Free pat on the back for whoever solves my fuel starvation issue!!!!

[challngd73]

I guess it is easier to keep telling him that his filter is clogged

Thank you for that strawdawg. 

And to the comment about a 40 year old tank with not a spec of dirt in it.... I didn't say that.   All I can comment on is the sock is CLEAN the filter and pump are CLEAN and free of debris.  I can't report that there is dirt and debris in them when there isn't.  Believe me, if they were all clogged up, I'd be HAPPY because at least then I would have an answer.

If I had air getting into the line from one of the connections before the pump, causing the pump to suck air, would the line be leaking fuel?   Mine is not leaking anywhere, but it seems its sucking air and overheating the pump..

[Strawdawg]

Thank you for that strawdawg. 

And to the comment about a 40 year old tank with not a spec of dirt in it.... I didn't say that.   All I can comment on is the sock is CLEAN the filter and pump are CLEAN and free of debris.  I can't report that there is dirt and debris in them when there isn't.  Believe me, if they were all clogged up, I'd be HAPPY because at least then I would have an answer.

If I had air getting into the line from one of the connections before the pump, causing the pump to suck air, would the line be leaking fuel?   Mine is not leaking anywhere, but it seems its sucking air and overheating the pump..

a pin hole in the pick up in the tank will cause problems, or a less than tight connection any where before the pump.

[rockymopar]

I am probably just throwing **** at the fan at this point, but let me state the obvious... 5/16 fuel line was good for all the magnums, and I believe all the 5.7 hemis, maybe the larger ones too. I think most gm LS engines use 5/16 stock. So if you aren't making some good power, 5/16 done right is enough. If I had a plugged line, I would redo it with 3/8, just because it is cheap insurance. I did not catch, and maybe it was mentioned, was any of the filters plugged? I know 40 year old tanks are dirty, but how many of us have even bothered to change a fuel filter on an injected car? I have gotten a couple hundred thousand miles out of a few with the oem filter and fuel pump on 15-20 year old cars, no rusted tanks, but dirty fuel from bad gas station storage tanks over the years, I am sure. Voltage to the pump made a difference on my setup. I ran a 12 gauge wire to the fuel pump relay, It helped a bunch. The fuel pressure regulator is another area I would look into. I would crank the regulator up to 55-60 and see if it makes a difference. A slight lean mixture at 43 psi should be pig rich at 60psi. As far as baffling the tank, it is the best, but I took my megasquirted smallblock with stock tank and pickup to an empty parking lot with the fuel gauge on empty to do donuts to check for starvation, and had none that I could feel  Check to insure pump wiring is adequate, and check the regulator

[rockymopar]

Let me correct my statement, I ran a 12 gauge wire from the battery to the fuse that feeds the relay, from the fuse to the relay from the relay to the pump, and checked my ground, and put a big wire to the fuel pump from ground to. Bump up the fuel pressure. It should make a difference. A 5.7 hemi needs about 58 psi. I ran my 5.9 injectors at 60psi for a long time. Stock they should have 40-50psi. If it doesn't stall with more psi, at least you know it needs more fuel. Tuning could be a problem, or fuel starvation, but it could just need a better tune. How does it know how to tune? Is an o2 sensore used for feedback?

[challngd73]

Let me correct my statement, I ran a 12 gauge wire from the battery to the fuse that feeds the relay, from the fuse to the relay from the relay to the pump, and checked my ground, and put a big wire to the fuel pump from ground to. Bump up the fuel pressure. It should make a difference. A 5.7 hemi needs about 58 psi. I ran my 5.9 injectors at 60psi for a long time. Stock they should have 40-50psi. If it doesn't stall with more psi, at least you know it needs more fuel. Tuning could be a problem, or fuel starvation, but it could just need a better tune. How does it know how to tune? Is an o2 sensore used for feedback?

The system calls for 43psi, unless it's for a high horsepower combo.  My 440 is around 400 hp I believe.  Yes it does have an o2 sensor, and the filter is spotless.

[rockymopar]

Man, I would crank that regulator up as a test. If the injectors and rails can handle the pressure, it would not hurt to experiment. At idle, it should fatten the air/ fuel ratio up too much. but,at full thottle, it would have to improve a lean condition to some extant. If not, you may have a flow problem   Since you have feedback,(o2 sensor) It might be the time to crank up the pressure AND to re-learn or whatever your ECU does to program itself. You might actually be closer to a high horse motor than you think. On my megasquirt computer, I had to use as a baseline, tables in the area of 350-400hp for a stock 5.9 magnum to get the motor close to a good AFR, and yes, I have great flow.  By the way, my 38 year old rusty gas tank is doing fine on EFI.   

[challngd73]

Just an update.  I bypassed the gas tank and ran a fuel line right into a can of gas with the new pump, pressure only got to 20psi and dropped from there within a minute, until the car died.  Tried the same thing with the old pump, exact same result.  Also triple checked the new fuel sending unit to make sure it wasn't all crudded up and it is as clean as it was when I put it in.  My mechanic is testing the fuel pumps himself as well.  I mounted a bracket right in front of the tank, below the tank as well.  Ran the fuel pump wiring all the way back to the tank as well.  At this pointing I assume the first pump may have burnt out from pulling the fuel the 60-70 inches from the tank( f.a.s.t. Told me the pump should be within 24 inches from the tank) and the second pump was just junk from the getgo. Good times.

[ShelbyDogg]

Just an update.  I bypassed the gas tank and ran a fuel line right into a can of gas with the new pump, pressure only got to 20psi and dropped from there within a minute, until the car died.  Tried the same thing with the old pump, exact same result.  Also triple checked the new fuel sending unit to make sure it wasn't all crudded up and it is as clean as it was when I put it in.  My mechanic is testing the fuel pumps himself as well.  I mounted a bracket right in front of the tank, below the tank as well.  Ran the fuel pump wiring all the way back to the tank as well.  At this pointing I assume the first pump may have burnt out from pulling the fuel the 60-70 inches from the tank( f.a.s.t. Told me the pump should be within 24 inches from the tank) and the second pump was just junk from the getgo. Good times.

Are you bypassing the throttle body to bybass the internal regulator to check pressure? You can get a vacuum regulated regulator on the net for $20. All of your pumps can't be bad. I mount all of my fuel pumps right inside the passenger rear tire, right below the fuel level.

[Strawdawg]

What kind of volume was coming back thru the return line?

[ShelbyDogg]

You really need to get a hold of the FAST tech guys. It sounds like you regulator is bad and you may need to send the whole throttle body  back to get it replaced if the regulator is internl.   If you want to try an external one on your return line, $20 below. You can adjust it for 43lbs.

Got this tip from rockymopar

"The fuel pressure regulator was from advancedjdmparts.com Give it a whirl"

Here is what I bought.



Here it is installed on my 440 fuel rail.

[Cuda54]

Could you have water in the gas?The water may not lube the pump and make it whine. I have had bad gas in the tank and add octane boost just to get it to run. Just some thing to check.

[Strawdawg]

What kind of volume was coming back thru the return line?

It seems Rob has the same questions as I do.  If there is a good volume coming back thru the return line, momentarily block it to see if the pressure then jumps up.  If it does, then follow his suggestions as it would seem the regulator is bad. 

[challngd73]

It seems Rob has the same questions as I do.  If there is a good volume coming back thru the return line, momentarily block it to see if the pressure then jumps up.  If it does, then follow his suggestions as it would seem the regulator is bad. 

I have an in line regulator, and blocking it off on the return line made no jump in pressure.

[Strawdawg]

As you have replaced the fuel line already, I would guess you have a bad pump, again...long odds, but some eventually wins the lottery in spite of the odds

[challngd73]

Well, I hate to say you told me so, but you did...my mechanic said the pumps looked clean, but when he ran them, they did not hold pressure.  upon closer inspection with a magnifying glass, the pre filter screen was almost completely clogged, on both filters.  He said the debris is so small, it was passing right through the fuel sending unit sock.  Sooo the tank evidently needs to be addressed.  Thank you all for your assistance and help with this problem.