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2/16/2020 12:07 PM  #1


Fuel Related Problem/Questions

Well, this is strange. I last ran the car in September and rolled it out of the garage last weekend to start it since it was a nice warm day (for winter anyway) but it wouldn't start. A little trouble shooting revealed that no gas was getting to the carb. I dumped a little more gas in the tank to be sure it wasn't too low  (only had a gallon or two in it initially because I wanted to calibrate the EMPTY reading on the fuel gauge) and still nothing. So,  I pulled the line from the mechanical pump to the carb and stuck it in a can and it wasn't pumping any fuel when cranking. 

I thought it a little strange that a basically brand new Holley fuel pump with less than an hour of running time would crap out, but stranger things have happened.

So, I bought a new pump, threw it in this morning and it too isn't pumping any fuel. I drained all of the fuel out of the tank and then disconnected the inlet fuel line to the pump and blew some air through the fuel line and into the tank and air flows through the line perfectly fine with no problem, which it should because it's a brand new one piece 3/8" line from tank to pump.

I next pulled the sender and it also looked good and had no obstructions.

So, now I am left scratching my head as to why no fuel is making its way from the tank to the pump.

The only thing I can think is that I somehow I didn't have enough fuel in the tank for the sending until to pick it up. When I drained the tank, I would say about 2- 2.5 gallons of gas came out. I am using the 1970 tank and sending unit and I would think 2 gallons or so would be plenty for the pick up to pull gas from the tank, but maybe not?

Does anyone know what is the "minimum" amount of gas you have to have in the tank for the pick up to be able to reach the fuel and send it to the pump?

And one more related question, when I pulled the sending unit, the plastic float was about 7/8 full of fuel. The sending unit and float are also new. I assume (perhaps incorrectly) that the float should not have any fuel at all in it?

Thanks!

 

2/16/2020 2:19 PM  #2


Re: Fuel Related Problem/Questions

So you managed to get it work, or not?

The float definitely shouldn't have fuel in it. 

 

2/16/2020 3:13 PM  #3


Re: Fuel Related Problem/Questions

The float should be empty. If it is full, it can't float.


Good, fast or cheap. Pick any two...
 

2/16/2020 4:31 PM  #4


Re: Fuel Related Problem/Questions

Can you siphon fuel at the fuel pump inlet?
It's possible to install a pump onto the wrong side of the eccentric.


"Those telephone poles were like a picket fence"
 

2/16/2020 4:58 PM  #5


Re: Fuel Related Problem/Questions

zakdaddy99 wrote:

The float should be empty. If it is full, it can't float.

Yep thtas why it's called a float and not a sink!


Good work ain't cheap, Cheap work ain't good!   Simple Man
 

2/16/2020 5:03 PM  #6


Re: Fuel Related Problem/Questions

TKOPerformance wrote:

So you managed to get it work, or not?

The float definitely shouldn't have fuel in it. 

 
Assuming I would need to get a new float assembly, I did not put everything back together, refill the tank and try again.

I'll order a new float assembly, throw it in and see what happens.

50Vert- I didn't try to pull fuel from the line at the inlet to the pump. I assume the orientation of the pump to the eccentric was correct because it ran perfectly when I parked it in September and the new pump went in right where the old one came out.

If I still get no flow once I throw the new float assembly in and refill the tank, then I'll try siphoning and double check the eccentric.

     Thread Starter
 

2/16/2020 5:09 PM  #7


Re: Fuel Related Problem/Questions

I guess this float was more like a bobber!

Last edited by Chaplin (2/16/2020 5:10 PM)

     Thread Starter
 

2/16/2020 5:15 PM  #8


Re: Fuel Related Problem/Questions

When disconnecting the pump did fuel run out of the line?  Being low enough the line should gravity feed to the pump.  I've always had to plug the line while changing pumps to keep it from dumping a ton of fuel. 

 

2/16/2020 5:23 PM  #9


Re: Fuel Related Problem/Questions

Almost nothing came out of the line- a little dribble, that stopped almost immediately.

Another thought I just had...

Are the lengths of the fuel pick ups on the sending units for 70s different (longer) than they are on 65-66s?

My car is a 64.5, but when I bought the tank, I bought the 70 fuel tank kit that came with everything needed to install the 70 tank in the 65-66 car.

Maybe they mistakenly gave me a 65-66 sending unit with the 70 tank?

Of course, if there is no difference between the 65-66 and 70 sending units, that blows that theory out of the water.

     Thread Starter
 

2/16/2020 5:30 PM  #10


Re: Fuel Related Problem/Questions

Mine has been sitting in the garage for awhile. When I run it out of gas it seem the only way to get fuel primed back up to the carb is to spray fuel into the carb. Start it up and keep spraying fuel into the carb until the fuel pump gets primed and will run on its own. Running it seems to be the only way to get the fuel pump to start sucking fuel. I can crank it all day long and will not get fuel to the carb. 


If this forum can't fix it, it isn't broke.
 

2/16/2020 6:30 PM  #11


Re: Fuel Related Problem/Questions

I don't have both sending units side by side to compare, but from pictures on the web it does look like the '70 sending unit has a longer pickup tube.  It looks like '65-'68 were all the same, but there was a change for '69.  I'd agree that you should match the sender to the tank.  If yours is still out check out one of the online retailers websites and compare the picture and the part you have.  CJs had decent pictures. 

 

2/16/2020 7:22 PM  #12


Re: Fuel Related Problem/Questions

Well, I just ordered a new sending unit for a 70 with the brass float. The one I have has a plastic float, which apparently isn't a quality item.

Hard to tell what I have now from the pics because it appears that the inlet filter on mine must have fallen off in the tank because it wasn't on the unit when I took it out. Another quality piece. I'll have to figure out how to get that out of the tank.

Will compare the new one with the old one once the new one arrives.

Stay tuned....

     Thread Starter
 

2/17/2020 5:56 AM  #13


Re: Fuel Related Problem/Questions

Some of the reproduction sending units have shorter pickup tube inside tank.

I had to add a short rubber extension to make it match length of original unit.
That was what I could do at the time,
It lasted until I had a pin hole leak in original tank.

From tank floor, vertically was almost an extra inch higher.

If you look at how it’s mounted.
Fuel has to get above the bend to start gravity feeding.

 

2/17/2020 6:26 AM  #14


Re: Fuel Related Problem/Questions

Chaplin wrote:

Well, I just ordered a new sending unit for a 70 with the brass float. The one I have has a plastic float, which apparently isn't a quality item.

Hard to tell what I have now from the pics because it appears that the inlet filter on mine must have fallen off in the tank because it wasn't on the unit when I took it out. Another quality piece. I'll have to figure out how to get that out of the tank.

Will compare the new one with the old one once the new one arrives.

Stay tuned....

Borescope and mechanical fingers would making getting the sock out of it fairly easy.  No baffles in those tanks, just go right through the sending unit hole. 
 

 

2/17/2020 6:47 PM  #15


Re: Fuel Related Problem/Questions

you COULD get a piece of heater hose and tape it to your vacuum cleaner hose.  Stick it in and suck it!
6sal6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

2/17/2020 7:26 PM  #16


Re: Fuel Related Problem/Questions

I got the inlet filter out this morning without too much trouble. I don't know how they expected that filter to stay on the pickup tube.   Not sure if the filter expanded when exposed to gas, but it was so loose on the pickup tube it just slid right off. It wasn't like that when I initially installed it over the summer.

     Thread Starter
 

2/17/2020 9:40 PM  #17


Re: Fuel Related Problem/Questions

I just went through this with my 77 F100. Ethanol is not your friend. I siphoned all that I could out of the tank. You can't buy non ethanol gas in Harris county. Put 5 gals in tank and nothing came out by the fuel pump. Sealed the neck on the tank and applied a LITTLE bit of pressure to move the gas up the gauge tube and out of the tank. Once I saw gas come out by the fuel pump I knew that the siphon effect would take over and the line was full from the tank to the fuel pump. Later
Huh hell pay attention

 

2/21/2020 9:05 AM  #18


Re: Fuel Related Problem/Questions

Everything in the fuel system is new and the only gas that has ever been put in it is the 2.5 gallons that I drained and that was ethanol free av gas. So, as much as I'd like to blame ethanol, it's not the culprit THIS time.

The new sending unit arrived and the pickup tube is the same length as the one I took out. The only obvious difference is that the new one has a brass float instead of a plastic POS float on the one I took out.

After testing fitting the new one I pulled it out and the inlet filter was about 50% wet with fuel, even with the tank drained as much as I could, so the pickup tube was still reaching some residual fuel in the bottom of the tank. So with 2.5 gallons in the tank, the pickup tube was definitely submerged in fuel and that wasn't the problem.

At this point, I'm not sure what the problem was/is. Maybe the check valve in the first pump was bad and allowed fuel to drain back into the tank?  But even if that was the case, after installing the new pump and cranking it over on and off for a total of a minute or so, I would think that would have been enough to pull fuel from the tank.  The first time I put gas in the car and started it, fuel got to the carb in much less time than I cranked it the other day.

This weekend I will roll it out of the garage, put another few gallons in the tank, fill the bowls on the carb, crank it over and see what happens.

     Thread Starter
 

2/22/2020 3:47 PM  #19


Re: Fuel Related Problem/Questions

Well, it fired right up today. I ran it on and off for probably forty minutes while I tinkered with other stuff and it started right up each time.

I am still having a really hard time getting the timing set exactly because I can't see the timing pointer very well (p/s lower hose, low mount p/s alternator and 11 o'clock pointer) and the balancer is a Ford Racing unit and the whole thing, including the numbers and lines, is just clear coated steel.  A black balancer with white numbers/markings would be much better.

I put 3 paint marks on the balancer

Yellow at TDC
Blue at 10 BTDC
White at 20 BTDC

When the engine was running the only mark that I could see at all with the timing light was the white one. I think I may borrow some bright red nail polish and put that at 10 BTDC and see if I can see that with the timing light.

I guess it was good that I had the issue with the pump because i found the bad float when I pulled the sender. With the new sending unit and float my gas gauge now works, so that's good.

     Thread Starter
 

2/22/2020 4:25 PM  #20


Re: Fuel Related Problem/Questions

Glad ya got it sorted. Luv it when a fix is actually a fix.


"Those telephone poles were like a picket fence"
 

Board footera


REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.