dogfacedsoldier

I have a 1990 F150 XLT super cab long bed, 2WD.

The truck recently came out of Texas, now has a little of 40K original miles. When I first bought it, it had 31K miles. Rust free, bone stock, still has original plug wires.

When I first starting driving the truck, the front fuel pump was extremely weak, sending unit did not work. Rear tank pump and sending unit ran great.

Fast forward to today. Rear pump has gone belly up (no noise from pump at all), sending unit still works. Front fuel pump working, though I suspect it is weak... it has been reliable though. Sending still does not work.

I plan to change out the rear fuel pump. Should I just replace the pump, or the entire unit? Again, the sending unit works fine, pump toast. The tank is steel. Is the tank 18 or 19 gallons, I cannot seem to find a clear answer.... or does it matter?

I will replace the fuel pump and sending unit assembly in the front tank as a whole.

Thank you.

Steve83

Put that & everything else about the truck in your signature:


(phone app link)Since it has a 5-digit odometer, it's really difficult to know if it's 140Kmi or 540K.What exactly makes you say that?Click this & read the captions:


(phone app link)Those aren't your only choices, but it IS your choice, depending on what exactly has failed. But I'd start with the relays, as this & the NEXT few captions explain:


(phone app link)

After that, you can change the pump motor, or the reservoir assembly, or the in-tank assembly. Read these captions:


(phone app link)Depends on your truck. Once you find out, that could go in your signature, too:


(phone app link)I don't think so. Ford didn't make a different pump or reservoir for each tank size - the pump is always the same, and there are only 2 reservoir shapes (but it's only the BOTTOM part of the reservoir - the top is always the same). The tubes brazed to the tank plate are bent differently for each tank shape, but I think the 18 & 19 gal tanks have the same shape, and thus the same plate/tubes.I don't recommend it, and I'm not sure I've even seen them sold that way in the past few years. In any case, AVOID Spectra & Airtex brands - they're the worst on the market. The other cheapos aren't much better. Bosch seems to be OK, but of course MotorCraft is the best (and expen$ive$t).

dogfacedsoldier

Steve83, I appreciate your input. That said, I do prefer my Wheaties with milk.

I'm not completely ignorant to working to vehicles. I'm not a mechanic, but I have built a couple Jeep CJs from the frame up, one of which with a TBI conversion. That makes me far from an expert, I can follow directions, and have enough patience and common sense to claw myself out of a paper bag. Ha!

I am the third owner of the truck, with ample documentation. The second owner bought the truck from an estate in Texas and brought it to Michigan. He passed shortly after bringing it here, and I bought the truck from his daughter. Granted, it isn't uncommon for someone who doesn't know better to think (or chooses to BS others into thinking) that their 131K mile truck only has 31K miles on it. I'm not a used car salesman, and I have no reason to BS anyway. Then again, the woman whom I bought the truck off of got tired of people teller her that the truck "probably had 131K miles on it," and used that as leverage to low ball her... which helped me take the truck home.

The truck is exceptionally clean inside and out. Based my limited experience, with other vehicles, if doesn't surprise me that the fuel pumps may have been taxed in a truck that has spent most it's life sitting in a hot Texas pole barn.

Regarding the weak fuel pump. Initially it would not supply enough fuel to the engine to keep it running, while the rear fuel pump would. I could hear the pump turning. It would not register a fuel level on the dash. A few months into driving it, I switched it over to the front tank for ****s n' giggles, and it began working... not great at first, but it came around.

Yes, fuel filters have been changed (twice, CYA).

The rear pump quit on me on a road trip, while driving through a series of long hills. I pulled to side of road. No noise from rear pump. Sending unit still showed fuel at 3/4 tank. Switched to front fuel pump, finished trip home.

Thank you.