External FPR long stars

[pysical]

Does anyone have long starts with a return style fuel setup using a external FPR? The car will start up fine from a cold start. But when the car is warm it is a long start.

Setup:
New Index 12 Injectors
New HPFP
2x Walbro 535
BMP4 Controller
New ID 1050x injectors

 

[SLOWESTN54]

It's likely because a Walbro 535 does not have a check valve, you'd either have to add one or switch your main pump to a pump with a check valve.

 

[pysical]

Thats what I thought. But wonder why it starts up no issue when cold and not when hot? I figured it would still bleed out of the pump regardless if cold or not.

 

[Torgus]

Does anyone have long starts with a return style fuel setup using a external FPR? The car will start up fine from a cold start. But when the car is warm it is a long start.

Setup:
New Index 12 Injectors
New HPFP
2x Walbro 535
BMP4 Controller
New ID 1050x injectors

My only comment(as above) would be I thought the general consensus would be the 525 should always be the primary because it has the check valve vs 535 without as the secondary. The CV should stop the long start? The 535 with the CV is fine if you don't mind a long cold crank. But you have no long start when and no cv.

In your set up why when it is warm do you have the long crank? The long crank should be when cold when the fuel drained back because lack of a check valve...

 

[pysical]

My only comment(as above) would be I thought the general consensus would be the 525 should always be the primary because it has the check valve vs 535 without as the secondary. The CV should stop the long start? The 535 with the CV is fine if you don't mind a long cold crank. But you have no long start when and no cv.

In your set up why when it is warm do you have the long crank? The long crank should be when cold when the fuel drained back because lack of a check valve...

Yeah I have no clue why it is like that. The fuel pump primes really quick when it is cold. I honestly haven't checked when it was warm to see what happens. I wonder if I put a check valve in line then it would solve it instead of pulling out the pump and switching to a 525. I have -6an from the fpr and then -6an from the top hat that come into a Y that goes to -8an. I wonder if I put a check valve in the -8an it would solve it? Just don't want to hinder the flow with it.

 

[SLOWESTN54]

Yeah I have no clue why it is like that. The fuel pump primes really quick when it is cold. I honestly haven't checked when it was warm to see what happens. I wonder if I put a check valve in line then it would solve it instead of pulling out the pump and switching to a 525. I have -6an from the fpr and then -6an from the top hat that come into a Y that goes to -8an. I wonder if I put a check valve in the -8an it would solve it? Just don't want to hinder the flow with it.

Im not sure if i fully understand what you mean. But Wouldn't this almost cause more issues as the car would start but then die if the fuel pressure doesn't rise and re fill the line fast enough.

 

[pysical]

It would just be to prevent the fuel from going backwards and through the pump. It was while I had a hobbs switch. I drew up my fueling setup. My thought would be to put a check valve in one of the two places listed. Doing this it would not let the fuel go backwards and it would keep the fuel between the FPR and the check valve still pressurized correct?

 

[SLOWESTN54]

My only concern is your fuel pump may not prime as your lpfs would still see pressure. If that was the case wouldn't the car start but then die as fuel pressure would take a second or two to catch up as the line behind the check valve would be depressurized. I could be completely wrong and you probably have way more experience then i do.

 

[pysical]

My only concern is your fuel pump may not prime as your lpfs would still see pressure. If that was the case wouldn't the car start but then die as fuel pressure would take a second or two to catch up as the line behind the check valve would be depressurized. I could be completely wrong and you probably have way more experience then i do.

I see what you are saying. Yeah I am not sure. Maybe I should log a cold and warm startup and see what the psi is between the two.

 

[Dumaurier7]

There is a fuel FUELAB filter with built in check valve that will simplify things for you .

 

[pysical]

There is a fuel FUELAB filter with built in check valve that will simplify things for you .

I will have to look into that. I currently have a Precision Raceworks 10 micron fuel filter underneath the car. I will have to get some dimensions and see if I can put the Fuelab filter in the same spot, or I will have to redo the entire line and move it somewhere else.