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rpmdiag, Tech and Instructor
Category: Cadillac
Satisfied Customers: 8150
Experience:  Since 1975
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I think that I may have a bad fuel pump. The car is a 1940

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Hello. I think that I may have a bad fuel pump. The car is a 1940 Cadillac Lasalle. The car spits, sputters and dies when acceletating and especially when on hills. When I check the car the operating temp. is between 160 and 190 degrees. The fuel tank is between 3/4 and full. I also noticed the fuel bowl was only 1/4 full. When the car died yesterday, on amount of cranking would full the fuel bowl. Has the car towed home last nite. This morning when I looked at the fuel bowl it was full. I have noticed this on several occasions. Is the fuel pump bad in the the diafram has a hole/tear allowing the fuel to siphon in when the car is on a level slightly down hill plane?your help is appreciated on this. thanks. Dave
JA: Has your car been stalling? I think they do a wonderful job. All Experts must pass our rigorous 8 Step Expert Quality Process. This ensures that you get the most knowledgeable, trustworthy help anywhere on the Internet. You can learn more about it here: What is the model/year of your Cadillac?
Customer: No, The car just started this stalling and dieing on a road trip yesterday.The year of the car is 1940 Cadillac Lasalle 52-19 Special.
JA: What year is your Special?
Customer: 1940
JA: Are you fixing your Special yourself? What have you tried so far?
Customer: Yes, I will fix this myself. Not certain what is
JA: Anything else you want the mechanic to know before I connect you?
Customer: The fuel pump has not been rebuilt to my knowledge. I have rebuilt the carb., the distributor and water pump.
Customer: replied 8 months ago.
My computer froze up before I'm could finish. Not certain if I'm signed up correctly.
Customer: replied 8 months ago.
Went out to check. The bowl is full of gas, the fuel filter is full of gas, and the carb. Is empty. Have engine running. The carb. is now full so is the fuel bowl and so is the filter. Still does not explain why the bowl would not fill when on a hill and during accellerstion.

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

Check the fuel pressure and volume with a gauge. 4-7 psi is what you're looking for and 1 pint in 30 seconds of volume.

It's also possible that the needle and seat inside the carb is bad.

Thanks, Ron

Customer: replied 8 months ago.
Hi Ron, Carb. was rebuilt and flow tested. So far it has worked well for about 700 miles.
My thing is, if the fuel pump bowl isn't filled high enough to fill the filter, then the carb cannot get fuel.
When it was on the hill the fuel level in the fuel bowl was below the inlet pipe. If could not get it to fill at all.
After it was towed home and sitting on level ground the bowl and filter filled with fuel without running the engine.
The bowl stays filled on level ground but won't fill itself when on an incline. On level ground the engine runs fine once the carb is full.
Does this change anything on your diagnosis?
Thank you.

Another possibility is a worn cam lobe causing the the pump arm to NOT be in full swing. An electric pump would cure that versus changing a cam shaft.

If you are satisfied with my answer, I would greatly appreciate a 5
star rating now and I will still assist you after you have rated me
too if another question pops up. I don’t get credit for helping you
until you rate me.
Thanks again, Ron

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