Fuel System Issues

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Millertime

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'73 mustang fastback mach 1
I have an issue with my fuel system. I've replaced the tank, fuel sending unit and fuel pump but I'm not getting any fuel down the line at all. For starters, I flushed the line between the sending unit connection and the in line fuel filter with the old fuel pump in place until carb cleaner came out clean. I then tested the fuel sending unit and my gauge read a full tank prior to install. However, when it was installed in the tank, mounted and I poured around 5 gallons of gas in, the gauge only comes up to empty. I understand the tank to be 20 gallons so it should read a quarter tank...? Lastly, I swapped out my fuel pump this morning, but I'm not getting any fuel to squirt into a bottle where I disconnected the fuel line before it reaches the in line fuel filter. I was thinking I could try running my fuel line from the pump into a jerry can to see if it's pumping correctly? And then that would mean my issue is between the fuel pump connection and the gas tank? Or do I just need to add more gas to the tank? I've added photos of my sending unit connection and fuel pump connection in case I messed something up... Thanks!

View attachment IMG_7431.HEIC
View attachment IMG_7432.HEIC

 
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From your pic, you may have the wrong sender or in incorrectly. Here is a pic of the way it should look. The one I used was the Dorman 692232 from RockAuto. Tank was the Spectra Premium F32A and pump was the Delphi MF0007. At first, I ordered the Spectra Premium sender # FG87A which is incorrect, reversed tube, but R/A exchanged it for the Dorman. Also I note you had a gear clamp on the inlet to the pump, I really hope that is just temporary. ALL clamps on fuel line need to be proper fuel line clamps.

IMG_1107-1.JPG

 

Millertime

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Thanks, looks like my sender could be the issue so I'll check that out. The hose clamp was the one that was on before I swapped the pump out from the previous owner I guess. But that's good to know, I'll swap it out too. 

 

Don C

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It's not unusual that the sending unit has to be adjusted, you'll need to jack up the left (driver side) of the car high enough that the sending unit can be removed, bend the float arm down a little, lower the car and hopefully your gauge will read 1/4.

As to not getting any fuel, did you replace the rubber lines with ethanol resistant hose? The old rubber hose may be collapsing internally and blocking the fuel flow. Do you have a hand operated vacuum pump that you can connected to the fuel line before the fuel pump to see if you can draw any fuel out? If not, your idea of trying to pull fuel out of a gas can is a good one. If you have a vacuum gauge you can connect it to the inlet side of the fuel pump to see if the pump is sucking.

I couldn't open the pictures, I don't like Apple and won't install it on my tablet.

 
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Millertime

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'73 mustang fastback mach 1
So I was out of town all week working, but I got my sending unit functioning properly last weekend and I'm getting my gauge to read around that 1/4 tank mark.

As for the fuel pump, I disconnected the line towards the tank and ran a fuel line into a jerry can but it's still not pumping, so I'm unsure of the problem. I've also rebuilt my carburetor but I don't think that would have anything to do with my problem. Is it possible I'm just putting it in wrong? I've put it in sliding the arm down low then raising it up so that it's under the cam shaft spring (I believe that's how it works). Any insight is awesome, thanks guys!

 

Tommyt

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On my fuel system the line itself was bad. I did new tank new sender new pump but couldn't get gas. I then added a electric pump back at the tank and it got gas and ran. I could spray cleaner through the line when off the car and the cleaner came through. I then pulled the big steel line again and replaced with aluminum tubing and that fixed it. That old line must have been corroded inside. Now gas flows good fills up filter fast with just the stock mech. Pump and I had to put a regulator on it since I'm running a new edlebrock carb.

 
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