i know right!! I really want the OP to figure this out. The suspense is killing me

 

I'm trying...

The relays are getting hot so I'm looking into the amperage on them they might of got swapped on install.


I might be on to something else the AN fittings on the FPR might be threaded in to far and cutting in to flow. I'm going to cut them down and log tomorrow.

 

Isn't your FPR post rails? If so wouldn't the, threaded too far restriction, cause an increase in pressure?

 

a restriction in the return side would cause the pressure to rise when the fuel being used is minimal, once a large portion of the fuel being pumped through the system is being used then the pressure would gradually start to drop and match what the regulator is set to.

 

I'm trying anything I can since I've replaced or tested everything so far.

Still working on the relays.

Can I simulate flow by running the pump off a battery and sending pressure to the FPR? This way I can see if it's maintaining pressure I have no check valve?

 

Checked the relays no issues besides getting a little hot. The fittings didn't change anything either.

I'm running a -6 hose from the pickup to the fuel rail I will report back.

 

If not maybe try the 8??

 

I thought -8 would be to large for my power goals at 400whp mustang max. The Bosch would run out of fuel before -6 lines correct?

My main issue is the fuel pressure drop at 11 psi I can see it being a problem at high levels but not lower levels that I'm experiencing it at.

 

Not sure if you have this problem, but perhaps it is something to look at.

The little vacuum nipple on the side of my Aeromotive FPR was screwed in too far. What happens when it gets screwed in too far is the spring behind it does not function correctly and contacts the spring preventing correct regulation of the pressure. I unscrewed mine a little out and it worked again normally.

Perhaps you have the same problem???

 

the regulator is a very simple assembly, might be worth just taking it apart and inspecting everything internally. if any of the fittings are going into the housing too far you could just cut them down some.

 

I rebuilt my FPR added some Teflon tape to the port when that didn't work I tried another FPR with no success.

The other thing is I'm getting fuel pressure it's just not holding.

Thank you for help
-J

 

the issue is likely just a simple restriction as you probably are already aware since you seem to have been trying to track that down, or a volume issue with the pump itself, which you also seem to have addressed.

say the pump is pushing 200liters per hour through the system back into the tank all said and done, the engine under load is using 150 liters per hour and you are noticing the pressure begin to drop off as the need for fuel reaches 150+ liters per hour. the more it uses the more the pressure will drop, meaning the volume output is getting close to being met. but for example the pump should be putting out 350 liters per hour, so the pressure drop is coming far too early. the larger the restriction is the more dramatic the drop will be, so your restriction is probably rather minor and making it more difficult to find.

i would suggest just do as you have been doing and start monitoring volume levels at each stage of the system. the only difficult point will be at the regulator since it cannot be regulated to 0psi for a static volume test and the upstream channels done at the pressure the engine will be using at 40+PSI.. so a single test is usually done at the tank return, any irregularities noticed with line sizes upstream are addressed until the volume is close to what it should be.

it just sounds like you have been unlucky with a single bottleneck that you just haven't been able to locate.

 

the one thing people havent taken note of is the heat in the relays .. i think they may be telling you that the earth on the pump may not be sufficient

this can also cause the issues as noted

 

Very true it's been a struggle to find this bottleneck. I figured I only have a few things left fuel line and fuel pickup assemble to eliminate now.

 

I've ran the pump direct to the battery and it has a clean chassis ground setup. It's been checked by three shops so far and they found nothing wrong.

It has two large bulkheads on sender with 10 Gauge wire ran all the way through.

But yes the relays are getting hot under logs.

 

I haven't had time to work on it lately hopefully I will have time this week.

Just a question could it be possible that the -6 feed hard line is not sufficient enough even at lower power levels on the E85? Someone told me -6 and the 5/16th stock line are similar internally.

-J

 

I had little over 400hp, single bosch pump, stock hard lines under the car

 

-6 is 6/16 aka 3/8
-8 is 8/16 aka 1/2. Not sure if it's ID or OD however. I still think running -8 is worth a shot.. Also maybe run a ground wire to battery vs chassis ground...

 

No Dash 6 line can easily support 500rwhp. Not your issue.

Its either your pump or a blockage in your filters.

 

I had little over 400hp, single bosch pump, stock hard lines under the car. This was on regular fuel right?

-6 is 6/16 aka 3/8
-8 is 8/16 aka 1/2. Not sure if it's ID or OD however. I still think running -8 is worth a shot.. Also maybe run a ground wire to battery vs chassis ground... Yeah inside diameter and I've tried the ground no difference.

No Dash 6 line can easily support 500rwhp. Not your issue. On E85?

Its either your pump or a blockage in your filters. I've replaced both no difference.

 

No, it was on E85

 

FWIW, i had no problems at 575 on E85 with dash 8 under the car, dash 6 to the rails a FFS and a stock undercar return line.

 

im swapping lines now but not because of issues with pressure.
Issue is feed line rusted and started leaking and im also changing all the hard brakes lines as well.
I have all -8 and -6 return sitting in a box ready to go in

to be honest I was going to keep the stock return line but dont want it rusting in the near future.

 

BTW I read and dont think you mention removing the sock to see if solved your issues?
That sock doesnt look like it has a skeleton to keep it from collapsing. I know the sock jay racing sells for the bosch originally didnt have the skeleton and it would collapse on some cars.
Their new one comes with the skeleton frame work

 

I had little over 400hp, single bosch pump, stock hard lines under the car.
What was your whp and did it max out at that point?

I know -8 is over kill for my setup but what ever does the job at this point.

Your right I never pulled it out because I tried the Walbro 485 pump and filter earlier and had the same results. It's been checked a few time and kept it's original shape it's metal haha