Bittersweet post, finally a problem I can't fix
Thread Starter
8th Gear
Joined: Apr 2012
Posts: 8
Likes: 0
Bittersweet post, finally a problem I can't fix
Hi there
I just got a 77 a couple weeks ago that is in far from perfect condition, however it isn't exactly the worst thing rolling around on four wheels. Like the title says the post here is bittersweet because while I've been lurking and searching for answers for a while, this is the first I've not been able to figure out. While driving if I get up to about 50mph the engine makes a noise like it's being overloaded and immediately looses power. It will bog and buck until what I assume is the proper mixture of air/fuel is flowing again. I'm a pretty handy garage mechanic but when it comes to these older carb engines I'm no expert. I would say that there's a fuel feed problem from the way it feels/sounds, but what I think is weird is up till about 50 I can slam the pedal and the car roars. Any help would be greatly welcome. I'll be working on it for the next two days, but after that I'm gonna need to probably take it to a *shudder* professional
I just got a 77 a couple weeks ago that is in far from perfect condition, however it isn't exactly the worst thing rolling around on four wheels. Like the title says the post here is bittersweet because while I've been lurking and searching for answers for a while, this is the first I've not been able to figure out. While driving if I get up to about 50mph the engine makes a noise like it's being overloaded and immediately looses power. It will bog and buck until what I assume is the proper mixture of air/fuel is flowing again. I'm a pretty handy garage mechanic but when it comes to these older carb engines I'm no expert. I would say that there's a fuel feed problem from the way it feels/sounds, but what I think is weird is up till about 50 I can slam the pedal and the car roars. Any help would be greatly welcome. I'll be working on it for the next two days, but after that I'm gonna need to probably take it to a *shudder* professional
Racer
Joined: Mar 2005
Posts: 287
Likes: 0
I would recommend checking around for an older guy that builds street rods or something.
That is where I find the most knowledge locally.
I agree that "professionals" are who you seek when you are at your wits end.
Good luck.
That is where I find the most knowledge locally.
I agree that "professionals" are who you seek when you are at your wits end.
Good luck.
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
I would change the fuel filter , check for any rubber fuel lines that could be collapsing and the tank venting system . Sounds to me like it is running out of fuel. Could also be a plugged exhaust systen, mufflers or plugged converter .
Bill
Bill
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Sounds like a fuel volumn issue. My guess would be one of the following in order of likelyhood:
1. Fuel filter.
2. Strainer sock in tank
3. Weak fuel pump
63split63 posted while i was slowly typing.
1. Fuel filter.
2. Strainer sock in tank
3. Weak fuel pump
63split63 posted while i was slowly typing.
Pro
Joined: Jul 2010
Posts: 691
Likes: 25
From: Boynton Beach Florida
I agree with the above recommendations and also check for a collapsed fuel hose. I had the similar problem luckily I have a fuel pressure gauge and noticed a loss in pressure. Found the interior of the fuel supply line had deteriorated and was causing a massive block/restriction. New $2 hose and problem solved.
Thread Starter
8th Gear
Joined: Apr 2012
Posts: 8
Likes: 0
Well all the exhaust and emissions were just replaced before the guy I bought it from moved from California. Today I was driving and whenever I got up above about 40 the car would seriously start bucking and just die. It did this about 5 times before I got it home. But I found if I kept it under 35 then it wouldn't have a problem.
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Verdad Gallardo
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
Probably not but I had a Mailbu once and it started sort of doing this
If I went easy it would drive along up to about 50 and then start bucking. If I slowed back down it was ok.
If I jumped on it, it would be ok for a minute then start into the bucking again as it gained any speed
Turned out the fuel line had a hole (rusted through) in it. When I was going easy it was ok but at the point where it started really pulling fuel it would just start sucking air, engine would drop off, fuel would flow again, repeat. It was on the point where it ran over the wheel/frame so it was pretty much the highest point and didn't leak anything onto the ground.
Worth a look, pressurize the fuel line
Mooser
If I went easy it would drive along up to about 50 and then start bucking. If I slowed back down it was ok.
If I jumped on it, it would be ok for a minute then start into the bucking again as it gained any speed
Turned out the fuel line had a hole (rusted through) in it. When I was going easy it was ok but at the point where it started really pulling fuel it would just start sucking air, engine would drop off, fuel would flow again, repeat. It was on the point where it ran over the wheel/frame so it was pretty much the highest point and didn't leak anything onto the ground.
Worth a look, pressurize the fuel line
Mooser
Le Mans Master
Joined: Jun 2007
Posts: 7,666
Likes: 1
From: Where it's always hot as Hell-South Louisiana.
St. Jude Donor '07-'08-'09-'10-'11-'12-'13
Fuel supply problem it sounds.
with that thought in mind, go from the tank to the carb and inspect / replace as much as you can.
with that thought in mind, go from the tank to the carb and inspect / replace as much as you can.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
It's located on the end of the pickup tube on the sender. The tank will have to be dropped and it would be a good idea to clean it while you have it off.
Thread Starter
8th Gear
Joined: Apr 2012
Posts: 8
Likes: 0
I replaced it today. It did make a difference (if not in my mind) and now instead of having to crank the motor for a good 10 secs on a cold start the problem still persists. I don't particularly have the means to drop the tank and clean out the sock, is there another way I could do it? Also, any info how to change the fuel pump?
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
I replaced it today. It did make a difference (if not in my mind) and now instead of having to crank the motor for a good 10 secs on a cold start the problem still persists. I don't particularly have the means to drop the tank and clean out the sock, is there another way I could do it? Also, any info how to change the fuel pump?
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
Disconnect the line at the pump and carefully use a compressor to blow some low pressure (like 5-10 lbs) air backwards (into the tank). If you can have someone watch (should be able to look into the tank and see) to watch for any crud.
I'd still disconnect the rubber line at the tank and plug it and pressure test the line, again only 5-10 lbs or so
Mooser
I'd still disconnect the rubber line at the tank and plug it and pressure test the line, again only 5-10 lbs or so
Mooser
