Partially plugged or kinked fuel line? :dunno: That's where I'd start if you haven't already.


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You do not want nor need over 60 psi for fuel pressure. I'd be wondering what could possibly be collecting on your fuel pickup screen. Some tanks have had issues where the liner starts pealing off.


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As far as I know all fuel lines are good. I will have to go do a good inspection though. Thanks for the idea

The fuel pick up screen is like the sock filter on a gasser fuel pump correct?

 

I have a hard time believing that a stock fuel pump will keep up with aftermarket injectors and a heavy tune at WOT.

 

I have a hard time believing that a stock fuel pump will keep up with aftermarket injectors and a heavy tune at WOT.

I hear ya, but he has 155/stock with a new pump and the blue spring, so 35 psi or better at WOT depending on how he pushes into it. If he dumps the foot, it will have a hard time to build up pressure after the initial fall. I guess it also depends on how long he holds it as well. I haven't seen mine go below 30 psi with larger nozzles. This picture is typical. But I do see higher values rolling in the power. Fuel pressure is top right.

 

My guess is you either have something blocking the pump inlet/outlet. A good inspection is going to be necessary. Also, a real regulated return (after the injectors) would help you tremendously. As for the HFCM not being sufficient, it's more than sufficient. That thing is capable of some serious pressure. Its demise is lack of volume but pressure, it has that all day long.

 

The HFCM, unless you have a freak one, will NEVER sufficiently keep up with large injectors. 45 psi fuel pressure will kill your injectors. According to all the FORD and Navistar engineers I've talked to 50 psi should actually be the BARE minimum. Why would you want to make a large $$$ investment and be too cheap to protect it? Lack of fuel will do serious damage to the plungers. The pump MUST have volume capability AS WELL AS pressure capability. The higher pressure you run the pump the less fuel you are actually getting. That's the way it is.

 

I have to diasagree with you about it being capable. I fully understand its pressure capability (it is rated at 100 psig discharge), but all centrifigal pumps discharge pressure will fall off as flow increases to (and past) its upper limits of design flow (or volume as you put it). The HFCM does not have the flow capability for hot tunes. That is why the pressure drops off.

Ford recommends no lower than 45 psig - ever. Casserly recommends no lower than 50 psig. Ford states low fuel pressure to be the #1 cause of injector problems.

FASS and AirDog have made some good money because of the need for higher fuel flow at delivered pressures above 50 psig.

 

I have to diasagree with you about it being capable. I fully understand its pressure capability (it is rated at 100 psig discharge), but all centrifigal pumps discharge pressure will fall off as flow increases to (and past) its upper limits of design flow (or volume as you put it). The HFCM does not have the flow capability for hot tunes What kind of "hot" tune do you think he's running with 155 injectors? . That is why the pressure drops off.

Ford recommends no lower than 45 psig - ever. Casserly recommends no lower than 50 psig. Ford states low fuel pressure to be the #1 cause of injector problems. That's purely speculative. Ford also tried to blame International for the number of oil cooler warranty problems they had and International told them to pack sand...for a really good reason. Furthermore, there is zero substantive information to support the claim that fuel pressure destroys injectors, although extremely low fuel pressure is NOT desirable, they will still function. International "recommends" no less than 45psi. For that, I would side with International before Ford, but again, it's merely a recommendation.

FASS and AirDog have made some good money because of the need for higher fuel flow at delivered pressures above 50 psig. They also have a great reputation at repeated failures of their pumps and even poorer customer service when such failures occur.

For your tunes and injectors I am telling you that a brand new HFCM is marginal. Incomprehensible for one to believe and HFCM is incapable of supplying 155 injectors with stock nozzles. Yes you could still have a blockage (sounds like you do because I agree that 28 psig is VERY low), but it doesn't change the flow rating of a brand new HFCM.

I have stock injectors and my fuel pressure at WOT can drop below 45 psig. I assure you my fuel system is not clogged and the pump is working quite well.

So with all that, I'll state this much:

I have 175/75's with an MTW Hybrid. I'm running an SRL+ tune and my fuel pressure never drops below 45psi....with a yr old HFCM. I will also be using that same HFCM along with a 6.4 HFCM and a true regulated return...once my sump shows up.

Although I respect your opinion, I really disagree with your logic on the HFCM's performance, or lack thereof.

 

I know the min it's supposed to be that's why I am asking what y'all think isgoing on with it. That's why I changed the hfcm in the first place. Regulated return is in the future when I get the money. As for the hfcm it is brand new. I had to swap out the cover for the lines in and out of the pump because my new pump didn't have the fuel heater but the new pump was clean as a whistle and the in and out tubes were clean. There are alot of people that say they don't see their pressure drop more than 10psi and I was wondering why mine was acting so different.

 

For your tunes and injectors I am telling you that a brand new HFCM is marginal. Yes you could still have a blockage (sounds like you do have an issue because I agree that 28 psig is VERY low), but it doesn't change the flow rating of a brand new HFCM.

I have stock injectors and my fuel pressure at WOT can drop below 45 psig. I assure you my fuel system is not clogged and the pump is working quite well.

IMO the fuel delivery needs to be upgraded before you get (or in conjuction with it) a return regulated system.

 

How soon after the blue spring mod did you see the low fuel pressures?

If you do not have funds (or intentions) of an upgraded pump, then I would take apart and re-build the fuel pressure regulator.

Also, I would bet that you have already changed the fuel filters, but with even one load of marginal qiality fuel, filters can plug off enough to behave the way describe.

 

I appreciate the response and your opinion as well - even thoughI disagree with it - and I have seen MANY tuned systems.

The OP stated he had a hot street tune and stated his injector size. That pretty much will give a reasonable range for fuel needs - based on rear wheel horsepower being in the 450 range (maybe a little less).

Give an injector manufacturer a call - I have talked to Casserly about the pressure. I respect his opinion - even more than International or Fords stated positions. Ford's position of low fuel pressure causing injector issues is not speculative. They have issued several documents stating the limit. I have posted them and can do so again. Maybe they don't know what they are talking about, but they have stated it!

As for the OP, I say give Tony Wildman a call - see what he says about the capability of the HFCM.

As for your experience with fuel pressure, I would say that is the exception, not the norm with the HFCM. As I said, my fuel delivery is on the edge with a SRL+ system (stock nozzles). That is hard data I can not ignore. You say it is incomprehensible, but I see it every WOT run I make. Again - my system is NOT plugged, etc.

The only reason I am "dwelling" on the issue is that if a fuel system upgrade is eventually necessary (as I believe it is for long term injector health), installing it would most likely solve the problem.

 

I will attest as well.. I have a fresh hfcm pump and blue spring with 175/75's and matts srl tune... Pressure holds at 47-50 psi at wot....

 

I won't contest that there are better ways and when my HFCM goes again, it won't be replaced with another, but it's there, it works and it works well.

 

I hear you Mitch. AirDog has been especially disappointing. FASS sems to have faired a bit better over the long haul (some people have not ever had an issue) and has a new product out that MAY turn out to be a solution. None-the-less, they have sold a ton of products for the sole reason of supplying fuel for the higher flow applications. Maybe some people installed them without needing them, but generally people tried them to solve a fuel delivery problem. Also, I really wouldn't consider the SRL as a "hot tune" (it is still under 400 rwhp), but that is for another discussion.

Glad to hear that some peoples HFCM's can keep up. Many can't - that is why I chose the word "marginal". IMO anything over 400 hp is putting you in a very "marginal" position with the HFCM - 450 hp and it will not keep up.

I hope the OP keeps us informed. It could be a help to others once the issue is solved!

As far as fuel tank liners go, did any F250's (non chassis cab) have a steel (and lined) fuel tank?