Gas line priming

[Warren Watt]

I am working on a new problem. I have done a thread search to try and solve it. Maybe my search words cover too broad an area because I ended up reading about a lot of other non related issues.
To start: All of my stock fuel pumps had OLD rubber in them and I couldn't trust them. So, I bought a rebuilt unit from Midwest and traded an old one in. The new pump would not pull fuel at all. Neither would the hand prime lever. I went back over the fuel lines and made two corrections. I disassembled the pump and found that the shaft that moves with the hand lever allowed the plunger to go too high and obstruct the diaphram. I reassembeled the pump and made sure that problem wouldn't reoccur. Still the new pump wouldn't pump. I sent it back to Midwest. He mentioned that it had been bench tested but he'd look it over. I received another pump (or the same?) via UPS from Midwest. No note, phone call or email explanation...mmmm....so I'm thinking, everything must be ok. Well wouldn't you know, same results. I'm thinking of ways to help this situation out. I was able to connect up a vacuum indirectly to a long fuel line that had a see through filter installed. Turn the vacuum on and the line was full of gas in about 2 seconds. Ok, the lines are good, tank is good. Now I've got gas RIGHT next to the pump. Reconnect the lines as normal. Crank it over and over and over - no gas.....I'm thinking now that the lobe on the cam maybe not pushing the pumps arm in at all and not actuating the diaphram. But, I did see a wear mark on the pump arm when i removed it the first time.
Is there some old fashioned way to get these pumps to prime? The truck will run off a small gas can, gravity rig.
Lots of more adjustments to be done but no til I get this solved. Any ideas? I hope I am missing something basic.

[Gsmith]

Have you tried disconnecting the line at the carb and running a hose off of that to check for flow from the fuel pump? Run the hose into a clear container, might take two people. You should get a good squirt with every revolution.

[Charles Talbert]

I am working on a new problem. I have done a thread search to try and solve it. Maybe my search words cover too broad an area because I ended up reading about a lot of other non related issues.
To start: All of my stock fuel pumps had OLD rubber in them and I couldn't trust them. So, I bought a rebuilt unit from Midwest and traded an old one in. The new pump would not pull fuel at all. Neither would the hand prime lever. I went back over the fuel lines and made two corrections. I disassembled the pump and found that the shaft that moves with the hand lever allowed the plunger to go too high and obstruct the diaphram. I reassembeled the pump and made sure that problem wouldn't reoccur. Still the new pump wouldn't pump. I sent it back to Midwest. He mentioned that it had been bench tested but he'd look it over. I received another pump (or the same?) via UPS from Midwest. No note, phone call or email explanation...mmmm....so I'm thinking, everything must be ok. Well wouldn't you know, same results. I'm thinking of ways to help this situation out. I was able to connect up a vacuum indirectly to a long fuel line that had a see through filter installed. Turn the vacuum on and the line was full of gas in about 2 seconds. Ok, the lines are good, tank is good. Now I've got gas RIGHT next to the pump. Reconnect the lines as normal. Crank it over and over and over - no gas.....I'm thinking now that the lobe on the cam maybe not pushing the pumps arm in at all and not actuating the diaphram. But, I did see a wear mark on the pump arm when i removed it the first time.
Is there some old fashioned way to get these pumps to prime? The truck will run off a small gas can, gravity rig.
Lots of more adjustments to be done but no til I get this solved. Any ideas? I hope I am missing something basic.

Warren, check your private e-mail.

[Warren Watt]

Gas line

Thanks GS - I did attempt to see if there was any gas pumping out from the discharge side of the pump. The was none. Not even any air movement. After that, is when I decided to fill the gas line by vacuum method and try it again. Still no movement.

Charles - Thanks. Check your pm.

[Warren Watt]

Gas line primimg

Update on this situation.
After talking to John at Midwest we agreed to mail it back to him for another rebuild. As it turned out, the upper steel plate that sandwiches the diaphragm was the same diameter as the recess that it is supposed to go inside to allow the diaphragm to flex. Midwest rebuilt it with the correct size disc and returned it to me. I did get a phone call from John as well asking about the status. I appreciated that. Today it was warm enough to work on it. I was able to install it and sort of prime the lines by pouring gas in through a small funnel. I cranked the engine and it would start briefly and stop running. What I found next was more loose fittings in the new gas line. Tightened same. Reprime and retry. Still not getting a steady enough flow of gas to sustain the engine. What I do know at this point is that the pump does indeed pump gas when I use the hand prime lever. I can see it move into the see thru filter that is between the pump and carb. I am now wary of the cam lobe. It just doesn't seem to be actuating the pump diaphragm. Next step is to invite my mechanic / brother over and pick his brain.
Still puzzled but not giving up.....

[monkeymissile]

Warren,
you might consider calling Then & Now here in MA and talk to Tom. He helped me rebuild my pump and had all sorts of tips and tricks since he's been doing it for +30 years. Super nice guy too. Good luck

[Charles Talbert]

Update on this situation.
After talking to John at Midwest we agreed to mail it back to him for another rebuild. As it turned out, the upper steel plate that sandwiches the diaphragm was the same diameter as the recess that it is supposed to go inside to allow the diaphragm to flex. Midwest rebuilt it with the correct size disc and returned it to me. I did get a phone call from John as well asking about the status. I appreciated that. Today it was warm enough to work on it. I was able to install it and sort of prime the lines by pouring gas in through a small funnel. I cranked the engine and it would start briefly and stop running. What I found next was more loose fittings in the new gas line. Tightened same. Reprime and retry. Still not getting a steady enough flow of gas to sustain the engine. What I do know at this point is that the pump does indeed pump gas when I use the hand prime lever. I can see it move into the see thru filter that is between the pump and carb. I am now wary of the cam lobe. It just doesn't seem to be actuating the pump diaphragm. Next step is to invite my mechanic / brother over and pick his brain.
Still puzzled but not giving up.....

I see in the above post that we have talked about this issue, my problem is I no longer remember what we discussed. Anyway, I've seen the issue that you said John corrected for you before. Before making any assumptions about the cam lobe, I'd suggest removing the pump from the block & clamp it gently in a vise. Operate the cam lever while holding your finger over the fuel intake port to see if there is a good suction. Do the same at the outlet port to check for output. You should feel a good strong response at both ports. If the response isn't good, in my opinion a diaphram issue still exist. Now perform the same test using the hand primer lever. You should get the same action, even a little stronger. I have seen them pump fine using the hand lever yet no pump action at all when operating the cam lever. The fact is a longer stroke is applied by the hand lever than with the cam lever. If action is slim to none when operating the cam lever by hand, the problem lies within the pump. If the pump action is good on the bench, then you must assume the cam lever is not getting a full stroke of motion from the cam lobe. A worn cam lobe isn't a really common issue, in fact it is rather rare. If you determine that it is the problem, it can be addressed several different ways. It can be repaired or replaced. Another hardened lever contact pad can be added to the pump cam lever to restore the lost stroke also.

One other situation is this. Most rebuilders use a glass bead media in a blast cabinet to clean the pump housing components. On a couple of occassions I've seen tiny pin holes in housings as a result. This will cause the pump to not hold full prime & if bad enough not hold prime at all. This will produce exactly the action you have described.

[Warren Watt]

Prime

Thanks for the replys MM and Charles. I've been in Richmond for 3 days and working doubles for three more days / away from the computer as well. I am off Mon and Tues and will return to this problem then. I will try the bench test. I also want to pressure test the gas line from the tank connection to the pump connection just in case. I may even take all the connections apart for examination. If the line is tight, and the bench test results turn out good, I am going to reconnect everything up to the carb inlet. Instead of connecting to the carb, I'll run a hose to a bucket on the side. Then, connect my gravity fuel feed set up to the carb. Start the engine and observe to see if there is any gas coming from the pump. If not, then there is an issue on the cam lobe or pump arm. I think (?) I don't want to rule out anything and feel that this process and its eventual outcome will only make me a better informed Dodger. I hope to share the solution some day to another person who is scratching his head.
I will post next week with more. Thanks for reading and thanks for the support!!

[Warren Watt]

Glass beads

I definitely would not have thought about pinholes in the casing from being glass beaded. I won't rule that out either just in case. Thanks Charles!

[Warren Watt]

Priming update

Bench tested the unit. It did provide some suction at the inlet port when depressing the arm or the hand prime lever. Ok thats good.
Reviewed the fit of all the fuel line flare fittings, one needed a bit more tightening. Ok thats good.
Reinstall the pump, hand primed all the lines and bowl as much as possible. I have some visible gas in the see thru filter. Ok thats good.
Crank it up and start the engine. Starts up and runs for a brief time and shuts off. Ok thats not good.
The level in the see thru filter never changes. Ok thats not good.
Disconnected the gas line at the carb.
Connected the gravity feed gas line from a small can and primed same.
Started the engine and it ran fine. I expected to need to shut it off due to gas splashing out of the main gas line - not a drop comes out. Run the engine for about 5 minutes - nothing coming out. Level never changes in the see thru filter. Quit for the day and start chopping fire wood.

[712edf]

Chopped firewood. Ok that's not good.

[Warren Watt]

I like heat in the winter and low electric bills....

Splitting firewood is one of those chores like cutting grass where there is an opportunity to forget about everything else. Plus there is a tangible result at its conclusion. I have been cutting wood since I was a kid so its kinda a part of me....

Anyway, the truck runs from the gas can fine. Not a drop out of the open gas line coming from the pumps discharge side. The pump is just not working period.

[712edf]

Splitting firewood is one of those chores like cutting grass where there is an opportunity to forget about everything else. Plus there is a tangible result at its conclusion. I have been cutting wood since I was a kid so its kinda a part of me....

Anyway, the truck runs from the gas can fine. Not a drop out of the open gas line coming from the pumps discharge side. The pump is just not working period.

I'm with ya own keeping warm & lower utilities.My 93 yr old grandma busts up here own kindling and goes through 6 or so rics of firewood a winter. She actually turns the breaker off to the cental heat/ac cause that buzzing noise is wasted juice....I'm at a loss why your fuel pumps not getting 'er done.

[Charles Talbert]

Splitting firewood is one of those chores like cutting grass where there is an opportunity to forget about everything else. Plus there is a tangible result at its conclusion. I have been cutting wood since I was a kid so its kinda a part of me....

Anyway, the truck runs from the gas can fine. Not a drop out of the open gas line coming from the pumps discharge side. The pump is just not working period.

Warren, would you let me have a look at that pump? Curiosity is driving me bananas as to what's going on with it. No charge for the service, I just hope I could help you figure it out. Charles

[Bruce]

Fuel Pump Woes

Splitting firewood is one of those chores like cutting grass where there is an opportunity to forget about everything else. Plus there is a tangible result at its conclusion. I have been cutting wood since I was a kid so its kinda a part of me....

Anyway, the truck runs from the gas can fine. Not a drop out of the open gas line coming from the pumps discharge side. The pump is just not working period.

This is still holding you up, I was hoping to read it had changed?