Engine acts like gas starvation

I am no expert but like you I believe you should be able to blow air into the tank.

If you would drive the car with a loose or removed gas cap that would clearly provide a vent and if you then found the problem was gone that would confirm the area you need to attend to.

Another possible issue would be clogging due to a flaking gas tank coating. Some of the old school coatings are not known for their resistance to the crap in today's gasoline. Did you have the tank coated when it was cleaned?

And of course mechanical fuel pumps do wear out and fail. Often the failure mode is a breached rubber diaphragm that may allow gasoline to leak into the engine oil. You might check the oil for such evidence.

Good luck.

Larry

Thanks Larry,
when I had the tank cleaned they said that it was in real good shape for as old as it was so there was no coating placed in it. Never thought about the pump getting gas in the oil but it makes sense if the diaphragm is bad. In the little time I've had it running the fuel filter between the pump and the carb is always full and the fuel pressure gauge reads about 7psi all the time. I never let it run long enough to duplicate the problem. I was thinking the same as you, drive it with the cap loose and if no starvation occurs then it must be the vent or cap.
Thanks
Curt

Thanks Marlin for your input. since I joined the Forum in 2004 I've always valued and respected your comments but I have to take offence with your comment "Somebody who knows what they are doing, needs to check out Your Engine". I'm 64 and have been working on engines since I was 17 and rebuilt many. I built this one and it has run great for years. I even filed the rings for each cylinder. I know I'm not an expert but I do know something. I went home form work and took a picture of the gauge and I was wrong about the pressure. It's 8.9psi, not 7. I could not see with the dip stick tube in the way. I've attached a pic. The pic was taken with the engine not running so it's holding the pressure just fine and has for years. When the engine dies I mentioned that the filter from the pump to the carb was empty. If it was flooding I would expect it to be full. I also took off the air filter and the carb was dry. I still value your opinion but try to not insult people on your responses. I remember Mike The Snake from a while back and I thought comments got a bit over the top.

Cheers
Curt

Curt, If you are running a pressure regulation as you should be I would reduce the pressure. 4-6 is a good number IMO. I would also check the float levels.

The gauge indicates 8+ psi fuel pressure, but the carb is dry? Is the gauge possibly in error?

You should be able to blow into the pump suction hose and hear the gas bubbling away inside the fuel tank. The fuel tank must be vented, the fuel pump can't draw fuel out of the tank if the tank is under a vacuum. If this is what's happening then temporarily removing the fuel cap should fix the problem. But neither test explains why you had 8+ psi on the gauge.

If venting isn't the issue then I would disconnect the fuel hose at the gauge, stick the hose end in a jar, and have someone crank the engine to see if fuel flows out the hose.

This "should" indicate where the fuel is blocked, upstream of the gauge or downstream of the gauge.

Thanks George, The gauge represents the pressure right after the car was shut off and idling perfectly. Maybe it is reading much higher than it actually is. Most likely made in China.

I think as you mentioned I should be able to blow in the vent hose and hear gas bubbling but it appears to be clogged because I can't blow any air in it. I'll take the cap off and drive it and see if the problem happens.
Thanks again George.

The original internal steel tube fuel pick up tube has a tendency of rusting through at some point along it's length.


In my case I have a 72-1/2", #4460. September 72 build date. It had the early fuel tank that had the gauge float assembly separate from the fuel tube pick up.

That tube was welded internally to the internal baffles of the tank and is not removable.

Mine developed a rust hole in that pick up tube at about 1/2 tank fuel level.

I think this was caused by the tendency of me of storing the car with about 1/2 a tank of gas.


At some point, I had EXACTLY the issue that you now have. The tank had 1/2 tank of gas in it and the carb would run dry.

Cut to the chase. The pickup tube had developed a rust hole at the level of the fuel in the tank. At that level the hole would not let the pick up deliver fuel with the fuel level below the hole. The siphoning effect was broken there at that point. Above it, there was no problem.

You have all the symptoms of this in your car.



My solution was to install the newer type of fuel pickup with the integral fuel gauge float. That solved the problem.

With the new pick up assembly, there is one issue that was unexpected though, YOU must calibrate the float on the new pickup by bending the rod. Simple but takes a few hours of finagling to get the gauge to read approximately correctly.


Hope this helps.

Wow Doug, I hope that is not the issue. I do store the car with the tank not full. When I rebuilt the motor about 8 yrs ago I installed a new pickup assembly and float from Hall Pantera. Do you think that it could be rusted in 8 years.
Thanks for your suggestion.
Curt

Easy enough to find out. Pull it out and check it.

I just deal with the symptoms. If it quacks like a duck...

Disconnect the fuel line at the carb,check the stone filters at the inlet, then have someone turn the motor over, you should have gas flowing out freely and at 8psi. like a mini fire hose, now if you do not have fuel at the carb work back to the tank, the fuel pick up tube can and will over time fail, like Doug mine developed a crack in it about half way up the tube and would suck air at that point and the engine would starve out. You could if you suspect the fuel pick up tube run a hose into the tank and go directly to the pump, isolating your problem can be frustrating, take your time, you will be able to fix it.

I wish it was that easy. I installed the tube with the tank out of the car. To get the tube out with the tank in the car requires the window to be removed, well from what I've read on the forum. quack, quack
Thanks

quote:

Originally posted by 74LQQKR:
To get the tube out with the tank in the car requires the window to be removed,
Thanks

True enough and actually, quite easy.

Just yank on the window a little, comes right off.

Just a side note. If you put the car in long term storage (more than 3 months) the fuel tank should be either completely empty and dry or completely filled with stabilized gas. I doubt your tube would rust through in only eight years but who knows?

Doug M

You should first establish if the pick is the problem, run down to the auto parts store get 6 feet of fuel line stick it in a 21/2 gallon gas can run it to your fuel pump and start it up. Now you know if the pick up is bad. You can do it, if it is bad removing the side window is incredibly easy. cheer up you could have a serious issue like a blown engine.

Update: Got a cheep gas cap and drilled 3 - 1/4" diameter holes in it to vent. Drove 15 miles around, some heavy accelerations once in a while. Stopped a couple time to view the filters and the one from tank to pump was approx. 1/4 full, from pump to carb completely full and engine running perfect. Thought the problem was solved. Was going to head home but decided to go a bit further and it happened. Starts cutting out like running out of fuel so I pull over and engine is barely idling. I open the back and the filter from the tank is the same but the one from the pump to the carb is "swishing" fuel. Not full as before but I was able to limp home. Last night I removed the Holley fuel pump and put in a stock pump from O'Rilly's. Will connect hoses tonight hopefully and test. I'll let you know how it goes.
Just another thought: I have a MSD Blaster coil with MSD Dist. Was thinking that after a while the coil might be cutting out. It's been in since 2003.
Thanks all

quote:

Originally posted by 74LQQKR:
Just another thought: I have a MSD Blaster coil with MSD Dist. Was thinking that after a while the coil might be cutting out. It's been in since 2003.
Thanks all

Do you also have an MSD box to go along with the distributor and coil? I had a similar intermittent symptom a couple of years ago that was driving me nuts. I eventually figured out that my MSD (6AL) was starting to fail until it completely died backing out of the garage one day. I trashed the MSD, wired up a red strain relief Duraspark box and haven't had a problem since.

MSD = might suddenly die.

Just remember one name for an ignition. Pantera Electronics.

With the Motorsport, you need to change the distributor.

With the P-E, you do not.

https://www.youtube.com/watch?...cFg&feature=youtu.be

Do you know of another, just one, that will fire and clean up a fouled spark plug? This one does.

Note. The engine will run better with the plugs installed. I kept looking for more fouled plugs to clean up and forgot where I was supposed to be going.

Yep, ALL MSD parts.
Right after I rebuilt the engine I fired it up, topped off the coolant, got inside and it died. Never would start back up. Got a new 6AL and it fired right up. HUMMMM.

I lost count on how many Pantera owners here chimed in on one or more previous posts on the reliability of the MSD? A bunch.

The end result was an overwhelming reply of reliability issues with the 6a.



I personally had three fail on me before I thought it was more than coincidental.

I had MSD Customer Service tell me to stop calling them and please buy another brand.



You will find many here using the Motorcraft distributor and brain. I was formally. No problems with it. It is very reliable and inexpensive. Some here have had issues with the distributor drive retaining pin failing. I did not.

You will find as many using the Pantera Electronics, including me. I use mine along with a "Ford Racing" A341 distributor. Maybe it's an A342? I forget.

It's a great combination.



I run a set of Weber 48ida's so I like the added feature of firing fouled plugs and cleaning them while the engine is running. It would seem that Webers can foul up the plugs under certain conditions? Go figure?


As it turns out, there are some benefits to frequenting this site. You will likely find information ONLY posted here, i.e., such as the tendency of the Pantera internal fuel tube to hole through. Have you ever heard of that before? I haven't but I live a sheltered life.

Your primary float is stuck, tap the side of the carb with a screw driver, the float will release and you will run fine until it sticks again. dissemble and clean your carb.

Last test. Took the gas cap off so venting should not be an issue. I replaced the Holley fuel pump with a stock pump. $17.00 from Oreillys, can't beat that. Anyway, pressure is 5 psi and running perfectly. Went for a test drive and for the entire drive performed great with some 5.5k runs. Got near home and it hit again. Pulled into the garage and both filters were dry. Conclusion, something is in the tank. I have to admit I did not keep up with fuel stabilizer in the tank when the car sat while I worked over seas for a 4 years so I'm guessing that I've got a glob in my tank. I'll first try to open the drain plug in the bottom of the tank, guessing it wont budge. Then pull the pickup assembly, and learn how to remove the window. Then try to suck it out. Not really ready to yank the engine again to get the tank out. Maybe a winter project.
Thanks all on the site for your support.

Did you say that you had eliminated the fuel pickup tube in the tank as a possible?

Does this issue re-occur at the same place on the fuel gauge every time?

Apparently you don't want to hear from me on this and that is fine. This is sticking out like a sore thumb to me?

It doesn't matter how new or old that pickup is. If there is a hole in it send it back to Wilkinson and thank him for the junk he sold you?

quote:

Originally posted by 74LQQKR:
Last test. Then pull the pickup assembly, and learn how to remove the window. Then try to suck it out.

I have chance the fuelpick up several times and it's not needed to remove the window.

Simon

quote:

Originally posted by Simon:


I have chance the fuelpick up several times and it's not needed to remove the window.

Simon

Maybe not, but it makes it a LOT easier

Doug, sorry, I'm not ignoring you. The tank at 1/4 full now but has been doing this at 1/2 full so if it was a hole I would assume at 1/4 it would not get any fuel. But, I'll find out shortly when I pull the tube. You could be correct.
Thanks

I'm just trying to help.

Pulling out the tube/float assembly will also let you verify that the float is set correctly, that you do in fact actually have 1/4 tank left, and you aren't empty.

I have Wilkinson's assembly in mine also. The float rod needed to be bent to get the level correct when I got it.

It was not when I got it. Mine was off by around half.

That took me a while to figure out what was wrong there. Steve was like tits on a bull. Totally useless and my words although he heard them meant nothing too him.

No need to remove the pickup to determine if it has an internal leak. Just put a transparent tube/hose on the pickup and siphon the fuel into a canister on the floor next to the tank. If air bubbles start to form thats the level were the leak is

There are two possibilities: if its an early fuel tank with a separate fuel-out line via a banjo fitting, that tank has an internal fuel line welded to the tank wall, and a fabric 'sock' on the end. Over 40 years, the sock gets coated with varnish from fuel and seriously restricts fuel out flow. The sock is not serviceable; it must be torn off. Some use an air compressor to blow the sock off the end of the line but this risks pressurizing the tank into a very expensive thin-wall steel balloon or rupturing a weld.

More safe is pulling the rear quarter window for tool access, removing the fuel gauge sender and reaching in thru the resulting 2" hole with a long rod to tear the sock off (if it's still there), then fish out the remains. Be VERY careful in using trouble lights around an open-top tank! The banjo fitting on top of the tank may also have a huge build-up of varnish that restricts fuel flow out.

The welded line sometimes rusts through about half-way down its length even if the tank itself is fine. The fix is to use a late model sender with an integral fuel-out line built in. It fits perfectly. The banjo can be plugged or used later as an EFI fuel return.

Late tanks already have the late sender with integral fuel line and no banjo. Removing the sender, you can check for leaks. Normally, there's no sock nor filter on the line end. I've never seen a leaky line but that doesn't mean its impossible. I have seen weak fuel pumps that keep up OK at low engine speeds but gradually run out of gas at high rpms. A 0-8 psi gauge temporarily spliced into the carb feed line visible thru the rear window with mirror will tell you if fuel pressure gradually falls off.

Thanks Boss, this is late model (74).
Here's a pic of the tank when I rebuilt the engine. I installed a new float and pickup from HALL. I had the tank checked out and it was not coated inside, they said it was in very good condition.

Simon did you check the stuck float? The symptoms sounds classic stuck float.

This was what I had said when I started the post.
"I thought that a float might be stuck since the car sets a lot and the primary side (Holley) looked perfect and was not stuck"
Yes, I took the carb off completely and the primary bowl (vac, secondary). The float was perfectly free to move up and down and the needle and seat were fine.
I was able to remove the pickup and float without removing the window. I plugged one end and blew in it and no air escaped. I have to assume that something is floating in the tank. I'll siphon out what's left of the fuel and see what comes out.

The way to test that assembly is with a vacuum pump and a gauge. It needs to hold vacuum without bleeding down.

I got tired of fuel pressure issues. I had a fuel pressure gauge in the fuel rail in the engine compartment.

I installed a fuel pressure gauge in the dash where I can watch it. It has an electric sender so there is no fuel line in the cabin.

I put a vacuum gauge in the dash also.

Very cool Doug. Nice looking dash..

Thank you. I got rid of the dual pod dash. Went to this single pod. It helps a lot by putting what I need to know right in front of me.

Flashing lights, like on the "low fuel" warning, help get my attention.

The red button on the left that says "Hazard" was converted to the button that ignites the ejection passenger seat.

"When you press it, it releases this section of the roof and..."

IQQkr, see that black thingy next to your fuel-out sender? Cut the rivet heads off and add Hall's anti-roll-over valve and grommet for a cheap safety upgrade. Vent hose still goes out to the cannister or to the air cleaner housing. At $35, its about 10X cheaper than the bulky 3-piece one DeTomaso once offered, and works the same. You won't need it but once.....

quote:

Originally posted by PanteraDoug:
I got tired of fuel pressure issues. I had a fuel pressure gauge in the fuel rail in the engine compartment.

I installed a fuel pressure gauge in the dash where I can watch it. It has an electric sender so there is no fuel line in the cabin.

Nice set up! I though I was the only Pantera owner with a vacuum gauge. Of course I also have a fuel pressure gauge, oil temperature, fuel air ratio and outside air temperature gauge. I just can't seem to get enough information, but with EFI it is nice to know what your fuel pressure is on your system.
I put a vacuum gauge in the dash also.

quote:

Originally posted by JFFR:

quote:

Originally posted by PanteraDoug:
I got tired of fuel pressure issues. I had a fuel pressure gauge in the fuel rail in the engine compartment.

I installed a fuel pressure gauge in the dash where I can watch it. It has an electric sender so there is no fuel line in the cabin.

Nice set up! I though I was the only Pantera owner with a vacuum gauge. Of course I also have a fuel pressure gauge, oil temperature, fuel air ratio and outside air temperature gauge. I just can't seem to get enough information, but with EFI it is nice to know what your fuel pressure is on your system.
I put a vacuum gauge in the dash also.

This car in particular, for me, needs more information then originally supplied by the stock instumentation.

If I was going to race seriously, I probably could justify an oil temp gauge also. On the street with an oil cooler and a 10qt Aviad pan you don't need one to tell you the oil is too hot. Not at all. It takes a while for the oil to heat itself up.



What you are not seeing in mine is the LED's added. They are less intrusive then gauges.

The additional vacuum gauge and fuel pressure gauge help me the way this car is set up. Those two alone give a wealth of information including whether there are fouled or fouling spark plugs.

One of the LED's tells me when the auxiliary oil cooler fan turns itself on. There is another for low oil pressure. Another for high water temp.

Some blink, some just show a solid color.

With Webers fuel pressure is critical. With EFI it is also. It helps to know where all levels are at with just a glance.



Jon Haas has LED's in all of his electronic devices. None are driver accessible. They are for device status monitoring. Those are good ideas but you don't crawl under the dash to monitor them when you are driving.

When I did the fuse panel, I got the version with the volt meter built into it. When analyzing an issue, that can help, but that is when the car is in the shop, not when driving it.

I have this vision of having radar detection built into the dash inconspicuously but that would take up critical space in the dash.



The other reality with instruments is that when you are driving a vehicle at speed, the driver is looking down the road. FAR DOWN THE ROAD. Every heartbeat of time might be the length of a football field distance wise.

I know that I can not look down at my instruments, my eyes focus in detail and read them instantaneously after driving "at speed". Those dials are just a blur and I can only see "about" where those needles are pointing.

This is why if you look at the gauges in many race cars, the gauges are all adjusted to a point where when everything is about right, the needles all point in one direction, usually all to the top.

A driver at speed taking their eyes off of the road even for an instant could be catastrophic.

Many times more gauges just adds more confusion to a driver. In a sense, the quantity of gauges should be limited. That's my choice, anyway?

Current instrumentation in F1 cars is a good example of limiting the info to one point where the driver can focus on with a glance.



One could argue that the counterpoint would be something like a Ferrari "Daytona" 365GTB where seemingly there is a gauge for everything? To me, some of those gauges are close to useless and just there as a design statement of automotive jewellery.

The dials on these gauges are all coordinated. Where the needles are pointing makes sense to me and helps instantaneous focus?

What would have been perfect for me here in my gauge set up would be if the speedometer could be reversed indicating on the dial like the Smiths speedo in the Cobra is? Then all the pointers would be sync'd to the center making them simpler to read at speed, all pointers starting pointing at center?

You can get a better idea of what I mean in this closer up pic.



I now return you back to your regularly scheduled programming. Sorry for the side trip. I do try to make it entertaining though in hopes of a good review?