chris_kriner Posted August 29, 2021 Share Posted August 29, 2021 Question: I am starting out with a new mechanical fuel pump. Other than putting on a PSI gauge to see what I am getting. I have a sneaky suspicion that I am not getting the correct PSI... Correct me if im wrong is like 2 or 3 max. Now.....My question is there a adjustment on them? Could the rod that is going down into the block be worn over time and not getting the correct, or was once the full rotation? lift? extension? (Not sure of correct term) to fully work that diaphragm to achieve the right PSI. I hope this makes sense. Thoughts? Thank you every one in advance..... Link to comment Share on other sites More sharing options...
edinmass Posted August 29, 2021 Share Posted August 29, 2021 My guess would be two or three pounds. Not familiar with your particular pump, some have adjustable stroke and settings. Look at a National service book......it will have your pump in it. 1 Link to comment Share on other sites More sharing options...
19tom40 Posted August 30, 2021 Share Posted August 30, 2021 The pressure should be between 1.5-3.5lbs. The rod stroke is around 1/4". The pressure is controlled by the fuel pump return spring and the stroke of the push rod. A good rule of thumb is to replace the pushrod when you replace the fuel pump. Boose-Herrel has the pushrod. Fuel pressure is not very critical on a carbureted engine. You need just enough pressure to prevent vapor lock and to overcome the float pressure. Most new pumps deliver around 3 lbs of pressure with a 1/4" stroke. Fuel volume is important. Insufficient fuel volume can lead to missing under load or going up hill and hard starting. The pushrod can affect the fuel volume as well as other items in the supply side of the fuel delivery. 2 Link to comment Share on other sites More sharing options...
chris_kriner Posted August 30, 2021 Author Share Posted August 30, 2021 Thanks Tom! I'm getting to the nitty gritty and last resorts of why she spits and sputters. I have rebuilt the tank, new lines, plugs. wires, rebuilt carb. coil and had the distributor timed. I was thinking it may need a helper 6v pump (as u seen in my other threads I posted) Added a new clear in-line fuel filter and even though glass bowl is full...watching the filter it never fills up...and dribbles in while running. Yes a lil faster when revving the engine. But with out putting on a psi gauge, I don't know what I have, BUT Sure doesn't look like 2 or 3 pounds. And NO I did not replace the rod when the new pump was installed. I will call Chris at Boo's.....This is why I was asking because I have seen some chats that they wear down down over time.....hence not getting a full stroke and fully moving that diaphragm in pump up and down like it should. Being a new pump I shouldn't have to mess with the spring? If I do, What would I do? Wish there were videos lol thank you for the info and will look into that! Thank You! Link to comment Share on other sites More sharing options...
19tom40 Posted September 1, 2021 Share Posted September 1, 2021 Chris, IMHO adding a fuel filter just adds to the problems with fuel delivery. You add 2 or more connections that can lead to the pump sucking air instead of fuel. Here is a section on fuel delivery from an article that I wrote 10 years ago. Insufficient fuel delivery: This condition shows up when driving at highway speeds as a miss or the engine dies. Vapor lock occurs when the fuel pump output pressure is very low and the engine is hot. It is much rarer than commonly thought. Most cases of suspected vapor lock can be attributed to another problem such as a weak coil or condenser, but can be caused by a weak fuel pump. To determine if you really have vapor lock, remove the air cleaner and look in the bowl of the carburetor, while operating the accelerator linkage. You should see two streams of gas in the carburetor if you don’t, you have a fuel pump problem. Fuel pump pressure is controlled by the return spring under the diaphragm, too little pressure means the spring is weak, too much pressure means the wrong spring was used. Pressure should be between 1.5 - 3.0 lbs at all engine RPMs. Too much pressure will not allow the float to control the amount of fuel in the carburetor bowl, low pressure will affect fuel delivery. To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas. Insufficient fuel delivery can be caused by a vacuum leak, plugged flex line, worn pivot in the pump arm, stretched diaphragm, plugged fuel line or tank pickup, plugged tank vent or wrong gas cap or a worn push rod. 2 Link to comment Share on other sites More sharing options...
chris_kriner Posted September 1, 2021 Author Share Posted September 1, 2021 Tom, I will look into that. Talked to Chris at Boo's and got a new rod coming to me. He did mention to me..."Boy I hope your bushing isn't bad".... Looked into that and what it takes to change that. UMmmm no thanks! I hope not to! Does not look fun to do. I will keep you updated on issue! Thank you. Link to comment Share on other sites More sharing options...
chris_kriner Posted September 4, 2021 Author Share Posted September 4, 2021 UPDATE........Received fuel pump rod and changed them out. Still Sputters but not as bad.....it was worn down a little as you can see in picks. Worth a shot changing and learned something doing it. Link to comment Share on other sites More sharing options...
JFranklin Posted September 4, 2021 Share Posted September 4, 2021 (edited) Does the new rod give the pump its proper stroke? After re-reading your initial post I would say you should be more concerned with the pump output than PSI. Edited September 4, 2021 by JFranklin (see edit history) 2 Link to comment Share on other sites More sharing options...
chris_kriner Posted September 4, 2021 Author Share Posted September 4, 2021 I would say it got it closer. maybe a better psi. All the things I read even the wafer thin gasket can effect the proper lift/stroke. As you can see my rod was worn down flat as the other has a tapered top. I had to at least check it to see. I still think I have a sneaky suspicion my timing is off. I cant think what else it could be... What bothers me, is that I had it sent out to be all set up after the rebuild (distributor) and new rebuilt coil...... Link to comment Share on other sites More sharing options...
Ray500 Posted September 4, 2021 Share Posted September 4, 2021 And you have to watch that the diaphragm in the fuel pump isn't leaking gas into your crankcase. They do fail and that will thin your oil which is a problem. Newer cars solved that problem with electric fuel pumps, but the older engines with manual ones can be an issue. If your crankcase is increasing in volume you might have a fuel leak in the pump! It sits right on top of the oil intake. Time for a new fuel pump! 1 Link to comment Share on other sites More sharing options...
19tom40 Posted September 4, 2021 Share Posted September 4, 2021 Chris, what are your symptoms and what have you tried to eliminate them? Did you do the fuel delivery test? Does it miss when going up hills? Does it cut out when going around corners? Does it bog down when you try to accelerate? You can buy a vacuum and fuel pump pressure gauge for less than $30 and it is a good tool to have in your garage. It will tell you if your carburetor is adjusted correctly, your timing is correct, or if you have internal engine problems. Link to comment Share on other sites More sharing options...
chris_kriner Posted September 5, 2021 Author Share Posted September 5, 2021 Tom.... Note** over drive is unhooked...But I dont think that would have anything to do with it. Starting off in 1st gear. all the way through the rev range to bring it to 2nd. it will sputter. In 1st-2nd and 3rd. It cuts out like its starving for gas. (hope this makes sense) RRrrrrrrrrrrrrr..sput..RRrrrrrr sput sput....RRrrrrrrrrrrrrrrr in to 2nd....same thing all the way into third till I reach 45 or level out. At that point I have no over drive gear to give me that "next gear" and I have 4:44 rear gears so anything over 45/50 shes screaming. NEW or rebuilt: Gas tank fuel line Fuel Pump (new) Carb (rebuilt) Coil (rebuilt by skip) Distributor rebuilt and Sun tested timed and dwell with new condensers Plugs and plug wires Link to comment Share on other sites More sharing options...
19tom40 Posted September 5, 2021 Share Posted September 5, 2021 If I interpret your post correctly, the engine starts missing at high rpms. Fuel pressure would not be as critical at high rpms as it would be at low rpms. The fuel pump only needs enough pressure to overcome the float pressure. Float pressure would be at its highest during low rpms because the bowl would be closer to full. Fuel starvation at high rpms can be caused by the fuel level in the carburetor bowl being too low. The causes of this can be that the pump is unable to deliver enough fuel or the float level in the carburetor being too low. As I said in my article "Insufficient fuel delivery can be caused by a vacuum leak, plugged flex line, worn pivot in the pump arm, stretched diaphragm, plugged fuel line or tank pickup, plugged tank vent or wrong gas cap or a worn push rod." If you are not delivering enough fuel, you should check to make sure that the fuel line from the tank has all of its fitting tight. The fuel line should be a copper coated steel line, rubber fuel injector lines are made to hold pressure not vacuum. The flex line from the pump should be one made for the car, not a fuel injector line with hose clamps. Next check the gasket for the sediment bowl. I like the rubberized cork gasket as they seem to seal better and hold up better. If your is the rubber gasket, make sure that it is pliable and that the bowl is seated on the gasket. Next, check the float bowl fuel level. Start the engine and let it idle for a couple of minutes. Then shut it off, and remove the top of the carburetor. The fuel level should be about 1/8"-1/4" lower than the hole for the accelerator pump. If it is more than this adjust the float to raise it. Have you tried pulling out the choke about 1/4-1/2 way to see if that improves the performance? If it doesn't, you may have ignition problems. Link to comment Share on other sites More sharing options...
chris_kriner Posted September 5, 2021 Author Share Posted September 5, 2021 I am going to have to make a video. Hahahhah All that is new..I did check and sealed....Yes metal fuel line from tank. Sediment bowl is always full! No issues there! Only "Flex" hose I have is about 3 inches from hard line from firewall to pump. I know you said you dont like it but I have a inline fuel filter. Then from pump to carb is hard lined again. (Video to come i guess)............BUT...... I had a thought (gets me in trouble at times) When I hade looms off and re wired the looms with new spark plug wires I disconnected the coil/over drive and temp gauge that runs through the looms as well. When I reconnected them I accidently rewired the left bank coil wire to the heater temp gauge. Resulting in my temp gauge not working and only 1/2 my engine running. (right side) I soon discovered what I had done and corrected the issue. Temp gauge works again and all cylinders are firing. BUT MY THOUGHT IS..... When I reconnected the left and right bank wires from the coil up into the spark plug loom, out the end and into the correct wire they were connected too, what if I have those backwards? Would that make a difference? On how it fires? Does that make sense what Im saying? Lets say the one wire off the coil/condenser (lets say right side) up through the loom into main wire harness but I accidently hooked it to the "Left side" wire...instead of the right side????? Link to comment Share on other sites More sharing options...
ralphnof49 Posted September 6, 2021 Share Posted September 6, 2021 My 47 has an electric pump near the tank, as well as the mechanical one on the engine, so when the engine is starving for fuel at higher speeds I turn on the electric pump and it runs good again. 1 Link to comment Share on other sites More sharing options...
19tom40 Posted September 6, 2021 Share Posted September 6, 2021 Are you asking if the primary wire to the left side coil is switched to the right side coil would make a difference in running? If that is your question the short answer is NO. The feed from the ignition switch to the ignition resisters is common to both resisters and both resisters should be identical. I was not concerned about not enough fuel in the sediment bowl, but how the gasket seals the bowl to the vacuum from the fuel pump. This could be a source for insufficient fuel delivery. I suggest that you do the fuel delivery test, so you can eliminate concerns about fuel starvation. Link to comment Share on other sites More sharing options...
chris_kriner Posted September 6, 2021 Author Share Posted September 6, 2021 Got it...Ok I will next time I am by car. Its stored 2 hours away from me. And yes that was what I was asking. Link to comment Share on other sites More sharing options...
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