Technical Hard Starting After Sitting

This is a common problem with Autolite 2100, trying to nail this one down. When engine is warm, just a flick of the key it will start in a split second. The next day starts as normal. Let it set in the garage for a several days though, a week say, and it requires 10 or 20 seconds of cranking. What I have learned to do (to save wear and tear on battery and starter) is pour about a tables**** of fuel down the carburetor, and it starts right up first thing.

So I "***umed" the fuel bowl was empty, that it was evaporating or something like that.

Checking inside the carb, that's not the case. Plenty of fuel in the bowl. So then I ***umed it was leaking past the accelerator pump or something, checking for a couple good squirts of fuel from the nozzles out of the accelerator pump after a week. No problem there either! WTF?

Carb has been rebuilt and tuned proper. No vacuum leaks, new lines and tank, hoses, etc. Everybody who uses the 2100 complains about this. It doesn't make sense though.

 

My o/t has the same issue.
I was thinking I might need an inline check valve?
Haven't really checked it out yet, I'm waiting for my shop to warm up, sometime in April.

 

Try 5 or 6 pumps on the pedal turn the key

 

Does your choke work ? Is it set correctly ?

 

I'm gonna have to try the 5 or 6 pumps.

The choke is adjusted correct afaik, it's a manual so not much to it. The carb installed before ran so rich no choke was needed, even on subzero days, this one is a bit different.

 

I think it's punishment for not driving them every day. I have two with the 2100 and another with a Holley 4000.

On one the 2100s if I smack the pedal to the floor quickly and release, it seems to set the choke. That helps. And sure, maybe someday I will adjust it out.

 

I fit ***le of your thread pretty good: Hard Starting After Sitting - post pic of your set up - fuel pump/line leaking?

 

Bingo. You just need to retrain yourself. You said you had pump action. Was it a good hard stream ? Or just a limp stream ?

 

We had a run of problems with 911 Porsches that wouldn't start after a 3 day 'sit'.
Culprit was a 2 meter plastic fuel supply line with faulty one way valve.
Edelbrock 600 has the same symptoms on my F100. 3 days and reluctant to start...auto choke resets with throttle...then start. Not immediate like with my Holley 650...

 

It was healthy. I only goosed it once, as I was actually blocking the throttle open to do a cylinder compression test. But it had sat for a long time (cold compression test).

So I was really surprised to see that, since my theory was, the accelerator pump was losing prime, on account of the fact that a little fuel down the carb throat remedied the situtation. So it's a case of the fuel bowl has fuel, the accelerator pump works. It acts just like the carb is bone dry except, it isn't.

If I'm a little shy on the s****ful, engine will stall out when that bit of fuel is used up. Engine needs full choke when cold and fast idle cam is adjusted about right. When it's warmed up, can reach in through the window with just a flick of the key, maybe a 1/8th turn of the crank. Digging around online shows quite a few folks have the same issue. Oftentimes the suggestions are to install an inline electronic fuel pump, and juice things up. My theory is that, if the fuel bowl has fuel, and the accelerator pump shot is adequate, it should start right up even after weeks of sitting.

 

My PQQR ol henry did the exact same thing, found the accelerator pump just flat out gave up, and with the replacement, a new one, it now responds as it should, pedal, gas, pump, (2) two times and WALA pops right OFF.

 

Nothing seems out of the ordinary from what is said. But what if you pump the accelerator more than once after it has sat a long time. Can you get 4 to 5 even 6 good shot's from the pump. Check this both after a long sit and after just one day. If the number of pumps change or become less with time your fuel is evaporating over time. And with the accelerator pump being sideway's it is more prone to draining back as fuel level drops from evaporation as compared to a Holley that has it's pump located under the fuel bowl. One last thing. Is the float level correct ?

 

See how high the fuel inlet is for the accelerator pump (see pump check valve) ?

 

I'll have to try that, it has been at least a week or so. Will give it a half dozen pumps and see if that works.

What I did was set the the dry float height as the manual says, but the wet fuel height in the bowl ended up being too high. It is now set real low, but at idle (with the horn removed) the actual fuel height stays at the correct height of 29/32" from the machined surface at the top of the bowl to the fuel itself. It's my understanding that's what really matters. It does seem like maybe the fuel pump pressure must be pretty high, but I'm told this is the correct way to do it.

edit: going to garage to check

 

HenhyJ1951 has a valid point that you should check as well. When open see if check valve is deformed.

 

The check valve ball looked a little worn when I had it apart. I re-set it with a little love tap with a small hammer, as the manual sez.

Ok, so I pulled the oil bath and peered down the carb throat. Went 5 pumps and had two streams the whole time. Went 5 more with good fuel delivery, what the hell. Went to start at full choke and it fired off for a second! Then pumped 5 more and it grumbled.. 5 more and it started right up.

It's 40°F in the garage right now. I'm guessing about 20 pumps and full choke will git er done lol

Had a 500 CFM two barrel Holley on it for years, it didn't really need the choke as I recall.

 

This is an early iteration, the check valve isn't the red umbrella lookin' deal that most are familiar with. It has a phenolic gizmo spacer as seen in pic. The top screw on the housing keeps a ball check from being ejected from the tube it is installed in. The rest of it is pretty much the same, using a square diaphragm pump. The ball check here is in addition to the ball check and weight ***ociated with the venturi cluster. I'll dig around in the rebuild kit stash and replace both ball checks and see if that helps any. 15 to 20 pumps seems like a lot, but it will start this way. Accelerator pump rod is in the "cold as hell" hole so it should be getting max charge.

 

She's a cold blooded one. Try a fatter idle mixture for now.

 

You did tune this with an O2 sensor right? You've got it dialed in at operating temp so until it reaches that you've gotta deal I guess

 

Yes, had idle AFR set super lean before using the wideband (16-1) it's set pretty rich now and close to stoich when fully warmed up.

One thing I've heard recommended is to use a sealant on power valve and housing gaskets, and accelerator pump gasket. Does Seal-All or another product hold up to gasoline? The wrong stuff in a carb and it will cause more problems than it solves. "Fuel resistant" is just market speak for "worthless".

 

Just drive it more often.


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If it starts after one day but not after several, I suspect the combustible hydrocarbons are evaporating out of the gas in the carburetor leaving the less flammable liquids in the carburetor.

 

It would be kind of a h***le but to test that theory I could remove the air horn, draw off some of the fuel that is in the carb bowl, and use that down the carb throat, start purposes. Thing is, it WILL start with the fuel remaining in the carb - it just takes several pumps to do the job. Two or three won't do the job as I discovered last night.

 

Johnny Gee, that what my DR. asked me.LOL.Bruce.

 

Well Bruce I'm sorry to say I am of no help in that department. But if you'd like I can PM you this urologists number.

 

Hard starting after sitting more of a issue as I get older. Hard stream, limp stream is getting kind of personal.

 

Well it's not leaking anyway!

 

Jonny Cat isn't just for driveway's, garages and cat's anymore. Try some around the bed and toilet. You'll be glad you did.

 

You people need help! Between the dealer stories thread and the "I'm never towing anything again, ever" thread I've never laughed this much in a long time..

 

Well I can sure feel Truck64's pain we have two trucks on the place that act the same way or worse and neither gets driven enough. My 77 Chev dualie with a 454 and mom's 78 F250 with a 300 six. Both only get driven when they have a job to do and the dualie usually only goes to the dump or lumber or metal yard about once a month. The Ford only gets driven when my family members do clean up around mom's house.
I've though about putting an electric pump on both to get fuel up to the carb to start that can be turned off an let the gas flow through when running.