manual pump not pumping fuel on 38 buick

[boug]

we are working on a 1938 buick straight 8 series 90. my friend's father passed away that owned the car his name was JW PASCOE. we are having fuel problems could the lobe be worn on the camshaft, the fuel pump was sent away to get rebuilt same problem. we are getting fuel to the pump, just thinking about the lobe on camshaft. please reply thank you

[Bloo]

It could happen. It has happened on some cars. I don't think I have heard of it happening to a 1938 Buick.

 

Could it be the wrong pump? I don't think the trouble in the following thread applies to you because you have the 320 engine instead of the 248, but there is a chart posted right at the end showing the correct pump for a 1938 90. It should be an AC 422.

 

 

@DonMicheletti @MCHinson @38Buick 80C

 

Edited September 14, 2022 by Bloo (see edit history)

[DonMicheletti]

While possible, very, very unlikely.

Are you sure the pump is correct and that the line from the tank is OK?

[DonMicheletti]

Bloo,

It looks like your pump is upside down.

[DonMicheletti]

Bloo,

Usually those engines have a single action pump, but some have double action pumps - I think they came later. The above is my "38 Special

[Rock10]

Should be able to check the tank side of the pump for vacuum and the carb side for pressure. That will tell you if it's working.

[MCHinson]

1 hour ago, boug said:

we are working on a 1938 buick straight 8 series 90. my friend's father passed away that owned the car his name was JW PASCOE. we are having fuel problems could the lobe be worn on the camshaft, the fuel pump was sent away to get rebuilt same problem. we are getting fuel to the pump, just thinking about the lobe on camshaft. please reply thank you

Welcome to the AACA Discussion Forum. Most likely, there is an issue with the fuel tank, fuel tank pickup, or fuel line. I would suggest you try a temporary fuel supply tank to see if the fuel pump will pick up the fuel. While it is posible that the lobe on the camshaft could be worn, that would be the last thing I would suspect. I actually suggest a temporary electric fuel pump mounted near the fuel tank to be used to "prime" the system after it has been sitting for a few days or more, as well as for use to combat vapor lock in some high heat situations. 

 

Bloo is correct that your 1938 90 Series 320 engine should have a double action AC 422 fuel/vacuum pump. The vacuum and fuel circuits of the pump are separate. Since the fuel pump was removed to be rebuilt, I would double check that you have the fuel and vacuum lines plumbed correctly.

 

I would also suggest you consider joining the 36-38 Buick Club. I think you would find the newsletter helpful. You can find out more information about the club at http://www.3638buickclub.org/. If you contact me via a private message on this forum (when you have enough posts to utilize the private message function) or through the contact the webmaster link on the 36-38 Buick Club website, I will be happy to send you a sample .pdf copy of a recent club newsletter. 

[Rock10]

https://www.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html?campaignid=12144811130&adsetid=117789279118&product=62637&store=743

[38Buick 80C]

@Bloo

thanks for the tag.

 

@boug the name JW PASCOE sounds very familiar. I believe I may have knew him but not of the car specifically.

 

I agree cam lobes rarely wear out on these 320 motors. the more likely culprit is the pump, but having been rebuilt that seems odd.

 

So a couple silly questions.

1. how do you know you are getting fuel to the pump, I assume because the fuel bowl is filling (HOW? what is filling it? an electric fuel pump I assume?)

2. how do you know you are NOT getting fuel to the carb?

 

I struggled with fuel issues on my 80C with the same motor so I definitely have heard all the various things. I run an electric pump nearly full time in spite of a mechanical pump that is working seemingly properly.

[boug]

MR Pascoe was a member 36-38 club for a lot of years. his 38 Buick limousine was one of kind. it was brought across the pond and a famous coach builder re did it. 

     1. we disconnected the line at the pump, blew air in tank it filled up the filter just before the pump and trickled out.

 

     2. we disconnected the line at the carb then cranked it over nothing. we feed the carb with gas and had it running for around 3 min. after that it did not run on its own. we are going to buy a 6 volt pump 4 to 7 psi and 30gph is that the right pump to use. 

 

                thanks for the reply

Edited September 15, 2022 by boug
forgot the last part (see edit history)

[EmTee]

It sure sounds like a bad rebuilt pump...

[Rock10]

You could check the cam lobe with a dial indicator, but I have no idea where to find the travel spec.

[38Buick 80C]

5 hours ago, boug said:

MR Pascoe was a member 36-38 club for a lot of years. his 38 Buick limousine was one of kind. it was brought across the pond and a famous coach builder re did it. 

     1. we disconnected the line at the pump, blew air in tank it filled up the filter just before the pump and trickled out.

 

     2. we disconnected the line at the carb then cranked it over nothing. we feed the carb with gas and had it running for around 3 min. after that it did not run on its own. we are going to buy a 6 volt pump 4 to 7 psi and 30gph is that the right pump to use. 

 

                thanks for the reply

 

Is this the one where he made power windows regulators for the car of his own design? and several other very hidden but very highly engineered upgrades?

 

Thanks for clarifying my silly questions

 

with the pump off the car can you verify it pumps (i.e. can you hear suction when manually moving the cam rod in and out?)

[kgreen]

A pressure test from the tank to the pump will verify continuity in the fuel line, but won’t verify a leak in the line. Small rust hole or old synthetic fuel line could still be the culprit. 

[Bloo]

IMHO the best way to test a line to the rear of the car for leaks is to disconnect the gas tank and plug the line, then check from the front with a mityvac. It should not  leak down, at all.

 

If all is stock at the back, I think the line on the car has a double flare with a male nut, so you would need a fitting to accept the double flare and then a cap to seal it (with sealer on the threads of the cap of course. At the front you would probably need the fitting from your fuel pump, which probably has pipe threads, and a hose adapter for the pipe threads.

 

I would also point out that cracks in the fuel pickup tube on 30s Buicks are common. You need to drop the tank to check that. Look where the sender has a steel support crimped around the copper pickup tube. There is one place like this inside the tank and one outside. The one outside is more likely to have a crack, but check both. This assumes the gas gauge sender is the original type.

 

Edited September 17, 2022 by Bloo (see edit history)

[hook]

On 9/15/2022 at 8:59 AM, EmTee said:

It sure sounds like a bad rebuilt pump...

 

I think a bad pump. Sometimes a rebuild job only includes the diaphragm, valves and springs. No linkage replacement or pins. Also, maybe they dressed the arm that rides against the cam. If the tank fuel line proves OK, definitely try an electric pump.

[critterpainter]

IIRC there is a flex line by the starter to the frame.  If original it will have a steel braid on it.  Many bad fuel pump issues can be traced back the that flex line being plugged or cracked.  Often it won't leak fuel but it will suck air!

[37_Roadmaster_C]

20 hours ago, hook said:

 

I think a bad pump. Sometimes a rebuild job only includes the diaphragm, valves and springs. No linkage replacement or pins. Also, maybe they dressed the arm that rides against the cam. If the tank fuel line proves OK, definitely try an electric pump.

I will freely admit to preferring stock to modified, unless it involves safety, 100% of the time. With this said, I would get the stock fuel system working first, then evaluate the need for adding another failure point to the car. Electric fuel pumps have their place, but like 12 volt conversions, they are not a fix all!!!!  Ok, rant off 😇.

[hook]

3 hours ago, 37_Roadmaster_C said:

I will freely admit to preferring stock to modified, unless it involves safety, 100% of the time. With this said, I would get the stock fuel system working first, then evaluate the need for adding another failure point to the car. Electric fuel pumps have their place, but like 12 volt conversions, they are not a fix all!!!!  Ok, rant off 😇.

I said try an electric fuel pump, not replace the system with one. After proving the tank and line are good, you can use an electric pump to prove the mechanical isn't working.

[Mark Shaw]

2 hours ago, hook said:

After proving the tank and line are good, you can use an electric pump to prove the mechanical isn't working.

You will eventually need an electric fuel pump to save your battery while cranking to prime the mechanical pump for starting.  The electric will also serve to overcome vapor lock on hot days or when driving at higher altitude.  Just wire it to run from a separate switch on the ignition circuit for safety.

[hook]

21 hours ago, Mark Shaw said:

You will eventually need an electric fuel pump to save your battery while cranking to prime the mechanical pump for starting.  The electric will also serve to overcome vapor lock on hot days or when driving at higher altitude.  Just wire it to run from a separate switch on the ignition circuit for safety.

Speaking of safety. If you use an electric fuel pump on any vehicle, modern or antique, please, please for your own safety and others include an inertia switch. This will shut down the pump after an impact and prevent fuel from being shot everywhere. I will now get down from my soapbox.