Fuel pressure regulator

[Garbage_Mechan]

Of course some thought would have to be put in to the flow pattern to be sure the return flow off the injectors was not pressureized.

 

[War Wagon]

I was going to go the route of the SD 7.3L electric pump I got from the salvage yard, knowing I would need to run a dedicated regulated return. I have been reconsidering lately something in the Facet line up.

 

[leswhitt]

I tried this set up on the 86 because I didn't like the pressure dropping to 2 psi at WOT. I used a Walbro pump, and a regulator. No problem with the return flow. I did have two observations: Anyone who thinks the fuel pressure doesn't affect the timing better re read how the cold timing advance works.....by increasing case pressure. I know that if I ran the fuel pressure up, the engine sound and performance changed. 15 psi fuel pressure was fun but I knew better and tried it just for a few minutes. The big downside to the regulated system where the flow is tank>pump>regulator>filter >IP is that it won't prime. With the Walbro or Carrier (Facet duralift) pulse type electric pump, it will easily prime and get running again if you forget to change tanks or otherwise get massive air in the system. With the Walbro powrstroke style fuel pump, it wouldn't prime without taking something loose. It didn't seem to help performance any even though fuel pressure was rock steady any RPM or throttle setting. A couple of other observations. The more fuel we move but don't use, the more heat and aireation we create, both enemys of effecient injection.

That's excellent tech, thanks for this post!

I wonder why the PSD pump won't prime the system, that's one of my primary reasons for switching to the electric pump in the first place. What's the difference between the Facet and the Walbro that makes one prime and not the other? I'm not familiar with a pulse type pump, would you mind elaborating on that a little bit?

As for creating heat and aeration, the heat is great for the WMO and the aeration will hopefully keep my mix consistent so for a WMO/WVO user, those are both plusses.

 

[leswhitt]

I was going to go the route of the SD 7.3L electric pump I got from the salvage yard, knowing I would need to run a dedicated regulated return. I have been reconsidering lately something in the Facet line up.

The return isn't complicated, there's a $20 regulator on Ebay (but don't know how they work) that would go between the SD pump and the filter and then you run a fuel line back to the tank. Shucks, that link I posted earlier is a $70 pump/regulator/gauge combo but it doesn't have any reviews...

 

[leswhitt]

Second question: Why not make it a "regulated return" set up so a regulator set at 8psi is installed at the return flow outlet of the pump. Fuel would still flow through the pump and back to tank but only the volume needed to keep it at 8 psi. More return flow at idle, less at WOT. It works on the 7.3 Powerstroke, yes at 60 psi but same concept. And the later 7.3's upgrade to a regulated return to improve performance. The only thing that could go wrong would be if there were not enough return flow to cool and lube the pump. Thoughts?

I don't understand what you mean when you say "set up a regulator... at the return flow outlet of the pump." Are you talking about a 3 port pump with a built in regulator?

 

[Agnem]

You want to regulate to 5 PSI. That is the spec to which Stanadyne designed the pumps, and to which the industry calibrates. It is a fact that higher inlet pressures will start to screw with the timing on the pump, and invalidate your calibration.

 

[leswhitt]

You want to regulate to 5 PSI. That is the spec to which Stanadyne designed the pumps, and to which the industry calibrates. It is a fact that higher inlet pressures will start to screw with the timing on the pump, and invalidate your calibration.

I've heard numbers from 5-10 as to what the stock pump needs, I checked my stock pump and it was putting out close to 6.5.

What do you think'll happen if I run 8?

 

[theguruat12]

If you're running dedicated returns for the regulator (sorry didn't see that) then I suppose it would work. It seems like a lot of extra work though.

 

[Ugly Moosling]

Are you running dual tanks? If so, how will you switch return flow on your dedicated return to the proper tank? I think one reason many shy away from a higher pressure pump regulated down is the complexity of the regulator return. If you run it through the stock return you can have problems with excessive pressure. If you create a dedicated return you have to be able to switch tanks so you don't end up overflowing one tank. You also need to make sure the regulator can both handle the 70psi or higher, and allow enough flow at the low pressure you're setting it at.

As far as the injection pumps, like Mel said they are commonly calibrated with 5psi feed, however you can always specify to your pump builder if you'd prefer it built with a different spec. It will work ok with slight pressure deviation up or down, but it will affect the calibration the further you go away from 5 psi.

 

[leswhitt]

Are you running dual tanks? If so, how will you switch return flow on your dedicated return to the proper tank? I think one reason many shy away from a higher pressure pump regulated down is the complexity of the regulator return. If you run it through the stock return you can have problems with excessive pressure. If you create a dedicated return you have to be able to switch tanks so you don't end up overflowing one tank. You also need to make sure the regulator can both handle the 70psi or higher, and allow enough flow at the low pressure you're setting it at.

As far as the injection pumps, like Mel said they are commonly calibrated with 5psi feed, however you can always specify to your pump builder if you'd prefer it built with a different spec. It will work ok with slight pressure deviation up or down, but it will affect the calibration the further you go away from 5 psi.

Right now I only have a single tank but am planning to add another, my application is an International MDT and not a pickup so I'd like at least a 100 gallon capacity (twin 50 gallon tanks). Once I add the 2nd tank, I was thinking a 3 port pollak valve would do the trick. The original return line would always return into Tank A, the new return line will always return into Tank A, and I'll have a choice whether to pull from Tank A or Tank B.

My thought would be to run Tank A down to 1/4 full, switch over to Tank B, and pull from there until it's near empty because of the two returns emptying into Tank A, and then switch back over to Tank A. I *think* my pump is roughly 45 gph so I think it'd be something like;

Run 500-ish (11mpg w/ 50 gals) miles on Tank A > Switch to Tank B and run for about an hour (40-ish gallons will pump over to A) > Switch to Tank A (now full) and run another 500 ish miles.

The danger is overflowing Tank A but maybe I could rig up an automatic timer for running on Tank B OR just never fill tank B to capacity....

That seems like the cheapest/easiest option as it'll keep the tanks completely separate and uncomplicate where the returns flow to.

 

[79jasper]

On a MDT, just set the tanks up like a semi.

You don't select which tank.
Pulls from driver tank, return to passenger. Passenger flows to driver.

Sent from my USCC-C6721 using Tapatalk

 

[leswhitt]

I thought about that but since it'll be off-road every now and then, I don't want something to reach up, snag the equalizer line, and drain both of my tanks.

 

[leswhitt]

After looking up 3 port pollak valves and seeing that they run about $60, it'd be cheaper to pick up a 2nd pump, use the 2nd tank as a transfer tank, and pump over the fuel from Tank B to Tank A when I start to run low.

Digital timers are less than I thought, Ebay has them for $6 with free shipping. Between a $20 pump and a $6 timer, $26 isn't too bad for installing a 2nd tank.

http://www.ebay.com/itm/LCD-Digital...-Relay-AC-12V-16A-1Min-168Hours-/141123150071

 

[War Wagon]

You want to regulate to 5 PSI. That is the spec to which Stanadyne designed the pumps, and to which the industry calibrates. It is a fact that higher inlet pressures will start to screw with the timing on the pump, and invalidate your calibration.

Thanks, Mel.
I was almost going to call you on this very subject, but that's just the information I wanted to know.

 

[racer30]

I think you are over estimating how much fuel returns from the IP and from the Injector caps...I ran my engine on a engine stand with a electric pump strait to the IP at 5 psi measured at the IP with the IP return and all the injector caps ran into one line and when the engine is at idle the return just dribbles fuel...when held at 2000 rpm its running about a cup of fuel per minute. If you T into your return line where it increases in size right at the rear of the engine you will be fine....You said your pump runs 60 or 70 psi...But at what volume? the pump will only get to that pressure if you restrict its flow. If the pump is returning a significant amount of fuel you won't build high pressure. Just make sure there is enough return flow to keep from over pressuring the caps...maybe you could return some of the flow back to in front of the pump just use a T to make sure all the air returns to the tank and only return filtered fuel back to in front of the pump with a check valve to be sure to make it pressure sensitive. The fuel pressure would have to overcome the check valve spring before it would flow back to the inlet side. we use a similar system to set minimum pressure on the race car....