Classic Mustangs List Archive

This read-only message was archived from a public mail list.
Mail From: Mulcahy (email redacted)

Maybe someone can tell me what's going on here. Ever since I bought my
'66 coupe this has been going on. When I drive it at about a half tank
of gas or lower at highway speeds it will die. But this only happens
with less than a half tank AND at above about 60mph. Then the car acts
like a car that is running out of gas and may backfire a little. After
that I can easily restart it and drive away as long as I stay below 60.
It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
thinking that maybe the fuel line is curled up in the tank, but that
doesn't explain why it only happens above 60. I know the gas guage is
correct because when it's half full it takes 8 gallons.

Thanks,
Keats Mulcahy
'66 289 coupe

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Mail From: Sam Weatherby (email redacted)

For a second there I thought you were crazy. I am used to a 22 Gallon. Tank.
I know on EFI vehicles that the fuel rails are pressurized and the more fuel
used the more needed to keep the pressure so my truck will keep run at 30
when it won't at 70. Of course that's when I switch to the other tank...
I don't know how this could apply. since unlike EFI, excess fuel isn't
returned, it just isn't allowed into the carb.

Sorry if this post makes no sense or is pointless.
-srw


Sam Weatherby (email redacted) insert.com/sammy
'70 Mustang Grabber Sportsroof
'93 F-150 XLT Lightning

-----Original Message-----
From: Mulcahy <(email redacted)>
To: Multiple recipients of list <(email redacted)>
Date: Wednesday, September 17, 1997 6:44 PM
Subject: [CM:6021] Dying on half a tank


>Maybe someone can tell me what's going on here. Ever since I bought my
>'66 coupe this has been going on. When I drive it at about a half tank
>of gas or lower at highway speeds it will die. But this only happens
>with less than a half tank AND at above about 60mph. Then the car acts
>like a car that is running out of gas and may backfire a little. After
>that I can easily restart it and drive away as long as I stay below 60.
>It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
>thinking that maybe the fuel line is curled up in the tank, but that
>doesn't explain why it only happens above 60. I know the gas guage is
>correct because when it's half full it takes 8 gallons.
>
>Thanks,
>Keats Mulcahy
>'66 289 coupe

This read-only message was archived from a public mail list.
Mail From: (email redacted) (email redacted)

Mulcahy wrote:

> Maybe someone can tell me what's going on here. Ever since I bought my
>
> '66 coupe this has been going on. When I drive it at about a half tank
>
> of gas or lower at highway speeds it will die. But this only happens
> with less than a half tank AND at above about 60mph. Then the car acts
>
> like a car that is running out of gas and may backfire a little. After
>
> that I can easily restart it and drive away as long as I stay below
> 60.
> It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
>
> thinking that maybe the fuel line is curled up in the tank, but that
> doesn't explain why it only happens above 60. I know the gas guage is
> correct because when it's half full it takes 8 gallons.
>
> Thanks,
> Keats Mulcahy
> '66 289 coupe

How long have you owned this car? Has it been sitting long? If so,
you might want to check the gas tank because it may well be very dirty
due to rust and corrosion; also check your fuel filter(s), they might
also be clogged for that same reason.
-Val
'68 Fastback
302 4spd.

This read-only message was archived from a public mail list.
Mail From: Randy Siwik (email redacted)

>From: IN%"(email redacted)" 17-SEP-1997 21:57:10.77
>Subj: [CM:6021] Dying on half a tank
>
>Maybe someone can tell me what's going on here. Ever since I bought my
>'66 coupe this has been going on. When I drive it at about a half tank
>of gas or lower at highway speeds it will die. But this only happens
>with less than a half tank AND at above about 60mph. Then the car acts
>like a car that is running out of gas and may backfire a little. After
>that I can easily restart it and drive away as long as I stay below 60.
>It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
>thinking that maybe the fuel line is curled up in the tank, but that
>doesn't explain why it only happens above 60. I know the gas guage is
>correct because when it's half full it takes 8 gallons.
>
>Thanks, Keats Mulcahy 66 289 coupe

Ok, Here's my shot at it. On a mechanical fuel pump, does
it not create more pressure the faster you 'pump' the drive
handle? If you have 'crud' in the tank, and not much gas to
suspend the crud (as in less then half a tank), The faster
moving pump (car going over 60) could suck 'crud' down
into the fuel pickup line, restricting the supply of gas.
To test, I'd install a big clear plastic in-line fuel filter
try to see if you're getting 'crud' in the filter.
This may not catch big stuff from the tank if it never gets
into the line.

Second guess: Piece of rubber fuel line could be sucking shut
under pressure. Check under the car to see if any of the metal
line has been replace w/ a piece off rubber hose and inspect.

Good luck, Let us know what you find.

Randy Siwik '70 Mach 1 351W 4V 4-speed
Central Ohio '70 Galaxie 500 Fastback

This read-only message was archived from a public mail list.
Mail From: Collins, Jackie, MAJ (143TRANS) (email redacted)

I had a car that did the exact same thing. Turned out to be a clogged
screen on the pickup. It let enough fuel pass to run fine at low
speeds, but not enough to go over 60. Pull the sending unit/pickup
assembly, clean or replace, and your trouble should disappear.
Jack

> ----------
> From: Randy Siwik[SMTPemail redacted)]
> Sent: Thursday, 18 September 1997 09:30
> To: Multiple recipients of list
> Subject: [CM:6035] Re: Dying on half a tank
>
> >From: IN%"(email redacted)" 17-SEP-1997
> 21:57:10.77
> >Subj: [CM:6021] Dying on half a tank
> >
> >Maybe someone can tell me what's going on here. Ever since I bought
> my
> >'66 coupe this has been going on. When I drive it at about a half
> tank
> >of gas or lower at highway speeds it will die. But this only happens
> >with less than a half tank AND at above about 60mph. Then the car
> acts
> >like a car that is running out of gas and may backfire a little.
> After
> >that I can easily restart it and drive away as long as I stay below
> 60.
> >It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I
> was
> >thinking that maybe the fuel line is curled up in the tank, but that
> >doesn't explain why it only happens above 60. I know the gas guage is
>
> >correct because when it's half full it takes 8 gallons.
> >
> >Thanks, Keats Mulcahy 66 289 coupe
>
> Ok, Here's my shot at it. On a mechanical fuel pump, does
> it not create more pressure the faster you 'pump' the drive
> handle? If you have 'crud' in the tank, and not much gas to
> suspend the crud (as in less then half a tank), The faster
> moving pump (car going over 60) could suck 'crud' down
> into the fuel pickup line, restricting the supply of gas.
> To test, I'd install a big clear plastic in-line fuel filter
> try to see if you're getting 'crud' in the filter.
> This may not catch big stuff from the tank if it never gets
> into the line.
>
> Second guess: Piece of rubber fuel line could be sucking shut
> under pressure. Check under the car to see if any of the metal
> line has been replace w/ a piece off rubber hose and inspect.
>
> Good luck, Let us know what you find.
>
> Randy Siwik '70 Mach 1 351W 4V 4-speed
> Central Ohio '70 Galaxie 500 Fastback
>

This read-only message was archived from a public mail list.
Mail From: wrk (email redacted)

I have had a fuel filter that is starting to clog up act like I was running
out of gas, but only at higher speed (~70mph). When I slowed down
it seemed okay. With time, the speed at which this happened got
lower, presumably because the filter was getting more clogged and
delivering less fuel. This has been a periodic thing. I think I need to
get my tank cleaned or replaced. For now, I keep the filter fresh.
If you remove it and can't blow air through it easily, replace it.
Mine seemed to be worse when it was low on gas though. Perhaps,
this has nothing to do with your problem, but it is easy (& cheap) to
check. If the filter is not clogged, just put it back on.

Russell Kumpe
(email redacted)
70 Grande 351W-4V

*********** REPLY PARTITION ***********

On 09/17/97, at 10:40 PM, Mulcahy wrote:

>Maybe someone can tell me what's going on here. Ever since I bought my
>'66 coupe this has been going on. When I drive it at about a half tank
>of gas or lower at highway speeds it will die. But this only happens
>with less than a half tank AND at above about 60mph. Then the car acts
>like a car that is running out of gas and may backfire a little. After
>that I can easily restart it and drive away as long as I stay below 60.
>It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
>thinking that maybe the fuel line is curled up in the tank, but that
>doesn't explain why it only happens above 60. I know the gas guage is
>correct because when it's half full it takes 8 gallons.
>
>Thanks,
>Keats Mulcahy
>'66 289 coupe
>

This read-only message was archived from a public mail list.
Mail From: Christopher Russell (email redacted)


I've been trying to think if more gas in the tank will help
"push" the gas thru the line to make the job easier on the
fuel pump... intuitively the answer seems to be yes, but I'm
not sure... anyway, I'd guess it is the fuel pump and/or
fuel filter(s). Also there is a screen/filter thing inside
the gas tank too, which is on the fuel sender unit.

Fuel pumps are pretty cheap and easy to replace, so you might
want to just go for it. Definately try the filter if you
haven't already... the one on the gas tank could be a bigger
job... If you gas tank is rusty or has crud in it, as the
gas level gets lower it tends to suck more crud which clogs
the filter faster... so if you replace the filter and that
fixes for a while you may need to clean-out/reseal your
tank and/or replace it...

The right way to do it I suppose would be to check for fuel
flow (check the shop manual on the procedure)... basically
disconnect the fuel line at the carb and crank the engine
over for X time and the pump should pump Y amount of fuel.
The other test is pressure which requires a pressure guage
(which is not a bad tool to have).

Good luck! ...Chris

> For a second there I thought you were crazy. I am used to a 22 Gallon. Tank.
> I know on EFI vehicles that the fuel rails are pressurized and the more fuel
> used the more needed to keep the pressure so my truck will keep run at 30
> when it won't at 70. Of course that's when I switch to the other tank...
> I don't know how this could apply. since unlike EFI, excess fuel isn't
> returned, it just isn't allowed into the carb.
>
> Sorry if this post makes no sense or is pointless.
> -srw
>
>
> Sam Weatherby (email redacted) insert.com/sammy
> '70 Mustang Grabber Sportsroof
> '93 F-150 XLT Lightning
>
> -----Original Message-----
> From: Mulcahy <(email redacted)>
> To: Multiple recipients of list <(email redacted)>
> Date: Wednesday, September 17, 1997 6:44 PM
> Subject: [CM:6021] Dying on half a tank
>
>
> >Maybe someone can tell me what's going on here. Ever since I bought my
> >'66 coupe this has been going on. When I drive it at about a half tank
> >of gas or lower at highway speeds it will die. But this only happens
> >with less than a half tank AND at above about 60mph. Then the car acts
> >like a car that is running out of gas and may backfire a little. After
> >that I can easily restart it and drive away as long as I stay below 60.
> >It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
> >thinking that maybe the fuel line is curled up in the tank, but that
> >doesn't explain why it only happens above 60. I know the gas guage is
> >correct because when it's half full it takes 8 gallons.
> >
> >Thanks,
> >Keats Mulcahy
> >'66 289 coupe
>
>


--
Christopher L. Russell Sr. Software Engineer -- Schlumberger ATE
emailemail redacted) WWW: cs-students.stanford.edu/~chrisr
Work:408-437-5185,800-538-6838 x5185 Home:408-296-7582 Page:408-237-1922

This read-only message was archived from a public mail list.
Mail From: Sam Weatherby (email redacted)

Perhaps if you siphon out as much as possible (should be able to get most of
it out), then pour some more in, and siphon back out. Kind of flushing it.
This may be a way to avoid removal of the tank.
Also, drain say 1 gallon at time, if it's clean then pour it into a larger
container. this way you can reuse the good gas from the top and get rid of
the bad stuff on the bottom.
I think it should be rather easy to remove the tank however so maybe that
wasn't a great idea, but if it works , could be less downtime.
-srw(missing his car. Monday is SO far off...)

Sam Weatherby (email redacted) insert.com/sammy
'70 Mustang Grabber Sportsroof
'93 F-150 XLT Lightning

-----Original Message-----
From: Christopher Russell <(email redacted)>
To: Multiple recipients of list <(email redacted)>
Date: Thursday, September 18, 1997 11:28 AM
Subject: [CM:6052] Re: Dying on half a tank


>
>I've been trying to think if more gas in the tank will help
>"push" the gas thru the line to make the job easier on the
>fuel pump... intuitively the answer seems to be yes, but I'm
>not sure... anyway, I'd guess it is the fuel pump and/or
>fuel filter(s). Also there is a screen/filter thing inside
>the gas tank too, which is on the fuel sender unit.
>
>Fuel pumps are pretty cheap and easy to replace, so you might
>want to just go for it. Definately try the filter if you
>haven't already... the one on the gas tank could be a bigger
>job... If you gas tank is rusty or has crud in it, as the
>gas level gets lower it tends to suck more crud which clogs
>the filter faster... so if you replace the filter and that
>fixes for a while you may need to clean-out/reseal your
>tank and/or replace it...
>
>The right way to do it I suppose would be to check for fuel
>flow (check the shop manual on the procedure)... basically
>disconnect the fuel line at the carb and crank the engine
>over for X time and the pump should pump Y amount of fuel.
>The other test is pressure which requires a pressure guage
>(which is not a bad tool to have).
>
>Good luck! ...Chris
>
>> For a second there I thought you were crazy. I am used to a 22 Gallon.
Tank.
>> I know on EFI vehicles that the fuel rails are pressurized and the more
fuel
>> used the more needed to keep the pressure so my truck will keep run at 30
>> when it won't at 70. Of course that's when I switch to the other tank...
>> I don't know how this could apply. since unlike EFI, excess fuel isn't
>> returned, it just isn't allowed into the carb.
>>
>> Sorry if this post makes no sense or is pointless.
>> -srw
>>
>>
>> Sam Weatherby (email redacted) insert.com/sammy
>> '70 Mustang Grabber Sportsroof
>> '93 F-150 XLT Lightning
>>
>> -----Original Message-----
>> From: Mulcahy <(email redacted)>
>> To: Multiple recipients of list <(email redacted)>
>> Date: Wednesday, September 17, 1997 6:44 PM
>> Subject: [CM:6021] Dying on half a tank
>>
>>
>> >Maybe someone can tell me what's going on here. Ever since I bought my
>> >'66 coupe this has been going on. When I drive it at about a half tank
>> >of gas or lower at highway speeds it will die. But this only happens
>> >with less than a half tank AND at above about 60mph. Then the car acts
>> >like a car that is running out of gas and may backfire a little. After
>> >that I can easily restart it and drive away as long as I stay below 60.
>> >It's fine with 2 gallons of gas at 30mph or 10 gallons at 80mph. I was
>> >thinking that maybe the fuel line is curled up in the tank, but that
>> >doesn't explain why it only happens above 60. I know the gas guage is
>> >correct because when it's half full it takes 8 gallons.
>> >
>> >Thanks,
>> >Keats Mulcahy
>> >'66 289 coupe
>>
>>
>
>
>--
>Christopher L. Russell Sr. Software Engineer -- Schlumberger ATE
>emailemail redacted) WWW:
cs-students.stanford.edu/~chrisr
>Work:408-437-5185,800-538-6838 x5185 Home:408-296-7582 Page:408-237-1922
>
>

This read-only message was archived from a public mail list.
Mail From: Bradburn, Michael (email redacted)

If you suspect the sock in the tank to be the culprit AND you are
planning on taking the tank to have it cleaned you can disconnect the
fuel hose from the pump (the line that runs from the tank to the pump),
remove the gas cap, and then back blow air from an air compressor
through the line to the tank. This will either blow most of the crud
out of the sock in the tank, or blow it off the line completely. Either
way, you can now test to see if the problem has gone away. If you do
this, you must either remove the tank and have it cleaned and sealed or
put a clear in-line filter BEFORE the fuel pump to catch the stuff that
the sock used to catch in the tank.

>-----Original Message-----
>From: (email redacted) [SMTPemail redacted)]
>Sent: Thursday, September 18, 1997 1:20 PM
>To: Multiple recipients of list
>Subject: [CM:6052] Re: Dying on half a tank
>
>
>I've been trying to think if more gas in the tank will help
>"push" the gas thru the line to make the job easier on the
>fuel pump... intuitively the answer seems to be yes, but I'm
>not sure... anyway, I'd guess it is the fuel pump and/or
>fuel filter(s). Also there is a screen/filter thing inside
>the gas tank too, which is on the fuel sender unit.
>
>
>

This read-only message was archived from a public mail list.
Mail From: Mulcahy (email redacted)

Thanks for all the responses. I have replaced the in-line filter twice
in the last month, so no problems there. I guess I've got to go ahead
and check inside the tank. I just wanted to make sure before I siphoned
8 gallons of gas (messing around with tools in a tank with gas vapors
scares me a litte). It makes sense to me that it could be pulling crud
at higher speeds and lower fuel levels. Who knows what could have
dropped into the tank in 30 years? Unfortunately I had to take the car
to a mechanic (another story) so I may not be able to work on it for a
couple days. I'll be sure to tell everyone what I find out.

Keats Mulcahy
'66 coupe