1991 F150 DIY Rear Fuel Tank and Fuel Pump Replacement

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1991 F150 DIY Rear Fuel Tank and Fuel Pump Replacement. The old fuel tank on my bee-truck (work truck) had sat empty for 10+ years, there was a LOT of rust, and the fuel pump had rusted completely. Time to replace the tank, fuel pump, and the grommet for the vapor check-valve. Also check out about 3:25 minutes into the video... Broke a Harbor Freight wrench. I changed the fuel filter as well - but that was not captured on video.
The tanks: Driver side 19 gallon tank: from 1A Auto (as well as replacement vapor-seal grommets) - Rear tank was from AfterMarket Auto Parts (on ebay).

[@Tsalaqna]

Wow. This is exactly the vid I've been looking for.. my dad's truck has been sitting for just about the same amount of years. So I'm already hunting for parts haha. Thank you!

[@HarmonyHollowApiary]

Good luck Jeff! It's definitely a journey of finding and repairing things on these older vehicles. I'm just happy that I CAN work on them.

[@thekingsilverado3266]

Check out my videos on Holley Anne a 1988 Brick nose that was left in an abandoned house for 25 years. She is slowly coming back to life but the cost of the parts is killing me bad...

[@chadgentry4159]

I am gonna do that to my 1991 ford truck soon. I got 2 bolts out so far and replaced them with new ones. Had to use nut splitter and drill since it was rusted.

[@HarmonyHollowApiary]

What part of the country are you in? Lots of salt used for ice in the winter?

[@chadgentry4159]

@@HarmonyHollowApiary Washington state here. Yeah they do use salt parts of the area

[@spacemissing]

Never as easy as the book says or the video shows.

[@garymanning9040]

Thnx just did both tanks on my 96 f250 4x4 both pumps is new and functional. I liked the way you did your video . Again thnx. BEAR

[@freezeinak]

I found that the Ford stock fuel pump lock ring was way more sturdier than the after market lock ring that I got with my replacement fuel pump so I just re-used the Ford lock ring.

[@henryguajardo5334]

no rush on photos. and I appreciate you very much.

[@HarmonyHollowApiary]

Just sent the photos.

[@HarmonyHollowApiary]

+Henry Guajardo - Did you get the truck / fuel pumps working?

[@1979rdg]

great video, quick question i have a 91 with the 4.9, replaced rear tank but kept pump now truck is hard to start, will sputter and die a few times before it will stay running, was not doing this before i replaced the tank any suggestions as to what may be causing this

[@HarmonyHollowApiary]

when you change the tank or pumps, you should go ahead and change the fuel filter. make SURE your hose connections are on good for the supply and return lines. I have mistakingly put one on before - but not far enough onto the pipe nipple - and it would not give enough fuel psi. also check voltage on the wiring harness pins for power. you'll need a 2nd person go help with that.

[@terrypoe2638]

@@HarmonyHollowApiary Also check to see if the ground wire is connected if it has one ?

[@DS-mo6md]

Hi I have a 91 E150.. engine has some performance upgrades so I had to upgrade the fuel. Dual tanks. I can't seem to find anything online but the dual tanks actually have 3 pumps... I ordered new tanks the sending units.. pumps assuming these were the only two.. they are higher flowing @ 150 lph.. but they are rated at 7 psi.. (like a carb).. so I thought they were wrong but theyre the only ones there seem to be that fit the sending unit... then I realized after the selector valve there is a single high pressure pump. So does that make sense that the in tank pumps would only be 7 PSI on an EFI system? and the high pressure pump after the tanks is what compensates for the low PSI after the valve? Thanks for any help.

[@HarmonyHollowApiary]

The '91 models had a mix of technology. Some had an electronic switch that simply electronically selected the tank/pump. Others had a mechanical switch - and i believe it was those that had the 3rd fuel pump. My f150 has pumps that provide fuel at a minimum of 65psi (if i recall correctly). I am unaware of the required psi on each for the models with the mechanical switch.

[@DS-mo6md]

@@HarmonyHollowApiary oh awesome thanks for getting back.. yeah.. I found a description for the in tank pumps on an ebay store saying " uses two in tank low pressure pumps as well as high pressure in line".. So I guess I'm correct about the tanks having two 7 psi pumps.. man that could have been bad. Yeah the inline pump is like.. near the column shift mechanism and it's above this coffee can looking canister which i thought was a fuel filter.. So I have a toggle switch in the cab then the selector valve. So It must be a way to keep carb and EFI sending units universal? but yeah the in line should at least be 30+ psi.. I think the system runs at 39.. my setup i have to run 24 lb/hr or 36 lb/hr with my adjustable fuel pressure regulator. but i felt pretty dumb when i realized the thing has 3 fuel pumps lol...... sheesh. i was worried there was no way to have more horsepower .

[@mattreyes79]

Is it possible that fuel tank vent valve would get clogged up and not let the tank vent properly? I’ve read how over filling the tank could potentially get gas into that valve and push it through that line and make it back to the charcoal canister. I’m having issues with putting gas into my tank at the stores and it may be a venting problem. By far the easiest things I can do is change out that charcoal canister to see if that’s an issue. Changing out that vent valve won’t be easy as I’d have to remove the tank for access.

[@HarmonyHollowApiary]

My truck has a flatbed on it - and the fill tubes are pretty horizontal. It takes me forever to fill the tanks because I have to hold the nozzle in weird ways so it doesn't click off. It very well could be the vent tube to canister... Or the canister or the purge vent itself. I just haven't been that motivated to dig in deeper at this point.

[@patrickbatman9299]

Good video sir! I did the exact same thing , when I was finished I took truck for a test spin. It ran great, I parked in driveway to check for leaks. Then all of a sudden fuel started coming out the front tank cap. So it was pumping gas from rear to front truck causing it to overfill. Now I bought a new fuel pump but I purchased the one where you take parts off old one and put on new. All went smooth with that, so what did I do wrong? I’m wondering if I crossed the lines, but you would think the wouldn’t connect. Maybe it’s the check valve? I noticed in your video I didn’t see a check valve on you new pump. Any suggestions would help tremendously sir. Thanks.

[@HarmonyHollowApiary]

Make sure the connector tubes going into the pump module itself are completely in. That happened to me after having replaced the pump - and from factory it hadnt been pushed fully into the pump module, so something went wonky with the internal check valve - and it overflowed my front tank through the gas cap exactly as ypu mentioned. AZ swapped out the pump for me anyway - but I feel like pushing it in fully would have fixed it.

[@patrickbatman9299]

You know I thought to myself those tubes didn’t look pushed down far enough. Everything was lined up so I thought it was ok. I’ll take pump back out and check. But I have to ask this, if it had the recall check valve on the fuel line and the new pump has internal check valve, would this cause any problems? Thank you for your help!

[@patrickbatman9299]

I dropped fuel tank and it was a pinched fuel line! Easy fix! Thanks for your help!

[@devinespinosa1923]

Did you pull the filler neck before? I’m trying to pull my tank and I cannot get it to detach from the filler hose

[@HarmonyHollowApiary]

I believe I had to during the process. Maybe the inside of the neck is gunked up and needs a screwdriver or something to break the seal?🤷

[@kcfirstassemblyofgod9652]

What size is your gas tank? I am replacing my pump (1990 F150) 18.2 gal tank. My pump looks identical to yours (fuel lines and wiring connector). As I search for new pumps I find the ones with the same wiring connector is listed as 19 gal tank.

[@HarmonyHollowApiary]

I have 2 tanks. One is 19 gallons, the other is 18 gallons. I don't recall right now which tank has the highest volume.

[@freezeinak]

Why didn't you use the box end of the wrench for the bolt head on the straps ? Especially after you broke the open end side of the wrench. Box end holds better anyway.

[@HarmonyHollowApiary]

I really don't remember. It may have been a matter of room around the bolt head.

[@mattreyes79]

Did you ever get a replacement check valve? Where can it be purchased?

[@HarmonyHollowApiary]

If I recall correctly - I got a replacement rubber grommet for the rollover check valve (that goes on too of the tank). If you are speaking of the check valve that is attached to the fuel pump assembly - no. That problem in OE pumps was fixed in aftermarket pumps - so that add-on check valve is not needed with a new pump.

[@mattreyes79]

@@HarmonyHollowApiary Good to know. I'm replacing a rear fuel pump soon. Although the pump works, it's crossfilling into the front tank that doesn't work at all. I'm hoping that with a new fuel pump it will eliminate that problem. If the aftermarket pumps fixed that problem then I should be good. I did find the check valve on eBay. They are very pricey.

[@majorahole]

Where did you buy the tanks and pumps from?

[@HarmonyHollowApiary]

The tanks: Driver side 19 gallon tank: from 1A Auto (as well as replacement vapor-seal grommets) - Rear tank was from AfterMarket Auto Parts (on ebay). The pumps are Spectra brand - which I CANNOT recommend. They work for about a year, then tend to lose pressure. I've replaced more pumps in this truck than I can think of. I finally bought same pump from AutoZone because they would honor a warranty on the pump. Buying it online or through RockAuto - no warranty is honored by the manufacturer if you self-install.

[@chadgentry4159]

I just got some tanks for my truck online at autozone

[@russellfrentz344]

Driver side door electrical window motor

[@HarmonyHollowApiary]

Are you seeking a video on replacing one? I've never owned a vehicle with motorized windows.... Lol. I guess I am old-school. 🤣😳🙄

[@birdwing98]

11:06 I'd figure out a way to test the new fuel pump before you re-hang that tank. At least Ohmn it out.

[@henryguajardo5334]

wasn't able to find the selector valve on this very truck you're working on where can I find it???

[@HarmonyHollowApiary]

@Henry Guajardo - This year (1991) and this particular body did not have a selector valve. The selection is done electronically through the electronic switch on the dashboard. That enables and energizes either fuel pump to be used, and de-energizes the other pump. Then the return is also activated for that pump's tank - so that the fuel return goes to the correct tank that is being used.

[@henryguajardo5334]

Ok here's the problem we're having. We changed the rear tank and fuel pump. It was running but wasn't running properly. So we switched it to the first tank and it ran great. But, the issue we're having is we lost both pumps, and neither pump is running. We have power but no pump. What could cause this issue? Thanks for replying back

[@HarmonyHollowApiary]

Check (a) the fuel pump relay - under the hood - near the brake booster. (b) the rollover/accident switch may need to be reset - it's on the drivers side floor panel/firewall - and sometimes may trip... and check the electronic switch itself for voltage. Last month, I wound up changing BOTH of my fuel pumps again - as well as the dashboard switch. All is well, now.

[@HarmonyHollowApiary]

And double check all wiring harnesses. Sometimes there are corroded connectors.

[@henryguajardo5334]

I kept telling my friend that it didn't have one.

[@johnjohnoj6408]

I,m doing mine 96 ford , try good video

[@henryguajardo5334]

my buddy said we'll look at it in the morning.

[@luckychucky3426]

I seen a video of another guy who took off the bed and it look like it was easier and he did it all by himself

[@HarmonyHollowApiary]

lucky chucky my flatbed is heavy steel and way too heavy for a one-man-show. The tank was rusty and needed to be swapped out anyway.

[@chetmyers7041]

8:02 Study wire colors and terminals on OLD PUMP and NEW PUMP before installing! Make sure you understand what each terminal on pump is for. DON"T want to have pump polarity REVERSED, and pump turning wrong way. Verify operation of sender unit before installation of tank in truck. Heck, with my bad luck, I plan on test running the pump in some clean fuel before installing in tank! Imagine the horror of a perfect install, and then find out, the Chinese fuel pump is a dud. KZbinr Brian Ealy has a video "F150 fuel pump wiring harness install / Spectra fuel pump" where he talks about the insanity of different wire colors on different harnesses. Seems, in some cases, a RED wire is actually the negative lead to pump. Some folks have ended up with a pump running backwards. Might work for a while, but pressure is low, and a short life for pump. Test it on the BENCH, and know what you have.

[@majorahole]

If you used a longer rachet it would have been easier. You need leaverage!

[@HarmonyHollowApiary]

Agreed! This last year I bought an F250 7.3L (2001) - and have upgraded the size of my tools.

[@freezeinak]

All my fuel tank strap bolts were rusted bad. I couldn't take the nuts off even with a cheater bar. Pulled out the ole air tool and it did the trick. Without it I would have had to cut the bolts with my angle grinder and buy new bolts, which I did for the front tank anyway. I live here in Florida now on the saltwater and everything, especially the underside of my pickup is rusted to hell and back.

[@brainsaver9982]

Where did you source your parts from? I’m currently having to redo the fuel system on my 89 and the fuel systems are almost identical, I just don’t know what to get

[@HarmonyHollowApiary]

The fuel pumps... Ugh! I have gone through SEVERAL (understatement). Spectra brand is what I used for the pumps - as I have been unable to find any other brand. They last about a year or so, and lose pressure to supply the PSI required for the fuel system. Spectra refuses to honor their warranty if home/self installed. So - I bought another set from AutoZone, and they offer (and honor) the same lifetime warranty. The tanks: Driver side 19 gallon tank: from 1A Auto (as well as replacement vapor-seal grommets) - Rear tank was from AfterMarket Auto Parts (on ebay).

[@tomw9256]

BrainSaver998 rock auto. I paid about 155.00 for both tank and pump

[@thekingsilverado3266]

Geezus cripes these poor bastards working doing jobs like this without air tools is kinda is just like watching a cave man brushing teeth...

[@HarmonyHollowApiary]

Love that analogy! 🤣

[@henryguajardo5334]

yeah but found out the diode went out on the rely. then found out rear tank line was blogger, it has rust build up in it. but my buddy sent it to the shop instead

[@rexfletcher6851]

I just want to know how to wire the pump if the wires are different colors and the plug is also different on a 1992 to a 1993 change out rear tank

[@rexfletcher6851]

That will be F 150