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

[Will Kooiman]

Sorry - long.

I went through the same thing a few years ago.

I started with the normal setup - fuel line attached at the top of the tank,
mechanical pump, filter between the pump and carburetor.

Once I determined it was a fuel delivery problem, I changed the pump and
filter.  It didn't help.

I decided the tube in the tank was plugged (after all, what else is left?),
so I moved the feed to the bottom of the tank.  I also moved the fuel filter
to the suction side.  It ran great for about a month.  Then it would die
every once in a while.  I thought it was a coil problem (which I also had),
but then I hooked up a fuel pressure gauge and could tell I still had a fuel
delivery problem.

I hooked up an electric fuel pump thinking my new mechanical pump was bad
(it was - cheapo china part).  The new electric pump didn't help.

I bought a Holley mechanical fuel pump (much better quality than local parts
store).  It didn't help.

I even tried both - the electric and mechanical.  I wasn't planning on
running that way, but I was curious.  It didn't help.

I finally pulled the new filter thinking it had to be the problem, and it
was completely plugged.  You could hold it upside down and the gas wouldn't
drip out.  Turn it the other way, and all the gas ran out.  It looked like
it was clogged with rust dust.

I ended up buying a fancy AN-8 Earl's filter, but the filter element was the
size of a quarter.  I don't think I even installed it.  Instead, I bought a
mongo-er filter that's about 5 inches long.  I think it was a Moroso part.
The filter mesh is shaped like the filter.  It's hard to explain, but it has
a lot more mesh.  I kept the feed at the bottom of the tank.  I kept the
mechanical fuel pump, and I moved the filter to the pressure side of the
pump.

I don't have fuel delivery problems anymore.  I clean the filter every year
or two.

I hope to paint my car soon.  When I do, I'll either move the feed back to
the top or I'll protect the line at the bottom better.  For now, however,
I'm enjoying the car without fuel delivery problems.

Will.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of MikeLDrew at aol.com
Sent: Friday, April 04, 2008 12:58 AM
To: garth_rodericks at yahoo.com; detomaso at realbig.com
Subject: Re: [DeTomaso] Three steps forward, three steps back....


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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