86 Suburban: different fuelpumps?

[kikkegek]

can you guys help me?

I need to change my fuel pump.

What is the difference between these two fuel pumps?



and this one:


the second one has three connections on the bottom and the first only two.

please help?

[Prong]

The second pump (with 3 lines) is for a fuel return to the tank (which you most likely have). Just compare to your existing pump and you'll know which one to get.

[kikkegek]

Originally Posted by Prong

The second pump (with 3 lines) is for a fuel return to the tank (which you most likely have). Just compare to your existing pump and you'll know which one to get.

I got the second version, with the return.

what is the function of the return?

My car is dual fuel. So I run on LPG and regular fuel. When I switch from fuel to gasoline, the supply to the carburator is cut of with an electric valve.

This means the pump will be pumpin, cause its mechanical, but wont be moving any fuel.

wich pump would you prefer in this situation?

[kikkegek]

I have found some information while surfing.

I found this:

http://www.classiccarauto.com/impala...uel_pump.shtml

For newer cars with a vapor return, there were 3 lines. One is the gas supply line, one is the vapor line and the third is the pressurized outlet. The supply lines in each case are joined to the fuel pump inlet(s) with a rubber fuel hose and retained with small clamps. The pressure side or outlet line between the fuel pump and the carburator is metal with flare nut fittings on each end. To change the fuel pump you don't need to undo the flare nut fitting at the carburator, only at the fuel pump.

So I guess if the second "return-line" is only a vapor-return, then there is no danger of using a fuelpump with only two connections. Because the second connection is only for returning fuel-vapors back to the gastank.

When I got my car, it was still fitted with al these emssion andfuel-vapor control systems. We took as much off as possible, but didnt get to al of it yet.

This vapor-return-line is probably one more of these things. It is better for the environment to have the fuel-vapors of the fuelpump being returned to the fueltank, but in my case of no use. (I think)

Can somebody confirm this?

what happens inside the fuelpump, when pumpin fuel to the carb with a closed valve in the way?

[kikkegek]

*bump*
anybody?

[MTCK]

It will be returning fuel, not vapor. There is likely a third line TO the tank that goes to a charcoal canister under the hood. I'd just get the pump that is the same as what you have.
Posted via Mobile Device

[gloriavoxdei]

The fuel return line was put on to reduce vapor lock. The increased flow from the fuel tank helped keep the fuel line cool but was too much pressure for a carb so the return line ran the unused fuel back to the tank.

[kikkegek]

I have been thinking and thinking.

And I think I am gonna go with an electronic fuel pump.

Now JCWithney is offering all kinds. Since it is only for backup, I wanna go with a cheap solution.

but what to choose? can you guys help me?
http://tinyurl.com/34nsa4b

[thepenguin99]

Originally Posted by kikkegek

I have been thinking and thinking.

And I think I am gonna go with an electronic fuel pump.

Now JCWithney is offering all kinds. Since it is only for backup, I wanna go with a cheap solution.

but what to choose? can you guys help me?
http://tinyurl.com/34nsa4b

Why? The mechanical pump is one of the least troublesome pump designs ever. My truck is getting a carter electric pump but it only because my cam won't run a mechanical pump.

[kikkegek]

Originally Posted by thepenguin99

Why? The mechanical pump is one of the least troublesome pump designs ever. My truck is getting a carter electric pump but it only because my cam won't run a mechanical pump.

like I said. We never drive on regular gasoline, so why keep a mechanical pump connected and pumping, when no fuel is used?

and the advantage of an electrical pump is that the flow is not determined by the engine rpms, but is always fine. This makes filling the empty carb easier/quicker when switching from LPG to gasoline.

[motornut]

i changed the pump to electric on my 80 firebird ,had to replace the carb as the fuel pressure then showed the carb was leaking.but then it was ok,had a switch on the dash and wired to the alarm
took abit to get used to useing it,but yes it would fill the carb quickly

[kikkegek]

any advise on what to buy? I see al kinds of GPH and psi . But dont know what to choose? what are the needed specs?

[motornut]

mine,it might be different it was a buick engine
but a lower pressured electric carb fuel pump as apposed to a FI pump should do that for you

[kikkegek]

ok, but what to buy now? what specs do I need? how much gph and psi?

[motornut]

5-9 psi
1/2 a pint or more in 15 secs
according to my newest copy of Chev.....
kikkegek can you get these books?
i had to order mine $25 took a week(that was in store not online)
http://www.canadiantire.ca/AST/brows...airManuals.jsp
guess i didn't have to scan the cover lol

[lindstromjd]

I agree with the electric swap. In your case, it just makes more sense. And it should be a lower psi pump, definitely less than 15 psi because that would just be total overkill for your carb. Any parts store should have "on the shelf" generic pumps that should work just fine for you.

[kikkegek]

Originally Posted by motornut

5-9 psi
1/2 a pint or more in 15 secs
according to my newest copy of Chev.....
kikkegek can you get these books?
i had to order mine $25 took a week(that was in store not online)
http://www.canadiantire.ca/AST/brows...airManuals.jsp
guess i didn't have to scan the cover lol

thanks , yes I already have the ?Haynes and already checked it, but didnt see the specs at the bottom of that page. stupid me!
thanks man.!
I'll order some soon. and when the weather changes here.

[lindstromjd]

Haha. Looks like pretty crappy weather. Or pretty awesome weather, depending on how much fun you want to have in it off the road.

[kikkegek]

please help!

the Haynes says 1/2 pint per 15 seconds = 2 pints per minute = 120 pint per hour = 15 GPH. right?

I found thuis nice little fuel pump. Not to expensive! The pressure is just right, but it delivers 35 GPH. Will that be a problem?

http://www.summitracing.com/parts/PFS-10700/?rtype=10

and they advise the use of a fuel filter before the pump? is that really necessary? Because there is already a fuel filter at the inlet of the carb?

[motornut]

sounds likes it's a bigger line or higher pressure
and the filter there for sure ,for what ever reason dirt gets/got in
the fuel tank,you save the pump,clear ones are the easiest to see for confirmation of fuel delivery