Fuel pump wtf?

[Massacre-77]

i have 74 chev truck 350. new mech. fuel pump with the same problem..
if the truck sits for a week or 2 all the gas drains back to the tank.
it takes about 10 min of cranking to to get it running.. this sucks!

 

[Confedneck]

is there a check valve in the pump? new doesn't always mean good, but I think this is a carburetor problem, leaking pressure off

 

[shaun89]

i dont no if ur exaggerating or not but it shouldnt take 10 mins to start a truck out of gas with a mechanical pump. ive had mine run out a couple times,it only takes about 30 seconds-1 minute to get it started.

 

[Massacre-77]

leaking pressure off/??? how would this happen?
it took about 5 to 8 min. to start i had to poor gas in the carb to get it going after 5 or 6 cranks it started to run thanks..

 

[Fordum]

The carb will hold gas in the bowl for a length of time. If there is seepage somewhere, it may leak out.
Also, if the outside temp is hot and it sits in the sun, the gas will evaporate out faster than if its cool.
There is a gap between the fuel in the bowl and the float valve, so it cannot siphon back out.
But I would suspect that the fuel pump is probably worn. The valves in it are designed to hold liquid, not air.
So if it goes dry, then it will not pump well until gas hits it. If its worn, it pumps less until it gets wet.

And, of course, a clogged fuel filter will slow things down too.

I have a 1966 F600 Ford Boom truck at my farm.
It may sit for months until its needed.
It would take a long time to fill the carb after sitting that long.

I finally broke down and bought a small electric fuel pump designed for carbs. Now, I just turn on the key, wait until the pump changes tones to indicate that it has filled the carb, and it cranks right up.

Did the same thing on my bass boat. Darn motor has three carbs, and I would get a hand cramp pumping the bulb to fill all of them.
Now, I just turn on the key, listen for the little whine to change, and go.

 

[diesel4me]

The only disadvantage to the electric pump is the fact your engine will now start instantly--something that an engine that sat for months may not take too kindly too--the oil will have drained off all the moving parts,and it would probably suffer less damage if it spun over awhile before it fired up,and built some oil pressure up first...

I say this because I added an electric pump to a truck at the junkyard that sat a lot,only got used a few times a year--it never had any bearing clatter when we'd crank it over for 30 seconds or so before the carb filled up and it fired off--but once the electric pump was added ,aand it would now fire up on the first few revolutions,we heard a woodpecker knock coming from the bearings every time we started it--we decided to put a toggle switch on the pump so we could crank the engine over until we saw the oil pressure gauge move to the normal range,then turn the pump on and let it fire up...then it would start without the nerve wracking bearing clatter and knocks...

 

[dremu]

I finally broke down and bought a small electric fuel pump designed for carbs. Now, I just turn on the key, wait until the pump changes tones to indicate that it has filled the carb, and it cranks right up.

Where'd you connect the electric pump, i.e. at the tank, up front by the mechanical fuel pump, or other? I assume inline with the existing one?

If you also happened to have a part # or link to a similar pump that would be spiffy too

-- A

 

[Fordum]

If you also happened to have a part # or link to a similar pump that would be spiffy too

I knew that was coming. Its been about 3 years since I did that on my truck, and 10 since it was done on my boat for me, so make and model numbers have faded into the distance.
My truck had a rubber hose coming down from the behind the seat tank, so I just spliced it in there and bypassed the engine fuel pump.
If I remember right, I just hooked a hose from the intake to the output of the engine fuel pump because I didn't have a blockoff plate handy.

But its been a while. Next time I get close to the old truck I'll see if I can read the name.
Meanwhile I'll check around.

BTW, if you do this, don't do like I did, get a blockoff plate and take the old pump off.
That is what I am going to do, when I get around to it..........Any day now.....

 

[dremu]

I knew that was coming. Its been about 3 years since I did that on my truck, and 10 since it was done on my boat for me, so make and model numbers have faded into the distance.
My truck had a rubber hose coming down from the behind the seat tank, so I just spliced it in there and bypassed the engine fuel pump.
If I remember right, I just hooked a hose from the intake to the output of the engine fuel pump because I didn't have a blockoff plate handy.

But its been a while. Next time I get close to the old truck I'll see if I can read the name.
Meanwhile I'll check around.

BTW, if you do this, don't do like I did, get a blockoff plate and take the old pump off.
That is what I am going to do, when I get around to it..........Any day now.....

Ahh, so you replaced the mechanical pump with the electric. (You're leaving the mechanical there, by the way, as back up in case the electric fails. Yep yep, that's the ticket... )

I seem to recall the mechanical ones have three connections, maybe fuel in from the tank, out to the carb, and a return line to the tank 'cuz there's a regulator built-in?

-- A

 

[Fordum]

OK, did some searches, and found the brand, Carter.
Model number, not a clue.
There are several rotary vane pumps that should work.
To give you an idea of some of the places I visit, here is an actual instruction for one of the model pumps.

<
Carter P74019

• OEM Fit and work - recess and vent positions fit pilot
• 100% manufactory well-tried trustworthiness
• Factory specified force per unit area and flux
• Remember: To render certain drawn out lifetime and stay fresh your stipulation inviolate, be trusted to instal a young fuel filtrate on the recess face of your linguistic universal pump!>

Here are some models.

http://www.amazon.com/Carter-P74019...3?s=automotive&ie=UTF8&qid=1315610589&sr=1-13

http://www.amazon.com/Carter-P4070-Electric-Fuel-Pump/dp/B000CIQ5DG/ref=pd_sbs_auto_1

No idea of which is the one you want. Carter does not have specs on their website I can find.

 

[Fordum]

Well, that was weird. In looking around in Amazon, a message popped up when I hit this one.
http://www.amazon.com/Carter-P4070-Electric-Fuel-Pump/dp/B000CIQ5DG/ref=pd_sim_auto_4

That said I had purchased it in 2008. So, that is the one I used!

Now, I would like to give a glowing review of that pump, and it has not given me any problems, but I imagine total hours on it are in the 30 to 40 range if that much.
The truck is used mostly around the farm, and very seldom sees any highway travel.

So, long term evaluation is not available from me.
I did find where it is 4 to 6 pounds of pressure where the other is 6 to 8. Unless you are pumping up a big hill, that should be enough.
I suppose if your truck was standing on the back bumper it might lessen some of the fuel pressure to the carb, but I doubt the carb would perform in that case either.
At least not long.

And the fuel pumps on the old Fords were two fittings. Inlet and outlet. The internal spring determined the output pressure.
When the carb was not calling for fuel, it just stalled in place. No bypass needed.

 

[dremu]

Remember: To render certain drawn out lifetime and stay fresh your stipulation inviolate, be trusted to instal a young fuel filtrate on the recess face of your linguistic universal pump

Nothing says "Engrish" like "young fuel filtrate."

Thanks!

-- A

 

[Massacre-77]

i took the pump off and took it back for an exchange. i got it put on
and the fuel pressure went over 6 psi.. so with the fuel line empty the
truck started in like 3 sec.so i hope this fixed the problem. thanks for all the replies..