Fuel pressure regulator

[Ironman03R]

I know IDI's dont have one, but IF someone were to put one on a 7.3 would it be ok to plumb it inline on the return line out of the filter/seperator?
I havent taken the filter head apart so I'm not sure how the return system works, but if I were to guess, I think putting it there would regulate to a consistant pressure w/o restricting the flow to the IP. I would leave the IP return intact for cooling/lube.
Is there a max psi or flow rating that the stock return system can handle?

Last question is for anyone using an electric fuel pump:
Did you notice any difference in mileage after the swap? I've heard most say they gota boost in power but no one has ever said if it affected the mileage.

 

[Agnem]

What are you hoping to achieve? Putting a presure regulator on the return side of the fuel filter head would be completely pointless, and probably result in air being trapped.

 

[Jake S.]

My mileage went down from the extra power....

 

[sle2115]

Putting the regulator on the return side is common practice on gassers. It does just as described, keeps a constant fuel flow and pressure, MUCH better than having it before the fuel system. When I small blocked the few S10's I did, we just continued to use their fuel pump with the regulator on the return side with very good results. Those pumps would easily make 12-15 PSI and we used carbureted small blocks where 6 PSI will almost always push fuel past the float/needle valve. I say give it a try and report back.

My truck had an electic pump on it when I got it. I have changed it as it went out and there was a noticeable power increase. I also had to change the IP when I bought the truck and I figure the old was saw fuel starvation and poor lubrication. At any rate, I get very good fuel mileage anyway for having 4.10's, but most of my driving is back roads and limited highway miles where the 4.10's really start to eat fuel.

 

[Ford428CJ]

You got to remember that Diesel are the opposite of gassers . You don't want to restrict the return lines at all. If you do, you will end up with problems! I read that somewhere. I'll see if I can find it!

 

[Ironman03R]

You got to remember that Diesel are the opposite of gassers . You don't want to restrict the return lines at all. If you do, you will end up with problems! I read that somewhere. I'll see if I can find it!

That was my concern... I know from working with drag cars w/ SBC's we put regulators in the return side, also if you look at most any OEM fuel rail the regulator is on the return side. But I'm realy not restricting the whole system, if anything I will be increasing the flow through the return lines; thats why I'm wondering what the max rating is on the return.

What I'm toying around with is this: Stock lift pump is 4-7psi from what I've read. Holley Red is 7psi constant. I want to test different fuel pressures to see what is the ideal range for these engines.
My thought is 4psi or so should be all thats required at Idle, but as RPMs and boost increase so should lift pump pressure. If it dont work or I dont get good results, I just take off the regulator and set pressure to a constant number, then I'm just out time and some money.

 

[Ford428CJ]

That was my concern... I know from working with drag cars w/ SBC's we put regulators in the return side, also if you look at most any OEM fuel rail the regulator is on the return side. But I'm realy not restricting the whole system, if anything I will be increasing the flow through the return lines; thats why I'm wondering what the max rating is on the return.

What I'm toying around with is this: Stock lift pump is 4-7psi from what I've read. Holley Red is 7psi constant. I want to test different fuel pressures to see what is the ideal range for these engines.
My thought is 4psi or so should be all thats required at Idle, but as RPMs and boost increase so should lift pump pressure. If it dont work or I dont get good results, I just take off the regulator and set pressure to a constant number, then I'm just out time and some money.

oh man.... Your a Chevy guy J/K. On your return side of the house (if you where testing it) should be less then 3psi of resistance. If it is more.....Then you got problems! So it should flow fairly free as I recall.

I run a Carter HP4600 pump (7psi) and haven't had a single problem with it and I don't run a regulator on it. You should be fine with the Holley pump as well... Do away with the regulator in my book. It will only uses what it needs.

Also you got to get rid of the gasser thoughts (you are no longer sparked fired now). Diesels are a different bread and it took me a little time to learn about them and how they work! JMO

 

[RLDSL]

You got to remember that Diesel are the opposite of gassers . You don't want to restrict the return lines at all. If you do, you will end up with problems! I read that somewhere. I'll see if I can find it!

Well, that's an old truck driver trick for making company trucks scoot. We'd take a set of vice grips and pinch off the return line a little at a time till it built up excess pressure in the system and it would overcome the governer. You could get an extra 20 mph out of some of them with a lot more kick, the tricky part was trying to shift because they wouldn't idle down Not for the weak hearted

No you do not want to put any restriction on the return line, that would be bad. If you want to regulate the line pressure , do it on the feed side.

---------Robert

 

[Ironman03R]

I run a Carter HP4600 pump (7psi) and haven't had a single problem with it and I don't run a regulator on it. You should be fine with the Holley pump as well... Do away with the regulator in my book. It will only uses what it needs.



This is my point, is 7psi really needed at idle?
I'm afrade that if I regulate any flow before the IP it wont recieve the lube/coolant it needs.
By putting it in the line between the filter head and where it hooks into the injector lines it not restricting any flow from the injectors or IP return, its only regulating a constant pressure at the filter head(IP inlet)

I could be over thinking this, but the final pressure at the injectors will be higher w/ higher supply pressure. So why not make the fuel system ad a little more supply pressure at full boost when more fuel is needed?

 

[Ford428CJ]

I run a Carter HP4600 pump (7psi) and haven't had a single problem with it and I don't run a regulator on it. You should be fine with the Holley pump as well... Do away with the regulator in my book. It will only uses what it needs.



This is my point, is 7psi really needed at idle?
I'm afrade that if I regulate any flow before the IP it wont recieve the lube/coolant it needs.
By putting it in the line between the filter head and where it hooks into the injector lines it not restricting any flow from the injectors or IP return, its only regulating a constant pressure at the filter head(IP inlet)

I could be over thinking this, but the final pressure at the injectors will be higher w/ higher supply pressure. So why not make the fuel system ad a little more supply pressure at full boost when more fuel is needed?

You are over thinking this a bit. I wouldn't worry about it. But if it bothers you then throw one on. I don't have any problems with mine, even at a idle. I just think its a waste of time and a little money myself. Unless you are running more then 7psi, that would be a diffrent story!
But to each to their own.

Or you buy one of those Spendy MSD units that controls your pump! But there really isn't a need for one.

 

[Agnem]

I think the big thing that your overlooking here is that the purpose of the fuel line from the filter head to the injector returns is to vent air. There is no significant presure at this location to regulate in any way. Even if you completely block this line, the amount of presure going to the IP is not going to change. Additionally, there is no presure in the fuel returns in general at all. Part of what my security system on the Moose Truck does when it's dumping fuel is it is blocking the return lines. During this period, there is no change in the way the engine runs. I can tell you from having built the Moosestang, that a 50+ PSI electric fuel pump will sound fine at idle, but make the engine run like crap as you throttle up. NO fuel presure will also work fine. For a little while. The transfer pump in the injection pump nose cone regulates the fuel presure to something higher than what the delivery presure is anyway. This internal presure changes with RPM and is part of what controls injection timing. Running too high an inlet presure prevents the timing from retarding adequately. Running too low only creates a situation where the pump will starve for fuel. So ideally, the external fuel pump's only job is to deliver a supply of fuel in sufficient quantity to keep the internal pump supplied, and at a presure level below what the internal pump produces. This allows the full range of timing values to be achieved internally. The quantity of fuel being delivered at said presure externally, is in excess of what the pump requires, and the bulk flows through the pump to provide cooling and lubrication, however it is still regulated by the internal pump. What this means is that no matter what you do to the external presure or attempts to regulate it, there will be a net change of zero to the fuel system provided that the quantity is sufficient, and the presure below the threashold for the internal pump. The most usefull accessory modification that I can see for the fuel system besides an electric pump, is simply an alarm to alert you of a drop in fuel presure so you can pull over and get off the road before the fuel supply quits entirely. I sure could have used such an accessory last summer when I switched tanks going up an on ramp and the selector valve jammed between tanks unbeknownst to me. I ended up running out of fuel where there was no great space to pull over on, where as if I had stopped a 1/4 mile before, it would have been a lot better. An alarm would have detected the loss of fuel and I would have known to stop immediately so I wouldn't be on the highway with big rigs whizzing past my ear as I lay underneath reinventing the fuel supply.

 

[sle2115]

I guess I ass/u/med that you were using a higher pressure pump, like a 15 PSI blue pump. I really don't see any reason to regulate one that is 7 PSI max either as that is what I am running with very good results. Not a Holley, but a similar pump in the Carter flavor.

Still in all, if you are running a 7PSI pump, the regulator is not going to make the pressure any more than 7 PSI, it will bypass anything below that anyway, so unless the internals of the regulator were restrictive (which a HP fule regulator is not) it wouldn't change the pressure anyway, they don't magically make higher PSI than what the pump could make.

So I guess I don't understand the need or want to use a regulator on a 7 PSI pump...

 

[Ironman03R]

Mel, This is the kind of answer I was looking for. I'm not saying anyones right or wrong, but if that return lines primary porpuse is to vent air why is it routed into the ingector return lines? I thought air in the return system was a bad thing and I was also under the impression that air can not move through a sealed system. Also what your saying is that the internal transfer pump has a set pressure that it is set at? Does this ever change/vary? Unless the transfer pump is regulated internally somehow to a set pressure, the higher supply pressure would equil more pressure out of the transfer pump...Right? And yes I know that changing the pressures will change the timing, Thats one of the reasons I wanted to try something with this.

SLE, Yes I'm tinkering with a higher pressure pump but I'm useing a rising rate regulator that uses boost refrence so I can start off with low pressure but as boost rises so will the pressure. I have been told that a holley red will make more pressure by shimming or replacing the spring inside. I think thats the only difference between the red and blue pumps.

 

[Jake S.]

Also what your saying is that the internal transfer pump has a set pressure that it is set at? Does this ever change/vary?

The pressure changes based on the RPM of the motor. The higher the pressure the more advanced the timing runs. So if the input pressure is higher than what the transfer pump put out, the timing won't be right. And if the transfer pump puts out a higher pressure than normal, the timing curve will not be right for the RPM that the motor is running at. The IP can provide more than enough fuel for a turbo app. The answer I found is to cut fuel on the low end till boost rises. Hypermax has a aneriod thingy that will do this. I think that the factory turbo pumps are aimed also.

 

[smokin69]

So if I want to use the Holley Blue pump sitting in my garage I need to use a regulator before the IP?