Hot Rods electric fuel pump wont pump

Have a 32 ford roadster in the build process. Got the ignition wiring in so naturally I wanted to here the motor run. Well that's where the fun begins.
New fuel tank from Tanks Inc. Ran fuel line to a electric fuel pump which I mounted just in front of the rear end. then continued the fuel line to a Mechanical pump. I just want the electric to get fuel to the three deuces if the car sits a while so I don't have to crank and crank to get it started.
Now I know for a fact the pump is good as I checked it off the car from one bottle to another. Pumps plenty of fuel.
Put it on the frame rail, flip the switch and the best I get is a dribble...kinda like when old guys go to the bathroom....but....If I blow into the vent hose to build a little pressure in the tank.....Walla!!
I have bypassed the electric pump and the mechanical pump will work like a champ but oddly enough if I pull the bypass off the hard line I get no fuel leaking out. Now you would think you would get a small amount of fuel run out of the line....??????
The vent hose is higher than the tank as it is supposed to be.
Am I missing something here?
Any help is appreciated for sure.

 

It sounds like wherever you are bypassing the plumbing is above the level in the tank. If this is where
your electric pump is mounted, it will not self prime. I don't know what kind of pump you have, vane or otherwise, they need to be mounted lower than the tank level as the NPSH available needs to exceed
that of required. If it is a vane pump and it ran dry, the vanes may already be damaged.

 

I think Yellow Dog hit one point, If the hard line isn't low enough compared to the top of the tank where the fuel pickup goes into the tank and below fuel level it won't siphon the gas when you pop the line off leaving the no gas dribbling out condition you describe. Just think how a siphon hose works there and you get the concept. That drop before the electric pump would also keep the electric pump primed as the fuel in the line coming down from the top of the tank should be enough to keep prime on the pump.

 

Check the ground wire

 

As said, they'll only push fuel if low enough. Sitting for a while and having to crank longer off the mechanical pump isn't a bad thing, building oil pressure 1st is a positive. Post a couple of shots of the setup.

 

Thanks... I will have to take a good look and see just where it is mounted in comparison to the tank. I don't think it is lower than the tank. Never really paid attention to that. I just looked for a good spot on the frame and bolted it on.

 

Do you have it mounted on a runner pad to deaden the noise,you may need a better ground. HRP

 

I don't understand the 2 pumps. I run an electric at the tank. 3X2 carbs. Can sit for weeks, fires right up. Float bowls should stay full.

 

Because on a counta ya wanna know why??? Thought it might just could be handy some day.

 

What we are missing on trying to help statesblue is why there is no fuel in the fuel line after he runs the car. He has by-passed the electric fuel pump with a rubber gas line, which is mounted below the tank. Starts and runs the car. Engine runs good. Shuts the engine off and immediately disconnects the bypass hose he has mounted on the frame rail where the electric pump would be mounted. There is no gas in the fuel line. Sounds impossible, but true. If he takes the vent line, that he has running out of the top of the gas tank, and blows into the vent line, a full fuel line of gas comes out. Stops blowing in the fuel tank vent and gas immediately stops coming out of the fuel line. How and why. All answers and suggestions appreciated.

 

Pics of the associated gas tank install with where the hoses are attached would help a lot in trying to solve this problem. If you bypass the electric fuel pump and everything works as it is supposed to then that tells me the electric fuel pump is shot, or installed ass backwards. Also you don't mention if you have the cap on the tank or not when trying this out. Here is some info directly from Tanks Inc. website.

Fuel Tank Venting
Your tank has to breathe. In order to breathe, your tank must have a vent somewhere that will relieve both vacuum and pressure. Gasoline expands in volume as it warms up and shrinks in volume as it cools down. The fuel level of your tank changes throughout the day, even if you are not driving it.

You cannot put fuel into your tank, unless you can get the air out...and you cannot withdraw fuel from your tank unless you can let air in.

Up through the 1960's, most vehicles used vented gas caps. This is simply a gas cap with a hole in it. Unfortunately, this hole would allow the fuel to splash out when accelerating or turning a corner.

If you are running a vent line it is important that the line is ran higher than the highest point on the tank including the fuel filler neck. Also, the vent line cannot have a dip in it where fuel or condensation can get trapped in the line. If fuel becomes trapped in the line your tank will then build pressure or vacuum until there is enough pressure to purge the vent which will cause gas and/or odor to come from the vent line. If enough pressure builds up damage could be caused to your tank.


If you are using our remote rollover vent valve # VVR make sure that the vent is mounted vertically. Mounting the vent at an angle may cause the vent to shut off.

 

An additional thought is that this may be a vacuum problem in the tank with the mechanical pump strong enough to overcome the vacuum and the electric pump not able to. Only thing I can think of that would explain no gas in the line after running it from the mechanical pump.

 

Thanks, Gordon for the reply. This is a stock 32 style fuel tank from the company Tanks. It is located in the stock location on the back of the stock type 32 rails. Gas line runs down the passenger side of the rails directly to the mechanical fuel pump on a small block Chevy engine.
I got involved in this problem and am trying to figure it out. I have mounted many early ford tanks in the stock location and never seen anything like this before. Will try mounting the vent line in the trunk above the gas line. Perhaps that will do it. Thanks again.

 

Your welcome. And let us know if/when you get it figured out as we could all stand to learn from this!

 

OK guys here's where we are.
I have loosened the line from the frame along with the electric pump. At this point the pump is below the bottom of the tank. The fuel line is continually pitched down to the pump.
Flip the switch and the best I can get is a dribble.
Yet by blowing into the vent line, which by the way is above the highest point of the tank by at least a foot, I get a nice strong stream of fuel. If I place my thumb to block the line to hold the pressure it will send fuel until I take my thumb away and we are back to the dribble.
The pump, by the way, is a Mr. Gasket #12s gravity feed micro pump. 4-7 PSI, 35 GPH Self-Priming.

 

Statesblue for lack of any better ideas is there a way to reverse the line connections on the tank and try it? It sort of sounds like when you blow in the tank your pressurizing the tank and forcing the fuel out a line that would not normally have flow, which would be what a vent line normally is? Doesn't make sense that a mechanical pump would pull fuel through it tho? How much fuel is in tank?

 

Also does this have the roll over protection valve on the vent line? If so I would remove it and test it again.

 

Gordon
At this point I would try anything. The line I'm calling the vent is in a position I could run to the fuel line. I'll give it a try tomorrow and thanks for your input.
Boy, if that's the problem, will I have egg on my face.

 

Seen a few bad electric fuel pumps.
FWIW, I put a cheapo electric pump(looked a a 2x2 square box) on the fenderwell of my '42 PU...at least 18 inches above the tank and maybe 4-5 feet away from it?

Worked fine.

 

statesblue just read a new thread on here where mud daubers had blocked up a guys vent on his gas tank. I thought given everything your going through it might be something to look into. They do like open holes that aren't being used or left open. How long did the tank sit before it was installed?

 

Nope.....brand new tank. vent cant be blocked as I can blow into it with no problem..
Trying to get ahold of Mr Gasket tech line to see if they might be able to shed some light on this problem. Thanks for sticking with me on this.

 

I don't know if you have the same pump I have but mine would not pump.
Mr Gasket tech said it had to be mounted at an angle not straight up and down. Go figure it worked after the change.
Nick

 

Go to: http://www.catalograck.com/ImgVD/MRG/micro_electric_fuel_pump_12S_42S.pdf

Look at diagram at bottom and read install instructions.

Nick

 

Interestingly enough I also have a Mr. Gasket pump installed, at 45 degrees, but don't have any fuel in my tank or the wiring to the pump yet. Working on getting my rebuilt flatty prepared to fire up for the first time.

 

Not in the trunk! Not inside the car!

 

You don't say (or if you did I missed it) if you are pulling from the bottom of the tank or out over the top like a straw? The pump you have clearly states that it is a gravity feed meaning the fuel should flow to the pump via gravity, it does not have suction or lifting capability's on the suction side of the pump.
Here's the one I use and it clearly states it can dry lift 12". My tank is 8" deep I pull over and out the top with zero issues.
https://www.summitracing.com/parts/...h5Yw8BDLhuUwew5kmAoZWU8_ifOLMgUUaAoSOEALw_wcB

 

I agree not in the trunk. Bad statement, especially if the battery is in the trunk. I always put a breather loop in the trunk with the actual end outside the trunk area. Thanks for the link to the Holley pump. GordonC - that might be the answer. Did not realize this pump had to be mounted at a 45 degree angle. Thanks for pointing that out. When in doubt read the instructions. Thanks again guys.

 

At the risk of hi-jacking, can anybody clarify the conflicting information on putting a loop in the vent line? I've seen loops advocated many times on the Hamb and was planning to do it. But the Tanks Inc. instructions Gordon posted here (post #11) say, "Also, the vent line cannot have a dip in it where fuel or condensation can get trapped in the line." I am confused (which some might say is my normal state...)

 

SSrodder I think nickleone suggested that 45 degree thing. Now I am concerned that mine will not pull from the top of the Tanks Inc tank I have. I'll need to check into this further.

As for the loop in a vent line I don't recall seeing a factory oem set up that had a loop in it? Not saying it isn't done just I haven't seen one.

 

Just to clear up something. Here is a picture of the instructions that came with the pump. Says nothing about 45degree angle. so who's right and who's wrong??? What ever makes it work I guess.
Decided to look into the pump Sheep Dip showed the link to. Actually think it may work better for my situation.
When it comes to these pumps I have to wonder if any of the guys that design these things have crawled under a car to see what your up against when you have to mount one.