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Blazer wont go over 35 MPH

T

tdcombs

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Well i got my Blazer started but when i got the test drive it today it has no power and wont get over about 35 MPH. Its a 72 that has a 383 in it. At least thats what the previous owner told me. It has a Carter Carb on it. Does this carb have an internal fuel filter? I took the fuel line off at the carb and it was under pressure and shot fuel all over the engine bay.

Any ideas? Where do i need to start? Im just wanting to get this thing running so i can drive it this summer. It was fun the 5 miles i got to drive it at slow speeds :) . Any help will be greatly appreciated.
 
Its an automatic tranny i think th350. I checked and its in 2wd that was the first thing i checked.

Where is this vacume modulator line?
 
if you have a 350 tranny it is on the back side of the tranny it is a cylinder about an inch and a half across. It should have a rubber line running to a steel line that runs to the carb and attaches to a vacum port on the car.
 
Any other ideas????

Is the fuel line supposed to be under that much pressure when the truck isnt running?
 
Hmm, sounds like when I bought my truck. Mine was a bad fuel pump, coupled with less than desireable spark plugs and distributor, and vapor lock issues.
 
Mine did that, couldn't go over 30, trans shifted fine. Ended up having clogged fuel filter.

I think Carter has one, but not sure where it is...
 
It seems like a fuel filter but i replaced the inline one. Dont know where or if there is one in a carter. Looked where it would be on a Qjet and there was nothing there. Its a new tank with new fuel so i know its not bad fuel.

Talked to a mechanic friend of mine that works for GM at lunch and he thought fuel pump so i guess ill pick one up after work and try that.
 
is there more then one fuel filter inline? The one i replaced is a glass one thats just before the Carb. There isnt another one under the Blazer is there?
 
What does it do when you reach 35?

Perhaps people that have had weak fuel pumps can comment, my only experience with a bad fuel pump was the engine stalled twice, and wouldn't start until the pump was replaced.

When my engine was starved of fuel, (float bowl was emptying) once I hit the magic RPM, the vehicle started to buck violently as fuel was "injected" into the carb each cam revolution, but thats not enough quantity to supply an engine as large as it was under WOT. I could make it stop bucking by letting up on the gas.

Could be something like an exhaust restriction as well as fuel. I can think of a few possibilities that could prevent acceleration beyond a certain point, I'd hate for you to replace a good part only to find it wasn't the problem. Unfortunately it's pretty hard to test the output of the pump unless you've got a fuel pressure gauge hooked up that you can watch.
 
"""Could be something like an exhaust restriction"""

that is what i was thinking but will it reve up quick and at what rpms is this happen?????
--- i am going with the cloged cat thery--- as i fish for more info :D
 
ramjet gmc said:
"""Could be something like an exhaust restriction"""

that is what i was thinking but will it reve up quick and at what rpms is this happen?????
--- i am going with the cloged cat thery--- as i fish for more info :D
Click to expand...

No cat and no tach. So thats not much help either. It doesnt buck just wont go any faster. Push the gas farther down and it doesnt make any difference. It doesnt seem to have alot of power getting up to 35 either.
 
When my fuel pump went out it would still pump, just not enough. The truck would get into the 30's then would starve out, and start surging.
 
wraenking said:
have you checked your throttle cable for any play, or make sure its pulling all the way back?
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Just replaced the throttle cable and checked it so thats not the problem. It still pulls back more just nothing happens
 
tdcombs said:
Just replaced the throttle cable and checked it so thats not the problem. It still pulls back more just nothing happens
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can you feel a difference at idle when you manually move the thorttle cable? or is it only under a load?
 
wraenking said:
can you feel a difference at idle when you manually move the thorttle cable? or is it only under a load?
Click to expand...


By manually are you meaning work the linkage by hand under the hood?
 
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