Odd 2150 carb issue when starting

[Blue71]

On the 76 Camper Bronco , stock 302, 2bbl 2150, I have a carb issue after it sits for a few weeks. Most Broncos I have or have had alway take several cranks after sitting a while to get the fuel flowing through the carb again before starting. Since I don’t drive the 76 Camper but every few months, I at least like to start it every week or two. After sitting a week you can get in and crank it over and over and it won’t start. Put a spoon full of gas in the carb and it fires right up and runs great. No stumbling or anything. Restarts everytime. Just not sure why just a small prime has to be done for it to start after sitting and it won’t get fuel to start with. New filer at carb, New fuel pump(mechanical),New acc pump, cleaned carb, still does it.

Thanks

Andy
Blue71

 

[Bradsp8]

I'm no carb or endine guru and I don't recall where I learned this procedure but here it is for what it's worth...........

My 75 often sits for a week sometimes several between drives and it's stock everything under the hood. My process whether a day or several weeks is as follows and it works every time.

1. push accelerator pedal to floor but let up on it SLOWLY.
2. turn key (without depressing accelerator) let crank over several times....stop.
3. turn key again and vroom she starts right up.

I guess what I'm doing is priming the carb like you are doing with the spoonful of gas?

 

[SHX669]

There are multiple threads about this - has to do with the "new gas formulation " . It evaporates from the carb fuel bowls.
One fix is to go to an electric fuel pump and let it "prime " for a bit before trying to start.
If they haven't been started for a while I use this technique for both my Broncos ; turn the key to start for 3-5 seconds , then depress the throttle one time to floor board , turn the key to start again for another 3-5 seconds . If it doesn't start after that then depress the throttle again one time to floorboard . They usually start after this procedure - I think I'm priming the carb . But both my carbs are adjusted and both electric chokes are adjusted properly .

 

[Slowleak]

Sure sounds like the accelerator pump is not doing its job. Once the bowl fills from cranking, the accelerator pump should provide the prime.

I think I would let it sit and then pull the top off the carb to see if the bowl is dry. If so, crank it until the bowl fills and then verify that you see a stream of fuel squirting into the carb when working the throttle lever. Could be you just need to move the accelerator pump rod to another hole so it squirts more. Check the choke too...... I have seen electric chokes that would open before the engine started if you had to crank for a long period of time to fill the bowl.

 

[blubuckaroo]

There are multiple threads about this - has to do with the "new gas formulation " . It evaporates from the carb fuel bowls.
One fix is to go to an electric fuel pump and let it "prime " for a bit before trying to start.
If they haven't been started for a while I use this technique for both my Broncos ; turn the key to start for 3-5 seconds , then depress the throttle one time to floor board , turn the key to start again for another 3-5 seconds . If it doesn't start after that then depress the throttle again one time to floorboard . They usually start after this procedure - I think I'm priming the carb . But both my carbs are adjusted and both electric chokes are adjusted properly .

This is exactly what's happening.
Sometimes I don't use the Bronco for a month or two at a time. I even keep a battery tender on it when it sits like that.
Before I even try to start it, after sitting a long time like that, I prime the carb. I use a plastic squeeze ketchup bottle filled with gasoline with a tube added to fill the primary float bowl. (don't just squirt come down the throttle bores)
This keeps the cranking to a minimum. All that cranking on a dry motor is tough on everything.

 

[SHX669]

Ya Blubuckaroo I need a better method than the excessive cranking . Only had this problem about the last year and half but seems to be getting worse. There are probably a lot of wet ,dark winter days on the horizon ; just to get the ambition. lol

 

[blubuckaroo]

Ya Blubuckaroo I need a better method than the excessive cranking . Only had this problem about the last year and half but seems to be getting worse. There are probably a lot of wet ,dark winter days on the horizon ; just to get the ambition. lol

I really hate the idea of putting in an electric fuel pump when it isn't absolutely necessary. Typically that would mean using a carbed 5.0 that has no fuel pump eccentric.
However...
Like with a lot of things, my reasoning is coming around.
An electric fuel pump would do the trick. Just make sure it's equipped with some sort of automatic kill system.

 

[jckkys]

When used as a DD, the problem never comes up. In the summer the fuel is gone in 3 days. In the cool Tucson winters only long, as in 2 week or more periods of none use, does this phenomenon occur. It's clearly just evaporation. It's been this way for 100 yrs. I like to squirt about 2 oz. of fuel into a float bowl vent. This way the air cleaner stays on. I can't see getting a noisy electric fuel pump to deal with such a minor issue. But a pull through electric pump that's only used for this and powered through a manual switch would work too.

 

[byson1]

I agree with Slowleak. It's very easy to pull the top of the carb off and see how much fuel is in the bowl. You will also be able to see if the needle is sticking or opening like it should be. Every carbureted vehicle I've owned always takes some cranking if it's have been sitting for a week or more but eventually it will start. Some are worse than others. I have a boat with a Holley 2bbl that usually fires right up even if it's been sitting for weeks. I also have a Jeep with an Edelbrock 4bbl that's difficult to get started if it's been inactive for only 4-5 days.

 

[67RT]

I just ditched my Eddy 750 on my 440 mopar and switched to a Holley 770 Avenger. After one week the 750 would need 3-4 long cranking periods pumping gas (usually killing the battery) whereas the avenger is three to four times turning over and boom, start. SO much better.

 

[metal1]

it really sounds like a fuel pump issue I read you installed a new one ,but is it pumping like it is suppose to ?have you checked fuel flow at the carb after sitting for awhile .I had similar issue after a new pump install ,ended up finding a fuel filter under the body right after the fuel selector valve that was just about plugged solid got rid of it and just use a filter right before the mech pump ,now it only takes few cranks to start after sitting

 

[jckkys]

Blue's problem is clearly simple evaporation. Fuel filters between the tank and the pump are never a good idea. A simple pump output test rules out both a bad pump and fuel line blockages including the pickup filter. The reason Holleys don't suffer when the float bowl is only partially filled, is the accelerator pump intake being at the bottom of the bowl. All the other carbs need a 1/3 to 1/2 full bowl. Many factors contribute to the speed at which the fuel evaporates but but it always will.

 

[Slowleak]

Blue's problem is clearly simple evaporation. Fuel filters between the tank and the pump are never a good idea. A simple pump output test rules out both a bad pump and fuel line blockages including the pickup filter. The reason Holleys don't suffer when the float bowl is only partially filled, is the accelerator pump intake being at the bottom of the bowl. All the other carbs need a 1/3 to 1/2 full bowl. Many factors contribute to the speed at which the fuel evaporates but but it always will.

This Bronco may have some additional issues which become apparent as a result of evaporation.

He made the statement "After sitting for a week you can get in and crank it over and over and it won't start". Its a statement which can be interpreted subjectively as "it take too long to start" or objectively and literally as "it wont start". The fact that he pours gas into the carb implies to me that this may be the only way he has been able to get it to start after sitting. That's not a normal thing.

 

[jckkys]

A lot of things COULD be contributing to the need for extended cranking. Nothing in the original post indicates that. If a fuel pump flow test were done initially, there would likely have been no reason to replace the fuel pump or accelerator pump diaphragm. Now, with the fuel continuing to evaporate, as it always will, pouring fuel down the throttle bores isn't a safe way to deal with empty float bowls. It risks a fire. All 2100/2150s have bowl vents to fill the bowls, if the extended cranking is too much for the starter motor or battery. Also just starting the engine every couple days, will refill the float bowl before it evaporates.

 

[blubuckaroo]

Blue's problem is clearly simple evaporation. Fuel filters between the tank and the pump are never a good idea. A simple pump output test rules out both a bad pump and fuel line blockages including the pickup filter. The reason Holleys don't suffer when the float bowl is only partially filled, is the accelerator pump intake being at the bottom of the bowl. All the other carbs need a 1/3 to 1/2 full bowl. Many factors contribute to the speed at which the fuel evaporates but but it always will.

jckkys, you've hit it out of the park!
That's definitely the reason some carbs act dry before others. Their accelerator pump feeds from the bottom of the bowl.
Same with the jets. some feed from the bottom and some (Holley) feeds from the metering block.

No...
I'm not saying I've changed my mind about Holleys. I still hate the metering block design. It's just that in this case, Holley wins.

 

[jckkys]

Unfortunately they loose when it comes to leaks. You can't win em all.