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
> Dual carbs, Fuel delivery
arkitect
post Sep 29 2014, 05:31 AM
Post #1


Senior Member
***

Group: Members
Posts: 617
Joined: 3-March 10
From: Stockton, CA
Member No.: 11,426
Region Association: None



I've been working on my dual carb setup for awhile now. Thought I would have them sorted by now. Having trouble with getting fuel to the passenger side carb. I can see the fuel going into the driver side fine but the passenger side just barely one barrel getting fuel.

I am using the Weber IDF40 carbs with a faucet electric pump. Maybe not enough fuel pressure?

After the fuel filter I have a single to dual fitting to split the fuel line to the carbs. Stronger pressure to one side?

Any comments would be helpful. Thanks.

Dave
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Sep 29 2014, 07:18 AM
Post #2


Advanced Member
****

Group: Members
Posts: 3,824
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None



QUOTE
Having trouble with getting fuel to the passenger side carb. I can see the fuel going into the driver side fine but the passenger side just barely one barrel getting fuel.


Explain more please.
How can you tell "barely one barrel getting fuel"?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
wndsrfr
post Sep 29 2014, 07:24 AM
Post #3


Senior Member
***

Group: Members
Posts: 1,427
Joined: 30-April 09
From: Rescue, Virginia
Member No.: 10,318
Region Association: MidAtlantic Region



Crack the inlet fitting to the passenger side carb......I'm betting that you have adequate fuel there and the problem is inside that carb....
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jsaum
post Sep 30 2014, 10:34 AM
Post #4


Senior Member
***

Group: Members
Posts: 530
Joined: 12-June 07
From: Everett, WA
Member No.: 7,809
Region Association: None



Are you using a fuel pressure regulator? Here's a picture of my set up with EMPI 34's on a 1.8. I used a T fitting and didn't have any issues.


Attached thumbnail(s)
Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
URY914
post Sep 30 2014, 05:35 PM
Post #5


I built the lightest 914 in the history of mankind.
****************************************************************************************************

Group: Members
Posts: 119,619
Joined: 3-February 03
From: Jacksonville, FL
Member No.: 222
Region Association: None



Get a real fuel pump and use a real pressure regulator.

Attached Image

Attached Image



User is offlineProfile CardPM
Go to the top of the page
+Quote Post
URY914
post Sep 30 2014, 05:38 PM
Post #6


I built the lightest 914 in the history of mankind.
****************************************************************************************************

Group: Members
Posts: 119,619
Joined: 3-February 03
From: Jacksonville, FL
Member No.: 222
Region Association: None



And an inline pressure gage

Attached Image

Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
arkitect
post Sep 30 2014, 08:22 PM
Post #7


Senior Member
***

Group: Members
Posts: 617
Joined: 3-March 10
From: Stockton, CA
Member No.: 11,426
Region Association: None



Here is a shot of both carbs. The driver side carb shoots a nice stream of fuel to both barrels. The passenger side carb, not so much - the barrel closest to the fire wall, dribbles out and the rear barrel has no fuel coming out of the jet.

Attached Image

Here is a close up of the driver's side, the jet is visible in the left barrel, bottom.

Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jsaum
post Sep 30 2014, 08:55 PM
Post #8


Senior Member
***

Group: Members
Posts: 530
Joined: 12-June 07
From: Everett, WA
Member No.: 7,809
Region Association: None



Try switching the carbs. If the problem follows then you'll know it's the carb.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
vw505
post Sep 30 2014, 09:00 PM
Post #9


Member
**

Group: Members
Posts: 228
Joined: 17-April 03
From: San Antonio, TX , Navy retired
Member No.: 579
Region Association: None



Could be a bad diaphragm
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jsaum
post Sep 30 2014, 09:01 PM
Post #10


Senior Member
***

Group: Members
Posts: 530
Joined: 12-June 07
From: Everett, WA
Member No.: 7,809
Region Association: None



Even easier just switch the hoses around. If you have flow problems then it's in the hoses or your connections. Eliminate each section until you find the issue.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
arkitect
post Sep 30 2014, 09:20 PM
Post #11


Senior Member
***

Group: Members
Posts: 617
Joined: 3-March 10
From: Stockton, CA
Member No.: 11,426
Region Association: None



Thanks for the suggestions. I was thinking along the same line, blocking the fuel line to the driver side carb and see if there is a change.

Switching the carbs, not so easy. I've had the passenger off and on so many times that I'm getting quicker with it. The driver side carb didn't go on as easy and will be a major pain to take off.

It would be nice to actually drive this car instead of it being a yard ornament.

Dave
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Sep 30 2014, 10:15 PM
Post #12


Advanced Member
****

Group: Members
Posts: 3,824
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None



QUOTE
The driver side carb shoots a nice stream of fuel to both barrels. The passenger side carb, not so much - the barrel closest to the fire wall, dribbles out and the rear barrel has no fuel coming out of the jet.


So you are talking about when you turn the throttle and the fuel squirts down the barrel?
If so, that is your accelerator pump. And as mentioned above, bad diaphram or clogged jet. Or if you have the adjustable accel pump lever, it may be out of adjustment or broken.

Or do you mean you are looking down the barrel with the engine running and are seeing gas dribble?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
arkitect
post Sep 30 2014, 10:48 PM
Post #13


Senior Member
***

Group: Members
Posts: 617
Joined: 3-March 10
From: Stockton, CA
Member No.: 11,426
Region Association: None



QUOTE(stugray @ Sep 30 2014, 09:15 PM) *

QUOTE
The driver side carb shoots a nice stream of fuel to both barrels. The passenger side carb, not so much - the barrel closest to the fire wall, dribbles out and the rear barrel has no fuel coming out of the jet.


So you are talking about when you turn the throttle and the fuel squirts down the barrel?
If so, that is your accelerator pump. And as mentioned above, bad diaphram or clogged jet. Or if you have the adjustable accel pump lever, it may be out of adjustment or broken.

Or do you mean you are looking down the barrel with the engine running and are seeing gas dribble?


Without running the engine. I key on the electric fuel pump to get some pressure then throttle by hand to see if I get the squirt. I've checked the diaphram and it's good. Maybe clogged jet?

Dave
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
stugray
post Sep 30 2014, 11:10 PM
Post #14


Advanced Member
****

Group: Members
Posts: 3,824
Joined: 17-September 09
From: Longmont, CO
Member No.: 10,819
Region Association: None



Another possibility is a stuck float.
you can pull the tops and see if the bowls are full, but you would need to do that to check the accel pump input valve/jet anyway.

You 'should' have a set of spare gaskets before you pop the top one one of those.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
pilothyer
post Sep 30 2014, 11:36 PM
Post #15


Member
***

Group: Members
Posts: 838
Joined: 21-May 08
From: N. Alabama
Member No.: 9,080
Region Association: South East States



(IMG:style_emoticons/default/agree.gif) Did you check the floats in the carbs before you put them on? Have you had them apart or just bolt them on?

GENERAL INSTRUCTIONS: Float level, in mm, typically refers to the distance from the face of the carburetor top cover to the float. With the top cover held vertically (float pivot at the top) and the float tab (Lc) resting against, but not depressing the spring loaded ball in the needle valve, measure between the face of the carburetor top cover to the top of the float. On carburetor models where it is required to remove the float to replace the top cover gasket, the measurement should be made with the gasket in place to the gasket face. You need to set the floats to 10 mm closed and 32 mm opened as shown.

Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
URY914
post Oct 1 2014, 04:30 PM
Post #16


I built the lightest 914 in the history of mankind.
****************************************************************************************************

Group: Members
Posts: 119,619
Joined: 3-February 03
From: Jacksonville, FL
Member No.: 222
Region Association: None



That's just a temporary location for your pump right?

You can't mount a pump higher then the bottom of the tank. Pumps are made to "push" the fuel from the tank to the engine, not to pull a vacuum and especially not up hill from the tank.

Also get rid of that glass filter.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
URY914
post Oct 1 2014, 04:35 PM
Post #17


I built the lightest 914 in the history of mankind.
****************************************************************************************************

Group: Members
Posts: 119,619
Joined: 3-February 03
From: Jacksonville, FL
Member No.: 222
Region Association: None



My car is plumbed like this:

Tank-pump-filter, in the front of the car.

Regulator-pressure gauge-Y- carbs, in the engine compartment.

You may want to add a return line before the regulator but I don't run one.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

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

 



- Lo-Fi Version Time is now: 28th March 2024 - 05:56 PM