Fuel problem...need help

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Skat pack

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I have a 69 dart with a 440. After the engine has been running for awhile and gets hot,it shuts off. I though it was an electrical problem but,I unscrewed the fuel line from the carb and cranked the engine....I wasn’t getting any fuel out of the line. I already replaced the fuel pump and have the same problem. Any ideas?
 
Hello,
Check to see if the tank has a good vent. You can try the same test with the cap off.
If that is not the problem you can connect a test gas can to the input (suction side) of the pump. Re do test.
If still NG do same test at the tank.
NOTE: if you add a T at the carb inlet Or the output of the pump you can monitor the pressure with a Gage during testing.
Also check for cracked / rotted metal / rubber lines.
Hope this helps
Keep us updated
happy Mopar :)
Arron
 
Check the little rubber hose back at the fuel tank outlet/sender to hardline. Chances are it's cracked and the fuel pump is sucking air.
That or the pick up might be clogged if it sat long with old gas. Make sure the cap is vented too.
 
Hello,
Check to see if the tank has a good vent. You can try the same test with the cap off.
If that is not the problem you can connect a test gas can to the input (suction side) of the pump. Re do test.
If still NG do same test at the tank.
NOTE: if you add a T at the carb inlet Or the output of the pump you can monitor the pressure with a Gage during testing.
Also check for cracked / rotted metal / rubber lines.
Hope this helps
Keep us updated
happy Mopar :)
Arron
Thanks for the help..I’ll try it
 
Hello,
Check to see if the tank has a good vent. You can try the same test with the cap off.
If that is not the problem you can connect a test gas can to the input (suction side) of the pump. Re do test.
If still NG do same test at the tank.
NOTE: if you add a T at the carb inlet Or the output of the pump you can monitor the pressure with a Gage during testing.
Also check for cracked / rotted metal / rubber lines.
Hope this helps
Keep us updated
happy Mopar :)
Arron
Thanks for the help
 
Check the little rubber hose back at the fuel tank outlet/sender to hardline. Chances are it's cracked and the fuel pump is sucking air.
That or the pick up might be clogged if it sat long with old gas. Make sure the cap is vented too.
Thanks...I’ll check it
 
Thanks for the suggestions....but,if it is one of those things. Wouldn’t there be a constant problem? Not just when the engine gets hot? Because , before it heats up,the car runs great
 
If its getting hot and doing it, i an thinking you're getting vapour locked. Once the car cools down, and if you open the gas cap up and close it again will the car start? At what point does the car start again? Is there at least a 3/8 fuel line from the tank to the pump and up to the carb.
 
Check your fuel pump push rod, I had this problem on a new engine. Original rod was not compatible with the new cam and got worn down. Replaced it with a Comp Cam push rod and haven't had problems.
2017-09-30_001.jpg


Alan
 
As much as I don't like them get a clear fuel filter and see what is flowing when hot. Might have a carb float needle seat sticking issue?
 
Post #3 is going the right way. You want to make SURE the source (tank) is clean and everything associated with it is in good shape. If it was mine, I would remove the tank and have it cleaned by a competent radiator shop. That's the only way to know for sure you have it clean. Then, as MOPAROFFICIAL said, make sure all the rubber hose in the fuel system is new and clamped properly. Fuel hose is cheap. If you remove and install the tank yourself, that's pretty cheap too. All it takes is a little effort and you can have a really nice clean fuel system.
 
If its getting hot and doing it, i an thinking you're getting vapour locked. Once the car cools down, and if you open the gas cap up and close it again will the car start? At what point does the car start again? Is there at least a 3/8 fuel line from the tank to the pump and up to the carb.
Once the car cools back down it will start right back up.
 
As much as I don't like them get a clear fuel filter and see what is flowing when hot. Might have a carb float needle seat sticking issue?
I unscrewed the fuel line from the carb and not a drop of fuel is coming up from the pump. If I let the engine cool back down,then I get fuel.
 
Post #3 is going the right way. You want to make SURE the source (tank) is clean and everything associated with it is in good shape. If it was mine, I would remove the tank and have it cleaned by a competent radiator shop. That's the only way to know for sure you have it clean. Then, as MOPAROFFICIAL said, make sure all the rubber hose in the fuel system is new and clamped properly. Fuel hose is cheap. If you remove and install the tank yourself, that's pretty cheap too. All it takes is a little effort and you can have a really nice clean fuel system.
I’ll pull it this weekend
 
I unscrewed the fuel line from the carb and not a drop of fuel is coming up from the pump. If I let the engine cool back down,then I get fuel.
If its vapor lock, then based on what you describe here, its on the suction side. Check the routing of the entire feed line.
 
If its vapor lock, then based on what you describe here, its on the suction side. Check the routing of the entire feed line.
The worn down push rod will cause vapor lock symptoms as well as running hot. It was driving me nuts as to why my car was running hot even when it was not hot outside.


Alan
 
The worn down fuel pump rod is a really good suggestion, as I have seen that happen before.
Also one might consider replacing the rubber lines with EFI hose.
It's a lot tougher and todays alcohol mixed fuels don't affect it near as bad.

Taking the fuel cap off after it quits and hearing a long WHOOSH is a clue to no venting, which can override the fuel pump suction.
 
I appreciate all the advice. I’m going to go through everything this weekend. I will let you know how I make out.
 
I finally got a chance to work on my car. I pulled the fuel pump and the pushrod looks worn down. I ordered another one.
 
Hello Scat Pack,
Thanks for the update.
Let us know when you replace it if that cured the problem
Happy Mopar :)
Arron
 
Hello Scat Pack,
Thanks for the update.
Let us know when you replace it if that cured the problem
Happy Mopar :)
Arron
I will, I also dropped the tank which is very clean inside and ordered a new sending unit. I’m hoping the problem goes away !
 
I will, I also dropped the tank which is very clean inside and ordered a new sending unit. I’m hoping the problem goes away !

Hello Scat Pack,
Just as a word of caution.
Some aftermarket sending units don't accurately tell your gauge the correct level of fuel in the tank.
Does your old one work correctly?
Is so when you get the new one you can temporally wire it up with the tank still out (plug it in and Ground it). and see if it works from empty to full.
When i replaced mine (Aftermarket) i found that out of the box the OHM readings were way off from what the factory recommends.
I wound up buying three until i found one with 10 OHM at empty and 73 OHM full.
Knowing that aftermarket units are not would progressively so that they will read correctly i decided to start with a empty tank and 5 gallons at a time and watch the gauge. I did this until the tank was full so I know what is really in the tank vs what the gauge says.
If yours is a OEM and still works i would go with it.
Change the gasket !!!
There are plenty of posts on here that address tank senders.
Hope this helps.
happy Mopar :)
Arron
 
Hello Scat Pack,
Just as a word of caution.
Some aftermarket sending units don't accurately tell your gauge the correct level of fuel in the tank.
Does your old one work correctly?
Is so when you get the new one you can temporally wire it up with the tank still out (plug it in and Ground it). and see if it works from empty to full.
When i replaced mine (Aftermarket) i found that out of the box the OHM readings were way off from what the factory recommends.
I wound up buying three until i found one with 10 OHM at empty and 73 OHM full.
Knowing that aftermarket units are not would progressively so that they will read correctly i decided to start with a empty tank and 5 gallons at a time and watch the gauge. I did this until the tank was full so I know what is really in the tank vs what the gauge says.
If yours is a OEM and still works i would go with it.
Change the gasket !!!
There are plenty of posts on here that address tank senders.
Hope this helps.
happy Mopar :)
Arron
Thanks for the warning. I’ll check it first!
 
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