VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1938 Fuel Issues

I'm having issues with my 38 chevy. It is very hard to start and doesn't respond under acceleration. If I dump a little gas down the carb, it starts right up and idles decent. If I press on the gas pedal, it hesitates and wants to die. Carb issue, fuel pump, looking for suggestions.

Thanks

Look down the carburetor intake, with the engine not running. Move the throttle shaft to accelerate and see if gas squirts out. If not the accelerator pump is not working. Just had this problem on my 46 pickup. Changed carb and it is a lot better, but still have some hesitation when I hit the gas.
Also how long has it been setting when you are trying to start it?

I would also suspect the accelerator pump being the culprit.
Tony

This right here is yet another example of the negative effects of ethanol. Fill the tank with non-ethanol and your problem will be solved. All your problems fuel related.

Enough of that. I agree with the previous posts. Carburetor accelerator pump. Could also be:

a. Float (don't ask me how)

b. Timing.

c. Points.

d. or anything related to the spark or gasoline. KK was right on in his advice so check to see if the accelerator pump is working normally.

Good luck with it.

Charlie

You may have multiple issues.

The hard starting issue is probably the fuel:

http://www.thecarburetorshop.com/Troubleshooting.htm#Hardstartcold

The hesitation is probably a different issue. Before throwing rocks at the carb, I would check the dwell, timing, and distributor advance mechanisms.

The most common issue with 1937 and newer Carter W-1's is not the accelerator pump, but it is related. There is a bracket attached to the back side of the throttle shaft that is attached to a rod that activates the pump and the metering rod. The round hole in the bracket wears oblong, and the round rod inserted into the hole wears with a flat side. When moving the throttle, the throttle can rotate significantly BEFORE the accelerator pump actually moves. Replacing a good accelerator pump with a new accelerator pump if the bracket/rod combination is worn only lightens your wallet.

Very easy to test the above.

Remove the dust cover
Watch the accelerator pump, and rotate the throttle
The accelerator pump should move almost instantly

If not, pull the pin spring holding the rod to the bracket, and inspect.

While these parts are not in modern rebuilding kits, they are available mail order.

The vehicle CAN be driven with a defective (or missing) accelerator pump. I have posted this before, but again: it was common practice during WWII (at least in rural Missouri) to REMOVE the accelerator pump ENTIRELY (gasoline was rationed). Many farmers survived driving this way for several years.

Jon.

Heed Jon's advise. Also hesitation can be lessened by enriching the idle mixture slightly. The idle will get a little rougher. I suspect that it is a little wear on the throttle plate shaft allowing a bit more air to enter. It has been supported in some cases but not all.

A responder's question above asks "how long had it been setting?" A couple years ago I acquired a '39 that had been restored including having the gas tank removed and relined by a shop that specializes in this work. Since that work was performed, the vehicle was driven just + - 600 miles.

I acquired it. It started OK and idled fine, but on the highway (40 MPH) would cut out. Nothing in the inline (2) fuel filters. When we (eventually) drained and flushed the gas tank, there were tiny bits of material that I believe was deterioration relating back to the 10 or 15 year old relining job. It starts & runs fine now.

My two cents

While there are many good sugestions I will vote for the accelerator pump in the carburetor. He mentioned as soon as gas is poured into the carb. it starts and runs. This eleminates ignition type probles. From my experiance an engine is very difficult to start when cold if the accelerator pump does not squirt in some gas, even is the choke is closed.
Would suspect that either the accelerator pump link is disconnected, exterior rod off or pump leather competely gone is the cause. Perhaps the pump jet is plugged up causing the carb. to not "open-up" and some one removed the link so car could be driven. I did this one time for a member when we were out on a tour.

Thanks for all of the great responses. This has been a three year project. It first ran ( rebuild engine, new gas tank, rebuilt carb) 2 years ago. Since then it has sat while the body work and interior have been done. So close to finishing now. I suspect today's fuels did me in. I will be looking into the accelerator pump this weekend.

Thanks!