at idle.   In fact if the carburetor is full, I can get some serious 
performance out of the engine for a few seconds at least, before it falls 
flat.


>  4. Do the symptoms show up only under load, or do they show up when 
> revving the engine with the clutch in too?
> 
>>>Only under load.   The fuel demand for an engine with no load is so small 
that I can't replicate the fuel starvation problem when the car is stationary.
>   
> > If your filters are new and the big one is between the pump and 
> the standard filter, then lets
>  take a different approach...  It sounds like it could be spark related 
> (although that doesn't
>  explain the 0-psi on the fuel pressure gauge, although at idle the pressure 
> may be too
>  insignificant to register on the gauge). 
> 
>>>At idle, yesterday, the gauge showed 7 psi.   This is *very* clearly a 
fuel malfunction as opposed to spark, because it is very repeatable.   I can 
force the malfunction to occur with my right foot, and I can also cure it with my 
right foot.   An igition problem would be more random.


> Maybe your coil or the ignition module is cutting out.
>  Are you running an electronic ignition?  If so, which one? These items are 
> often temperature
>  sensitive when they have problems.
> 
>>>I have an MSD ignition, and in fact have experienced that failure *too* in 
the past.   It felt/acted very different than this.   I've had this failure 
twice in the Pantera last year, and once in the Cobra the year before; in all 
three cases it felt/acted exactly the same, and in all three cases the problem 
was a clogged fuel filter.
>   
> > I've heard you could try to lightly spritz some water (as in spray bottle 
> to mist plants, etc)
>  onto the coil to see if the problem is magnified, but I've never tried this 
> myself and make NO
>  REPRESENTATION about how safe it is for your ignition system. Do this at 
> your own risk.
>  You could try swapping your ignition module and/or coil if you have spares. 
> Or see if
>  someone else nearby has a known good module of the same kind that you could 
> try before
>  spending $6-$100 for a new one.
> 
>>>I have a spare, my original MSD that I had rebuilt when it blew up a few 
years ago.   But thankfully I have both historical experience and empirical 
evidence that it's a fuel problem; the only issue is determining the cause.

At this point, I am suspecting that the cause might actually be upstream of 
the filters/pump, inside the tank itself.   The fiber 'sock' broke free last 
year, and it seems possible to me that pieces of that sock combined with pieces 
of RTV might have plugged the pickup pipe inside the tank.   Mine is an early 
tank, so I am drawing fuel from a stand-alone pipe, as opposed to the later 
cars which used a pickup integral with the fuel level sender.

Tomorrow will reveal all, hopefully!

Mike


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