Here's a new one for me....:(

[Double Venom]

As most of you know, I now own a Blue & White really neat & custom built Cobra. Seems the prior owner didn't like the Carter fuel pump I originally installed and have been using over 30 years without the first failure.

Any way it now has a very nice (read expensive) Holley black and chrome fuel pump in its place. (Remember the complaint about my customizing the fuel tank pick up system and after +/- 6 months started to drip-leak at the fitting to the pump? It seems whoever installed the new Holley pump galled the A.R.E. threads on the fitting. I cleaned up the threads, re-tightened the same fitting and...no more drips!)

Anyway...this same system has a full sized fuel filter, read same size as a normal oil filter, which I had originally installed.

Well.....Although "WE" all know Cobras do not run out of fuel! Ok, I did. This thing is NOT a fuel miser by any means. I put in 5 gallons...and the car refused to start! Checked the fuel pressure and read -0- while the pump was running..

Since the pump was running, no other indications anything else was wrong... I pulled the fitting off the tank, dropped the tank! , eventually pulled the pump, took it apart looking for either a running pump or an obstruction. NOTHING!

Ok, re- installed the tank, fule pump, fuel lines after cleaning them out etc.. Hit the safety switch, pump kicks in, NO start! NO pressure on the regulator!
The Holley is only putting out 4.5 psi by the way.

I've got it! The filter must be clogged! OK, can't figure out why with limited run time, but.....??? The Holley pump is running, I crack the first A.R.E. fitting to the filter and get a huge rush of air! I think to myself....hmmmm?? Tighten the fitting again, look at the pressure gauge ---wow a full 4.5 p.s.i. immediately.

Turn the key and fires right up! (Did all of the above twice!)

OK, moral of the story, IF you run out of fuel, re-load and if you are using one of the larger filters and it wont start. Check for an "Air-Lock" at the filter!

Never used a Holley pump before, maybe it's low pressure refused to blow by the large air bubble in the filter. Or the air-block would have happened regardless of the pump!?

Moral: Don't run out of gas!

DV

[Tommy]

Three thoughts on this, Ed. First, according to their web site info, the fuel pressure output on this pump is adjustable with an external pressure relief valve. Perhaps the original installer set it at 4.5 PSI. Second, if the pump was higher than the fuel level in the tank, and the pump had an air bubble in it, that may also have contributed to the problem. Third, if the owner does not have an external fuel pressure regulator, suggest he install one and reset the fuel pump to the full 14 PSI output. Letting the fuel pump regulate the pressure results in excess fuel being shunted from the output side of the pump back to the input side. On a hot day with a hot pump, this can overheat the recirculating fuel and create a vapor lock problem.

P.S. I suspect the problem was that your pump produced 4.5 PSI pressure on air before fuel arrived at it causing the internal pressure regulator to function. From that point on, the pump was simply recycling the same air. Opening the fitting at the filter allowed the pressure on the output side of the pump to drop below 4.5 PSI, bypassing the internal regulator and allowing the pump to push the air out and get to the fuel.

[WardL]

I doubt the fuel pump will pump much air. You need to bleed enough gasoline to the fuel pump before you will be pumping much fuel. Air in the lines between the pump and the engine will be pushed out. Air between the tank and the pump will cause the pump to not pump. At least that is my two cents....

I had an uncle say "I learned a long time ago cars don't run without it". I got the gene from dad that makes me play the "Let's see how low you can go before buying gas" game. I got my SPF below empty line, it was sprinkling and we were in somewhat of an area we were not familiar with. We stopped at three stations before we could buy gas. We bought 16.5 gallons....

[Double Venom]

Tommy, I agree totally to all. I too read the info on the Pump and read it is adjustable.
With a regulator I ASUME the pump is pumping maximum pressure. 14 lbs. +? If there is a regulator buried on this thing somewhere I haven't found it! (But I will look again today!) The pumps 'intake' is located just inches from the tank and about parallel with the top of the tank. The output of the tank is what I originally custom made; a 1/2" pickup 14"s long, running length wise in the tank. It then feeds out at the lowest section of the tank then 'UP" about a foot. The weight of the fuel alone should force fuel into the pump!

All information I have ever read says the fuel going into the carb should be 5.5lbs minimum. Motor doesn't miss or act like it is starved even under maximum hang on load!

Also so, being carbed; Holley-this is not a closed or a return type fuel injected system needing a return line.
Read: Out of Gas, the floats are fully down, opening up the jets in the carb,allowing air from the system to escape under pressure. In other words when the pump pumps fuel it will run along the line from the tank, to the filter then "through" the filter to the Carb. filling up the float cambers, eventually raising the floats high enough to shut of the flow, at which time the automatic by-pass in the pump takes over..... In other words NO air lock.! Hmmm????? Still thinking about this one!

DV

I think more info to come on this situation!

[Tommy]

Originally Posted by Double Venom

In other words when the pump pumps fuel it will run along the line from the tank, to the filter then "through" the filter to the Carb. filling up the float cambers, eventually raising the floats high enough to shut of the flow, at which time the automatic by-pass in the pump takes over..... In other words NO air lock.! Hmmm????? Still thinking about this one!

I was thinking about that too and here's my theory. When the system is filled with fuel, the fuel filter acts as a restriction in the line. But as fuel is not compressible, it does not significantly affect the pressure in the fuel line. Air is compressible, so I suspect the fuel filter acted sort of like a resistor in an electrical circuit. I believe it provided just enough back pressure to open the 4.5 PSI bypass valve in the fuel pump, effectively stopping the pump from moving more air. Meanwhile, air on the other side of the fuel filter easily escaped through the carburetor, showing a pressure of 0 PSI. Given enough time, I suspect the fuel pump would have eventually pushed enough air through the filter to start pumping fuel from the tank. But it may have damaged the pump impeller by then.

[jagrolet]

ed
one thing that i have found years ago, is that most pumps,(electrical or mech) do not draw fuel very well from below their level.Basically,most electric pumps are "pushers" not "pullers".

In 1972 i had the same situation with a 66 bb vette,the hot ticket at the time was ac delco industrial strenth electric pumps. After a bunch of head scracthing and pump replacing,the pump was put as low as possible with the scrub line of the tank,and with no upward motion of the infeed line to the pump.
I sure wish i could remember that part number,it may have been in the motion hand book.

Also,check (if running carbs) manf"s recomended fuel pressure to needle seat. This is one of the major mistakes people make with holleys (it results in all kinds of mayhem). And what gives alot of holleys a bad rap.

[Double Venom]

Jag..,
No doubt I am not a Holley lover since the early 60's blown power valves with as little as one backfire, float settings being a night mare, etc. however ONCE right they really can't be beat.

I also completely understand what you are saying, it's kind of like a biblical passage to electric fuel pumps. That is why, the way I have this set up the pressure of the fuel in the tank will force the fuel to the height of the pump on it's own,

Tommy you just filled in the missing blanks for me. Why does it only have 4.5 PSI and no regulator. (Still haven't found the regulator) It also explains why cracking the line at the filter lets the air out and the pressure immediately jumps to the 4.5!

Got time today so will follow the line from tank to filter to carb/fuel log to see if Ed's mechanic didn't install a pressure gauge somewhere. I never installed a pressure regulator as using the Carter fuel pump and a Edelbrock Carb. a regulator would be redundant!

DV

[jagrolet]

Ed
The point of the pump mounting position is that you can't always rely on the weight of the fuel to "push" up to the pump. Depending on the style of pump (vane,rotor,etc.),leak-thru for prime,may be at best,minimal. The upward loop of the line,is the air bubble,and alot of vane pumps,with internal regulators,won't let the air past by gravity alone.
Jaguar,on the XJS models,address this very intuatively,with a baffling resevoir and pump posistion.
thanks
wally

[Double Venom]

WELL, much checking and this particular Holley pump, as usual, is not working as it is supposed too. Holley is replacing with a new one. Actually ran out of gas again today! The thank sending unit is set to -perfect-!

Still read almost a half tank! 4.5 p.s.i. just wasn't strong enough to keep it running!Pulled of the road,sat for a second,ran the pump for a few minutes and the pressure came right up to ....4.5. Practically Ideled it home. Now waiting for a new pump that is supposed to be putting out 7.5 p.s.i.

The pump is "geared" much like an oil pump. Not a vane type pump!
We'll see.
DV

[Tommy]

A few years ago, I dropped off a used outboard motor to be repaired at a shop. Four weeks later I called to find out when it would be ready. The owner, who was not the person working on the motor, gave me a long, drawn out explanation about why it was taking so long. He explained that some of the screws that had to be replaced were very unique and had to be ordered and back ordered from the factory. Fifteen minutes later he called back to tell me my motor was ready. The mechanic had substituted some ordinary screws from the local hardware store. I asked him if he was sorry he had wasted one of his better excuses when it wasn't really needed.

I feel like I've wasted a perfectly good technical explanation on a phenomenon that was actually just a broken fuel pump. Oh well, it sounded good.

[Double Venom]

Tommy,
It ALL goes into the 'problem shooting file!
DV

[jagrolet]

Sorry too Ed,just trying to relieve some angst in your situation.
Over the years i have been reading your inputs,and builds,and it has helped me in finishing my CR. It was one of those deals when customer cars pay the builds,but the CR was something i really enjoyed.What really suprised me,was what a really solid car it turned out to be,neutral handling,firm ride(thanks to all the facts and posts by you),and just plain fun to drive. I have alot of odd cars in and out of my shop,but the cobra always seems to draw the most interest(even the young guys"tuner car",seem to stop to look when it is outside. Now to get the time to use it(instead of going "under the covers",with the rest of my dust collectors at the shop.

thanks
Wally

[Double Venom]

Well thank you Jag.

Since this fuel problem is a dead horse topic,(been on the forum so many times before.) I thought I'd go from start to finish on this so it makes sense-I hope! In other words, read bored at 5:00 AM

1.) Stock CR tank with top mounted pick up.
2.) Tank opened up, a long copper tube 1/2" diameter was mounted in the very bottom of the tank feeding directly out of the side. Fitted with A.R.E. fitting to adapt the stainless fuel line too.
3.) A modified, hand formed float to match the Smith Fuel Gauge- use a '88 Ford Mustang sending unit and modify to work.
4.) Tank was patched, mig welded and pressure tested for over 24 hrs. "Passed" Test.
5.) A top line "Carter" Electric pump mounted about 4"s in front of tank.
6.) CptEddy complained that the tank was dripping at the patch for "outlet"
7.) I take control of the car and immediately check into the "Drip" at the gas tank.
8.) Close inspection shows the fitting was the actual culprit! Highly unusual for an A.R.E. fitting to leak!
9.) Took it apart only to find the threads on the fitting have been "Galled"!?
(I Do NOT use any parts that have bad threads!???)
10.) WHOA, I then noticed that the brand new (Blah Looking) Carter fuel pump had been replaced with a brand new (Pretty) Black and chrome Holley pump! I have to assume this is where/how the fitting threads got galled!
11.) Removed the fitting, cleaned and made sure the A.R.E. fitting went on perfectly straight this time - no leaks! Pressure tested again-still no leaks.
12.) Took my new Cobra for a test run, damn..., very fast, steering TOO fast, with a small wheel and a "Quick Ratio" Flaming River wrack and pinion This thing was ready for "Danica" to drive!
13.)RAN OUT OF GAS! Tank read well over a 1/4!
14.) My wrecker driver who is always on call for one of my cars immediately responded with a "roll back". Boy is this sad for one of my brand new Cobras!
15.) Back to the shop, dropped the tank, removed my custom built fuel gauge
and re-set it to show EMPTY with 1" fuel in the bottom!
16.) Filled with 10 gallons of fuel-Motor refused to start!
17.) Tracked it down to a vapor lock at the large fuel filter. Cracked the line, let the air out and immediately the the fuel pressure gauge went to 4.5 p.s.i. . Should have been, per Holley 7.5 p.s.i.
Oh well the motor ran fine...wrote it off as the pressure gauge must be off - another Holley part!
18. Another test ride- WOW, ran great under normal conditions, finally tested the Mallory Chip (6,000 RPM) and worked as should. Back to cruising- RAN OUT OF FUEL ...AGAIN! Gauge almost at half full!?
19.) Buffalo'd, I sat for a few minutes, turned on the pump, like a miracle it started to read 4.6 lbs. Hit the key, started right up and cruised it home.
20.) Checked the entire line for a pressure regulator which I had not originally installed, kinks in the line, blocked fuel line---nothing abnormal!
21.)I know electric pumps don't "pull" well and that is why I mount ALL my electric pumps within inches of the tank. The Holly Pump "125" has a inspection screw at the rotors. Removed that and fuel poured out. As thought and originally planned for the weight of the fuel in the tank was enough to force fuel to the pump, read a distance of 8.5 inches of line from the tank to the pump!
22.) Back to Holley, this pump is self regulated to 7.5 lbs. Not 4.5.
23.) Holley stated this monster motor was eating more fuel under load than the pump was supplying!
24.) NEW, (again) pump on the way to be installed!
25.) (AND "I" get blamed for gremlins like this! )
26.) All is very good. Changed the wheel to one size larger, new pump that now reads at least 7.5 P.S.I., tinkered with the Coil-Overs, re-adjustd the seats. (Now a little guy like myself 200+ LBS., 5'9"s tall can easily reach the pedals and can actually push the clutch pedal all the way to the floor.

There you have it, my fuel headache all fixed!

DV

[Wisconsin_Snake]

Question regarding your perference on where to mount the pump.
I take it that you mount your pumps on the beam infront of the tank with the lip that jets out about 2 inches. Are you mounting the pumps there?
If so, on the top half or bottom half of that lip?

I will be running a fuel injected 5.0 and I am trying to determine a good place to mount the pump.

[Double Venom]

Fella, I have used both places on the lip you are referring to. However mounting them directly on the frame rail to the rear of the shocks seems to work better. This way you are only "Pulling" about 8"s right next to the tank. Way within bounds for even the cheapest electric pump!
DV

[Double Venom]

Hmmm,
Doing some final detail work on this Lady. Went to move it out of the shop and the engine wouldn't stay running again .... (Haven't got the new pump yet.) Checked pressure gauge and -0- again!

Ok, I do what I do best, I tore the brand new Holley 150 apart. Figured I couldn't hurt it.
Motor is totally seperate of the gears. Taking it apart there is an '0' ring on top of the gears- OK makes sense, then a large donut rubber gaskets with slots for fuel flow. Then a large matching metal washer with matching slots... Hmm?
How is the fuel supposed to go from the rubber washer though the metal plate and into the gears?

I simply changed the positioning of the rubber and the metal washer, Reinstalled, hit the switch and lo and behold, there it was... 7.5 p.s.i. vs. 4.5/0 p.s.i.!

And I thought it ran good before! Now I am thinking about doing my mods to the stock, (crappy) sidepipes!!!!

DV