Inverted Fuel Pump 55-56 F100

Steves46

Steves46

Well-known member
Here's an interesting Ford odditiy.

I recently replaced my defective fuel pump with an Airtex 4208. Installed it right side up with the outlets on the bottom and with the push lever angling downwards. It works fine but now I think I am getting too much pressure to my Holley 1904. I read an article in one of those Ford F100 history books and it mentioned that the 54 & 55 6 cylinder models used an inverted pump.:confused: Interesting so I checked out the fuel pumps for 55's on Mac's Auto Parts website and sure enough the picture appears to be my Airtex pump only inverted. Did I install this incorrectly or am I using the wrong pump. I wasn't having flooding issues until I changed the pump. Maybe with the lever pointing downward is making it produce too much pressure. Needless to say I'm a bit confused on this one.
 
The early 215/223 used the inverted pumps. The actuator arm on the early pumps rides on top of the cam lobe while the later ones ride below, the angle of the arm is different. The way to tell which pump you need is the fuel pump boss on the block. On the latter blocks the two threaded holes that retain the fuel pump are exactly in the center of the symmetrical flat boss while the early blocks have the holes up higher in an asymmetrical boss that matches the pump mounting flange. Hope this helps!
 
Yes it does and I appreciate you taking the time to explain. I went and took a look at the boss and it appears the 2 mounting holes are slightly above the center of the diamond shaped boss so I suspect the inverted model is what I need. I am really starting to believe that the incorrect pump was producing too much pressure. I ordered the correct pump from C & G and hopefully my issue will be resolved. Although I am not ruling out that my Holley 1904 may need a rebuild, it was performing great until I replaced the fuel pump. By-the-way, does anyone know if the Holley 847 will work? I understand these 1904s are quite troublesome.
 
i have found that most new and rebuilt pumps put out to much pressure, most carbs only need 2 1/2#, the pumps i have bought put out between 5 and 7#, and i only needed 2 1/2 #,, i finally gave up and bought a fuel pressure regulator
 
You know that is what I will do next in the event I do not get the results that I am looking for. What type of Fuel Pressure Regulator did you get...was it a Holley? Thanks.
 
:mad: i got mine at Kragens and i dont remember what brand it was i think i payed around $20 for it it works alright for me
 
If your Holley 1904 was rebuilt in at least the last decade, I is a good bet that the fuel inlet fitting has a larger hole than the original part which allows about 3 times the volume to flow into the float chamber than the original. Under full fuel pump pressure thats enough to force the needle down and keep it there, causing the carb to flood out.
I have a rebuilt Holley 1904 on my 55 Courier, 223 I-block 6. The carb would immediately flood the first time the float would drop to let fuel in until I installed an inline Mr Gasket model 9710 fuel pressure regulator. It worked great for 13 months but now it has failed. Apparently, the little regulator is not capable of holding back 7PSI for a prolonged period of time, and I am beginning to suspect that heat is detrimental to the regulator also. It may be necessary to replace it with a BYPASS type regulator, but that involves running a new line all the way back to the gas tank and modifying the gas tank to accept the return line. I hope I dont have to do that
 
Most causes of excess pressure is the big spring under the diaphram is too strong put a lighter one in there and you will be good to go.ken ct.
 
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