[DeTomaso] Pantera low fuel pressure indication--FIXED!
Mike Drew
MikeLDrew at aol.com
Fri May 18 19:06:33 EDT 2018
All,
Sometimes the hardest problems to figure out are the easiest to fix.
I have a fairly convoluted fuel plumbing scheme which, I realized while walking through Target, could lead to an air bubble in a line. With a small amount of fuel in the tank and the system otherwise dry, the fuel pump was sucking a mix of fuel and air.
So I put another eight gallons of gas in the car. It now shows full on the gauge. This raised the fuel column in the tank and made the fuel pump's job much easier. Turned the key, VAROOM and it started right up, and the gauge immediately jumped here:
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Perfect, in other words.
Now that the system appears to be fully primed, there is no reason to believe it won't work as normal even when the fuel level in the tank gets very low.
Thanks for all the suggestions--I'm glad the fix was so simple!
Mike
Sent from my iPhone
> On May 18, 2018, at 14:39, audionut at hushmail.com wrote:
>
> Hey Mike--
>
> Pull the pump, take it apart and have a look?
>
> Just dealt with a similar problem on my old Cadillac (1960 390
> V8/modern Edelbrock Performer 4 barrel). The car was consuming fuel
> pumps at the rate of 1 - 2 per year. Disassembly of the failed pumps
> always showed the same thing: press-fit valve popped loose from it's
> bore indicating that it was being overworked.
>
> I started at the tank by pulling a hose end off the tank spigot and it
> flowed prodigiously. I then checked the fuel lines for kinks forward
> from there. All these looked fine. Fuel filter was okay, no
> restrictions in the carb inlet.
>
> This may bear no relation to your situation, but the problem turned out
> be chronic back pressure created by intermittent vapor lock.
> Apparently modern 91 boils at a lower temperature than it used to.
> Removing the carb also revealed an open conduit from the exhaust
> through the intake manifold venting directly on the carb base/throttle
> plate. This bit of brilliant caveman design was a solution way back
> when to enable an engine to warm up quicker. I blocked the open
> conduit with a metal gasket that had no opening for that and also used
> a heat-shielding thick paper gasket on top of that.
>
> In the spirit of overkill, which always seems like a good idea on old
> cars, I also installed a modern cold air intake to further keep the
> carb cool. Recently did 6 hours to Vegas and back and no problems.
>
> In your scenario the only thing that comes to mind is that using 2
> filters may be overworking the fuel pump? These modern replacement
> pumps (or so I've heard) can be of poor quality due to parts companies
> assigning manufacturing to the lowest bidder and more often than not,
> China gets the contract.
>
>
>
> Perhaps your fuel pump is doing it's best with a slightly dislodged
> valve inside?
>
> John #5909
>
> (See you in Monterey!)
>
> Sent using Hushmail
> On 5/18/2018 at 12:55 PM, "Julian Kift" <julian_kift at hotmail.com>
> wrote:
>
> Assuming it isn't the pump (but really sounds like it is) it can
> only really be a restriction on the pump feed side; sock on fuel
> pickup or one of your filters blinded?
> You say a new tank, is this a 'new to you' tank perhaps even
> refurbished or brand spanking new? The former could perhaps have a
> coating that has failed and come off?
> Julian
> ________________________________
> From: DeTomaso <detomaso-bounces at server.detomasolist.com> on behalf
> of Mike Drew via DeTomaso <detomaso at server.detomasolist.com>
> Sent: Friday, May 18, 2018 12:32 PM
> To: De Tomaso Forum
> Subject: [DeTomaso] Pantera low fuel pressure indication
> Hi guys,
> Getting my Pantera ready for Monterey. It received a new fuel tank a
> couple of. Moths ago and was started for the first time and all
> seemed well. After sitting for a month it was very hard to start,
> requiring multiple manual injections of gas into the carb.
> Eventually it started and continued to run, and revs happily in
> neutral to 5000 rpm.
> But at idle it registers somewhere between 0 and 1/2 psi of fuel
> pressure. At 3000 rpm it goes to about 2 psi.
> Besides the obvious (bad fuel pump) what could cause such a thing?
> There are no indications of a leak anywhere. The tank has five
> gallons of gas. I have two fuel filters, one of them mondo sized.
> See video here:
> [1]https://youtu.be/jqNnqP_kxH4
> Thoughts?
> Mike
> Sent from my iPad
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