Carb woes

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mtldart

mtldart

74 dart sedan
Joined
Aug 20, 2019
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Location
Montreal
74 all stock dart sedan. Slant six. Holley 1945 carb. No automatic choke, manual choke installed by previous owner.

My car started stumbling a bit ago so I tossed a carb I bought off someone here and rebuilt myself in and it was running great again. Except for one detail. If I didnt drive it for a day or two I could not start the car without starter fluid. Once it got started, usually a spray or two, it ran fine and I could restart it all day with no problem.

I rebuild the original carb and it was ******* filthy, which is why it was stumbling. In an effort to fix this whole not starting issue I put the original carb back on (mind you it's been rebuilt) and now I am having the exact same issue with both carbs. I thought mayyyybe it's an issue with the accelerator pump so I put the original rubber cap back in but that didn't change anything.
I have not adjusted the float level on either carb. The original one is a little low from what the carb rebuild manual recommends and the second carb has it at the spot the manual says. Both do the same thing. I have also checked both floats for stickiness, rubbing, and leaking. Nothing wrong there.

I thought maybe my backflow valve on my fuel pump is bad (if that even is a thing), so I replaced that, nothing changed.
I replaced my spark plugs juuuust in case, but nothing has changed.
I did follow what the rebuild manual/videos say about checking if the weight and ball check valve are working and everything seems to be working right

I am really really frustrated and don't know what else I can change.

The only thing I can think of is that the carb rebuild kit fuel inlet valve has a different throw in it or something and is somehow letting the fuel drain out over night enough that it's not getting enough to start?

It also doesn't matter how long I crank. I killed an old battery trying and then today my brand new battery died while I was trying to trouble shoot the problem.

The car will be put away for winter within the next month and I won't be able to touch it til spring so I'd LOVE to not have this same problem in the spring.
Any ideas? I'm sincerely at a loss here. The thing that bugs me is I was having zero issues like this til I rebuilt the carbs and now it's just been a very very long headache because I can only trouble shoot every couple of days when I get the no start issue.
 
Fuel filter was replaced a year ago....about 5000 miles since
But maybe I'll replace it again just in case.
 
mtldart said:
Fuel filter was replaced a year ago....about 5000 miles since
But maybe I'll replace it again just in case.
Click to expand...
Has the gas tank been cleaned out? Verify that you have a clean tank because if you don’t your just clogging up your filter, lines and carb.
 
No the tank has never been dropped as far as I know.
Definitely won't be able to do that before winter though that's for sure.
 
For good measure I just went out and disconnected the line after the fuel filter and cranked it for a bit and its gushing out plenty and the fuel looks good, so that's not the issue.
 
Run the engine, then switch it off. Actuate the throttle lever while looking into the carb bore. Look for the accelerator pump shot/stream. No shot means defective acc pump.
 
I would start by throwing the Holley in the ditch. I just don't have any like for them at all. I like the Carter BBS much, much better. Some people love the Holleys and have good success with them. I do not.
 
Bewy said:
Run the engine, then switch it off. Actuate the throttle lever while looking into the carb bore. Look for the accelerator pump shot/stream. No shot means defective acc pump.
Click to expand...
yup when i do this i get plenty of shots coming out.
even in the morning ill get a couple shots coming out, it will idle for about a second or two then die and then i get no more shots coming out.

im starting to wonder if the float is sticking up and the car running shakes it loose?
i wish carbs were clear!
 
mtldart said:
yup when i do this i get plenty of shots coming out.
even in the morning ill get a couple shots coming out, it will idle for about a second or two then die and then i get no more shots coming out.

im starting to wonder if the float is sticking up and the car running shakes it loose?
i wish carbs were clear!
Click to expand...
The fact that you can get a couple of shots initially, then nothing tells me the fuel pump is likely suspect. Fuel has drained back from the carb bowl because the pump check valve is bad. The starter fluid gives the engine enough time to refill the bowl with enough fuel to get it going again. Pump time.
 
mtldart said:
yeah i replaced the pump because thats what i thought too!!!!
Click to expand...
Perhaps a bad new pump? After the engine is hot and you shut it off & remove the air cleaner; do you see anything leaking into the bores or vapor coming up through the carb?
 
the only time i see vapors is when i give the throttle a push and it squirts.

I would also assume that cranking it a bunch would fill the bowl and allow it to start. I actually tested that last night. I disconnected the fuel line, cranked it and it shot out a ton of gas, consistently, into the water bottle to catch it. I then checked to see if it would squirt and I got nothing (which makes sense). then I reconnected the fuel line, cranked it a couple times and tried again and it would squirt, so it was filling the bowl up.

the next time i get the no start issue I guess what i will do is i will again verify that its not pumping from the accelerator pump after cranking it a bunch of times., which would be a sign my float is sticking and holding the fuel inlet valve shut? last night after having an empty bowl i cranked it three or four times and it let me get some fuel squirts out of the accelerator pump.
 
mtldart said:
the only time i see vapors is when i give the throttle a push and it squirts.

I would also assume that cranking it a bunch would fill the bowl and allow it to start. I actually tested that last night. I disconnected the fuel line, cranked it and it shot out a ton of gas, consistently, into the water bottle to catch it. I then checked to see if it would squirt and I got nothing (which makes sense). then I reconnected the fuel line, cranked it a couple times and tried again and it would squirt, so it was filling the bowl up.

the next time i get the no start issue I guess what i will do is i will again verify that its not pumping from the accelerator pump after cranking it a bunch of times., which would be a sign my float is sticking and holding the fuel inlet valve shut? last night after having an empty bowl i cranked it three or four times and it let me get some fuel squirts out of the accelerator pump.
Click to expand...
You verified the pump is filling the bowl. With a full bowl, you should be able to get a lot of AP squirts before the bowl level drops too far. After sitting for several days, there still should be enough fuel in the bowl to provide lots of squirt action. If not, then the fuel is draining off somewhere.
 
Alright so it's sat overnight.
I took a pair of pliers to the clip on the fuel line after the filter and the second I loosened pressure on the clip fuel wanted to squirt out, so there was still pressure in the line from last night, which means it didn't flow back from there.
I cranked it, it fired right off and immediately died. I took off the air cleaner, no more squirts at all.
I connected my trigger starter thing, sprayed a tiny bit of starter fluid and it literally lit right off and idled. It's raining, and cold. I pulled the throttle a touch and it died (not abnormal). Cranked it about two seconds and it fired right off without giving gas or starter fluid.
I'm stumped.
 
I have two carbs, both with the same symptoms. I guess I'll fill the bowl of one with the top half off and let it sit overnight and see what happens?
 
So you have a manual choke now. It may need to be closed more for the first few minutes of engine running until the engine gets some heat into it.
 
Does it squirt a STRONG stream AS SOON AS you move the throttle? The accelerator pump rod bends to adjust. If it does not immediately squirt fuel when the throttle blades are cracked, then it needs adjusting. Also, the stream should be strong and about the size of a #2 lead in a lead pencil. If not, the accelerator pump is suspect. You've determined the system has pressure to the carburetor after sitting overnight, so the issue is not supply, but delivery. The accelerator pump check ball might be gummed up, and not allowing fuel to enter the pump chamber when the pump is released. The pump itself could still be bad. You'll likely not know until you remove and disassemble the carburetor. Unfortunately aluminum is not transparent, like in Star Trek.
 
Is there anywhere to buy just the accelerator pump rubber cap?
I saw a video or a post where someone said the walker kits can come with one of three different ones but theres only one that's the right one.
I'm starting to think I have the wrong piece in there, like maybe it's a 1/16" of an inch too big or something.
It just doesn't make sense that the accelerator pump was working perfectly before the rebuild and now it's not at all.
 
I've bought just the cups not too long ago when I rebuilt a carb and pinched the pump cup that came with the kit upon trying to slide it into the accel
pump well. Cost nearly as much as a whole nother kit would have
 
mtldart said:
Is there anywhere to buy just the accelerator pump rubber cap?
I saw a video or a post where someone said the walker kits can come with one of three different ones but theres only one that's the right one.
I'm starting to think I have the wrong piece in there, like maybe it's a 1/16" of an inch too big or something.
It just doesn't make sense that the accelerator pump was working perfectly before the rebuild and now it's not at all.
Click to expand...
Actually, it makes perfect sense. If the kit you got is not ethanol friendly, therein could lie the problem. What I suggest is calling the guys at Daytona Carburetor. They use ethanol resistant parts made in USA. Call them.

Daytona Parts Home
 
I would get 2 high faiure rate item. Ethanol does tend to swell these cups, fine sand paper a rough bore.One good tip for install, new or used cup. Put top of the carb into freezer that will shrink the cup size down a little.
 
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