Loss of fuel under throttle.

MightyMats

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Good Evening all. This pertains to the 440 in my 67 Chrysler. Stock rebuild with a very mild cam and a msd pro billet distributor and msd box.

The short of it is that I have a fuel issue at all speeds where I just seem to run out of fuel in the bowls and the car surges under load. The issue is intermittent and sometimes I have to manually fill the bowls up through the vent tube because cranking the engine doesn't get fuel into the bowls.

Two months ago I drove from Boston to Norfolk VA for work. Stayed there for 2 months, drove aound, no issues besides my ignitjon coil going bad. I then drove down to Jacksonville FL last week.

Halfway down to Jacksonville my engine started to surge at 75mph under throttle. Thought it was weird, couldn't fix it so I continued my drive because of a timeline i had to meet. Drove it until that night when it died on the on ramp and would not start back up. Had it towed and replaced my fuel pump the next day because I thought that's what it was "no fuel in the bowls." I also checked the needle and seat, there was some gunk in there.

I thought it was fixed but it wasn't. Made it to Florida though. I have been here a weeek and cant figure out wtf is going on. It is definitely a fuel issue. When the car dies and doesn't want to start I dump fuel from a Jerry can down the carb and it starts then it just dies. I have to manually fill the bowls through the vent tubs when it's acting up and it usually gets me back to base...

I have a FST carb (850 w/ vacuum secondaries) that I took apart last weekend and did only a thorough cleaning, found a bit of wire in one of the jets, I thought that was the issue... nope still surges but the 440 runs better now.

My gut tells me this is a bad needle and seat. Like the seat is getting stuck closed not letting fuel into the front bowl. This may explain why it's an intermittent issue. Thoughts?
 
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MightyMats

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Did you make sure that there is no blockage from the tank to the fuel pump?
I did not, however I did take the fuel line off and pump gas into a 1 gallon bottle to verify the new fuel pump was working.

I guess I can check that as well though. Thank you.
 

57fury440

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From what you have done already it sounds like it's something with the carb. You said you cleaned up the carb. Did you check the float levels?
 

MightyMats

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The float levels looked good when I opened it up. They moved freely and should bring the fuel up to halfway up the sight bowl. but I can barely see any fuel in the front bowl when it's running.
From what you have done already it sounds like it's something with the carb. You said you cleaned up the carb. Did you check the float levels?
 

Davea Lux

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Sometimes a car will seemingly run out of fuel because the fuel tank vent is plugged. This causes the tank to build a vacuum which gradually reduces the fuel flow to the carb as the fuel pump struggles against increasing vacuum. The next time the car tries to quit, remove the fuel cap, if you get a rush of air, the vent is plugged. This condition can also happen if someone has installed a non vented cap on a tank designed for a vented cap. Also check the short hose connections at the rear of the stub frame and the fuel tank for cracks. A small pinhole is all it takes to reduce the fuel flow significantly. Sometimes a clogged sock on the fuel pickup inside the tank will also cause fuel starvation. The car will start and run for a while aand then crap out as more debris get sucked up into the sock.

Dave
 

CBODY67

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Persoanlly, I would not just "check" the rubber fuel lines before the pump, mentioned above, but replace them and be done with it.

You mentioned "gunk" in the carb, how did it get past the fuel filter?

Do NOT forget that an ignition problem can present very similar issues as a fuel system problem. Might have a spare fuel pump for good measure, too.

What caused the ign coil issues you mentioned? Just curious.

If the fuel tank cap is causing a vacuum to form in the tank, the bottom of the tank should be concave rather than straight when that happens, I suspect.

Just some thoughts,
CBODY^7
 

mrfury68

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Do NOT forget that an ignition problem can present very similar issues as a fuel system problem. Might have a spare fuel pump for good measure, too.
This piece of advice was given to me in my late teens and has saved me quite a few times over the years.
 

Loadrunner

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You mentioned "gunk" in the carb, how did it get past the fuel filter?

I rebuilt the BBD on my '70 383 back in 2013 - I always date kits and keep them on the shelf - and as we were leaving the yard one day to go get wood, truck barely made it across the road going towards the woods, and died.

I thought out of gas so went and got a can, but no can do.

So I had no choice but to pull the top off the carb at the neighbors, and found a whole bunch of brown gunk in there, and concluded it was from the gas evaporating and leaving crud behind, no other logical explanation.

I only put non ethanol premium in any of these farm rigs now, and they start every time, some sitting for 6 months at a time waiting for action.

This is what was in the carb, you can see why it might not run right like that.

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Trade school made carburetor rebuilding tray.

This is that truck yesterday, not carb troubles since, even with the heat dome thing last year.

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P1250408.JPG
P1250412.JPG
 

MightyMats

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Left the shipyard today to try to get the car on base to the shop. Made it 2/3 of the way there. I changed out the needle and seat on the side on the road. It did nothing, more to follow.

Reading a book at Starbucks while I wait for the car to cool down. I don't think the issue is vapor lock because regardless of Temps it will still lose fuel pressure. Although I do think the problem is exacerbated by the engine Temps eg: exhaust crossover heating up the intake and carb. Although I do have a Wilson Aluminum spacer, the carb still gets hot.

I may just toss this FST carb in the trash and throw a holley back on it and see what happens. Still planning on replacing the fuel lines. They have compressed air at the shop so I'll be able to blowout all the orifices in the carb to see if there is anything stuck in there.
 

Loadrunner

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Electric fuel pump w/pressure reg and your problem is solved, assuming that the gas cap vent is working correctly.

Plumb it at the back by the tank, and do not exceed the psi rating for your carb via a regulator if needed.

If you still want to run the mechanical as your main pump, you can run the electric pump on a toggle or momentary switch, just to start the rig after sitting when the bowls are dry and the fuel has drained back to the tank.
 

MightyMats

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Been messing with the car all afternoon. Front float wasn't set right. Fixed it but one of the bolts that holds it in snapped off. However I can still secure the float. These FST carbs are painted black. And you can see in the photo that the gasoline eats the black paint, which then subsequently goes through the entire carb.

As far as I am concerned... these carbs are junk. They are a budget QFT carb but the paint on them just ruins the entire carb. I realize now that paint was the gunk I found in the carb.

Do yourself a favor, don't buy one of these. Stuck on the side of the road again after going out for a test drive

20221026_172859.jpg
 

Big_John

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I did not, however I did take the fuel line off and pump gas into a 1 gallon bottle to verify the new fuel pump was working.
Kudos for doing this simple test. No one ever wants to check that... and it's soooo easy and tells you sooo much. They'd rather fire up the parts cannon and shoot it at the car.

One more test is a little more involved, but really not hard. Fuel pressure. You can even buy a cheap gauge and tape it to the windshield and go out for a drive. This would tell you if it's fuel delivery or something else like the carb.
Been messing with the car all afternoon. Front float wasn't set right. Fixed it but one of the bolts that holds it in snapped off. However I can still secure the float. These FST carbs are painted black. And you can see in the photo that the gasoline eats the black paint, which then subsequently goes through the entire carb.

As far as I am concerned... these carbs are junk. They are a budget QFT carb but the paint on them just ruins the entire carb. I realize now that paint was the gunk I found in the carb.

Do yourself a favor, don't buy one of these. Stuck on the side of the road again after going out for a test drive

View attachment 564688

I think you've found your problem. Unbelievable that they sell carbs like that....

But if it doesn't turn out to be the issue, try the pressure test I suggested above.
 

Big_John

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I rebuilt the BBD on my '70 383 back in 2013 - I always date kits and keep them on the shelf - and as we were leaving the yard one day to go get wood, truck barely made it across the road going towards the woods, and died.

I thought out of gas so went and got a can, but no can do.

So I had no choice but to pull the top off the carb at the neighbors, and found a whole bunch of brown gunk in there, and concluded it was from the gas evaporating and leaving crud behind, no other logical explanation.

I only put non ethanol premium in any of these farm rigs now, and they start every time, some sitting for 6 months at a time waiting for action.

This is what was in the carb, you can see why it might not run right like that.
I think what happens is when cars (or farm equipment) sits around, the gas collects moisture and once it evaporates, that can be the crap left in your carb.

Back when we used dry gas in the winter, the ethanol (or methanol in the cheaper stuff) absorbs moisture and passes it through the engine to burn. Great for occasional use.... Now the stuff we buy is similar to the old gas, except being laced with so much ethanol, it's going to absorb and hold water... And that comes from the pumps at the corner station, moisture from high humidity and/or condensation collecting.

Not much to do except run no ethanol... or remove the ethanol from the gas. If you've ever watched any of the videos on how to do that, it's just dumping water in the gas, waiting for it to mix with the ethanol and separate and the pouring off the water/ethanol mix.

But, there's a lot of guys that do run the ethanol gas with no issues... Most likely they are using the cars more so everything gets pushed through faster. It's been my observation that the cars that sit are the ones having the most problems. Myself, I buy the ethanol free gas.... One of the things about living in the Finger Lakes area is all the boats around and as you get nearer one of the lakes, the more stations have the ethanol free gas. I can think of 3 stations within a few miles of home.
 

MightyMats

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I swapped the bowls and made it home. Had to remove the power valve linkage. It was a **** show. On the side of the road for too long..

Not sure if I'm going to keep this or throw it in the garbage. But thank you for all the help.
 
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