Buick Won't Start (Figuring it out)

[TK3295]

About 2 weeks ago I was driving my 1938 Buick special series 40 when I was driving -- I got small bursts of power and then the car began to coast. At first I thought this may have been the condenser. This sort of thing had happened to me in the past and the forum helped me solve it! After being on the side of the road for a few mins, a fellow classic driver came by and kindly gave me another condeser as I believed this to be the problem. I quickly changed out the condenser and went to turn the car back on at least I tried to no avail. I then went to check for a spark which the car had and still does(attached below). I then put little more gas in the tank nothing. Upon pouring a little bit of gas into the carburetor, the car sputtered for a moment or so before going silent once again. I noticed that whenever depressing the pedal no gasoline would be squirted into the carb(attached below) The pump's bowl wasn't really filling with much of any gas either. Unfortunately, I had to call triple a and have the car towed back to whete I store it. Today I went to the car and looked at the bowl and carb -- I cleaned the bowl which only had a dribble of gas in it and some small bubbles slowly flowing in after I had pressed the pedal a good deal of times a few mins prior. After having cleaned the bowl, and the little bit of sediment, I went looking at the carb. When I came back around about 15 mins later the bowl was nearly full (attached below); however, once again, whenever the pedal was pressed no gas was squirted into the carb. Because of this, I think its safe to say the carb went, but I am wondering if the fuel pump has gone bad or if there is a line issue. I'll send some photos here. However, I took videos as well (too big to send here) I do know gas is going from the tank to the pump and is filling the bowl at the very least (although it might be slow). In the coming days, I'm going to decouple the lines ahead of the pump to see if there is a blockage in there. The most likely scenario is the carb went out and needs to be replaced/ repaired. I just wanted to post this here because everyone on this board is always so helpful and kind with their responses and I wanted to see if others had similar problems. Thanks so much!

-Evan

[1937 Buick 66C]

Hello Evan,

 

The symptoms you describe, as well as your observations indicate that the car is not running due to fuel starvation.  Carburetors don't "go out" per se, and there are several potential sources for your symptoms.  Your symptoms sounds very much like vapor lock (fuel boiling in the lines due to high temperature - the mechanical fuel pump cannot push vapor into the carburetor).  I suggest the following steps to further isolate the problem:

1. Add a couple of gallons of fresh fuel to the tank to make sure you have adequate fuel in the tank to cover the intake for the fuel pump.  It is important to be absolutely certain that you have some fresh fuel in the tank.
2. Disconnect the fuel line at the carburetor.
3. (It's helpful to have a second person to do this and subsequent steps)  Crank the engine as if to start it.  Once the fuel pump has fuel (maybe 10 seconds) fuel should squirt out of the fuel line you have disconnected in pulses.  If no fuel, your fuel pump is suspect and should be rebuilt.
4. If you have fuel, reconnect the line to the carburetor.  Again, crank the engine as if to start the car.  After another 10 seconds, the fuel pump should have filled the carburetor bowl with fuel and the car should start.  If the car does not start, peer down the carburetor with a flashlight and open the throttle by hand.  There should be a squirt of fuel in each throat of the carburetor with each stroke of the throttle. 
5. If no fuel is observed, the needle valve in the carburetor is likely to be stuck.  Try lightly tapping the top of the carburetor, near where the fuel line attaches with a metal tool.
6. Repeat step 4.   If still no fuel observed when opening and closing the throttle, there is either a problem with the needle valve or accelerator pump that will require that you remove the carburetor from the engine and disassemble it for overhaul on your workbench.

Fuel containing ethanol is problematic in old cars.  Of immediate concern is that ethanol dissolves the rubber diaphragms in mechanical fuel pumps as well as the o-rings and seals in the accelerator pump in your carburetor.   If you have not had either your carburetor or fuel pump rebuilt in the last few years, you will need to do so for them to continue working with modern fuels.  Specifically, if you are rebuilding these yourself, or having the work done, it is important to make sure that the soft parts you are using are ethanol resistant (viton).

 

I also suggest that you consider installing an electric fuel pump as a supplement to the mechanical fuel pump.  This will reduce the probability of vapor lock in the future, especially when using fuels with ethanol which have a lower vapor pressure than pure gasoline.

 

[Larry Schramm]

Good advice from 1937 Buick 66C.  Especially about changing the fuel pump with a new pump or diaphragm. 

 

I changed the fuel pump on our 76 Corvette recently just because.  Even though it was working fine I do not remember the last time it was changed, meaning before or after the widespread adoption of E-10 alcohol fuel.

[Century Eight]

About a year ago there were several threads on this subject involving auxiliary fuel pumps and vapor lock.  I would suggest referencing those and checking out the tips as well as safety suggestions.  Quite helpful and well explained.

 

but if it wont start after 10-15 min, I would rule out vapor lock and check the fuel pump or electrical issues.  The auxiliary fuel pump makes a nice addition.

Edited February 19 by Century Eight (see edit history)

[Hubert_25-25]

Evan, 

    I have a 38 Buick Special 40 that is showing some similar problems as you describe.  This may be a bit of a shopping guide for you.

1) After the car warmed up, it would stop running when the engine speed slowed down to idle.  The car would not restart until it cooled off.  If you looked inside the carburetor, you would see gas boiling inside below the throttle plate.  You could hear it bubbling too.  You do have to install the blanking plate between the intake and exhaust manifolds.   This also won't just "slip in" between the flanges.  Purchase exhaust and intake manifold gaskets and the downpipe gasket, as both intake and exhaust manifolds need to come off to put the plate in.

2) This car has an electric fuel pump at the gas tank, and a second one next to the mechanical fuel pump.  Bob's Automobilia has rebuild kits for the original fuel pumps.  As discussed above, I am going to rebuild the existing fuel pump as surely the diaphragm needs to be replaced.  I will remove the electrical fuel pump closest to the mechanical pump.

I would start with these 2 items.  You need item 1 to handle the modern fuels, and item 2 just because of age.  

After doing this, you can also get some fuel hose.  Remove the fuel feed line to the carburetor.  Connect the fuel feed line to the hose and put the other end of the hose into an empty gas can.  Run the fuel pump (or crank the engine) for 30 seconds.  See if you appear to be getting sufficient flow of fuel to the carburetor.

Hugh 

Edited February 19 by Hubert_25-25 (see edit history)

[IFDPete]

Is Fuel Filter clogged?  Sounds to me like a restricted fuel flow issue.  Had similar problems on my 49 Super and it was just a clogged fuel filter.  Try a new filter.  If the filter is stone try removing it and giving it a good cleaning.  Is there a screen in the fuel pump that needs cleaning?  My 49 has a screen in the pump - not sure about 1938 fuel pumps.  Is there a screen in the carburetor at the fuel line entry that is clogged?

 

Edited February 19 by IFDPete
wording (see edit history)

[Grimy]

Consider checking the integrity of any flex line between the hard fuel line and the pump.  These deteriorate from the inside out, and can pull in outside air (interrupting fuel flow) without leaking fuel out where it can be seen.

[TK3295]

These are all great aids thank you very much, I'll work my way down the list and try each one of these-- I'll also order those parts also right away. 

[TK3295]

She fired up, I added about 3 fresh gallons of gas. I looked at the lines too. Im guessing she had at least two or so gallons in the tank, but I agree the more the better. (I have to fix my gauge as the float must be stuck it always reads E) Also, I left the gas cap slightly open when I turned the car on just because I realized I must've stopped the vacuum in the line when I opened the bowl for cleaning. (I closed the cap up afterwards) All I did was put a bit of gas in the carb again and after a few sputters and giving the pedal some more pumps than normal while sputtery at first the car began to run. I will say I had to hold a low rev for about 10-15 seconds because the car would've stalled if I hadn't, but afterward the car remained running. I let her warm for about 10 mins (Oil Pressure read about 45psi and the temp was about 140-150F or so) I can assume the fuel pump is working A OK now because it ran perfectly -- I took her on a drive, albeit only a few mins, but it was most certainly doing its job. At the end of the drive I even turned the car off and back on and it came right to -- all seems well. As this really is a learning process for me I wanted to ask if the delivery of fuel could be affected by the rather cold temperatures my area has been experiencing lately. The day the car turned off it was clear, sunny, but about 26F the car ran noticeably colder than usual before when it turned off. I do of course know the car prefers warmer temperatures on startup as she will fire right up when its about 45-90F but it becomes a bit of a battle to get the car started in the low 40s and below. (And maybe STAY running in cold temps? That aspect is what i am wondering about.) Once again thank you all for your tips and advice. Have a great day/night

-Evan

 

[TK3295]

[Erndog]

Have you verified that there is no obstruction in the tank itself? I have had junk in the tank that will get sucked down and block the pick up tube, only to float away after it finished frustrating. Then repeat.

 

[Oldtech]

If your carb heat riser isn't working you may have had carb ice. that will stall the car, but have nothing to do with fuel delivery to the carb, Unless you have water in the fuel. 

[TK3295]

Interesting maybe there is something floating around in the tank, I plan on fixing the float soon so I suppose I'd check when I get to that.

 

The gas is good no water in it thankfully 

[EmTee]

If your '38 Special is like my Century (also the small body) there should be a drain plug on the bottom of the tank.  If so, you could try draining some gas and see what else, if anything, comes out with it.  If there's sediment on the bottom of the tank, you should see something in the sample.

[Skidplate]

All of your symptoms seem to be a common group of problems. 

A thick gasket between carb and intake will help with the heat... but it won't completely fix it. Modern fuel will tend to boil WAY before the old fuel did. I dropped my carb float level a bit. Less fuel in the bowl, less to bubble over the top. I also made a heat shield around the base of my carb. That also helped some. 
 

Clogs in the lines are also a big problem. Short of replacing the tank, there will always be crap coming up from there. Filters up and down the line do help but the best fix is replacing the tank sending unit with one that has the filter screen at the tank pickup, or... add a screen to the pickup. Oddly enough there are bunches to choose from online. I fought with various electric fuel pumps swearing up and down that they were the problem. Turned out it was just crap and more crap coming from the tank. Mine was the original sending unit so there was no screen/filter at all. Who knew?
 

So drain the tank like EmTee suggested. If you can, drop it and really blow it out good. Add the screen to the sending unit (and I mean one of those supper fine sock thingies that fit exactly over the tube). Blow air through the whole system to make sure all is clear. Maybe toward the tank as anything stuck in the lines will dislodge going back the other direction. Make sure your fuel pump is really clean since you're really starting fresh. Install those plastic disposable see-through filters wherever you can. The glass screen filters look cool but they aren't as effective. Make sure you're clean, up to and including into the carb and you should be good. 
 

One more thing. Make sure your exhaust butterfly valve (not sure what it's called but it's right below the carb) is working smoothly. If it's stuck closed or kinda closed, that will add extra heat to the carb and increase the vapor lock issue.

 

 

Edited February 22 by Skidplate (see edit history)

[nat]

On 2/19/2024 at 10:55 PM, Oldtech said:

If your carb heat riser isn't working you may have had carb ice.

     Icing will cause the engine power to fade away as the ice forms.  Once the engine stalls or is shut off, rising heat will melt the ice and it will run again.  It doesn't have to be below freezing for this to happen.