One last try at fixing weber 32/36 slow start, long crank - JeepForum.com
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post #1 of 32 Old 06-19-2019, 07:39 AM Thread Starter
lebowski94
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One last try at fixing weber 32/36 slow start, long crank

Hi,

I'm about at my wits with this Weber taking 1 minute of furious cranking to start when it has sat overnight. No problem when its hot or been driven in the last 16 hours or so. I've owned my fair share of carburetor vehicles and none do this other than the jeep.

I have replaced the following parts on mt 83 CJ7 258:

fuel tank
sending unit
ALL Rubber fuel lines/Hoses --at tank, check valve, and under hood --am I missing any?
Fuel pump
Fuel filter
Rebuilt carburetor

So an all-new fuel system and the problem persists.

I have tried running the carb with a Fuel pressure regulator with the original filter set up and still takes forever to start

I have tried with just the stock fuel filter and return line and still...

I have tried blocking off return line and still

Return line is at the 12 o clock position with fuel line below it

I even made a long loop of fuel line into a P-trap and allowed it hang below filter and still...

Any ideas before I give up?

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post #2 of 32 Old 06-19-2019, 07:58 AM
Matt1981CJ7
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Is the choke set up and working properly?

What happens if you dump a little fuel directly into the carb before trying to start it?

Is your ignition system in good shape?

Matt


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post #3 of 32 Old 06-19-2019, 08:32 AM
82Laredo-7
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I ended up going with a electric fuel pump after multiple unsuccessful attempts to solve this problem when I was running a Weber. Not the most helpful post but I feel your pain!

82 CJ7 Laredo 4.2L w/T5, Weber 38, 3:30's w/32's
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post #4 of 32 Old 06-19-2019, 08:37 AM
DesertRata
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Next time it has sat overnight, pull the air cleaner and pump the throttle a couple of times. Do you see a spray of fuel in the throat? If not, the carb is draining or perculating the fuel out after being driven. Cure? try electric fuel pump or heat shield or use starting fluid every time the rig has sat overnight.
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post #5 of 32 Old 06-19-2019, 09:14 AM
Matt1981CJ7
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The problem with the 32/36 is it's too small for a 258. In order to get a decent idle, you have to run the speed screw in beyond the idle circuit threshold. This exposes enriching holes in the throat of the carb, which in turn drain the fuel out of the bowl when the engine sits. That's why your engine takes so long to start after sitting for a while.

A properly sized carb, like the Weber 38/38, would not do this. There would be plenty of fuel in the bowl to quickly start the engine after sitting overnight.

Hope this helps.

Matt
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post #6 of 32 Old 06-19-2019, 10:02 AM
Shawn Watson
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My 38 would do what you're describing but it would take four or five days to evaporate the bowl dry in the Las Vegas summer heat. The electric fuel pump idea was a good one. I'm not sold on the enrichening holes drawing fuel from the bowl argument as the low-speed air correctors should act as a siphon break but Heaven knows I've been wrong before.


Shawn

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post #7 of 32 Old 06-19-2019, 10:10 AM Thread Starter
lebowski94
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Thanks for all your helpful advice. I think Matt nailed it--the carb is too small and thus tuned such to allow fuel to evaporate overnight.

Starting fluid or a shot of gas and she starts instantly. Ignition is good --> NOS USA made distributor, new cap, rotor, wires, and plugs. Nutter bypass etc...

Now one last bastion of hope before ditching Weber 32 is the choke. It does get power and open fully once warmed (takes forever too). However....I can't get the choke plates to close only enough to leave the desired 1/8 gap. Right now, when engine is cold, choke is 100% closed--this can't cause long cranking can it?
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post #8 of 32 Old 06-19-2019, 11:01 AM
uptillnow
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Quote:
Originally Posted by lebowski94 View Post
Hi,
I'm about at my wits with this Weber taking 1 minute of furious cranking to start when it has sat overnight. No problem when its hot or been driven in the last 16 hours or so.
Any ideas before I give up?
I have an idea that many many people experience just like you are...

The float bowl is draining due to the enrichening/progression holes being exposed because the throttle plate has to be opened too too far.

This is the problem, the 32/36 DGEV is to small to get this large 6 cyl engine to idle within the specs 1 1/2 turns in on the idle speed screw. This is the MAXIMUM setting! This is turned in to far because it is very difficult to get this to idle on the one 32mm barrel at the MAXIMUM setting of 1 1/2 turns in!

What to do? Get the correct size carburetor 38-DGES (two 38mm throttle bores).
OR, you can drill a 5/64" hole in the primary barrel of your 32/36 DGEV.

This hole will allow you to close the throttle plate some and allow you to have a higher idle speed. Closing the throttle plate up a little at or below the enrichening hole will stop the fuel bowl siphoning when you shut the engine off.

Hopefully my little pictures will show the throttle plate position compared to the enrichening holes. This is where the siphoning occurs.

UTN
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post #9 of 32 Old 06-19-2019, 11:11 AM
Matt1981CJ7
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Quote:
Originally Posted by lebowski94 View Post
Thanks for all your helpful advice. I think Matt nailed it--the carb is too small and thus tuned such to allow fuel to evaporate overnight.

Starting fluid or a shot of gas and she starts instantly. Ignition is good --> NOS USA made distributor, new cap, rotor, wires, and plugs. Nutter bypass etc...

Now one last bastion of hope before ditching Weber 32 is the choke. It does get power and open fully once warmed (takes forever too). However....I can't get the choke plates to close only enough to leave the desired 1/8 gap. Right now, when engine is cold, choke is 100% closed--this can't cause long cranking can it?


The choke is suppose to close all the way when then the engine is cold. When the cold engine first fires, the choke is suppose to open to about 1/8". This is called the choke pull-off. If it takes over say 3 minutes for the choke to completely open, you need to release some of the tension on the choke spring.

Matt
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post #10 of 32 Old 06-19-2019, 11:56 AM Thread Starter
lebowski94
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I actually did drill a 5/64 hole on the edge of the primary throttle. Which way do I turn choke housing to release tension?
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post #11 of 32 Old 06-19-2019, 12:01 PM
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Quote:
Originally Posted by lebowski94 View Post
I actually did drill a 5/64 hole on the edge of the primary throttle. Which way do I turn choke housing to release tension?
Unscrew the retaining plate on the choke housing. It will be obvious which direction releases tension. The choke plates should close completely when cold, but under very light tension.

Matt
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post #12 of 32 Old 06-20-2019, 06:49 AM
pedal2themetai
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Hi how about the timing being off woudn't that make it hard to start as well?
good luck
tim
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post #13 of 32 Old 07-24-2019, 10:02 AM Thread Starter
lebowski94
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Quote:
Originally Posted by pedal2themetai View Post
Hi how about the timing being off woudn't that make it hard to start as well?
good luck
tim
I think not because the cranking sounds absolutely normal. Also the problem goes away when hot?
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post #14 of 32 Old 07-24-2019, 10:40 AM
pedal2themetai
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HI, Just a thought. Don't mean any problems , But, Because of almost everything being EFI and computers now a days that does it for you. Most young folks don't know that on a Carburetor You HAVE to... OH I mean HAVE TO pump the gas two (2) times to inject the needed fuel, sets the choke and fast idle cam to start a cold motor.
are you doing this??
good luck
tim
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post #15 of 32 Old 07-25-2019, 01:56 AM
BagusJeep
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Not sure I buy the concept of draining the float bowl by exposing that progression hole by tweaking the primary throttle open when engine is off.

The progression hole and idle mixture screw are on the same passage, one just above the normal closed position of the primary throttle, one below. The progression hole is not blocked by the primary throttle plate. In other words, struggling to see what physically is different at the progression hole in either scenario.

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