Cuts out going up hill.

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Byron Gray

Byron Gray

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Location
Olympia Washington
My 67 Dart I can drive around town and on the freeway at speed just fine but when i got up a decently steep hill going 45 or faster the car will start to stumble like its losing fuel. When I step on the throttle i get nothing and i have to feather it until i get to the top and back on flat road. I stopped and the filter is full of fuel can hit the gas normal and the car seems fine get going back down the road and no stumbles can hit the gas hard it dosent fall on its face. Only when i go up hills. It has a 318 stock, 750 edelbrock carburetor and i have a holley mechanical fuel pump that has a higher gph then the stock pumps. Ive had this issue with stock pumps to. Only thing i havent checked is the sending unit I put a brand new tank in it a couple years ago with a new sending unit. Like when the fuel sloshes away from the pick up when going up hill my tank was full when it happend. Anyone els had an issue like this or other stuff i should check. I starting to lean to changing it over to and electric fuel pump and a tank with a pick up on the bottom of the tank.
 
This could likely be due to your carb floats out of adjustment, or stuck float valves.
- Since you mentioned the filter being full of fuel when it stumbles right?
- I would try to check those out first.
 
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I had the carb apart today i thought stuff was clogging it i didnt notice anything off with the floats. and the tank is full i had just filled it up before this happend and the hill is a decent hill its kinda long
 
Got a vented tank and or a vented gas cap?

Try pulling the long hill with the gas cap loose.

(Put a string on it so you don't loose it.)


☆☆☆☆☆
 
tank is vented it has a vent port above the sending unit and i believe my gas cap is vented i can try the cap lose or just take it off so I don't lose it
 
Byron Gray said:
I had the carb apart today i thought stuff was clogging it i didnt notice anything off with the floats. and the tank is full i had just filled it up before this happend and the hill is a decent hill its kinda long
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You did an excellent job of describing your symptoms.
It’s gotta be either the pump, the pickup or the lines between them.
Make sure no lines are sucking air anywhere, look for wet spots on the rubber ones, and replace any rubber that has hardened up.
Actually if you don’t have it already, use efi hose as it stands up to the newer fuels better and safer in my opinion.
 
Byron, my truck was doing that. Exactly as you describe. I very carefully went over the whole fuel system and found the culprit. The rubber hose from the sending unit to the hard line was very, very soft and I suspected that it was sucking shut. I replaced all of the sections of rubber hose with Gates Barricade EFI hose and the problem went away. It's worth a look.
 
RustyRatRod said:
Byron, my truck was doing that. Exactly as you describe. I very carefully went over the whole fuel system and found the culprit. The rubber hose from the sending unit to the hard line was very, very soft and I suspected that it was sucking shut. I replaced all of the sections of rubber hose with Gates Barricade EFI hose and the problem went away. It's worth a look.
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Exact same thing with the power wagon I gave my son...
 
Byron Gray said:
I wish I could do that. In Washington state unfortunately there is a lot of hills.
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There's not many less in oregon...lol...
Sometimes a little humor helps, but I'm sure you'll get this one fixed.It doesn't sound like it's an end all...
 
RustyRatRod said:
Byron, my truck was doing that. Exactly as you describe. I very carefully went over the whole fuel system and found the culprit. The rubber hose from the sending unit to the hard line was very, very soft and I suspected that it was sucking shut. I replaced all of the sections of rubber hose with Gates Barricade EFI hose and the problem went away. It's worth a look.
Click to expand...
I will look at that hose it is not that old but I know its not efi rated just normal fuel line
 
j par said:
There's not many less in oregon...lol...
Sometimes a little humor helps, but I'm sure you'll get this one fixed.It doesn't sound like it's an end all...
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Oh for sure its more annoying then anything lol but ya eventually will find the problem child
 
Byron Gray said:
I will look at that hose it is not that old but I know its not efi rated just normal fuel line
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That's not the only piece. Make sure to check them all. The piece that failed on me was probably no more than 5 years old. The EFI stuff is all I'll use now. I guess because of the truck's length, it had a piece of rubber hose about in the middle of the truck. It still had factory Ford part numbers on it. The truck is a 1975 model. lol It's funny though, although that piece was dry rotted, it was not all soft and mushy like the piece on the sending unit.
 
Make sure the met rod pistons are free to move up & down in their bores. As you load the engine, the piston springs should push the pistons UP so that the thin section [ enrichening ] of the m/rods are in the jets. Could be a broken spring, rare.
 
I think it might be fixed now wont be 100% until I take it on a longer drive. But I looked at my vent lines made sure they were all good, pulled my gas cap off and found it wasn't actually a vented cap luckily I had one already and put that on. I looked at the rubber line from the sender to the line and it felt a little soft so I changed it don't have any efi rated hose at the moment. Drove it to the hill and going up holding 50-60 mph it didn't stumble at all looped around and did it again and no stumble so think its ok for now. I appreciate all the helpful comments y'all gave me.
 
My son had that problem with his '68 Fury. Found the gas cap was not vented. He took the cap off and wooosh. Glad you found it.
 
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