Car Runs Like Crap
Thread Starter
Instructor
Joined: Jul 2006
Posts: 223
Likes: 0
From: Rhineland MO
Car Runs Like Crap
Got my car back from being worked on. I had the rear spring replaced, differential cover replaced, differential cross member replaced and replaced the gas line. The car has had a little spudder when taking off but I just figure that it is the carberator that needs to be rebuilt. Now when I am going about 55 mph and mash on the gas, it feels like to car wants to die. I let up off the gas and it takes a few moments for it to repsond again but I have to press on the gas very slowly before it responds. The car idles good and when I gun it whiile it is in park, it seems to be responding good and the secondaries do kick in. It is when you put a load behind the engine when it does this. The car worked good when I took it into the shop. I was thinking that fuel pump might have got some dirt in it from the gas old gas line or maybe the float in the carberator could be stuck.
Does anyone have any idea what might be going on? Plus, where is the build sheet for the car located. It was not on top of the gas tank when they dropped it. They did say there was a shield above the gas tank and it could possibly be there.
Does anyone have any idea what might be going on? Plus, where is the build sheet for the car located. It was not on top of the gas tank when they dropped it. They did say there was a shield above the gas tank and it could possibly be there.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BKbroiler
Start by replacing or rebuilding the carburetor.
Which model carb are you running?
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by 75BrownC3
This is a 75 L-48 Q-Jet. Is there a way to test to make sure I am getting enough flow through the gas lines?
I would change the fuel filter first.
I would also contact the shop that did the work and ask them what happened
Ran fine when you bought it in, now it runs like crap?
Not acceptable in my book
Racer
Joined: Sep 2006
Posts: 484
Likes: 0
From: McComb Ms.
there is a certain amount of fuel necessary to cross the 1/4 mile in a certain time frame. If your not pumping that amount your carb bowls will run out of fuel before that time frame.X amount for a 10 second car.X amount for a 12 second car etc I don't remember the figures and i can't find my chart. If someone else doesn't have that info i will look around the shop tomorrow. Anyway your pump should pump X amount of fuel in a minute to be acceptable to maintain fuel to the bowls during operation. Take a measuring device larger than a cup and put your fuel line closest to the carb into the cup and have someone turn the car over for 10 seconds and see how much you get in the cup, take that number and multiply it X 6, that will give you the amount your pump is pumping per minute.If there is a restriction u know its between tank and carb.Possibly a faulty fuel pump. I think u said u have a Q-jet so i'm guessing your filter is at the carb. So this test won't tell you if your filters bad.
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
when you say "replace gas line" which line are you talking about? tank to fuel pump, fuel pump to carb, return line, etc. ??? sounds like a fuel starvation problem and since they worke on the "gas line" i'd start with that.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Racer
Joined: Sep 2006
Posts: 484
Likes: 0
From: McComb Ms.
here are the figures for amount of fuel necessary to complete 1/4 mile run in a particular time frame. U can use this to determine your problem.
You must fill a 1 gallon can in this time frame using just your fuel pump to run a particular time thru the 1/4:
12 second car it should take less than 35 seconds
11 second car less than 30 seconds
10 second car less than 25 seconds
9 second car less than 20 seconds
8 second car less than 15 seconds
7 second car less than 12 seconds
that can be used as a guide to see the state of your fuel delivery system, also it should maintain 6-7 psi pressure
You must fill a 1 gallon can in this time frame using just your fuel pump to run a particular time thru the 1/4:
12 second car it should take less than 35 seconds
11 second car less than 30 seconds
10 second car less than 25 seconds
9 second car less than 20 seconds
8 second car less than 15 seconds
7 second car less than 12 seconds
that can be used as a guide to see the state of your fuel delivery system, also it should maintain 6-7 psi pressure
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by thrilher
here are the figures for amount of fuel necessary to complete 1/4 mile run in a particular time frame. U can use this to determine your problem.
The guy has a stock L-48
No offense but where are you trying to go with this thread
He has a sputter and what sounds like either starvation or a improperly set secondary air valve, or many other possible problems...timing, vacuum ect:
Sorry but I dont think the quanity of fuel to run a measured run in a certain time frame has anything to do with his problem at hand other than making it much more confusing to diagnose......
Thread Starter
Instructor
Joined: Jul 2006
Posts: 223
Likes: 0
From: Rhineland MO
The main fuel line and vapor lines were replaced. I took out the fuel filter to replace but I have the wrong one. The one I have is about 1/2 the length of the one that is in there. I blew through the original filter and it seemed to flow good. Just out of curiosity, what is the inside diameter of the main fuel line supposed to be? They replaced it with a plastic fuel line and I am wondering if the inside diameter might not be large enough to carry the volume of fuel needed.
My buddy who brought it home for me said it seems like it is getting worse. He test drove it yesterday for me because of my knee. I thought maybe it didn't have enough gas in the tank so I filled it up and it still spuddered pretty bad.
My buddy who brought it home for me said it seems like it is getting worse. He test drove it yesterday for me because of my knee. I thought maybe it didn't have enough gas in the tank so I filled it up and it still spuddered pretty bad.
Instructor
Joined: Apr 2005
Posts: 136
Likes: 41
From: Arvada CO
It sounds like the problem mine had and it was a pinched gas line. I am not sure if they replaced the fuel lines from the tank to the frame, but if they did they would have dropped the tank. My rubber lines from the tank to the frame were crossing and pinched and that was the cause of my fuel starvation. It acted the way you describe for a while (approximately 3 months) and then started to get worse and worse until the car would no longer start.
The other line to watch is from the frame to the pump. Regular hose would not make the "S" without pinching itself off. A molded hose is available for this application. Good luck.
The other line to watch is from the frame to the pump. Regular hose would not make the "S" without pinching itself off. A molded hose is available for this application. Good luck.
Racer
Joined: Sep 2006
Posts: 484
Likes: 0
From: McComb Ms.
so your telling me that if his car running 14's should take 45 seconds to fill a gallon jug by pump, and it actually takes him 2 minutes to fill that jug won't indicate he has fuel starvation issues and he can apply that same figure to test before and after different component tests in his fuel system isn't logical? it's only a figure to give him an idea given by a professional carburetor manufacturer. It may be confusing to alot of you. As i'm just an amateur at this whole game i'll shut my hole
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by thrilher
It may be confusing to alot of you. As i'm just an amateur at this whole game i'll shut my hole
It is confusing to me and I maybe the one that is way off
By no means did I ask you to :shut your hole"
I would like to learn more about your theory as I am an amatuer as well
Racer
Joined: Sep 2006
Posts: 484
Likes: 0
From: McComb Ms.
no man i reread his post, i thought he replaced his rearend ..i see the fuel line change too...i just did the test for the sake of it while replacing my carb, it was fresh on my mind and would be a two step method with recordable results..i really am an amateur i wasn't being sarcastic. and yuo were right i was probably complicating a simple troubleshoot...no problems here man
Thread Starter
Instructor
Joined: Jul 2006
Posts: 223
Likes: 0
From: Rhineland MO
I finally think we have it fixed. I know it has been a while but I have been having some problems with my knees that prevents me from getting on floor to look over the fuel line to check for pinching or even doing anything that might seem simple to others.
I replaced the fuel pump and noticed a real small kink up by the fuel pump. I added the S hose to relieve that kink and that didn't fix the problem. I got an Edelbrock carberator from a friend up the road several weeks ago that came off a 70 or 71 Camaro 350. While standing around the car the other night, my step son came over and we decided to go ahead and change out the carberator. We had to make a few modifications, get some parts, but now the car sounds like it is running strong.
He put the carberator on yesterday afternoon while it was snowing outside. Now I can't wait for the snow to get off the roads so I can take the car out for a test drive. We did do a small brake torque yesterday and it didn't die out like it did before. I guess the Quadra-Jet is a real Quadra-Junk.
Thanks for all your ideas on trying to help resolve my problem.
I replaced the fuel pump and noticed a real small kink up by the fuel pump. I added the S hose to relieve that kink and that didn't fix the problem. I got an Edelbrock carberator from a friend up the road several weeks ago that came off a 70 or 71 Camaro 350. While standing around the car the other night, my step son came over and we decided to go ahead and change out the carberator. We had to make a few modifications, get some parts, but now the car sounds like it is running strong.
He put the carberator on yesterday afternoon while it was snowing outside. Now I can't wait for the snow to get off the roads so I can take the car out for a test drive. We did do a small brake torque yesterday and it didn't die out like it did before. I guess the Quadra-Jet is a real Quadra-Junk.
Thanks for all your ideas on trying to help resolve my problem.
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Originally Posted by 75BrownC3
I guess the Quadra-Jet is a real Quadra-Junk.
Thread Starter
Instructor
Joined: Jul 2006
Posts: 223
Likes: 0
From: Rhineland MO
Originally Posted by dgruenke
No offense, but that statement is only made by people that do not know enough about them or how to tune them. If you ask many people on this forum, a Q-Jet can support upwards of 400hp when done right.
Drifting
Joined: Feb 2005
Posts: 1,438
Likes: 2
From: Melrose Florida
Change the fuel filter that is in the carburaetor inlet...this is my bet for the whole problem.
I have a tank from a '74 in my '69, when I got it from the parts car the tank sticker was right on top...but almost dust. That is where it should be, if not there, pretty slim chances of finding it elsewhere (although it reportedly has happened).
Steve
I have a tank from a '74 in my '69, when I got it from the parts car the tank sticker was right on top...but almost dust. That is where it should be, if not there, pretty slim chances of finding it elsewhere (although it reportedly has happened).
Steve