gasoline drainback

[AuroraGirl]

So, I made a post in the past about having to pump too much.

yesterday, I started truck after a cold snap and the filter was empty. The previous 2 weeks without driving it had gas, but it was warm. So I believe my hypothesis on fuel pump internal diaphram or something is leaking. I know guys will install check valves to keep the gas in the line up top the engine.

However, I was wondering if its not a bad idea to install one by the gas tank?

The rubber line between the tank sender and the metal line would fit one fine, and that would prevent drainback all the way. Right?

If so, the larger diameter hose off the tank is send, correct? The small is the return? And of course (middle?) smallest is the vent.

 

[Kevin McDermand]

Did you ever replace the fuel pump? I said in another thread that my truck would lose its prime and you couldn't pump it enough to start it. The fuel pump started leaking so I replaced it. Now one pump and pick up the throttle a little as you crank and it starts right up.

 

[AuroraGirl]

Did you ever replace the fuel pump? I said in another thread that my truck would lose its prime and you couldn't pump it enough to start it. The fuel pump started leaking so I replaced it. Now one pump and pick up the throttle a little as you crank and it starts right up.

Im avoiding replacing the pump until I get a regulator. I think my pump is weak enough it makes the perfect pressure for edelbrock.

 

[SirRobyn0]

Did you ever replace the fuel pump? I said in another thread that my truck would lose its prime and you couldn't pump it enough to start it. The fuel pump started leaking so I replaced it. Now one pump and pick up the throttle a little as you crank and it starts right up.

The pump is your problem, I agree. Installing a check valve is a bandaid and might just add enough resistance to effect the pump, especially since it's old, weak and clearly on it's way out.

Im avoiding replacing the pump until I get a regulator. I think my pump is weak enough it makes the perfect pressure for edelbrock.

My square rarely sits for more than a few days, but I've also got an old 1977 Cadillac Hearse, which can go all winter without bring driven. One pump and crank it, and it fires after a few seconds, once in blue moon I'll have to give it a second pump then crank again. My point is even if fuel has drained back and the carb is dry it should be ok. I wouldn't do the check valve.

 

[Rusty Nail]

Just buy a pump...$20-$30 bucks?
Prolly fix all your problems.

I have NOT heard of people installing one way valves to keep gas in a line before and I sure as hell wouldnt do it nor condone such a thing.

That creates a fire hazard.

 

[80BrownK10]

So if it takes extended cranking it's a bad fuel pump? Mine takes awhile to crank if it's sat days or a week or more. Just put a new in carb filter with the checkvalve noticed the old one had fallen apart. But that made no difference. This fuel pump has been in there for like 14 years so I don't remember what it did prior to this one. I replaced it as the old one leaked externally. I have not starving for fuel symptoms though.

Uncle Tony Garage said this is just a common problem with ethonol fuels that evaporate quickly.

I think I will live with it right now as it's not that big a deal to me. I pump the gas once and start it. It starts and idles fine once it fires.

 

[SirRobyn0]

So if it takes extended cranking it's a bad fuel pump? Mine takes awhile to crank if it's sat days or a week or more. Just put a new in carb filter with the checkvalve noticed the old one had fallen apart. But that made no difference. This fuel pump has been in there for like 14 years so I don't remember what it did prior to this one. I replaced it as the old one leaked externally. I have not starving for fuel symptoms though.

Uncle Tony Garage said this is just a common problem with ethonol fuels that evaporate quickly.

I think I will live with it right now as it's not that big a deal to me. I pump the gas once and start it. It starts and idles fine once it fires.

I would say quite likely, but I believe there was some discussion on Taylor's problem in another thread. The test would be to leave it sit for a week, crank it about 1/2 as much as you'd expect it to take to start, remove the air cleaner and operate the throttle by hand to see if you're getting a shot of fuel from the accelerator pump. Long crank times after sitting is often an indication of a week fuel pump, it can keep up with demand while running but has a hard time building pressure when cranking. I've seen some go on quite a long time like that though.

 

[Rusty Nail]

If you don't remember how it used to act, must not have been ******.
Lol?

14 years seems like a very long time.
Many people are SO QUICK to start tossing money at their trucks, and fuel pumps are very cheap...I'm struggling to undersrand why installing a new fuel pump OR A GAS CAP seems like pulling teeth around here.
These are "wear parts", they have a service interval. Born to die. Doesn't last 40 years.

Gas caps go bad.
It is Fact.

Two bolts.
3/8 or 10mm on a ratchet with a 3" extension
You'll need a 1/2 and/or 5/8 combination wrench also.

Little dab of bearing grease to hold the pushrod up for a second and viola!

Last one I changed was on the side of the road, it's not a big deal..only takes a couple of minutes AND you can bill an hour for it.

Most mechanics JUMP at those $150 fuel pump jobs. By the time you replace some hose , sell some shiny clamps, add a filter? Boom. $200 out the door and don't got a GRANT in it.
Won't come back.

Yes please! I'll change fuel pumps ALL DAY.
Line em up!
Could do it with my eyes closed I bet.


You touched something sensitive though.

ETHANOL.

is junk.
Crap.
****.
Bad for squares.
Not advised AT ALL if it is avoidable.
EVER.

Kills old and new fuel pumps.

 

[broketiredugly]

if truck wont start after sitting a little while, you need to rebuild the carb AND replace the pump.
carb is leaking fuel from bowl or carb was not full when engine was turned off. remove pump, engine will still start and run for little while!
replace pump because it is suspect is the the best time. they get old, probably has been replaced before and was probably replaced with the cheapest one available.
????? what is this about a regulator because you have an edelbrock carb? i dont think edelbrock used such cheap float valves or such tiny floats that a 4lb pump is gonna overwhelm.

 

[broketiredugly]

Just buy a pump...$20-$30 bucks?
Prolly fix all your problems.

I have NOT heard of people installing one way valves to keep gas in a line before and I sure as hell wouldnt do it nor condone such a thing.

That creates a fire hazard.

first i ever heard too! im guessing some kid put a big ol pink and green one on his honda to match the fart pipe and it got out on the interwebs that it was a major performance boost. ?
a perfectly dry pump out of a new box from the chinese parts store will, and does, pull fuel from the tank and fill the carb. !

 

[AuroraGirl]

Im not saying to use a check valve as a perm fix, im asking if htat would help keep the gas from draining back from it, because the pump is worn. i guess a similar concept even on a new pump. A pump has a diaphram that holds fuel in the line between it and the carb, hence why the gas stays in the filter on warm days and will be there for weeks, but when i get a cold snap i have an empty filter and no fuel in the line, annd have to crank a couple seconds to get fuel up in there before i can pump. Would a check valve keep the diaphram from holding that pressure against it or would it simply just add against it + a valve? and i will change the pump, but im gonna do a regulator at the same time, as mine is worn and i believe thats why it runs perfectly when others have issues with 1604 with high pressures.

And i dont have issues replacing gas cap, its just mine is vented through the cap as if it were a pre-canister truck and not through a third line on the tank but guys said that those caps cant be bought anymore. If they can i will buy one. Or get a vent for the third line on sending unit(currently plugged as the cap is doing the vent work)

The carb is also new, btw. in august. its run about 5 hours in run time since then.

And im curious about check valve and fire hazzard, im not denying it but curious on rationale. maybe im mistaken about the pump holding gas in the line between it and carb?

 

[broketiredugly]

Im not saying to use a check valve as a perm fix, im asking if htat would help keep the gas from draining back from it, because the pump is worn. i guess a similar concept even on a new pump. A pump has a diaphram that holds fuel in the line between it and the carb, hence why the gas stays in the filter on warm days and will be there for weeks, but when i get a cold snap i have an empty filter and no fuel in the line, annd have to crank a couple seconds to get fuel up in there before i can pump. Would a check valve keep the diaphram from holding that pressure against it or would it simply just add against it + a valve? and i will change the pump, but im gonna do a regulator at the same time, as mine is worn and i believe thats why it runs perfectly when others have issues with 1604 with high pressures.

And i dont have issues replacing gas cap, its just mine is vented through the cap as if it were a pre-canister truck and not through a third line on the tank but guys said that those caps cant be bought anymore. If they can i will buy one. Or get a vent for the third line on sending unit(currently plugged as the cap is doing the vent work)

The carb is also new, btw. in august. its run about 5 hours in run time since then.

And im curious about check valve and fire hazzard, im not denying it but curious on rationale. maybe im mistaken about the pump holding gas in the line between it and carb?

new in august aint new anymore.
5hrs in 8 months and ethanol is a carb rebuild needing to happen.

stock mechanical pumps do not make enough pressure to bleed past ANY float valve on ANY carb. those fart pipe guys have other issues.
your see thru filter is empty after a big temperature change because there is contraction. and /or a leak.
if the fuel were to drain all the way back to the tank, everytime you turned off the truck, it would still start and run normally........f there were no other problems. the carb bowl holds enough fuel to start and run for a lot of seconds. will idle over a minute.! so pump has plenty of time to refill line. perfect world: your see thru filter would stay full. if the carb bowl is not staying full, its because there is leaking past something like a power valve or checkball or whatever, there is some evaporation, but slow, as the bowl is vented. give a pint of gas an only opening the size of a small straw, and see how long it takes to evaporate, in the shade. hope that helps.

 

[SirRobyn0]

Ok I'm going to try to sort this all out for ya'll. First of edlebrock states no more than 6psi of fuel pressure into thier carbs recommended 5psi. All of the aftermarket pumps I've looked at at least in my area are rated for 7 or 7.5psi. Yes I have run edelbrock carbs without a regulator and not had an issue, but I've also run them and had to install a regulator. Brokentiredugly I'm going to site my 25 years as a mechanic and edelbrock tech support as my source, this is bs, its fact.

Second will the check valve help, maybe, is it a fire danger I have no idea I've never felt the need to install one.

Third, the gas. Yes ethonal gas goes bad much quick than the older gas did. Do I think Taylor's needs to rebuild her carb again, no I don't. I have an hearse that sits sometimes for more than 6 months before being driven. If I keep gas in it that's more than a year old I can tell by how it runs. In the 10 years I've been doing this with this car it hasn't ruined the carb yet. Is it best to run a little more gas though it sure. But as taylor has stated in other threads this is an off road truck only so it's just not going to burn a ton of gas.

I'm sorry but I'm not sure anyone has a really good answer on the check valve other than it's not how I would tackle the problem. As an alternative you could give it a quick shot of starting fluid before firing it up until you want to do the pump and regulator.

 

[idahovette]

Brake parts cleaner is much less volatile than starting fluid, easier on the engine and usually cheaper ,too.

 

[broketiredugly]

dont know about aftermarket mechanical pumps anymore, my experience since the 70's was a gauge woud always read at 3-4 psi. delco was common replacement item. gotta remember the material back when carbs were king was not viton! it was worse, and still NO carb problems ever from too much pressure because of mechanical stock pumps. carter afb's and their copycats included!
you never touched on why her fuel is drained back and her truck wont start!
oh, btw, dont expect ethanol to last that long in the south. it eats the fuel tanks on boats back home in lowsyana. it shrinks and twists and deforms carb floats too. but in only a few months, it will EAT a float valve and stick it in position like gorilla glue!