Need Help with EM Gas Tank

[priobe]

Hello All,

I already have a email out to Julie / Tom on this question but was hoping someone here can help me out.

I have the GEN III that was made in 2000 ( which I am very pleased with), before the stainless steel chassis.

I am having a problem with the gas tank that when I am filling it up it will not go to full. However, I get the indication that it is full by having the gas pump click.

The gas tank that I received from EM is their custom made aluminum 20 gallon tank. A friend pointed out that the filler tube is at the middle of the tank on the side. This could be the reason as to why I am only getting a half of a tank.

Furthermore, I refuse to believe that after all the gas tanks that EM created that I am the only one that has ran into this problem. There has got to be a resean why the filler is located at this position. I just cant see why.

I have included a picture of the gas tank to see if it matches the same tank that others have received with their replica.

[Tom Wells]

priobe,

I have the same gas tank. If I try to fill it full force from the gas pump it will not be anywhere near full when the pump stops automatically. It has always been cranky and slow. If I fill it slowly it will go all the way to full. It takes a few minutes of hand-squeezing the pump handle lightly. It has also taught me that the second time it shuts off while I'm doing this, I'd better quit unless I want gasoline on the fender.

However....

You knew there was a however

When the tank is really really full it will overflow. Not right when I fill it, but later after the gas warms up and expands. Unless I drive enough to burn off a gallon or two before I park it.

There's another observation too. If I fill the tank quite full, it will overflow when I take a corner. This can be detected by looking at the fender on the gas tank side after a run, where a residue and some road dust will be clinging to the area from the filler cap all the way down to the bottom rear of the fender below the tail lights.

The cornering-related overflow happens occasionally on the street and very frequently on the track.

To reduce/eliminate the cornering overflow I installed a check valve in the fill line. I found the valve somewhere (?) - sorry forgot where - a guy makes them to fit the '57 Chevy wagons which have this problem only worse. The valve is gravity operated and made of stainless and happens to be the correct diameter for the Cobra fill hose. It works fine!

I have the feeling I may not have answered the question If not, ask away!

Tom

[Tom Cimino]

Hi Priobe;

I have the same tank in my E-M. I installed a fuel vent line from the top of the tank to a fitting that I welded to the filler pipe, just under the fuel cap. It's been so long since I built my car, but I think there were two fittings on the top of the tank. One for the fuel pickup and one for a vent. If you don't have the second fitting, it wouldn't be difficult to install. You'll need a weld-in bung and have it welded in.This will allow the air to escape from the top half of the tank during filling. You have to be able to displace the air to allow the fuel to take it's place. Don't forget to ground the tank, filler pipe and filler cap to prevent a flash fire from static.

[priobe]

Thanks for the replies, I guess I will have to fill it slow and see what happens.

[Z-linkCobra]

I dont know who designed that tank but they should be fired. From the looks of it I think everyone has pretty much lost their job anyway. I have an older E.M. that I had a tank built for. Filler on the top like it should be. Yes the filler and vent come through the trunk, and you have to go over through the side panel of the rear wheel tub to get to the filler on the fender.

That tank is a fire waiting to happen in my opinoin. I didnt see a vent at all in the top section of that tank. All tanks have vapor build up but it is vented off and not allowed to build up any pressure. That tank has no way to vent the vapor pressure so in all reality you are pressureizing the whole tank. As the car vibrates and bounces going down the road it could possibly build up quite a bit of pressure essentialy making a ticking time bomb. That tank and any others like it need to be vented on the top. Just my thoughts.

[priobe]

Z-linkCobra,

Calm down

There is a vent on the top of the gas tank. I cant speak for yours but the one pictured above has a vent.

I am still waiting to hear from EM as to why the design has a filler mounted midway on the tank.

I am sure there is a reasonable explaination for this because I belive they kept it on the GEN IV model.

Hopefully they will be speaking up soon.

[Z-linkCobra]

If its vented then your ok. It looked to me like that small line coming out of the top was more for a return line then a vent. Maybe im wrong. I had a tank built to my specs cause at the time there was no getting a hold of E.M. . Plus I didnt really care for that design and it would have been real close clearing my rear suspension with full travel.

Mine is an older E.M. solid rear axle.

[priobe]

Z-linkCobra,

Not a problem, pictures speak a thousand words but sometimes they give a false illusion. At the time of having the Gas tank built I asked Brett to add a return line for the fuel next to the feed on the front of the tank.

I thought there is suppose to be a moderator for the vendor sections of the forum. I dont understand why it takes so long to get a response.

[priobe]

Boy it is quiet here.

Is there any support for EM?

This was posted on the 4-26 and EM still has not answered.

[tim]

Here's my 2 cents. I built the tank in my car but used the EM tank as a basic pattern. The filler is at the half full position because of the shape. It was the easiest way to make the tank wide enough to hold enough fuel and not put the filler hose in the trunk. Yes there is a vent from the top of the tank that should conect to the filler tube bellow the fuel cap to allow the air out of that part of the tank as it is filled. I know that I can't just lock the fuel nozzle wide open and fill my car. I usually just hold it and watch. I will say that when mine gets close to full I can see fuel being pushed through the vent in the filler tube. As for venting the tank from preasure, if you're using the LeMans style cap; it like most older cars vents itself. I do think some of the later EM's used a late model preasure style cap under the Lemans. This could change things greatly when fueling because the hole is probably just big enough for the fuel nozzle. I pour fuel down a 2" pipe under my fuel cap.

[priobe]

Thank you Tim for the explanation. This is exactly how my tank is designed.

I will try to fill the tank up slowly to see if it makes a difference.

Thanks again.

[mjhcobra]

My EM is a 93 frame and a 95 body and at that time they used a gas tank from a 68 Camaro. It has the factory sending unit, they just capped the fill hole and moved it to the fender position.
I hope to have it on the street by December, but my tank looks problem free.

[ratsnst1]

If you know your fuel gauge is accurate, turn key on and keep an eye on when its full thats my trick .

[951mat]

My dad recently bought an almost complete gen IV. He's enjoying it greatly but the gas tank does seem finiky. He emptied the tank (ran out of gas) and then put 5 gallons in it. He then put 11 more and it was full. He could see the gas in the fill tube. His is vented (althought poorly, the vent tube doesn't tie into the filler tube, yet). I'm wondering if the pickup is all the way down in the tank or not. Is there any easy way to check this? The two AN fittings at the top of the tank are for the vent and the PU going to the fuel pump. If I pull that one will I learn anything?

For what its worth, he said the gauge never showed it all the way empty and never all the way full either.

[tim]

951mat, I think the only way you're going to be able to evaluate the fuel pick-up in your father tank is to remove the fuel gauge sending unit. I'm not sure exactly were it is located in the newer cars; but check the truck floor for access. My cobra has a removable plate under the carpet in the trunk just for this purpose. Also. the fuel gauge sending unit may not have been adjusted correctly when it was assembled. The universal sending units can be a bit of a pain. I actually set mine before the tank was completely weld up.

[Excobrabuilder]

The Gen IV gas tank is completely different from all other E-M tanks. The fill neck, fuel guage sending unit, vent and pick up are all bolted onto an oval plate simular to those used on an ATL fuel cell. This plate bolts onto the top of the tank under the fuel cap. The only way to get any of this out from the tank is the tank has to be taken out of the car completely. It's not that hard if the car is up on jack stands and you use a floor jack with a block of wood to lower it after it's unbolted. If the fuel pick up provided with the E-M tank kit was used it should reach near the bottom of the tank. The fuel guage sending unit does not use a float. I can't explain how it does work, but there are no moving parts. If you remove the plate you will have to replace the cork gasket and the sealable washers for the bolts. The fittings use crush washers and the sending unit uses a rubber gasket. It should be noted that all Gen IV tanks have mesh foam inside them provided by ATL. Hopefully this info will help you be able to find your problem. Good luck!

[Michael C Henry]

My EM is of 84 vintage. The original builder had the tank built from his design describing it as a water tank. It is a great design lower sump where the fuel pickups are located, in the shadow of the differential. 25 gallon capacity. The fill tube is a three inch tube extending about eight inches from the right side about two thirds the way back from the front. Top of tank is almost flat so the amount of air that may be traped would be small. The spare tire is bolted to the trunk infront of the tank and a portion of the spare tire sits on the tank on tank. Works fine.