Car chugging

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Car chugging

Postby dalamar666 » Fri Mar 30, 2018 4:29 pm

Hi,

I have a 1975 Chevy Monza. It has been running great. I turned the A/C on while I was on the free way. A few miles later the car started chugging and dying. I turned off the A/C. I could start the car but it would chug and when it was chugging if I pressed on the gas it did nothing. I looked at the gas gauge and it was around 3/4. I figured it must be off and went and filled up. No change. When I would start the car and rev it up a little things sounded OK. When I started driving things then didn't sound right. I babied it home and it ended up just dying about every 50 feet the last few blocks. When I would rev the engine a little it would not rev right and had a deep bass sound to it. I have been thinking it was something in the fuel and need to replace the fuel filter. I just had a new carburetor put in and thought that would come with it.

Any other ideas???
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Re: Car chugging

Postby cjbiagi » Fri Mar 30, 2018 5:34 pm

Is this a stock engine or modified? It sure sounds fuel related. What type of carb and did you install it or have someone do it? Why did you recently change the carb? How is the exhaust system? Any chance that is damaged, bent, etc. Is this a 4 cyl or V8? Could be something as simple as a stuck choke or more complicated. Check the basics first, fuel filter would be a good start. Fuel pressure, air filter, anything that would obstruct fuel or air getting into or out of the engine.
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Re: Car chugging

Postby dalamar666 » Fri Mar 30, 2018 8:37 pm

cjb,

Thanks for the reply. It is not a stock motor. It is a GM crate V8. I had an edlebrock carb installed because the one that was on the enginge when I bought the car was a mechanical and the engine requires an electrical. My choke got stuck open and that is why I had the carb replaced. As far as the exhaust system, I am not sure.
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Re: Car chugging

Postby cjbiagi » Fri Mar 30, 2018 8:54 pm

Ok, well the Edelbrock is a pretty good carb, I have been running that for decades. A problem like this is hard to diagnose without seeing the car or knowing about it. Was it running fine just before you turned on the AC? These carbs require a external filter so that would be a easy first check. Have you checked ignition timing? That's another easy and free thing to check. Did you happen to just fill up with gas? What is the temperature where you are, hot? cold? We really need as much info that you can provide to offer suggestions on a forum
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Re: Car chugging

Postby dalamar666 » Fri Mar 30, 2018 10:12 pm

It had just gotten hot here about 65 or 70. It was running great and everything right before turning on the AC. Every since it has ran like shit. I have had the car back less than 2 weeks from getting the carb. My tank was about 3/4 and I have thought the gas gauge was lying. After filling up I found I had about 2 gallons in the tank. I filled up with gas thinking it was either out or that it was getting junk. I can check the air filter. I know when I start the car and rev it a little it had a bass sound when I was driving it the other day. I have not turned it on since. I have not checked the ignition timing. What are some other tell tale signs of that?

The car had been running great since I got it back. I was doing about 70 on the freeway when I turned the AC on. I also noticed that when I was driving if I got above 60 it triggered it to start chugging sometimes but not alwas. It would spurt get some power then spurt no power then spurt power. When I pumped the gas there were times it seemed like nothing was happening. Especially when it was close to dying. I would start to lose acceleration. I would pump the gas and sometimes i could get it chugging back to semi running and sometimes not. When it died I did not even have to let it sit or anything. Turned right over first time and revved up like normal when I would press on the gas. Up until about the last 4 or 5 blocks. Then it was hell getting it to idle correctly.

When I got home I checked under the hood and there was no coolant leaking or any signs of smoke or overheating, that was one of my first thoughts. The coolant reservoir had plenty of coolant in it. I am not sure how much it had used as they filled the coolant up when I got the oil changed about a month or so ago. The oil was good almost full. No milky look or anything nice and clean. I did not detect any odor from burning oil or anything like that.
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Re: Car chugging

Postby 283vega » Sat Mar 31, 2018 2:25 pm

check fuel filter. many have shit in tank that clogged filter
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Re: Car chugging

Postby dalamar666 » Sun Apr 01, 2018 3:49 pm

Thanks vega!!


Update: It is 75 outside, I do not have a temp gauge on the car, for some reason it didn't come with one and I need one badly. I replaced the fuel pump and filter. The one that was on the car was a generic and they did not have a filter at AutoZone for it. But they had the same pump so I decided rather than chasing around to replace that. I am lucky, the previous owner moved the fuel pump to right by the firewall on the drivers side so it is easy to get to. Took it for a test drive on the freeway. Got it up to 75 and went 5 miles and turned around. While accelerating on the on ramp coming back it stuttered around 45 50 and kept it up for about 100 yards. I pumped the gas and nothing, but found if I slowly accelerated, I could get it up to 65. It did not die and only stuttered the one time. I kept it about 65 the rest of the way home. Coming home I tested the acceleration using the same pressure I used on the on ramp and it accelerated fine with no stutter. I am thinking there might be something in my fuel line that just needs to work its way out. Maybe some water that caused air or something. It did not have the bass tone to the engine that it had previously and sounded normal. I checked the coolant when I got home and there was almost no coolant gone from when I measured it the other day. This is the first it has been out since then and I let the car idle for a bit before I left. It did sound normal idling and I did not have any stuttering then either.

I hope I am on the right track. If the stuttering continues, I may need to take it back in to the mechanic.

Any other ideas?

Thanks all for the responses!!!!!
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Re: Car chugging

Postby NVEGAR8D » Sun Apr 01, 2018 3:56 pm

Hi is the distributor tight? sounds almost like the timing went a bit off.
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Re: Car chugging

Postby kgroombr » Sun Apr 01, 2018 5:00 pm

For this to come on so quickly, I would check the fuel pump. Use a pressure tester. I think you can borrow one from some of the main auto parts stores.
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Re: Car chugging

Postby dalamar666 » Sun Apr 01, 2018 7:37 pm

Thanks all for the replies. I will check the distributor. I wondered if there was an issue with one of the plugs causing the chugging. I replaced the fuel pump. It was easier than I thought.
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Re: Car chugging

Postby cjbiagi » Sun Apr 01, 2018 8:55 pm

Electric fuel pumps are designed to push fuel, not suck it. That is why they are always mounted at the rear of the car or in the gas tank. Stock fuel pump is in the tank, do you know if that one is still in there? It could be defective so they just added a additional one at the front of the car (not the best idea) so now it has to suck fuel through the old in-tank pump. In tank pumps are available and I would go back to using that. If you need a pump feel free to let me know and I would be happy to get one for you. It's not hard to change assuming the gas tank is near empty,
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Re: Car chugging

Postby crawfw » Mon Apr 02, 2018 9:01 am

Does the Eldebrock have the float adjustment like the Holly. Ive only had one about 25 years ago so I don't remember. If so that would be something to check.
Also if the car still has the fuel pressure cut off, you could have a bad connection. Try bypassing that for diagnosis.
When it chugs while giving gas does it appear to be over fueling (flooding) or lack of fuel (lean condition)?
I'm assuming lack of fuel from what you describe. Also check voltage at battery while running to see what your alternator is putting out. You mentioned problem started when turning on the AC.
You could have something wacky going on with voltage/current supply to the system.
Your voltage should be approximately 13.5 to 14.5 volts at idle.
Just found a good link on adjusting eldebrock floats. Obviously they are not externally adjustable but looks easy enough without removing the carb.
https://www.youtube.com/watch?v=gXQ_mJhlZ0M
Also a fuel pressure guage may be necessary to assure you're not going over 6 psi
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Re: Car chugging

Postby dindin » Mon Apr 02, 2018 9:37 am

dalamar666 wrote:Thanks all for the replies. I will check the distributor. I wondered if there was an issue with one of the plugs causing the chugging. I replaced the fuel pump. It was easier than I thought.


I would check this , if it has headers you can run it then drop a little water on each tube to see if its hot..that low bass sound makes me think its not firing on all cylinders

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Re: Car chugging

Postby dalamar666 » Mon Apr 02, 2018 6:09 pm

The fuel filter was a false positive. I have found I have to really drive it around to get it to happen.

The fuel pump by the tank was removed. The previous owner told me he did that for convenience. I would be interested in putting it back. I will have to grab my service manual and see how hard dropping the gas tank will be. I will have to find some place that rents shop time or something as my apartment complex is picky about those things.

I checked the alternator a few months ago and was told it was fine, but it sounded fishy to me when I had a battery problem. I will have to get a meter and check the alternator.

Thanks for the link on the video for adjusting the floater. I will have to watch it.
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Re: Car chugging

Postby dalamar666 » Mon Apr 02, 2018 9:10 pm

cjb,

Thank you for the offer!!! What other parts can you get your hands on out of curiosity? Off topic, but I need some gauges for the front dash. My odometer is broken, fuel gauge still may be broken and I don't have a water temp/oil pressure gauge or a tach.
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