620 only starts with foot wot

[Sphynx88]

I have been trying to dial in my brand new weber 32/36. Recently, the truck started to be more difficult to cold start. I have to hold my foot completely down on the gas pedal and crank for 10 seconds for it to catch. 

Any ideas?

[Ranman72]

its an older vehicle not a fully pressurized fuel injected start at a moments notice motor 

are you using the choke ?

try pumping the gas a few times each time before you start

my car takes a few try when its cold and I don't have the chokes hooked up  BUT IT ALWAYS STARTS 

[robopineapple]

i have to pump my gas petal ten or 15 times after about eight hours of sitting, anytime before that it does just fine. pumping should build pressure 

[KlassicMotion]

Is it manual choke or electric?  If electric, is it working?

 

Have you checked the float level?

 

Have you checked the timing?

[Sphynx88]

Electric choke. Wire is plugged in and after I start it up And give it gas the idle will drop. Don't know if that verifies a properly functioning choke or not.

 

I haven't checked the float, brand new carb so I am trusting factory specs but might be a good idea at this point.

 

Timing is set at 12, could knock it down to 10 and see if it goes away to remove that variable.

[datzenmike]

On a cold motor take the top off the air filter. The choke plate should be open or part/mostly open. Have someone step on the gas pedal and release. The choke plate should snap full closed. This set's the choke to on, and engages the fast idle cam to hold the throttle partly open. A cold motor cannot warm and evaporate the fuel as well as a warm engine so running rich helps. The choke will force the engine to suck harder and draw in a richer fuel mixture and the fast idle cam speeds up the warm up time and prevents stalling.

 

Now pump the gas twice. This will pump the accelerator pump and squirt raw fuel into the intake manifold. I do this on extra cold days to help the choke. Crank the motor over with foot off the gas until it fires up and runs.

 

Properly set up the fast idle will keep the motor revved up and running. About 1,800-2,200 rpm. Performance is somewhat limited when the choke is on so if sudden acceleration is needed there is a choke un-loader function the pulls the choke off is the gas pedal is floored. Quickly stepping on the gas before the motor is warmed enough to run properly will  force the choke un-loader to pull the choke off too soon (it also removes the fast idle) and the motor may idle or perform poorly after. Try to avoid flooring the gas pedal during warm up.

 

I find the idle a bit high on my automatic 710 for shifting into reverse without clunking. After 10-20 seconds I lightly tap the throttle and the fast idle drops to the next lower position position, still faster than normal idle but not racing.

[Sphynx88]

Uhh this could probably be something important to note. Hard to see but the brand new fuel filter is COMPLETELY clogged with rust.

Interesting development. 

[datzenmike]

A clogged or partly clogged filter would not cause hard starting of itself. It would or could reduce the fuel available to the carb though. If your driving is such that you use more fuel than can be replaced by the pump then the carb will run dry and the motor will stumble at speed. Climbing hills or prolonged full throttle are good examples.

 

I have had a filter much like that and when removed the filter element had separated and was loose inside. Dirt was likely pushed into the fuel bowl, although it did run just fine. Do not run anything Fram and spend around $5 to assume you have some quality. $5 every year is incredibly cheap compared to a poorly running carb that needs to be taken off and cleaned. Skip your steamed, skim aardvark milk, choco molka, double dip cinnamon/nutmeg swirl,  cappuccino late, ennima from Starbucks for one day a year.

[KlassicMotion]

The float level is a long shot, but no, don't trust factory specs.  My Weber float was off from the factory.

[Sphynx88]

The float level is a long shot, but no, don't trust factory specs.  My Weber float was off from the factory.

It;s just the fact that it started all of a sudden that makes me think it would be something else. I'll leave it as an option though.

[Sphynx88]

Backed timing off a hair and started right up. I'll let it sit for awhile and verify she's fixed after she sits for an hour. Warm start ups were the worst. Now on to the light backfiring and randomly fast idle. Seems choke related.

[datzenmike]

Light backfiring.... check valve lash.

[Sphynx88]

Light backfiring.... check valve lash.

Dude you are the man. Seriously, thanks for all your help thus far and thanks to everyone else. Ratsun is one of my favorite forums I've come across over the yrs.

[banzai510(hainz)]

change the filter more often on trucks. why? the gas tank is exposed to the elements

[zed]

 Skip your steamed, skim aardvark milk, choco molka, double dip cinnamon/nutmeg swirl,  cappuccino late, ennima from Starbucks for one day a year.

 

This is hilarious - classic Ratsun