Fuel starvation with FI engine?

[gtzero]

Hi All,

I've had this problem ever since I swapped to my FI engine. When the tank is less than half full, I get fuel starvation problems when cornering. I've had this problem for so long now that I don't even notice which direction is the most problematic. I think it was on a left turn but I could be wrong. I've just gotten to the point where I try to keep my gas tank topped up.

Any ideas on why this happens only with FI?

And the obvious, any easy solutions?

I was thinking of finding a huge fuel filter and using that as a vessel to hold excess fuel just out of the tank. I shouldn't need too much to clear a nice bend in the road. Seems like it should work.

Thanks for any advice,

Manny

[houserc]

Where is your fuel pump?

Are you running a FI fuel pump?

How big is your fuel line from your tank to your fuel pump?

Is there a possibility that the screen sock in your tank has something (such as rust) restricting the flow?

I've heard stories of people finding trash or other items in their tank that plug the screen sock area.

I'm running FI also and I have my Pump located just forward of the rear axle with as large a tube as I could get from the tank to the pump (5/8). The fuel bar at the front should have about 35 pounds of pressure.

[Sportwagon75]

Manny - The fuel tank is configured a little differently on an F/I car. On a carburetted car, the bowl on the carb serves as a short term reservoir so you don't have that problem during hard cornering with low fuel level. On an injected car...the pump must have sufficient fuel to provide constant rail pressure at the injectors. When you go around a corner, your fuel goes to one side and there's nothing to keep it near the pickup sock...so the pump starves briefly. F/I tanks have a retainer bowl that serves as reservoir for the pickup tube. Also...the return line brings unused fuel right back to this bowl. To fix the problem completely, I suspect you'll have to find a fuel tank from a 75 car. Good luck. -Scott

[gtzero]

Originally Posted by houserc Where is your fuel pump? Are you running a FI fuel pump? How big is your fuel line from your tank to your fuel pump? Is there a possibility that the screen sock in your tank has something (such as rust) restricting the flow? I've heard stories of people finding trash or other items in their tank that plug the screen sock area. I'm running FI also and I have my Pump located just forward of the rear axle with as large a tube as I could get from the tank to the pump (5/8). The fuel bar at the front should have about 35 pounds of pressure.

I guess I forgot to mention that I have a GT.
With that said, I suppose it's possible that there is junk in the tank. But why would it only happen when the tank is half empty? If the stuff floats, then it shouldn't happen until the very end. And if it doesn't float, then it should happen all the time.

[houserc]

Is there something with the way your fuel line runs from the tank to the pump?

Could the fuel line be high enough in one location to be above the top of the fuel in the tank? Say, if the tank was half full or less, is there a location of the fuel line that is above that?

I ran into a problem with the tank rusting and flaking off. It caused me all kinds of grief. It would run fine at idle and low speeds, but when it demanded more fuel it cut out really bad. It seemed the injectors were clogged or the fuel filter was dirty. I ended up having it acid dipped and epoxy coated to cure it. And then I sent the injectors in to be cleaned.

Runs fine now.

[gtzero]

Originally Posted by houserc Is there something with the way your fuel line runs from the tank to the pump? Could the fuel line be high enough in one location to be above the top of the fuel in the tank? Say, if the tank was half full or less, is there a location of the fuel line that is above that? I ran into a problem with the tank rusting and flaking off. It caused me all kinds of grief. It would run fine at idle and low speeds, but when it demanded more fuel it cut out really bad. It seemed the injectors were clogged or the fuel filter was dirty. I ended up having it acid dipped and epoxy coated to cure it. And then I sent the injectors in to be cleaned. Runs fine now.

Thanks for the ideas. I hope I won't have to go so far as to remove my tank. Since I haven't replaced any of the fuel filters in many years, I'll start with that and while I'm at it, I'll check out the entire fuel line and see if, as you say, there are parts higher than the tank.

Thanks

[RallyBob]

Manny, this is not an uncommon problem with cars converted to EFI. In fact, on many cars that have factory EFI, but have, shall we say.....a less-than-sporting pedigree, often have fuel starvation problems under hard cornering or racing conditions. I mean, your GT was never envisioned to have 17" wheels/tires in a rubber compound that is stickier than any racing tire 30 years ago!

I am currently working on this issue with the turbo Manta for Carlisle, and had to order some special one-way check valve fuel pickups. I'll run three of them, one in the center of the tank, and one at each far side, so that no matter what, one is always submerged in fuel. EFI pumps can NOT be allowed to suck air, or the pressure falls and the engine will run lean. Most factory tanks are baffled or have some sort of built-in swirl pot.

Bob

[gtzero]

Originally Posted by RallyBob Manny, this is not an uncommon problem with cars converted to EFI. In fact, on many cars that have factory EFI, but have, shall we say.....a less-than-sporting pedigree, often have fuel starvation problems under hard cornering or racing conditions. I mean, your GT was never envisioned to have 17" wheels/tires in a rubber compound that is stickier than any racing tire 30 years ago! I am currently working on this issue with the turbo Manta for Carlisle, and had to order some special one-way check valve fuel pickups. I'll run three of them, one in the center of the tank, and one at each far side, so that no matter what, one is always submerged in fuel. EFI pumps can NOT be allowed to suck air, or the pressure falls and the engine will run lean. Most factory tanks are baffled or have some sort of built-in swirl pot. Bob

Hi Bob,

That's what I remember hearing as well, about the baffles and such. Since I'd really rather not have to take the tank out, what are my options?

Will my idea of using a large fuel filter work?

Thanks,

Manny

[rallye73]

I recall that someone was using a surgetank out of a Volvo after the pump to fix this problem. Maybe Otto?

Darrin

[davegt27]

i had the same problem with my FI GT

had to run around with at least 1/2 tank of Gas--- when i autocrossed anyway

when just driving on the street not to much of a problem
I've seen PICS of a few peoples GT's and they have the FI pump way under the car

that's to far away to not have problems. basically you want to duplicate the 75 FI setup with one addition

that is a Low pressure fuel filter between the tank and the pump (got to protect that high dollar FI pump)

the NA Manta tank pickup is absolutely tiny so don't go by that

Like houserc you need the biggest Fuel line you can get your hands on going from the tank to the FI pump

the Fords have a good system of in tank pickups where they have sort-of-a S type tube arrangement inside a Bowl

another options is to run a low pressure pre pump.


Good luck
Davegt27

[gtzero]

Originally Posted by davegt27 i had the same problem with my FI GT had to run around with at least 1/2 tank of Gas--- when i autocrossed anyway when just driving on the street not to much of a problem I've seen PICS of a few peoples GT's and they have the FI pump way under the car that's to far away to not have problems. basically you want to duplicate the 75 FI setup with one addition that is a Low pressure fuel filter between the tank and the pump (got to protect that high dollar FI pump) the NA Manta tank pickup is absolutely tiny so don't go by that Like houserc you need the biggest Fuel line you can get your hands on going from the tank to the FI pump the Fords have a good system of in tank pickups where they have sort-of-a S type tube arrangement inside a Bowl another options is to run a low pressure pre pump. Good luck Davegt27

Hi Dave,

So did you remedy your problem? What I gathered from your post was that you had the same problem but did as I did which was to keep the tank full. I'll definitely look into everyone's suggestions. I want to find the easiest fix. I just envision me under the car with fuel dripping all over me as I change fuel lines and stuff.

Thanks all for your inputs,

Manny

[davegt27]

No

the big problem was when i was racing solo II. had to have at least 1/2 tank of gas

driving around on the street it wasn't to big of a problem

i had an extra fuel tank which i cut in half and was going to do a proper

surge tank

my street car was totaled by some no driving chick and i moved into racing Opels


I am sure you fix the problem.

good Luck
Davegt27