Printable Version of Topic
Click here to view this topic in its original format
914World.com _ 914World Garage _ Fuel starvation on hard left turns
Posted by: tadink Oct 18 2013, 06:06 PM
HI guys -
I posted this issue before and got some good suggestions, many of them having to do with electrical connections, etc.
Since then, I've swapped out the 1.7L for a 2.0L, hoping that the problem would be somewhere in the engine and that it would go away. IT DID NOT. ugh.
So, hard left turns that load up the g-force, after a count of 1-2-3 -ish coming out of the corner, hard stumble / stutter for a few seconds and then back to normal.
It is annoying.
Some thoughts -
1. what does the 'sock' in the fuel tank look like and is it flopping over the intake and causing starvation? How long would the air bubble or whatever take to get thru the tunnel to the injectors? 1-2-3 -ish?
2. weak fuel pump?
3. somewhat clogged fuel filter?
4. 
Looking forward to clearing this up before the next AX if possible, looks silly to sputter after every left turn!!
thanks all
td
Posted by: bulitt Oct 18 2013, 06:21 PM
djet or carbs
Posted by: tadink Oct 18 2013, 06:26 PM
djet or carbs
great question - sorry I left it out - it is DJet with brand new injectors all around....
td
Posted by: SLITS Oct 18 2013, 06:36 PM
Since the pickup is on the right side of the car, in a hard left all the fuel would move towards the pickup.
You might want to see if it is possible your supply line is getting pinched by movement of the motor or associated fuel components.
Posted by: ThePaintedMan Oct 18 2013, 06:43 PM
Gotta have enough fuel in the tank to be able to pick it up in the first place. I recall some of you autocross guys in the Paddock saying to keep it above 1/4 of a tank, right?
Posted by: 914forme Oct 18 2013, 07:22 PM
Its a big tank, and a left turn moves all that fuel to the left side. Wheres the pickup, low and right. And well your running a HPFP, they still move a bunch of fuel.
Its like your oil, it will move out the left head, and you run out of oil = bad. So you add a sump extension, or dry sump system. You can do the same thing in your fuel system if you ned to. You can add a smaller tank in the tank, in the way of baffles. You can add an accumulator to cover you for your long turn, rock crawlers do this all the time. Pirate 4x4 shows tons of them.
I had another thought, does your fuel pump cut out, I know its hard to hear at full song. But maybe the left turn is causing your + or - side to break the circuit. That would cause you to cut out also. Its a remote possibility but I would check your grounds all over.
Posted by: The Cabinetmaker Oct 19 2013, 10:52 AM
Its a big tank, and a left turn moves all that fuel to the left side. Wheres the pickup, low and right. And well your running a HPFP, they still move a bunch of fuel.
Its like your oil, it will move out the left head, and you run out of oil = bad. So you add a sump extension, or dry sump system. You can do the same thing in your fuel system if you ned to. You can add a smaller tank in the tank, in the way of baffles. You can add an accumulator to cover you for your long turn, rock crawlers do this all the time. Pirate 4x4 shows tons of them.
I had another thought, does yoyur fuel pump cut out, I know its hard to hear at full song. But maybe the left turn is causing your + or - side to break the circuit. That would cause you to cut out also. Its a remote possibility but I would check your grounds all over.
Centrifugal force will move everything towards the outside of the arc. A left turn will cause fuel towards the outside, ie right side, which is the outside of the arc, or turn in this case. I know you know what you meant. Just clarifying for others benefit.
Posted by: tadink Oct 20 2013, 09:48 PM
Its a big tank, and a left turn moves all that fuel to the left side. Wheres the pickup, low and right. And well your running a HPFP, they still move a bunch of fuel.
Its like your oil, it will move out the left head, and you run out of oil = bad. So you add a sump extension, or dry sump system. You can do the same thing in your fuel system if you ned to. You can add a smaller tank in the tank, in the way of baffles. You can add an accumulator to cover you for your long turn, rock crawlers do this all the time. Pirate 4x4 shows tons of them.
I had another thought, does yoyur fuel pump cut out, I know its hard to hear at full song. But maybe the left turn is causing your + or - side to break the circuit. That would cause you to cut out also. Its a remote possibility but I would check your grounds all over.
Centrifugal force will move everything towards the outside of the arc. A left turn will cause fuel towards the outside, ie right side, which is the outside of the arc, or turn in this case. I know you know what you meant. Just clarifying for others benefit.
Thanks for all the thoughts on this - - I have run all the grounds, so I don't think that's it. I'll dig into the tank movement next....I do have a faint gas smell on hard right turns.....and full tank. And if the fuel pump cut out - I think that would be in the middle of the turn, not a few beats afterwards. I'm leaning towards some weirndess in and around the tank and assorted hoses.....but this is a real head scratcher for sure.
Happens whether full tank or 1/4 tank....
Posted by: SirAndy Oct 20 2013, 10:57 PM
Also check the fuel pump relay on the relay board and make sure it fits snug in the socket.
Might want to switch relays just to try.
Oh, and if you decide you need to clean those sockets, disconnect the battery first!
Posted by: rhodyguy Oct 21 2013, 07:24 AM
if the strainer sock is sucked flat and flopped over you need to replace it. buy new gaskets too.
Posted by: cwpeden Oct 21 2013, 01:44 PM
This is funny, I had the exact same problem.
New sock in tank 4 yrs before the problem started, still nice and clean. 3/4 tank fuel, new filter in rear, pump is running.
Problem just went away. Not sure why.
New motor mounts installed because I broke them about 4 months later. One may have already been gone and was contributing to it. Engine shifting causing electrical issue on corner?
Posted by: ChrisNPDrider Oct 21 2013, 01:48 PM
That is weird! 
I posted in the Paddock a while ago about this, but I am trying to do AX races w just a little fuel. I never get fuel starve w a near full or full tank. Find that thread to read about accumulators and other racey solutions.
How's the fuel pump mount? If it is located under the battery (OEM location in early years) it may be compromised by rust. If the pump is swaying back and forth, that may affect the electrical connections, hoses, etc and causing a problem.
Tough one! Good luck 
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)