Home
About Us
Calendar
Fiero Documents
Merchandise
Tips
Links
Members
Message Board
Other Fiero Clubs
VIN Decoder
Speed Calculator
GFC Facebook Page
 
« previous next »
Pages: [1]

Author Topic: Fuel pump  (Read 14099 times)

0 Members and 1 Guest are viewing this topic.

GTRS Fiero

  • Hero Member
  • *****
  • Posts: 12,510
  • It is what it is.
    • View Profile
Fuel pump
« on: December 23, 2018, 04:46:06 pm »
I'm just wondering why the Fiero has/needs an electric fuel pump.  Wouldn't it be better to use a vacuum pump?
Logged

Roger

  • Paid Members
  • *****
  • Posts: 843
  • If it’s the thought that counts, think money.
    • View Profile
Re: Fuel pump
« Reply #1 on: December 23, 2018, 05:30:03 pm »
Quote from: GTRS Fiero on December 23, 2018, 04:46:06 pm
I'm just wondering why the Fiero has/needs an electric fuel pump.  Wouldn't it be better to use a vacuum pump?

Just another Code 32.
Electric is just more efficient and cost effective.
Logged
You can't fix stupid but, you can adjust it with a 2x4.

Fierofool

  • Global Moderator
  • *****
  • Posts: 10,667
    • View Profile
    • Georgia Fiero Club
Re: Fuel pump
« Reply #2 on: December 23, 2018, 05:33:40 pm »
Where would the vacuum be generated?  If it's from the cylinders, fuel delivery would diminish as the rings and cylinder walls wore down and it began to lose compression.  Vacuum on a liquid also tends to pull gases out of the liquid, so you could get a vapor lock.  To demonstrate this, fill a glass Coke bottle with water then insert your finger to make a seal.  Try to pull your finger out while keeping the seal intact.  You will see air being pulled out of the water. 
Logged
There are three kinds of men:

1.    The ones that learn by reading.
2.    The few who learn by observation.
3.    The rest of them have to pee on the electric fence and find out for themselves.    Will Rogers

GTRS Fiero

  • Hero Member
  • *****
  • Posts: 12,510
  • It is what it is.
    • View Profile
Re: Fuel pump
« Reply #3 on: December 23, 2018, 06:01:48 pm »
Well, my ATVs use vacuum fuel  pumps.  The pumps are simple and inexpensive.  I have an ATV with 2,xxx hours on the engine.  My truck has 6,xxx hours on its engine, and has about 300,xxx miles.  Theoretically, my truck had 100,xxx miles at 2K hours.

The vacuum fuel pump is easy to access (not in fuel tank).

A vacuum fuel pump would increase flow as RPM's increased.

Everything vacuum-powered would lose vacuum with wear on the rings and cylinder walls.

Oh.  Vacuum drives the pump.  It does not pull the fuel up.  You don't put the electrodes for the fuel pump directly into the fuel, either.
« Last Edit: January 15, 2019, 06:12:17 pm by GTRS Fiero »
Logged

PK

  • Sr. Member
  • ****
  • Posts: 482
    • View Profile
Re: Fuel pump
« Reply #4 on: December 23, 2018, 11:05:27 pm »
Lots of motorbikes/atv use vacuum style fuel pumps.  As FF says you have to be careful with vapour and hydraulic lock as fuel can siphon to bores if diaphragm holed or worn. 

However I find on the boike vacuum pumps very reliable and its one less electrical gizmo.  After 27 years of use I removed the diaphragm from mine (still working) and cut a new one from a sheet of acetate and it's ready for another 27 years.  I did find an exact match for my £200 from Yamaha pump on a Polaris ATV .. .  £32.  Haaaaaa.  Maybe I will fit that in another 50 years or so.
Logged

GTRS Fiero

  • Hero Member
  • *****
  • Posts: 12,510
  • It is what it is.
    • View Profile
Re: Fuel pump
« Reply #5 on: December 23, 2018, 11:20:37 pm »
Maybe fuel volume is the issue.  Still, it seems to me that there could be a longer shaft between the vacuum area and the impeller.  The ATV vacuum fuel pump is about 2 inches in diameter, and a quarter of an inch in height.
Logged

GTRS Fiero

  • Hero Member
  • *****
  • Posts: 12,510
  • It is what it is.
    • View Profile
Re: Fuel pump
« Reply #6 on: December 23, 2018, 11:24:43 pm »
Unlike the electric pumps, running dry does not seem to bother them, they don't have issues in cold weather, they don't get too hot, and they pump a more appropriate amount of fuel.

Priming may be an issue, it occurs to me, because the fuel couldn't start flowing 2 until after you started cranking.
Logged
Pages: [1]
« previous next »