Gorts 5th

my fuel is draining back into the tank after she sits for a few hours or overnight so in the morning i got to re prime the fuel system by cranking her its annoying i am thinking an purchasing the mr gasket micro electronic fuel pumps they are 40 buck in stead of the 150 200 pumps i see available and they are available at the local parts store
has any one used these pumps or should i go with the oem replacement fuel pump im currently using one for a 360 on my 318 i don't have any fuel starvation issues with this pump i just think its the cause of the drain back to the tank
any input would be appreciated

Mr.4spd

Yeah, shouldn't there be an anti drain back valve built in? Perhaps it's smoked.

Gorts 5th

would that be in the tank or the fuel pump

440roadrunner

Is there some reason you cannot use proper punctuation so the rest of us can read what you type?

WHAT ARE you working on? 46 Stude? Farmall tractor?

Post 70's some kind of ?? Mopar?? If so, how about putting that down.

YOU MIGHT have a situation where the tank is improperly vented and causing a vacuum, especially when it cools down at night. Try leaving the cap loose overnight and see if that affects the problem. If you have a car which originally had a carbon canister under the hood, the system may have problems. If it's been removed, you may not have a vent for the tank at all

Modern gas is a real problem, it seems to boil and evaporate easier, and many guys are having similar problems.s

LISTEN as your remove the cap and see if the tank appears to be under pressure/ vacuum

I did three things on my 67 which greatly helped vapor lock/ fuel boiling problems

1--installed an electric pump back at the tank and removed the mechanical pump

2--installed a vapor return system, using a Wix filter with a built in orifice. Google up Wix 33040, 33041, 33054

3--Bought a (3/8?) or thicker insulator gasket under the carb.

Charlie72

My mechanic just removed the carbon canister from my 72 Charger SE. How big of a problem did we just create? Can I simply have him re-install it? He said it was dripping fuel when he removed it and it was a fire hazard.

440roadrunner

You can dowload a 72 shop manual for free in this thread:

http://www.forabodiesonly.com/mopar/...al%2C+download

The link:

http://www.abodyjoe.com/pictures/Mis...1%20wiring.pdf

Here's a functional diagram from the 72 manual:

You must be VERY careful if you remove this as you can create a situation where the tank is not vented. The filler caps are "pressure vacuum" only meant for safety, IE release pressure or let in air at a predermined pressure.

Your 72 I believe has a separate vapor can (in the trunk?) which was incorporated into the tank in later years. THE ONLY VENT is the 1/4" line to the front which hooks into the rest of the carbon can system.


The "overfill limiting valve" should be at the very end of the 1/4" line up front, and could be rusted shut

Gorts 5th

its a 86 chrysler 5th ave M body, i removed the canister about a week ago, but i never had it hooked up to the system other than the vent line, the canister is under the hood.
but it was draining be for that it just seems to be getting worse,
the vent to the tank that was on the canister is still open my fuel filter has the small return tab on it to allow the unused fuel to return to the tank when running the engine/wix filter.
i just did some work on it today and the 2nd fuel filter which is clear was empty.
i run the oem with the return first then farther up the line i use a clear filter these are all after the mec. fuel pump.
i thought the fuel pump kept the line primed.
i can get the before mentioned electric pump for $40 at the local parts store, or should i replace the mechanical pump?
if the mechanical pump is supposed to keep the system primed i would just replace it, i picked one up this morning but im waiting on some good advise here before i replace it.
if it is a plugged vent system a fuel pump wont change the situation.
i will look closer at the system around the tank before i install a new pump.

Gorts 5th

OK i installed the electric and the mechanical fuel pumps;
Any input here would be good?
i have run the car it's richer in its fuel mix the idles up about 50 rpm.
there is a location behind the right front wheel up in the frame where the fuel lines turn up into the engine compartment i located the electric pump there, the mechanical pump is for a 360 2bbl when i fired the whole system up it would not prime with out me cranking the engine once the electric got primed you could hear it.. then she fired up.
In the morning the filter was emptily again but when i turned on the ignition it took only a few seconds for the pump to prime up and when i cranked her she fired up big improvement.
Pondering the fuel system i think i need some type of check valve on the small vent from the charcoal canister to prevent the tank from depressurizing so as not to drain the fuel line empty?
i'm assuming the system needs to be sealed.
any input?

MrOldart2U

So you changed the mechanical pump and added an electric? Or did i misinterpret? If its for sure draining the carb, I would check the needle and seat in the carb, Thats what keeps gas in the carb. Todays fuels are more prone to evaporation/boiling away, especially during a 'heat soak' cycle. The fuel tank doesnt 'pressurize', but maybe needs a different type of cap. (vented vs non vented, or vice versa). Also if you are going by one of those 'see thru' filters they can be deceiving also.....

Gorts 5th

it's not so much the float bowl is draining down;or that boil's off its the fuel lines from the tank that have me puzzled?
and yes i did install a electric pump before the mechanical pump i have been running it for about 30 miles, so far no problems i don't have to crank her as like before to get the fuel lines from the tank primed.
i'm amusing that the fuel filter with the with the small return stem on it is why the fuel lines are bleeding down to a point but what will cause it not to hold fuel back to the tank on the supply side of the system?
is that a defective mechanical pump or /fuel leak in a line, or at the in tank plumbing ?

TVLynn

I would check all of the rubber lines at the tank for cracks. The tank connector that the lines connect to could be rusted out ??

Gorts 5th

i suppose it's time to check the tank or should i say drop it and check it i will get up under there to marrow and see what i can see