Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

 
 Reply to this topicStart new topic
> Fuel starve in AX sweepers, tech fix other than "add more gas"?
Chris Pincetich
post Aug 19 2013, 01:34 PM
Post #1


B-)
****

Group: Members
Posts: 2,082
Joined: 3-October 05
From: Point Reyes Station, CA
Member No.: 4,907
Region Association: Northern California
So this Saturday I dusted off the 914 and did an AX race after more than a year of being "too busy" w my great job at www.seaturtles.org
(IMG:style_emoticons/default/driving.gif)

I've ALWAYs shown up to the AX w less than a quarter tank of gas. I have a 1972 1.7 w stock D-jet and aftermarket intake and exhaust. Stock fuel pump, OE low rear mounted, stock gas tank and lines but with evap system on top of fuel tank completely removed (recently).

So, on runs 2-5 I get a period of "no power" after each of the long, fast sweeping left and right turns. Ok, either I have a fuel problem, or ignition. All wires solid, so I drive out and get 4 gallons of gas.

More gas = Problem solved! (IMG:style_emoticons/default/beerchug.gif)

I'm posting because I used to always do AX races w barely any gas and have never had this problem. Any ideas on why I had this problem? Fixes to improve for next time?

Thanks! (IMG:style_emoticons/default/beerchug.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Woody
post Aug 19 2013, 02:20 PM
Post #2


Sandbox Rabblerouser and head toilet scrubber
****

Group: Members
Posts: 3,858
Joined: 28-December 10
From: San Antonio Texas
Member No.: 12,530
Region Association: Southwest Region
QUOTE(ChrisNPDrider @ Aug 19 2013, 02:34 PM) *

So this Saturday I dusted off the 914 and did an AX race after more than a year of being "too busy" w my great job at www.seaturtles.org
(IMG:style_emoticons/default/driving.gif)

I've ALWAYs shown up to the AX w less than a quarter tank of gas. I have a 1972 1.7 w stock D-jet and aftermarket intake and exhaust. Stock fuel pump, OE low rear mounted, stock gas tank and lines but with evap system on top of fuel tank completely removed (recently).

So, on runs 2-5 I get a period of "no power" after each of the long, fast sweeping left and right turns. Ok, either I have a fuel problem, or ignition. All wires solid, so I drive out and get 4 gallons of gas.

More gas = Problem solved! (IMG:style_emoticons/default/beerchug.gif)

I'm posting because I used to always do AX races w barely any gas and have never had this problem. Any ideas on why I had this problem? Fixes to improve for next time?

Thanks! (IMG:style_emoticons/default/beerchug.gif)

switch to carbs. (IMG:style_emoticons/default/poke.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Randal
post Aug 19 2013, 06:20 PM
Post #3


Advanced Member
****

Group: Members
Posts: 4,446
Joined: 29-May 03
From: Los Altos, CA
Member No.: 750

Slosh boxes and foam work great.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Aug 19 2013, 08:18 PM
Post #4


Resident German
*************************

Group: Admin
Posts: 41,623
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California
QUOTE(ChrisNPDrider @ Aug 19 2013, 12:34 PM) *
Fuel starve in AX sweepers

I'm baffled ... (IMG:style_emoticons/default/shades.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
PlaysWithCars
post Aug 19 2013, 09:39 PM
Post #5


Senior Member
***

Group: Members
Posts: 524
Joined: 9-November 03
From: Southeast of Seattle
Member No.: 1,323
Region Association: Pacific Northwest
QUOTE(SirAndy @ Aug 19 2013, 07:18 PM) *

QUOTE(ChrisNPDrider @ Aug 19 2013, 12:34 PM) *
Fuel starve in AX sweepers

I'm baffled ... (IMG:style_emoticons/default/shades.gif)


(IMG:style_emoticons/default/lol-2.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Racer
post Aug 20 2013, 07:56 PM
Post #6


Senior Member
***

Group: Members
Posts: 787
Joined: 25-August 03
From: Northern Virginia
Member No.: 1,073
Region Association: MidAtlantic Region
Um, don't run sticky tires? (IMG:style_emoticons/default/wink.gif)

fwiw, I couldn't run below 1/4 tank in my '70 w/o starvation problems. I just ran 1/4-1/3 tank. An extra gallon or two sure prevents frustration and slower times despite any weight penalty.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
McMark
post Aug 21 2013, 09:23 AM
Post #7


914 Freak!
***************

Group: Retired Admin
Posts: 20,179
Joined: 13-March 03
From: Grand Rapids, MI
Member No.: 419
Region Association: None
For AX you could probably get away with mounting a small fuel cell in the front trunk with a selector valve to shut off the main tank.

Like this one.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brant
post Aug 21 2013, 01:26 PM
Post #8


914 Wizard
**********

Group: Members
Posts: 11,620
Joined: 30-December 02
From: Colorado
Member No.: 47
Region Association: Rocky Mountains
fuel accumulators work wonders too....

I haven't really heard much of a problem with stock stuff in autox though
surprised (But perhaps I'm misinformed) that your having this problem
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Chris Pincetich
post Aug 21 2013, 01:51 PM
Post #9


B-)
****

Group: Members
Posts: 2,082
Joined: 3-October 05
From: Point Reyes Station, CA
Member No.: 4,907
Region Association: Northern California
QUOTE(brant @ Aug 21 2013, 12:26 PM) *

I haven't really heard much of a problem with stock stuff in autox though
surprised (But perhaps I'm misinformed) that your having this problem

Me too! (IMG:style_emoticons/default/beerchug.gif)
Over a dozen races w no issues and always w very little fuel
More testing is needed
Best check my local AX calendar and go racin again (IMG:style_emoticons/default/driving.gif)
I have fun, but it's kinda depressing being on the back half of the standings.
If only PAX was horsepower alone, it'd be top 10 since I have ~90 HP (IMG:style_emoticons/default/laugh.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ChrisFoley
post Aug 22 2013, 06:33 PM
Post #10


I am Tangerine Racing
*****

Group: Members
Posts: 7,922
Joined: 29-January 03
From: Bolton, CT
Member No.: 209
Region Association: None
QUOTE(ChrisNPDrider @ Aug 21 2013, 02:51 PM) *

QUOTE(brant @ Aug 21 2013, 12:26 PM) *

I haven't really heard much of a problem with stock stuff in autox though
surprised (But perhaps I'm misinformed) that your having this problem

Me too! (IMG:style_emoticons/default/beerchug.gif)
Over a dozen races w no issues and always w very little fuel
More testing is needed
Best check my local AX calendar and go racin again (IMG:style_emoticons/default/driving.gif)
I have fun, but it's kinda depressing being on the back half of the standings.
If only PAX was horsepower alone, it'd be top 10 since I have ~90 HP (IMG:style_emoticons/default/laugh.gif)

I always ran an accumulator when I road raced with a d-jet injected engine.
Low pressure pump to keep a 1 quart cylinder filled with fuel and the stock FI pump to deliver fuel to the engine. Overflow from the FI system went back to the accumulator and a top fitting on the accumulator returned any excess to the fuel cell (tank).
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
grantsfo
post Aug 22 2013, 08:02 PM
Post #11


Arrrrhhhh!
****

Group: Members
Posts: 4,327
Joined: 16-March 03
Member No.: 433
Region Association: None
My Z has four scavenger pumps feeding an accumulator. Fuel starve what's that? I never ran less than 1/4 tank in my stock 914 tank - the weight up there in ax is good too!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
r_towle
post Aug 27 2013, 12:02 PM
Post #12


Custom Member
***************

Group: Members
Posts: 24,574
Joined: 9-January 03
From: Taxachusetts
Member No.: 124
Region Association: North East States
QUOTE(ChrisNPDrider @ Aug 19 2013, 03:34 PM) *

So this Saturday I dusted off the 914 and did an AX race after more than a year of being "too busy" w my great job at www.seaturtles.org
(IMG:style_emoticons/default/driving.gif)



Old fuel.

QUOTE

So, on runs 2-5 I get a period of "no power" after each of the long, fast sweeping left and right turns. Ok, either I have a fuel problem, or ignition. All wires solid, so I drive out and get 4 gallons of gas.

More gas = Problem solved! (IMG:style_emoticons/default/beerchug.gif)



Fuel filter replacement time.
User is online!Profile CardPM
Go to the top of the page
+Quote Post
dlestep
post Oct 3 2013, 08:01 PM
Post #13


I am smilin'...
***

Group: Members
Posts: 890
Joined: 15-January 08
From: Sunrise Florida
Member No.: 8,573
Region Association: South East States
I know that this was awhile back, but I was compelled to respond.
With fuel starvation problems, one might look to the off-road endurance setups.
In the 80's, a simple change to the carbs was the way to go.
The floats were removed and a plate added to cap-off 90% of the bowl.
I ran two pumps, one pressurizing the bowls, the other scavaging / fuel return.
or
fuel injection, mechanical or electrical.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Heater Guy
post Oct 4 2013, 02:46 PM
Post #14


Member
**

Group: Members
Posts: 74
Joined: 20-October 09
From: Walnut Creek, CA
Member No.: 10,960
Region Association: Northern California
Attached is a photo of a fuel collector. The low pressure fuel pump is always scavenging fuel from the tank and pumping it into the one quart container. On top of the container is a line back to the fuel tank. This keeps the container full. The high pressure or another pump supplies fuel to the fuel injectors or carbs. This system prevents fuel starvation no matter how much cornering you do. I can run my tank down to 1 gal.and never have a problem. This system is used on many hard corning cars like Toyota Atlantics and D Sport Roadsters.Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · The Paddock · Next Newest »
 

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 5th May 2024 - 08:17 PM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...