Odd Problem With Fuel Pumps (...That's Plural)

[BloodyKnuckles]

yep check that pin it seems to be a common problem with the new ones. What should I check for?I did what you did with your fuel line. I ran it to the inner fender, back to the firewall, then forward to a T to feed the duals, but basically the same route.

Since you are handy with the tin snips, my 56 had a sheet metal plate between the carb and the manifold. It faced forward and shileded the float bowl from manifold heat. That will help with perculation while the car sits after running, and during high under hood temps. I thought about building one.But what your are describing does not sound like perculation.

Do the flow test, to assure that the pump is providing proper quantity. Pull the line from the carb and direct it into a container, have your better half crank the starter (withthe coil wire pulled) and while it cranks, count the strokes from the pump out put. At 12 strokes you should have 8 ounces of gas or more in your container. I will do this in the morning. If not the pump is not flowing as it should. looks like you have a new line beween the frame and the pump??Yes.

If I do the flow test and do not yeild the proper amount and since I am on my 4th mechanical pump should I suspect a worn cam lobe and permantly install a good electrical pump (...Holley??)?

BloodyKnuckles

[JoelOkie]

Wow, a lot been said here already. It sounds like a float adjustment issue. I guess I'd start by doing the fuel pump test Greg said, and if you have the good volume of fuel you need coming up to there then I think I would try adjusting the float out a very little at a time, see how it drives, and then try a little more, ect. and see if that helped.

If you are not getting the good volume of fuel through the fuel pump I would try hanging a hose down in to a gallon fuel cell (securely attached)right up close at the fuel pump, then if you are getting a good volume you will then know once and for all the problem is from the fuel pump back.

I have been driving the hell out of my truck every evening, in 105 degree heat, and making some pretty long pulls, and generally just pushing the dogcrap out of it, and it gets very hot in my engine compartment too, but I haven't had one issue with vapor lock , or gas boiling, or whatever, and I don't have any heat shields, or any of that, and I haven't had any start right back up issues at all. Maybe some of that stuff WILL will solve your problem, but funny how it can be an issue in one vehicle and not in another running the same type engine, carb, fuel pump, ect. , huh? Good luck. Joel

Edited July 25, 2011 by JoelOkie

[Rodney Bullock]

I wanted to ask you a question, I have been reading your post and wondered do you have a spare coil? Have you tried it? Also if your car is sitting running can you rev the motor up and it takes it without breaking up.

I had a problem with my Plymouth and found it was ignition related. My timing was advanced to far. After running it for 30 min. it just started acting up.

[greg g]

The pins ar not properly staked in. As the cam follower moves the lever the pins back out, causing either total lack of pumping, or the lever gets kanked and does not deliver a full stroke, which deminishes the fuel delivered at cruise and acc. Mark A just had a problem with his fuel pump that let the lever enter the engine and did some damage. Something came out the side of the oil pan. I git an email from him regarding this hopefully he will post his finding.

But this pin problem has happened to several members where the pin has backed out and caused either a no run situation or a poor running deal. I believe Blueskies was the first to encounter this. His solution was to reset the pin and then he fabbed a metal u shaped piece to slip over it to keep it in place.

I suppose the electric is the fix for now if that or the cam is the problem.

[38plymouth]

I had a problem with my engine running rough on acceleration and higher RPM's and it started after I rebuilt the carb. After lots of work I discovered that the new needle and seat were different lengths than the old ones so the float was not set correctly. The car drove like it lost almost all power when accelerating or cruising. It idled fine though. I set the float correctly and it solved the problem.

[Joe Flanagan]

Aren't these things staked from the factory? I believe I checked mine before I installed it and it looked like the ends were mushroomed so it wouldn't move. Now I'm feeling like I ought to pull the pump and double check.

[BloodyKnuckles]

Just a bit of an update. I adjusted the float level higher and drove it hard for a while. It didn't sputter once. I stopped and shut it off for about 25 minutes and let it get hot. Went to start it and it stumbled and stalled. I pulled the choke on and cranked it a few more times and it started. Drove back home pretty hard without any stumbling. This is all with only the mechanical pump.

I am letting it sit for about 15 minutes and will try it again.

Updates to follow.

BloodyKnuckles

[Jim Yergin]

Aren't these things staked from the factory? I believe I checked mine before I installed it and it looked like the ends were mushroomed so it wouldn't move. Now I'm feeling like I ought to pull the pump and double check.

Joe,

In the legal world, if you end up pulling it out, that would be the definition of "a reasonable doubt."

Jim Yergin

[Jim Saraceno]

I would suggest you do some diagnostic work on your fuel system. Do a volume and pressure test at the carburetor. That will tell you if the problem is in the lines or the pump. If you can determine that fuel flow is adequate, then you can move on to the next possibility.

These symptoms can be indicate fuel flow or ignition problems. Start on one system, go through all the tests and move on to the next. Most all these components can be measured for proper function. It appears you have done much replacing and little diagnosing.

The pins are not always staked. New or rebuilt, you have to make sure the pin can not work it's way out (like it did on mine one time) but that would probably stop the flow immediately.

[38plymouth]

Just a bit of an update. I adjusted the float level higher and drove it hard for a while. It didn't sputter once. I stopped and shut it off for about 25 minutes and let it get hot. Went to start it and it stumbled and stalled. I pulled the choke on and cranked it a few more times and it started. Drove back home pretty hard without any stumbling. This is all with only the mechanical pump.

I am letting it sit for about 15 minutes and will try it again.

Updates to follow.

BloodyKnuckles

I originally rebuilt my carb because it was doing that. When the engine was hot and I turned it off all the fuel from the bowl would somehow leak down the throat causing the engine to flood and start hard. The rebuild fixed it but caused the float issue that I eventually figured out.

[greg g]

for hot start, treat it like it is flooded. Push the gas pedal slowly to the floor an dhold it there while cranking. This will clear any fuel that may have perqulated into the manifold through heat expansion. If this helps, then try lowering you float level so that the float bowl actually has less fuel in it. This will leave some room for expansion before the fuel spills over. Can you see any gas on the outside of the carb where the throttle butterfly pin goes through the casting? If so this would indicate puddling of raw gas onto the butterfly and then into the intake. Which is why you need to treat the engine as if it were flooded. You said i your last post you adjusted the float up, and I am suggestiong that you maybe went a bit too far, You will need to fiddle with it to find the happy medium. the difference may be as little a 1/32 of an inch, it can be that critical between to low stumbling and too high hot start problems.

Edited July 25, 2011 by greg g

[Jim Yergin]

Greg,

I had to perform that "pedal to the floor" procedure to get my car to start last Saturday. Not as easy as it sounds with a floor mounted mechanical starter and only one right foot. Would pulling the hand throttle all the way out have the same effect?

Jim Yergin

Edited July 25, 2011 by Jim Yergin

[Jerry Roberts]

Greg,

I had to perform that "pedal to the floor" procedure to get my car to start last Saturday. Not as easy as it sounds with a floor mounted mechanical starter and only one right foot. Would pulling the hand throttle all the way out have the same effect?

Jim Yergin

Your hand throttle probably doesn't make the gas pedal go all the way to the floor , so that wouldn't do the job . You can test it though , push your gas pedal to the floor and pull out the hand throttle , does the pedal stay floored ?

[JoelOkie]

for hot start, treat it like it is flooded. You said i your last post you adjusted the float up, and I am suggestiong that you maybe went a bit too far, You will need to fiddle with it to find the happy medium. the difference may be as little a 1/32 of an inch, it can be that critical between to low stumbling and too high hot start problems.

This is exactly right...just as easy to go too far and then you are flooding. That's why I suggested going very small increments at a time. Joel

[Don Coatney]

Greg,

I had to perform that "pedal to the floor" procedure to get my car to start last Saturday. Not as easy as it sounds with a floor mounted mechanical starter and only one right foot. Jim Yergin

How do you do this when parked on a hill and the E-brake will not hold?

[oldodge41]

How do you do this when parked on a hill and the E-brake will not hold?

Left foot on the brake, right heel on the gas pedal, and ball of the foot on the starter. Been there, done that.

[BloodyKnuckles]

I'm loosing the war guys.

Everything I've done today hasn't cured all my problems. I can now drive the car with the mechanical pump but I am still having, what I believe to be, vapor lock. If it sits for 10 minutes or more it is so tough to get it to run. Sometimes not at all for long time.

Not sure what to do. I am thinking the problem is low or no fuel pressure. The pump will pull fuel into the bowl but will not pump out. I did the fuel volume test but the first test was when it was hot and nothing. I let it sit for a while and tested again. This time maybe an ounce or so in 12 strokes. Then waited a while longer and pumped about 6 ounces.

I blew out all the lines again and blew back into the tank.

Not sure what else it could be. I am thinking that it may be a worn lobe on the cam. This is an on going problem no matter what mechanical pump is in there. Maybe I need to just run a good quality electrical pump.

Any other ideas??

BloodyKnuckles

[greg g]

remove the pump and see what kind of volume you get when you work the pump manually. its possible the pump is defective. While the pump is out try to stick a dowel or something into the hole and see if there is sufficient cam action, while craking the engine with the coil wire out.

And take a page from Mark A's roadside trouble, check the gasket between the glass bowl and the pump, his was ripped and sucking air preventing proper suction from being developed. especially when trying to start. Did you check for raw as on the throttle plate or in the manifold after sitting after a while after running.

fuel should get to the pump nearly on its own. the mechaical pumps job is only to lift it to the carb. wonder if thee is a bad check valve in the pump you are using.

[Don Coatney]

Is your fuel line from the tank to the pump copper or steel? Have you replaced this line?

[Tom Skinner]

Iron Lords Rule!

Ron,

Try using Marvel Mystery Oil in your gas. I had the same problem (gas boiling) from ethanol whatever filler they dump in it these days, and my problem went away. Of course I try not to drive when its above 95 out.

I tend to drive real early in the morning on Saturday or Sundays only. I do this more to avoid the Tweeter Twitter crowd more than anything (traffic) in general because the Cell Phone crowd is growing every day. I use a quart bottle every other fill up, that is to say a pint (16oz) on every fill up.

My car seems to like a pint - as much as most of us probably do.

Tom

Huntersville NC

[Jim Saraceno]

Here are the procedures for testing a fuel pump. As you can see, you may need to do all three tests to determine where the problem lies.

As you have replaced the fuel pump several times, I'd be very surprised that that is where the problem is. I'd guess a leak or restriction in your fuel line. If you get 1 oz during one test (should be 15 pumps according to procedure) then wait a while and get 6 oz., I would guess that would indicate some dirt or rust in the line that is getting sucked into a screen, either in the pump, a filter or inside the tank.

If you get 6oz. for 15 pumps all the time, I'd say your fuel pump and line are not the problem.

But as I said before, if you're messing around with it, I'd do all three tests so you knew for sure if the problem could be in the pump or the line.

Does anyone think the fuel pump cam could actually wear that much? It's on the cam shaft and I've never heard of a cam shaft wearing out.

[Don Coatney]

Here are the procedures for testing a fuel pump. As you can see, you may need to do all three tests to determine where the problem lies.

As you have replaced the fuel pump several times, I'd be very surprised that that is where the problem is. I'd guess a leak or restriction in your fuel line. If you get 1 oz during one test (should be 15 pumps according to procedure) then wait a while and get 6 oz., I would guess that would indicate some dirt or rust in the line that is getting sucked into a screen, either in the pump, a filter or inside the tank.

If you get 6oz. for 15 pumps all the time, I'd say your fuel pump and line are not the problem.

But as I said before, if you're messing around with it, I'd do all three tests so you knew for sure if the problem could be in the pump or the line.

Does anyone think the fuel pump cam could actually wear that much? It's on the cam shaft and I've never heard of a cam shaft wearing out.

Excellent procedure! Thanks for posting. I have never actually seen a cam failure where the fuel pump rides but I have heard old mechanics talk of such. I think it is very rare.

Hard to tell from this picture (and what I dont know is) does the cam have a special lobe for the fuel pump or does it ride on a valve lobe? If it rides on a valve lobe then I would think there would be a valve problem in addition to the fuel pump problem if that lobe failed. Anyone have an answer?

[Plymouthy Adams]

it's not uncommon to get wear anywhere metal to metal contact is made but with both surfaces smooth and hardened and the spring tension light (in comaprrison to the valve spring) it is not a common failure

[Don Coatney]

it's not uncommon to get wear anywhere metal to metal contact is made but with both surfaces smooth and hardened and the spring tension light (in comaprrison to the valve spring) it is not a common failure

True the spring tension is much less on the fuel pump but does the fuel pump have a dedicated lobe?

[Niel Hoback]

Yes, there is a separate narrow lobe just for the pump. You can feel it with a long finger.