# 70 GTO stalls going uphill



## WillC (Apr 28, 2012)

I have a stock 1970 GTO Conv, 400, auto. It runs fine on flat ground and i can power brake it and it doesn't bog. I had a Edelbrock on it but it kept stalling going uphill. So I sent off the stock Q-jet and had it rebuilt and installed it. Car still stalls going uphill. It stumbles, I pump the peddle, it stumbles more then dies. I changed the filter, carb to fuel pump line and the fuel pump. The tank is full. Timing is correct and I adjusted the screws on the q-jet with a vacuum gauge for the highest reading. Seeing as both carbs were doing it, and I replaced everything i can think of, does anyone have any suggestions?


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## GTO JUDGE (May 14, 2005)

What kind of vacuum pressure you have when under load? How are the vacuum lines, cracked any signs of air being sucked in? All vacuum lines connected properly? Was the float in the carb replaced? Is it moving freely? Was the bottom end of the carb rebuilt? Bottom end gaskets replaced? 

Sounds to me like not enough gas in the bowl and when going uphill the lack of gas in the bowl is causing hesitation. Sure there is no obstruction in the fuel line? How bout under the motor? Is the fuel line being compressed say by the motor resting on the fuel line from perhaps an in-need of replacing the motor mount?


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## 1970 Lemans (Jul 25, 2009)

Have you checked the rubber hose(s) directly from the fuel tank to fuel line? Could be there is a crack in the hose and, when the vehicle changes angle, it distorts enough to allow air in. If going uphill, the hose might be less likely to be saturated with fuel even if tank is full. Just a guess.


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## geeteeohguy (Feb 2, 2008)

My guess is fuel line, or pickup sock in the tank itself. Fuel supply for sure. A line could be cracked and not leaking fuel, but drawing air. This is somewhat common on the rubber line from the tank to the steel line in the frame. Also, fuel socks degrade over time. I've had it happen. When pulling a grade, the vehicle is under heavy load, and any deficiencies in the fuel supply will become evident there first. Don't bother checking for vacuum leaks at the intake....there is 0 vacuum at heavy throttle under load, so it would not be an issue.


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## WillC (Apr 28, 2012)

*Ok*

I will check all of those suggestions in the next day or so and report back. 
Thank you!


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## WillC (Apr 28, 2012)

I replaced the fuel hoses going to the tank and took it for a ride. Works great! I went up a very steep hill going very slow and it didn't miss a beat.
Thank you!


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## geeteeohguy (Feb 2, 2008)

Great news. Years back, that same hose on my '67 was cracked and sucking air, but not leaking fuel. Same symptom. Hard to suck through a straw with holes in it!!


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## Instg8ter (Sep 28, 2010)

perfect case of trouble shooting...simple stuff first, we always think the worst....arty:


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## jetstang (Nov 5, 2008)

Damn, I was going to say move..
Nice catch on the fuel line, but wouldn't this happen at a certain fuel level. It's hard to think a line would leak on suction and not sitting. But it has to leak sitting, but its only a small amount that you don't notice.


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## geeteeohguy (Feb 2, 2008)

Doesn't have to leak. Mine was split in a ton of places....when the pump tried to pull fuel, the splits got sucked inward and pulled air into the line. Like a one way valve. No fuel leakage. Just aerated fuel. Also, mine was evident up hill and under load (I vividly remember where it stalled out on HWY80 just out of Reno!) due to the increased load on the fuel system under these conditions.


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## WillC (Apr 28, 2012)

The lines were old and vulcanized to the steel lines. I originally didn't think that was the issue because i would power break it and under load it didn't stumble. I also gently blew air into the tank through the supply and return lines to assure there was no obstruction. (Take gas cap off when you do that). So i now have a whole new fuel system. I contacted Cliff from Cliffs Carbs and i asked him about float level. He said even if the float was set way off it wouldn't do that and hes never know it to happen so i didn't open my q-jet to check.


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## jetstang (Nov 5, 2008)

I am dealing with exactly the same thing on a 68 Camper Special Ford truck, won't pump fuel to the carb, but spirts in the filter. Already backflushed the sock. It will pump fuel into a clear filter, but wont fill the carb. But with the top off the carb it spurts gas. Replacing the fuel pump..


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