fuel psi drop

[lincolnlocker]

i have a 5/8ths pickup to a carter 4600 lift pump to a 40gph 7mic water/fuel separator to a brand new walbro to the stock fuel bowl and filter... its dropping pressure when on the throttle... up to 15psi at times... well was 15psi at times, but after the new pick up, it drops around 10psi now...

been threw hell and back trying to figure out why my fuel is dropping... while i had it at beans for my live tune session in dec 2010 we set the fpr spring at 65psi and would only drop 3-4psi on the dyno after jonathan put a new walbro in it... since then, that walbro took a **** so i ordered a new one and installed that with the prepump filter. was still dropping up to 15psi so i installed the carter, still dropping psi, so i installed the 5/8 pick up, still dropping, so i put new filters in it, still dropping but only around 10psi... been emailing beans to ask what they think and they got back with me quickly that way. thanks BEAN for the quick reply's...

right now its set at 75psi and drops to 65psi...
just wondering what you all think i should check for now?

sh!t i found in the tanks stock pickup tube.

 

[TARM]

Well first thing I see is your water fuel separator is WAY to small. Its only rated for a MAX flow rate of 40gph/. Your Walbro pumps is sucking about 35-45% more at around 65-70 gph. You should be looking for a water fuel sep that has around 100 gph rating as a minimum. Even with the carter on there its still not gonna help enough as its internally reg to 7-14 psi and once there is does not go over that regardless of flow rate. Your walbro pump is still trying to suck way more and is likely pulling a hard vacuum psi between the filter and pump inlet.

I know you found the pickup was clogged but I think this is a issue.

 

[indyF-350psd]

have you checked to make sure the carter isnt restricting the flow at all? just a thought....i think i saw your response about a sump before but you can run the lines from a sump so they cant get caught and yanked off like youre worried about....sump it to an airdog to the main pump and youll be fine.....

 

[Rideracelivemx7]

i didnt realize dropping 10lbs was bad with bigger sticks? its not like your dropping to incredibly low PSI, i thought 65psi was the typical DD setting for alot of diesels?

 

[TARM]

You want a good water fuel sep that flows well order this:

P550901 9.04" L @ 7 mic@99% 120 GPH recommended flow capacity

This has plenty of flow and even at a full 120 it has under well under 1 psi vacuum.

 

[TARM]

Its not that bad but the point is with that pump setup he is running it should not be happening. His injectors are not that big. I am running 465cc/200% with the same carter and bit larger main pump the bosch 044 and I have had zero issues. Charles is running 400% nozzles and his pump is set at around 65-70 gph and his holds rock steady. I am pushing 80-85 gph. The carters are good for around 100 gph before they start to be a restriction at all. As they are internally reg no damage was likely done to them for the most part from the filter.\


The twi things that are 100% for sure thing are :

1: you had crap in your pickup

2: A filter rated for max of 40 gph is likely causing serious vacuum with pumps running @ almost double that flow rate.

 

[97BambiBasherPSD]

So what filters do you recommend then? I'm getting psi drop also and I'm sure it's my filters causing the issue. Or my pump is starting to fail


Sent from my Pear phone using Tapatalk

 

[Rideracelivemx7]

good to know thanks tarm, i thought we were talking about a 6.0 at first for some reason hence the bigger sticks comment lol My bad, hope he finds the issue

 

[lincolnlocker]

sh!t sorry that was a typo its rated at 40 gallon per minute, not hour...

blew out all the lines form the bowl back to the tank and from the return lines to the bowl...

like tarm said, the fuel psi shouldn't budge with the setup i have...

i even bypased the prefilter and went from the carter to the walbro and it didn't matter.... i even took the stock fuel filter out of the bowl and put the stock cap on it and ran it that way, still dropped... i think i have tried just about every scenario.

 

[CSIPSD]

You still have the factory bowl? Regulator and all?

 

[TARM]

Have you confirmed the fuel pressure gauge or sending unit is not faulty?


glad that was a typo on the filter. I was thinking there was no way you would have done that. LOL



BTW what filter brand are you using in the fuel bowl?

 

[TARM]

OK so you are going 5/8 pick up to carter to fuel water sep to walbro to fuel bowl. I have not done much of anything with the stock fuel lines and high flow volume. What about those pieces inside the factor fittings that go into the fuel rails ports in the head. did you remove them or drill the out. I recall when I have looked at them even pushing air thru them was not fun not to mention the size. If there is restriction before the return it will show up as pressure drop.

 

[lincolnlocker]

You still have the factory bowl? Regulator and all?

yes i went back to that to try and this is what i've had on for a while now. http://www.riffraffdiesel.com/mm5/m...RRD&Product_Code=FRx&Category_Code=F731-FS-RR

Have you confirmed the fuel pressure gauge or sending unit is not faulty?


glad that was a typo on the filter. I was thinking there was no way you would have done that. LOL



BTW what filter brand are you using in the fuel bowl?

yeah i always figured my fuel gauge was crap(glowshift) but it did let me know that the fuel psi was dropping to 0 when my last pump took a ****. so i ordered a fuel psi test kit with a mechanical gauge... also i am pretty sure i pm'd you a pic of my setup either on here or the other place... and up until a couple days ago i always used wix filters but i found the ratings on it... there very sucky... i think it was 14mic and the h2o/fuel separation was even worse.. i think like 50%... WAY bad.. the stock motor craft is what it gets now... that one is 98% separation and i think 7mic..

OK so you are going 5/8 pick up to carter to fuel water sep to walbro to fuel bowl. I have not done much of anything with the stock fuel lines and high flow volume. What about those pieces inside the factor fittings that go into the fuel rails ports in the head. did you remove them or drill the out. I recall when I have looked at them even pushing air thru them was not fun not to mention the size. If there is restriction before the return it will show up as pressure drop.

i blew out every line... and like stated before.. when it was at beans it was completely stock with a walbro and it only dropped 3-4 psi... with all this its still dropping 10ish psi... i even took the lines of the riffraff RR and turned the key on and let the fuel flow out of the ports... gauge still read 30psi on a free flow while doing one line at a time while the other was plugged off.

 

[TARM]

So you are getting 30 psi with it free flowing. When you say the lines one at a time are you talking about the factory lines?

I doubt you can do this the way you have it setup but I wonder what pressure you would read in the main line going to the fuel bowl if it was disconnected from the bowl. I wish you had a way to bypass the fuel bowl completely to rule it out for sure. When the bowl is gone and its a straight up RR I find things easier to trouble shoot this stuff as there are only a few points it can be and you can bypass anything you want.


You could test your free flow rate of you pump setup. Get a 10 gal bucket and jump the pump with straight power from the battery. Put he hose going to the fuel bowl in the bucket. Time it and run it till it hits the 5-10 gal mark whatever. You can then get your rate with the time and gal. That will at least give you a base reading for everything from the tank to right before the bowl.

 

[TARM]

BTW the Donaldson P550437 IIRC is rated at 5 mic absolute when you get ready to do a filter change.

 

[lincolnlocker]

So you are getting 30 psi with it free flowing. When you say the lines one at a time are you talking about the factory lines?

I doubt you can do this the way you have it setup but I wonder what pressure you would read in the main line going to the fuel bowl if it was disconnected from the bowl. I wish you had a way to bypass the fuel bowl completely to rule it out for sure. When the bowl is gone and its a straight up RR I find things easier to trouble shoot this stuff as there are only a few points it can be and you can bypass anything you want.


You could test your free flow rate of you pump setup. Get a 10 gal bucket and jump the pump with straight power from the battery. Put he hose going to the fuel bowl in the bucket. Time it and run it till it hits the 5-10 gal mark whatever. You can then get your rate with the time and gal. That will at least give you a base reading for everything from the tank to right before the bowl.

if you look at this website below from riffraff you can see where the return lines screw into the fpr block.... i took them out and plugged the holes then capped each line one at a time and let if flow.... i have tried two different brand new walbro pumps with both the same results... i have tried going from the tank to the walbro to eliminate the carter and pre filter to make sure that there was still no restriction there. no change...
http://www.riffraffdiesel.com/mm5/m...RRD&Product_Code=FRx&Category_Code=F731-FS-RR

BTW the Donaldson P550437 IIRC is rated at 5 mic absolute when you get ready to do a filter change.

yes sir i just found that one yesterday... its saved to my bookmarks so the next online order i do i will get that one... but for now i can get the motorcraft at a couple spots in town.... what donaldson do you recommend for the prefilter? the p551000? the prefilter base i have is 1-14 thread size.

 

[TARM]

Right so the only area that has not been removed from the loop is the fuel bowl and those stock steel lines and fittings correct? That is also where you are still seeing 30 psi in the bowl with the one of the lines off the RR from Raff. To me I think that is where the issue may be. With all that crap you have in the tank what it some of that has ended up in those stock fittings from the bow and at the fuel rail ports?

Where are you reading pressure from? the fuel bowl service access port?

 

[lincolnlocker]

Right so the only area that has not been removed from the loop is the fuel bowl and those stock steel lines and fittings correct? That is also where you are still seeing 30 psi in the bowl with the one of the lines off the RR from Raff. To me I think that is where the issue may be. With all that crap you have in the tank what it some of that has ended up in those stock fittings from the bow and at the fuel rail ports?

Where are you reading pressure from? the fuel bowl service access port?

i have not completely removed any stock lines or the fuel bowl. i can blow air threw them all but i guess diesel is thicker then air.... i am reading psi from the bowl and i put a T fitting in the lines going from the heads to where it screws into the fpr block so that i can read psi from either head. reads the same psi from both heads and at the fuel bowl...

 

[TARM]

Ok so fuel pressure is the same in the bowl as it is coming out of the heads even when you have it free flowing?

Well without getting my hands on it the issue sounds like its somewhere on top the engine. Fuel bow fittings etc... I base this on you have checked everything from the tank to the outlet hose from the pump and have no flow/pressure issues at all. Its only when you get up top that things seem to have any restriction at all. Slapping on a normal RR I bet would take care of the issue but after spending the money on how you have it I doubt you want to do that.

Right now all I can think of is check the fittings and then see if there is anyway to rule out an issue with the FPR itself.

 

[lincolnlocker]

yes all pressures are the same. or are you saying that there shouldn't be any pressure with either line from the heads?

i am not sure how much of the crap that was in the tank actually made it to the fuel bowl. the walbro pumps have screens in the inlet side of them. i know they cant stop everything but i change the stock fuel filter every 8-10k miles... definitely no big chunks that can be seen with the naked eye...

i am very seriously thinking of just getting a regulator and running the lines from the riffraff kit to this http://www.jegs.com/i/Aeromotive/02...motive+13109&gclid=CNaomvvKgbACFUdN4AodZHE8FA if it is good enough , then to the return line to the tank...