Can anybody tell me what the difference in the fuel system on a 1991 as compared to a 1992 F-series?
Preferably from the rear tank forward?

 

'91s have low ppressure pumps in the tanks, and a high pressure pump on the frame rail, '92s have high pressure pumps in the tanks, no low pressure pumps.,

not sure if the high pressure pumps will fit on the sending units of the '91, but you will also need the lines that go from the back of the motor all the way to the tanks.

 

No, '87-'89 has three pumps.

 

he asked about a 91 model and a 92 model.

 

And you told him the wrong information.

 

A 91 doesn't have the three pumps only the two in the tanks. Like Sean said only the 87-89 had the three pump setup.

 

Ok the reason I ask is my 91 has a tiny pin hole in the rear tank and I have a 92 parts truck both have 5.8s and I know the tanks are the same part number just not sure about the pumps and stuff

 

There's differences in tanks, plastic or steel. Not sure if the pump is different between the different tanks but AutoZone has an app you can use to cross reference.

 

do tell?

because my 91 has two pumps(shortbed 4x4, single tank), my old 92 had 1(shortbed 4x4, single tank) , my 95 has two but they are both in the tanks(longbed 4x4, dual tanks)? the lines on my 91 are different than my 92&95, because of the frame rail pump on the 91. and because the 92&95 you have to use the tool on the fuel filter but my 91 has the little white clips that hold the fuel line on.

 

Your '91 must have a '87-'89 fuel system on it. People do crazy things when they have no money. I can buy all three pumps for the cost of one of the '90-'96 pumps.