Why two fuel pumps?

[Spot]

Two questions.

The PO installed an electric fuel pump in addition to the mechanical fuel pump. The electric pump has a switch to bypass it. The PO wasn’t present at the time of the sale and all the info I could get on the trucks history was through his son who was selling it for him. He was sketchy on why the pump had been added and why it could be switched on & off.

Long story short; the mechanical pump started leaking shortly after I bought it so I replaced it. Now the electric pump is leaking and before I replace it I want to know if I should just eliminate it and run with the new mechanical pump. That would be my preferred option.

So the first question is why would they run two pumps at once. Second question is what pressure is optimal for a stock Carter on a 302? Thanks.

 

[oleguy74]

3-5 is the most you will need.as for electric pump i run one just for a backup.just remove if you want.just make sure your plumbing is right after you remove it.

 

[DonsBolt]

Sounds like the same guy owned my truck too, as mine had both a mechanical and a electric pump.

One of the first things I did was to remove the electric pump on mine, and it ran much better without it.

 

[NYLES]

Im going far left on this one, I replaced my mech at OCBR with a Ele and will never look back at mech.

 

[sprinksbeme]

Many times the electric pump is added to help with vapor lock problems..

 

[OsideDave]

I would say for insurance purposes to not be stranded due to a bad mech fuel pump to go ahead and replace the electric as your back up. You can also use it to pump gas into a can or tank incase one of your buds runs out of gas. I have done this several times over the years and its saved the day. I also have gage inline with my fuel line to verify pressure, also good for troubleshooting.

 

[Rockin69er]

I would say for insurance purposes to not be stranded due to a bad mech fuel pump to go ahead and replace the electric as your back up. You can also use it to pump gas into a can or tank incase one of your buds runs out of gas. I have done this several times over the years and its saved the day. I also have gage inline with my fuel line to verify pressure, also good for troubleshooting.

If you ever go out for a drive in the hills or hunt alone like I do it might save you a long walk to find cell reception. Before I had the extra elec pump and before cell phones I had a nice 4 hr evening stroll off the mountain. Got home ~ midnight

 

[22213evl]

mine had a history of bad mech pumps ( receipts in glove )I replaced with an elec, no problems so far. also have a spare one onboard

 

[gjrock]

This is making me think I could use one piggybacked on my mech pump.

 

[DirtDonk]

Many times the electric pump is added to help with vapor lock problems..

I would say for insurance purposes to not be stranded due to a bad mech fuel pump to go ahead and replace the electric as your back up. You can also use it to pump gas into a can or tank incase one of your buds runs out of gas. I have done this several times over the years and its saved the day.

If you ever go out for a drive in the hills or hunt alone like I do it might save you a long walk to find cell reception. Before I had the extra elec pump and before cell phones I had a nice 4 hr evening stroll off the mountain. Got home ~ midnight

Pretty much what they said. Old-timers used to think of all sorts of little "just-in-case" kinds of things. Just like we do today, but with more cool stuff available to us.

One issue to always be aware of though, is that if your mechanical pump fails due to the diaphragm pumping gas into your engine oil (or on to the exhaust manifold like on an "M" engine), then the last thing you want is to keep pushing gas through the bad pump.
Just something to be aware of and verify before utilizing your spare.

Paul

 

[uncle ray]

my rig is supposed to be a getcha there, run the trail, and getcha home kinda rig. i just picked up a carter inline elec pump, and will carry an extra one too.

i can see two benefits not mentioned, first, fuel pumps work better pushing fuel rather than pulling it. second, if running a carb like i am, it can allow you to switch the elec pump off if you flood the carb and stall the engine on a steep or off camber hill so you can clear out the fuel bowl and restart the motor easier without pumping more fuel.

 

[Pa PITT]

my 2 bits ..

What if ...the old guy didn't start it but once a month or 2 ....and lets say it's a hard starter....so if he has charged the battery 2 hours before he is ready to start it...turns on the elec . pump ....then it may start easier...could this be on his mind..

 

[Wyldebill]

When you go into the mountains around here, (Colorado) you need to have a way home. Some times you don,t have the option, or time (winter) to walk out. I learned my lesson years ago and have carried a backup mechanical in the tool box since. Pump failed at least twenty miles from the possibility catching a lift, no spare, and losing day light. I ended up dropping the rear tank and strapping it to the hood. I used the extended vent lines I had put on my differentials and spliced them with the fuel filter, and gravitry fed fuel all the way home. Try that with EFI. I am betting that the electric that was on your Bronco was mounted as a back up, as I remembered, many years ago, reading an article about doing just that, but as I have never used the backup that I carry, I figured odds were against ever needing an up-grade in that area.

 

[Fathom]

When you go into the mountains around here, (Colorado) you need to have a way home. Some times you don,t have the option, or time (winter) to walk out. I learned my lesson years ago and have carried a backup mechanical in the tool box since. Pump failed at least twenty miles from the possibility catching a lift, no spare, and losing day light. I ended up dropping the rear tank and strapping it to the hood. I used the extended vent lines I had put on my differentials and spliced them with the fuel filter, and gravitry fed fuel all the way home. Try that with EFI. I am betting that the electric that was on your Bronco was mounted as a back up, as I remembered, many years ago, reading an article about doing just that, but as I have never used the backup that I carry, I figured odds were against ever needing an up-grade in that area.

NICE!!!!
that is thinking out of the box.......cool story

 

[NYLES]

As the OCBR 2008 crew knows a failing Mech can really screw up your thinkin, mine worked fine as long as I had 1/2 tank of gas I dont have that problem with the ele its working or isnt. I installed a regulator but need a pressure gauge....man that thing was driving me nuts...I was getting it running great in the parking lot at the hotel and "APPEARED" to be running out of gas 3 times on the way to the the trail. it would die then Id put gas in it then it would run like a top get back to 1/2 a tank it would die......think about trying to adjust fuel bowls. I found out the hard way that approximatly 12 gal off gas has enough hydaulic pressure to run it without a pump and any less wont. Yall think I was susspecting a bad fuel gauge? well yea I was.

Anyone remember that loud ass valvetrain noise? thank mech pump for that!

Lets just say Ive had it with Mech pumps!!!!!!! by the way this pump had less than a 100 miles on it was probably bad out of the box.

 

[Spot]

The truck was built to be a total hunting rig, not a wheeler or a daily driver. Every mod was done with the idea this truck needed to get to out-of-the-way places and be self-contained for days at a time. There is quite a bit of redundancy with it. So a combination of the explanations yall offered could be valid. Appreciate the input.

 

[67broncorebuild]

definatly stay away from the average mechanical pumps at auto parts stores!!! I went through 5 new pumps, and couldnt figure how gas was getting in oil. The crap shucks , or napa ones blow the diaphrams really easily!!
Get the ones through jegs, or summit that you can replace the diaphrams when they go out. I am wondering if us that have had this problem have had a upgrade in cams, making the pump blow.??? (just a thought)
those who are going to buy another mechanical, dont waste your money, buy rite the first time.
I do like the idea of a electric pump as a back up!! Verry smart guys, thanks for the tip!!

 

[NYLES]

pretty good cam in mine not huge but far from stock

 

[justinoshea]

Mine had the same two pump setup when I bough it. I removed the electric and it would randomly die. had a friend hold a 6 gal gas tank in his lap for 3 hours to get home one time. only one engine fire, luckily had a fire extinguisher. I couldn't build a reliable suction fuel delivery system and was one more reason to do an in-tank, positive pressure EFI setup.

 

[mustangtoby]

I run both on mine, with the electric wire through a switch. Vapor lock was the suspect when I installed it, but not the culprit. I does make it nice to start when it has set for a couple of weeks, instant fuel pressure if it has bled off from sitting to long. Also nice to know I have insurance, I have used the washer fluid jug from the passenger seat before too. It beats walking.