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Discussion Starter #1
New to the site, at least new to posting. I have been a member for just under a year.

My vehicle will hesitate when I try to go over 65MPH. Somewhere around 70. This is a fairly new issue. I installed a brand new weber carb over the winter, but this issue has been happening only over the past few months. Originally thought it was a vapor lock issue- which happened on hot days on my way home. I live outside of Boston, so the hot days are not often - but I no longer think this is my issue. It happened on my way to work and it was not very hot out or under the hood.

When I encounter the issue, I have to take my foot of the gas and let the car slow to 55-60 and then start speeding up again. If I speed up slow, I will get to 70 but that's about as far as I can go before the hesitation starts again. Last night, I floored it at 68 and heard a deep whine and lost speed and received a loud pop from the exhaust. I tried again a few minutes later and received the same answer from my car.

I think I am getting too much gas after 70mph, but I do not know how to get back to normal.

Help would be appreciated. BTW - I really tried to find my answer on the site before posting because from reading many posts, there are quiet a few on the site that rag on you for writing without research. I promise I tried, but I need your help and....

"I can't drive 55"!!!
 

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Super Moderator
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Sounds like fuel starvation. Probably the classic fuel sock blockage issue.
 

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Discussion Starter #4
Sounds like fuel starvation. Probably the classic fuel sock blockage issue.
Can you justify this for me? Why would a sock issue only be present after 65 mph, but never at lower speeds? I don't get it, but willing to listen if it fixes the issue....
 

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Can you justify this for me? Why would a sock issue only be present after 65 mph, but never at lower speeds? I don't get it, but willing to listen if it fixes the issue....
At low speeds there is low fuel flow. The fuel bowl stays full enough. At higher speeds/ loads the pump us sucking harder, and any debris in the tank gets sucked into screen and creates a blockage. VERY common issue with GT's
 

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Can you justify this for me? Why would a sock issue only be present after 65 mph, but never at lower speeds? I don't get it, but willing to listen if it fixes the issue....
It's not car speed related but more engine speed/load related, accelerate through the gears with the gas pedal to the floor and see what happens
 

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Can Opeler
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This problem happened to me after installing an OGTS fuel pump I bought 2 pumps and it happened with both. I cleaned out the little filter thing inside the carb inlet, and that improved it, but my problem didn't go away until I put on an electric fuel pump. It only happened on hot days for me as well. I also have a 1970 gt
 

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Über Genius
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Hesitation with new fuel pump.

I suspect your car has a fuel return line, correct?

If yes, then this is possibly what is happening.

Your old fuel pump was done so you buy a new one.
The new pump has more "flow" than the old one and, as such, returns more fuel to the tank as overpressure.
The increased fuel flow increases the turbulence of the fuel IN the tank and, thus, grabs more gunk from the tank.
This gunk clogs the fuel sock which, oddly, reduces the fuel flow.

So, your fuel sock is clogged
Your fuel filter gets clogged fast,
You have gunked up the pressure regulator
Or a combination of the above.
 

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Bikini Inspector
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Lets bring this full circle, what does all this have to do with the original question you say?

For things to run right you have to get rid of all the stuck up crap in the system.

fuel sock, fuel filter, drain and clean tank, filter in carb inlet and some fresh gas
 

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Can Opeler
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3,343 Posts
Lets bring this full circle, what does all this have to do with the original question you say?

For things to run right you have to get rid of all the stuck up crap in the system.

fuel sock, fuel filter, drain and clean tank, filter in carb inlet and some fresh gas
Speaking of which can you get the tank out without taking apart the interior?
 

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Über Genius
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Speaking of which can you get the tank out without taking apart the interior?
The only way to get to the tank is to remove the shelf over the top of it.

You have to remove the center support, and the spare tire hold down assembly.
Then remove the 10mm bolts on each side of the shelf.
You also need to remove the brackets that hold the shelf up. They are accessed through the outside in the wheel wells.
 

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Can Opeler
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The only way to get to the tank is to remove the shelf over the top of it.

You have to remove the center support, and the spare tire hold down assembly.
Then remove the 10mm bolts on each side of the shelf.
You also need to remove the brackets that hold the shelf up. They are accessed through the outside in the wheel wells.
Thanks! That will be a project somewhere down the road.
 

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Über Genius
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Thanks! That will be a project somewhere down the road.
It's not that big of a deal. It takes about an hour, tops.

Putting it all back together takes a little longer.

It takes longer to replace the vent lines than it does to pull the shelf.
 

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Can Opeler
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It's not that big of a deal. It takes about an hour, tops.

Putting it all back together takes a little longer.

It takes longer to replace the vent lines than it does to pull the shelf.
Yeah, I don't need to do it urgently, I've replaced my bottom drain (it was rusted out) but my gas tank seemed clean and I hardly ever get anything in my fuel filter, but cleaning it out good would be good preventative maintenance in the least.
I would do it now, but I don't have my GT back from the paint and body shop for a few months:/
 

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Discussion Starter #17
OK, I am no longer a virgin to posting on this site, but I have to say that I am very disappointed by this forum. I posted for help and found a bunch of guys (I suspect) with too much time on their hands who just want to banter and see who can piss higher on the wall.

I need help, real help or advise. It is not a sock issue. The only time the car hesitates is when I speed up between 65 and 70. THE ONLY TIME. It didn't happen EVER before I put my new OGTS fuel pump on. The car is fine when I floor it at any other speed, in any gear. I am leaning now towards the fact that I did not install an electric fuel pump. My guess is this is my issue. I believe one person replied and provided this hint to me.

In regards to the tank, I will be taking it down this weekend to repair the vent lines, since every time I add gas I smell it in the car. While doing this I will evaluate some other items mentioned on the site, so thanks to those who stayed focused on the purpose of the site.

I am not saying that banter is bad, but I do not understand why I had to sift through all the BS to get some help. If you want to help fellow Opel owners, then help. If you want to play high school antics then there are many sites open to that....like facebook and twitter to provide a few. My guess is there are those of you who will take issue with me calling you out. If you do, I guess I will see more immature banter, but I am serious. This is a great site and has a great mission, truth may hurt, but why not grow from it.
 

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Bikini Inspector
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you do not have to pull the tank to repair the vent lines. and unless you have an inspection camera it may still be the sock. It has happened many times before that a mechanical pump out of the box is not up to par.

If youre looking for no nonsense perfect help i suggest you call OGTS and ask for Dave.
 

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Discussion Starter #19
you do not have to pull the tank to repair the vent lines. and unless you have an inspection camera it may still be the sock. It has happened many times before that a mechanical pump out of the box is not up to par.

If youre looking for no nonsense perfect help i suggest you call OGTS and ask for Dave.
What's the best way to fix/check the sock?
 

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Bikini Inspector
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I would disconnect the fuel outlet from tank bottom and drain into a bucket. if it gushes fast and does not slow it may be fine. if it stutters and slows or has alot of color to it your tank needs a cleaning and sock removal. it is generally one of the first things you should do if a GT has sat alot.
 
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