help ! boiling fuel ? engine flutters after 5 miles, what is going on ?

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Rockin Ken

Active member
Joined
Feb 26, 2023
Messages
41
Reaction score
23
Location
Coral Springs, Florida
My Car
SATIN BLACK '73 Mach I /468-C4, 3.25 POSI
after a cruise for about 5 miles(daytime]the engine starts to flutter like it's going to kick off.
then I rev the engine and it goes away, this then repeats about every mile till I get home.
this hasn't happened at night yet.
any help would be greatly appreciated.
coincidentally this all started after a fill up at a strange station, bad gas?
maybe no relationship to the issue
 
well I know nothing about gas but I do not like coincidences.....so if it never happened before and started after a fill up I would pull all that fuel out and clean the system.
I added some fuel treatment and we're going to test.
it's too much gasoline to remove.
 
Put some fuel stabilizer in the tank. Sounds like you might have some water in the fuel.
after testing with the gas additive no difference.

what should the fuel pressure be? mine is fluttering between 2 and 3 psi .
 
So, from what you're saying, it seems like the car has not run in 12 years, is that right? I mean, even if you never filled the tank full, did you run the car in that time? If not, I would have to think something serious needs to be done, maybe even a new tank or at least new fuel lines as well as a carb strip and clean.
On my car, the tank was still good, but I decided to change it all, front to back. Here's what part of the fuel line looked like, and this was a better part of it.
If you do decide it's time to replace lines, please remember to use Fuel Injector grade rubber hose where needed as it is ethanol resistant. Also a pep peeve of mine, use proper fuel line clamps, NOT gear clamps that can and likely will fail.
 

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after a cruise for about 5 miles(daytime]the engine starts to flutter like it's going to kick off.
then I rev the engine and it goes away, this then repeats about every mile till I get home.
this hasn't happened at night yet.
any help would be greatly appreciated.
coincidentally this all started after a fill up at a strange station, bad gas?
maybe no relationship to the issue
I had a similar problem where the fuel was vapor locking due to heat from the top of the water pump or the close proximity of the water hose. There's a lot of heat in that area. I put a pc of wire loom over it and had no problem since. I still want to add an aluminum shield one of these days. I knew this since it only happened recently in hotter weather while the engine was hot. I just read about the 12 yr part. Leave no old gas prob drop and flush tank, flush lines and replace filter right before starting. Big difference of indoor or outdoor storage.
 
Last edited:
So, from what you're saying, it seems like the car has not run in 12 years, is that right? I mean, even if you never filled the tank full, did you run the car in that time? If not, I would have to think something serious needs to be done, maybe even a new tank or at least new fuel lines as well as a carb strip and clean.
On my car, the tank was still good, but I decided to change it all, front to back. Here's what part of the fuel line looked like, and this was a better part of it.
If you do decide it's time to replace lines, please remember to use Fuel Injector grade rubber hose where needed as it is ethanol resistant. Also a pep peeve of mine, use proper fuel line clamps, NOT gear clamps that can and likely will fail
So, from what you're saying, it seems like the car has not run in 12 years, is that right? I mean, even if you never filled the tank full, did you run the car in that time? If not, I would have to think something serious needs to be done, maybe even a new tank or at least new fuel lines as well as a carb strip and clean.
On my car, the tank was still good, but I decided to change it all, front to back. Here's what part of the fuel line looked like, and this was a better part of it.
If you do decide it's time to replace lines, please remember to use Fuel Injector grade rubber hose where needed as it is ethanol resistant. Also a pep peeve of mine, use proper fuel line clamps, NOT gear clamps that can and likely will fail.
Yep mine sat for a bit longer than his or was subjected to outdoor storage. I also needed a new tank, sending unit, fuel inj rubber lines n clamps, pump,hard line,inj line to carb new filter carb. What came out of that tank was pretty scary sh!t The brakes were just as bad.
 
@Rockin Ken,
If when you do get the car back up and running after you have fixed any and all fuel flow issues and you still have vapor lock problems, you may need to either add a heat shield plate or an insulating spacer under the carb, or a more drastic fix, remove the intake and block off any exhaust heat cross over passages in the intake that go under the carb similar to a 351C. BUT as you list your car as a 468, I assume a 460 bored oversize, I can't say if that is a possibility and of course you might have added an aftermarket intake.
Regardless, it sounds like you have some work to do, keep us posted on progress.
While I'm here, I see you have recently joined the Forum, congrats and welcome. If you did not already do so, there is a section for Introduction under "Forum". We'd all love to learn more about you and your car. We love pictures and the back story. If I missed your intro, welcome from SW Ontario, Canada.
 
So, from what you're saying, it seems like the car has not run in 12 years, is that right? I mean, even if you never filled the tank full, did you run the car in that time? If not, I would have to think something serious needs to be done, maybe even a new tank or at least new fuel lines as well as a carb strip and clean.
On my car, the tank was still good, but I decided to change it all, front to back. Here's what part of the fuel line looked like, and this was a better part of it.
If you do decide it's time to replace lines, please remember to use Fuel Injector grade rubber hose where needed as it is ethanol resistant. Also a pep peeve of mine, use proper fuel line clamps, NOT gear clamps that can and likely will fail.
all good advice,
I changed the fuel filter and it seems to be repaired, so far.
the psi went from a fluttery 3 to a steady 9 psi at idle.
this issue was just a symptom, the cause is the fuel tank.
it will arrive tomorrow, and I will change it out.
 
@Rockin Ken,
If when you do get the car back up and running after you have fixed any and all fuel flow issues and you still have vapor lock problems, you may need to either add a heat shield plate or an insulating spacer under the carb, or a more drastic fix, remove the intake and block off any exhaust heat cross over passages in the intake that go under the carb similar to a 351C. BUT as you list your car as a 468, I assume a 460 bored oversize, I can't say if that is a possibility and of course you might have added an aftermarket intake.
Regardless, it sounds like you have some work to do, keep us posted on progress.
While I'm here, I see you have recently joined the Forum, congrats and welcome. If you did not already do so, there is a section for Introduction under "Forum". We'd all love to learn more about you and your car. We love pictures and the back story. If I missed your intro, welcome from SW Ontario, Canada.
thank you, and I will post some pictures
 
all good advice,
I changed the fuel filter and it seems to be repaired, so far.
the psi went from a fluttery 3 to a steady 9 psi at idle.
this issue was just a symptom, the cause is the fuel tank.
it will arrive tomorrow, and I will change it out.
If the previous fuel smelled like varnish, I'd run some denatured alcohol through the lines (hard line). It will break loose the varnish that's going to end up in your new filter. Probably already has. We are lucky these tanks are cheap. I had to take the tank out and flush it for a week on an old Datsun 280z car. It took 4 cans of denatured alcohol (80.00) to do it. I cleaned the sending unit as well & saved 700 from buying a tank n sending unit.
 

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