Hey D.V. Good to hear from you!

Here's the poop... There was a plastic/mesh sock in the tank. Found it at the bottom and was not attached nor no way to attach it. This fuel tank was originally from a F.I. car and simply made it a manual pumping station. I also thought the sock at the bottom was the problem and I removed it because it wouldn't stay on. The inline filter was added in lieu of the in-tank sock as an after thought. The pressure was an issue before the in-line filter was added. I just put it in recently to keep some of the crud out of the tank. Other than that, the tank is pretty clean and free of debris. I was thinking of getting one of those Summitt filters that bolt to the engine compartment with the large replacable filters that go to 10 microns. I have been trying to troubleshoot this in a methodical one step process to keep from getting confused as to how many things were changed at once.

Rundown:

Lines were all disconnected fromt the tank pickup to the carb and blown out with air compressor.

In line clear filter installed to not only filter debris but aid in "seeing" how much gas was actually flowing as a diagnostic tool.

Pressue guage has been installed from day one at the carb. (Liquid filled from Jegs).

Fuel pump line to pressure guage was disconnected at the pressure guage. Also, disconnected the coil wire. Turned car over a few times to see if the pump was pumping...gas spit a fot or so out of the line which indicated that the pump was indeed pumping.

All tubing from the tank to the carb is 5/16" which should be adequate.

Carb sprays gas into the jets with great force.

Am thinking that there might be a small leak in the mechanical pump diaphram that is causing the pressure to drop. Can't be the pressure guage as I can see the depletion of gas through the clear filter. Not to mention the guage doesn't care if it's gas, milk or water that it's reading...shouldn't fluctuate and the in line filter substantiates that fact that there is less gas a half-hour after starting the car. I'm going to buy the mechanical pump from Carquest tonight for $22.49 it's a cheap diagnostic tool.

If this doesn't work, I'm going to run 15' of hose straight from the tank on the outside of the car to the new fuel pump to eliminate all of the existing lines that came on the car originally.

Whew!!!!

Ren Man
Steve mentioned maybe a rubber hose may be collapsing ,
on the suction side of your pump replace any rubber hose with steel line it may be your problem if the fuel pump does not fix it .
I would be best NOT to run any rubber hose on the suction side of your fuel pump because your mechanical pump is made to suck fuel .
If you go with an electric pump always place it as close to your fuel tank as possible they are made to push Not suck !
We hade a Pontiac 400 eng in a 1965 Ford farm truck and when we would stand in the pedal it wound fall on its face due to a New cheap 3/8 fuel hose on the suction side ! If it can happen it has happened to me but I still love the sound of a bad V8....
Mustang Mendez

Tony,

You think the 5/16" is enough or should I buy 25' of 3/8" stainless steel?

ps: Can the hose collapse if the fuel tank is vented even to the point of having the LeMans cap open???

Dave,

When I posted my comments above, I thought you had already changed the fuel pump. Might be the only problem.

On the fuel line side- back to JEG's or Summitt, buy a 25' roll of aluminum fuel line. Awesome stuff, easy to bend, especially in a completed car.

You aren't running a rubber fuel line the entire lenght are you?
DV

Ps, yup...you'll have some left over but they only sell it in 25' rolls.
Pss...yup the hose can collapse even with the cap open. Remember you're pulling fuel not air. If the hose is really weak it can collapse with or with out air venting the tank.

Thanks D.V.,

I'm running intermittant rubber lines from the tank. There is a spliced piece in the pickup in the tank about 4" long. from the fuel filter (in the engine compartment) to the pump there is new braided line about 7'. I'll give the pump a try first.

ps: another friend of mine here suggested if you can invision this, placing a 6' piece of hose in a 2-3 gal container of Gasoline. Connect the other end of the hose directly to the fuel pump, thus, eliminating the entire length of original hose from the fuel tank to the fuel pump. Then, see what the pressure does. If it holds steady, it's a collapsing line caused from the sucking of the pump. Anything after the pump would not cause a drop in pressue as the pump it pushing from that point to the carburator. If there were blockage there, then the pressure would in fact increase due to the force being put on the line. If the pressure still dropped I have effectively eliminated the majority of line and it must be a defect in the pump itself.

Sounded pretty logical????

Dave,

Sounds logical. Try it.


D.V. has a good suggestion on the steel line. If you only have short runs of hose try and get some of the hose that NASCAR uses.

Mike

Dave,
Being carefull, outside, not in the garage, that would eliminate a lot of trouble shooting if it holds pressure at that point.

I have done that numerous times over the years. Sure narrows down the search filed!
DV

Ren,
I have the fuel line DV spoke of. I have a (blue) Holley pump and it is regulated down to 6psi at the tank and a second regular at the Webers down to now 2.5psi. If I unhook the fuel line at the webers I still get a fuel squirt farther than one foot. Maybe the ID of your fuel line is the culprit. Maybe just not enough volume to maintain good presure. Mine is the 3/8's ID not OD. and I also have two fuel lines running forward to the carbs.

It very well could be a starvation problem with line size. I would try the gas in a bucket first, outside as DV says. You can't afford a fire, believe me, I know the hard way! It is snowing here in Dallas and colder than heck, but you do not want to warm up the whole neighborhood.

Also is it possible that your pick-up line in the tank is not completely submerged and thus causeing it to spiratically suck air?

Damn, this should not be this hard to figure out. Adjusting four Weber carbs on the same engine, yea Ok, but not a fuel problem. This still baffles me.

Ferrari Killer
Steve Parks

Lets take a vote
1-Fuel pump
2-Fuel line
3-Pick up tube to short in tank
4-other please specifie
I choose { 1 }
Hang in there Ren Man its not that tuff .It can be fixed, but maybe not in one day like you thought .
Mustang Mendez

Ren,
I originally brought up the possibility of a collapsing fuel line. But I am still not sold that it might be the pump. I thought of the idea of just running a shorter line from a bucket but had not put that down here. I say run that diagnostic and you should have your answer. Good Luck!

Dave,

The suspense is killiing me !!! :confused:

Wellll ????????????

My vote by the way is / was simply the pump.

Inquiring minds have to know!
DV

Verdict will be in tomorrow D.V. Had to entertain the 2 year old last night.:p

I keep checking this thread hopeing to see you post, you solved the problem. I know how the kids deal works, We have two and to tell you the truth I just like playing with them more than working on the Cobra. They are only small for a short time. Enjoy them while you can.

Thanks for the insurance tip. Dave

Ferrari Killer
Steve parks

I agree Steve. She's the light of my life! A friend told me before we had her, "Whatever you are doing, drop it for her".

Amen to the kido

I have been toughing it for 2 1/2 years so my wife can stay at home with our little Boy {Wyatt Anthony Mendez } they are great . No money in the world can replace your love ones ...

Money can always fix a car ...

Mustang Mendez

Here is a pic of the plan for tomorrow morning...
 

Thought I'd give a visual for what I plan on doing tomorrow to isolate this issue.

Hmmm...Let me try this again...

Boy You computer guys kill me .
HA HA !!!
Yes that looks like a good safe plan .
Mustang Mendez

That almost looks too simple to work.

Keep us in touch.

Ferrari Killer
Steve Parks

Play it safe! Make sure you do it outside and not in your garage.