Hello everyone: I have a serious problem with blowing the diaphrams on my fuel pressure regulators, # 4 to be exact. I have a 1995 Ford F-250 3/4 ton 4x4, engine is a 460 w/ throttle body. I also have a vortech supercharger on the truck with a banks powerpack stainless headers on back. The only time the regulator diaphram blows is I believe when it is under boost when pulling fiffthwheel and jet skis and or boat. I talked to a ford tech and he suggested that I take off the vacum line off of the reg and plug it. I did that and labor day weekend coming back from the lake it did it again. I am going for # 5 and at $54.00 a pop it is getting old and the dealer ship will not repalce anymore under warrany. The Vortech system came with a MSD module boost retard- and Fuel management unit. With the vacum line connected it fills all vacum hoses the intake-cylinders and to say the least the oil pan, then the engine hydro-locks. And when I shut then engine off with the vacum line connected or plugged the fuel pressure regulator shhots fuel about 3 to 4 inches out of the neck where the vacum line connects or will pop the rubber cap I have placed on it, and cover the manifold with gas. Before I can go on another road trip or call the insurance company cause my truck is on fire I could really use some advice from some one that might have had this type of experience. I have had the truck in two different performance shops and they don`t know what`s going on. And I am getting burn`t out on paying for diagnostic fee`s for someone not being able to figure out the problem as well as them spending more time on somethimg they cannot charge for, also I have called Vortech and the cannot help either. I am BEGGING FOR SOME HELP. Thank you in advance.

 

Help

 

Ford pressure regulators aren't designed to have boost run up against them. I believe Holley makes a replacement style regulator, but I can't find one at the moment.

 

Have you checked the actual fuel pressure? With the vacuum lone off, the boost should have no effect on the diaphram. Sounds like you may have too much pressure in the fuel system. You may also want to try a better regulator, such as a Mallory unit.
Jimmy

 

Thanx guys for getting back to me , I took my truck in to a performance shop and they did a fuel pressure check, every thing checked ok. I have looked into a high performance fuel regulator, but they don`t make one that goes onto the fuel rail. The only one I could find is mallory and I would have to do some fairly major modifying and from what I understand is pretty pricey. Do you think I can have a bad injector that is allowing gas to come back thru after I get out of boost and aplying back pressure to reverse on the regulator and blow the regulator

 

That's not how a regulator works. It allows unused gasoline to return to tank. The pressure at which it relieves is the pressure at which the injectors meter fuel, nometered fuel passes through the regulator.

Have you contacted the tech people at Vortech? It sounds like you have some kind of an incompatibility between your FMU and your regulator. Perhaps something is plumbed incorrectly, perhaps yuo ned a different calibration in the FMU

 

Strangeranger: hello I have called vortech the said everything is fine with there components, but the FMU and boost retard is made by MSD maybe I need to get in touch with them, thanx. Doug

 

Since you say it only happens in boost, maybe the FMU is jacking the pressure really high. REALLY HIGH! If it is then the stock reg. diaphram is just popping like a balloon. I think FMUs are adjustable.

The Corral has supercharger forums and they seem to hate FMUs in general.

http://www.corral.net/forums/

 

Thank you for your replies gentleman, today I spoke with a tech from MSD the company that supplies this equipment for vortech. He is checking with a couple techs from other manufactures and he suspects that a map sensor is possibly bad. He is supose to get back to me within a few days after consulting with these other companies, I am going to keep my fingers crossed. He is saying that possibly the sensor is telling the computer to send more gas when it is maybe sending it a false reading and it may be sending a surge of some sort. Again thank you I will post when and if we can come up with some type of solution. Doug

 

Sounds unlikely, but possible.
Jimmy

 

The computer can only increase the pulse cylce of the injectors. The FMU, if I am correct, goes between the manifold vacuum and the regulator to keep the boost from blowing out the diaphram in the regulator.
When I first installed N O S on my Mustang, it was a dry kit(no fuel solenoids) and it put nitrous to the regulator when activated to keep the fuel pressure up. The line pressure is 900psi to 1200 lbs. I'm not sure what it was after the N O S solenoid.
Is your FMU a large diameter (4" or so) disc that the fuel pressure vacuum line goes to and then a vacuum line goes to the manifold from the other side? This is what you need I think to keep ypur diaphram from blowing under boost.
Jimmy

 

thanks for your reply lxman1, the fuel vacum line does come off the FMU to a fitting on the intake manifold. It is my understanding that possibly the map censor is telling the computer the engine is running rich when I am in boost when it really is`nt, then when I back out it is getting a spike and popping the fuel regulators diaphrame with to much pressure. Other than that I am at a lost, I just do`nt know whats going on. I am at a lost at this point, Thanks Doug

 

Sorry for the double post I neglected to mention when under boost it smokes like a diesel with no power, that I think would tell ya its burning raw feel. So that is why I am so confused.

 

I am assuming that you are not running a mass-air system and are running speed density?
I would try putting a vacuum/pressure gauge on the port on the FMU that goes to the regulator that you can watch while driving it. If you get alot of pressure during boost, then the FMU could be bad, allowing too much boost into the regulator.
But I think you said earlier that the diaphram would bust even with the line off so that wouldn't do it.
What kind of fuel pressure do you actually have?

Jimmy


Also, what happens if you tee your map sensor vacuum in with the regulator?

 

lxman1: Hi Jimmy I have not tryed teeing off the map sensor vacum yet, and one of the shops I took my truck to put a vacum pressure gauge on it for a test drive. My fuel pressure is at 35 psi and when it goes into boost it read 45 psi I cannot contest to this , it is only what I was told and I am getting kind of lost with all this. I stopped wrenching a long time ago because of my patience level: its pretty low, but on this one it looks like its up to me and who ever can lend a little advice. I was a track vehicle mechanic in the service and in the real world for about ten years, but that was twenty four years ago when they made vehicles a little more simple. I am machanicaly inclined but the patience wears thin these days. I really appreciate all your feed back, maybe together we can get this one figured out, again thanks. Doug