Does anyone know what our stock fuel pump puts out (LPH)?
*1991 Ford F-250 Dual tanks

 

Don't know what it will put out but at the Fuel Manifold Test Valve it will have 45-60 PSI for a 4.9 and 28-45 PSI for all other gas engines while running.
Not running the 4.9 is 50-60 PSI and all other gas engines are 35-45 PSI.

 

I've heard that they are in the 85 lph range, but haven't tested one or seen specs on one to know for sure.

 

It's either in the 85LPH range or 100-120ish area. I know the 92-96's are 100-120ish. These specs are hard to find.

 

The two Ford liked to use were 88 lph and 110 lph. My factory 'Stang pump had a walbro pn on it...

They did use a 190 lph pump in later years too...

You should be able to put an aftermarket pump from Summitt/Jegs in. I put a BBK/Walbro 155 in a ranger, it bolted right in, no mods...

 

Did that ranger have the same type of FMU the trucks have?

I know that napa's replacement fuel pump for the 92-96s are listed as 120 or 130lph according to their website. I know that my stock pump in the 95 is more than 88lph because my 393 requires more than 88 and it's still working fine...so maybe mine is the 110 you speak of.

Your statement of the 190lph has me interested. Is that a reliable source? I need a 190ish or higher in mine cause my 393 is going to be revamped and make a lot more power. I'm having trouble with the fuel system modifications and getting the right fuel supply.

The stock FMU isn't happy with larger fuel pumps being stuffed in there cause of the check valves so I hear. I'd think you could stuff a 190 in there but...i hear otherwise.

 

It's not an FMU it's a Fuel Pressure Regulator. The regulator on the ranger is a little different shape, but same function (an accufab for a Buick GN will actually fit a ranger) The stock FPR on our trucks is identical to the '94-95 'stang unit. I actually put my old Aeromotive one on my truck for a show, then pulled it back off 'cause it's going on a buddy's Mustang. Stocker should be fine with a 190. You have problems with over a 255lph pump because the stock return line can't handle the amount of extra fuel and your pressure will spike. The way our return systems work, they simply pump back whatever the injectors don't use. That's how you know if you need a bigger pump, you watch your fuel press. on a WOT run, if it falls off at high RPM then the injectors are sucking more than the pump can handle and maintain pressure in the rail.

I'll double check on the 190, not sure what year/model they switched. The 190s are only a hundred bucks from Summit, not really worth the jy hunt for a questionable piece....

 

Interesting...

Well, I knew about the pressure drop off - I'm not loosing pressure as of yet but eventually I would like to get over 400 rwhp and fuel upgrades are in my future.

As to FMU/FPR, hope we're on the same page...you said "its not an FMU, its a FPR" - I was refering to our trucks FMU (fuel management unit for anyone else) that is in the gas tanks, not the FPR on the fuel rail (as to handling the extra fuel flow). Since you said you put a larger pump in there, I wondered if the FMU was similar to the FMU we have in our trucks. I've thought about taking the FMU out of my truck and taking the stock pump out of it and stuffing a 190 in there.

My truck has the FMU in the tanks, and the FPR on the rail like you're familiar with. I assume you're familiar with the FMU in these truck's tanks. The 87-91 and 92-96 are different. I've just simply heard that stuffing a larger pump in these FMU's can cause problems as they weren't designed to handle that pressure.

I'm now assuming the ranger's fuel pump isn't the same as the truck's FMU because it doesn't have duel tanks.

In the quest for fuel upgrading knowledge - I went to autozone and compaired a mustang pump to a truck pump. The FMU on our trucks have a slightly different pump inside than what setup the mustang uses. The pump itself is visually the same except the pump on our trucks doesn't connect to a rubber hose like the mustangs do. The mustang pumps have a nipple on the end to help clamp a hose on it - where the trucks do not have this nipple and it's a straight shaft that "plugs" into the FMU. If I were to install a larger pump in the trucks FMU it would have to be one that doesn't have a nipple on it like the mustangs do - or I file the nipple off if that is possible. That way it'll "plug" into the FMU. I thought of doing this but am unsure of whether or not the FMU would accept the extra fuel flow w/o problems. I'm leary because I don't want to spend a bunch of money on this stuff and find out it doesn't work.

I've had a hard time trying to find specs and info on how to upgrade these duel tank truck fuel systems. I havn't come across any mention of a 190 pump in there - that'd make my year if it were true as I wouldn't have to deal with this. But I'm assuming mine is around the 110-130lph area and that I'll need to upgrade it and deal with trying to figure out how to do so.

I've included a picture I have of the FMU that goes in my truck. It contains the fuel pump and other BS.

 

Okay I get what you are saying now. an actual "FMU" is actally a version of a Rising Rate Regulator that installs downstream of your pressure regulator and will spike pressure relative to supercharger boost, Vortech and Paxton use them a lot, they are falling out of common use due to true RRR's and the ability to tune a Blow-Thru MAF and bigger injectors.

Anyway, the Ranger unit was the same as a Mustang, that particular one wasn't equipped with dual tanks. Rangers can be, the bed we were going to put on it was a dual-tank bed.

I haven't disassembled the one on my truck yet, it only has 71000 miles and is working well.

What does the rest of the mount look like? Is it something you can swap the pump hangar out of a Mustang for? Just gotta make sure you get the pickup at the bottom of the tank, wouldn't be too hard if you really needed it.

Or you could go with a "T-rex" style external pump....

 

Could we use an in-line fuel pump with dual tanks?

 

The reason I'm asking is because I'm installing a 6 psi Powerdyne supercharger and I don't want to run lean.

 

Didn't know that - I've always heard people refer to the tanks in our dual tank trucks as an FMU, and I believe it's in the manuals...so that's why I mentioned it like that.


This auction has a pic of the sending unit and FMU...

Ebay: Z8025091584

I havn't taken mine apart either, that pic I put up is from the net. My front tank doesn't work anymore cause the pump died. I need to figure this fuel upgrade out, I might try to get a 190lph pump and file the nipple off (unless I can get one w/o it) and slide it into the FMU I have and see if it works.

I duno how I would use a T-rex pump because of the dual tank setup. Do you know anything about it?

Where did ya hear about these possibly having 190lph pumps? Do you have the source of where ya got that info? I'd like to know if that is really true...I've only heard the 88/110 type setups...havn't heard about a 190 before and am interested in finding out.

I think I'm gonna have to educate myself on how the factory system is designed and see if I can find a way to make something work with creativity.

You can, I've heard of other people do it. The Kenne-Bell Boost-a-pump is also an option...it increases the voltage to your fuel pump under boost. Shortens the life of the pump but you can talk to them about their stuff and talk to people who have it to see how it's worked for them.

 

Justin, I think the in-tank fuel sender letters you are thinking of is FDM - Fuel Delivery Module.

 

Hmm...could be...woops...

 

The 190's I think are in '99 and up 4.6L mustangs. Heard it on the corral I think..It might only be on the 99/01 Cobra, 03-04 Mach 1's....

Not sure how a T-rex would be done on one of these, might have to run 2. Never tried it.