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

[Don Coatney]

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

Then it is really hard to invision how that lobe could fail with the light spring pressure from the pump.

[greg g]

I believe that the fuel pump lever is activated by the lobe of a valve cam when it is at the bottom of its rotation.

[Jim Saraceno]

The fuel pump has its own cam between cylinders 1 & 2. The oil pump gear is between 3 & 4.

[Don Coatney]

I believe that the fuel pump lever is activated by the lobe of a valve cam when it is at the bottom of its rotation.

So what happens when it swings to the top of its rotation?

[Don Coatney]

The fuel pump has its own cam between cylinders 1 & 2. The oil pump gear is between 3 & 4.

Excellent picture. Thanks.

[Alshere59]

This picture shows the lobe right between the 1st and 2nd cylinder for general information.

Edited July 26, 2011 by Alshere59
Ok duplicate post oh well had to resize.

[Joe Flanagan]

Ron, have you disassembled the carb and examined it? I wonder if maybe something isn't amiss there. Seems like the fuel pump is not looking like a good suspect at this point. In an earlier post you said you replaced the rubber lines and I know you said the hard lines looked good but are they original?

[greg g]

Well if it were a regular cam lobe, it would open the assigned valve, but it has been shown that is not the case.

[Young Ed]

That lobe for the fuel pump is like Don C-eccentric. And I also agree with Don I've heard of supposed failures but I've never seen one in person.

[BloodyKnuckles]

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

The line is steel and I did not replace this line. When I cut the line to install the electric pump the inside of the line looked perfect.

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

Thanks Tom. I will try that. You know I drive my cars whether it's 15* or 105*. I have to get this right.

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.

I thought it was 12 pumps but it wouldn't have made much difference in my case as of now. I will do all 3 tests.

Thanks

BloodyKnuckles

[BloodyKnuckles]

Ron, have you disassembled the carb and examined it? I wonder if maybe something isn't amiss there. Seems like the fuel pump is not looking like a good suspect at this point. In an earlier post you said you replaced the rubber lines and I know you said the hard lines looked good but are they original?

I believe the hard lines to be original.

Guys, I can't thank you enough for continuing this discussion and assisting me to diagnose this issue. All of you have been a big help.

One of the things I find odd is when the car is hot it does not want to start and run but when it is cool, like in the morning, it will fire right up and run great.

When I get back from Pittsburgh next week I will change out all the hard lines and rubber lines, cover the lines in the engine bay with thermal protection and remove the pump and inspect and do the tests.

Even though I didn't get this squared away for this trip, I have to get it running before the end of August. I plan on a run to Charleston, SC for Heather's birthday.

Again, without this great forum and great guys I would be hard pressed in figuring this out. Thank you very much.

BloodyKnuckles

[Cpt.Fred]

what Joe said.

i just cleaned my carbs for the second time with compressed air,

but it doesn't seem to do the job like ultrasonic or hot tank cleaning would.

still acting up.

maybe some tiny passages in your carb are closed with some kind of crud?

i'm really curious what it will be in the end.

fred

[Cpt.Fred]

by the way, just came to think of it:

i had the same problem with an old opel once, wouldn't start when hot

but came to life immediately when it sat for a while.

back then i found out it was the coil.

[Joe Flanagan]

I think the coil was only briefly mentioned in this thread. Bad ones will act up when they get hot, as we know. I wonder if you've got an extra you could switch in just for kicks. I had one go bad on my old Toyota pickup (which I'm still driving 23 years later, by the way) and once I let it cool down it not only operated normally, it also tested good with an ohm meter. But once I got the engine up to temp, all hell would break loose.

[Plymouthy Adams]

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

yes Don it is a dedicated lobe..typically (at least to my limited experience) most cars with a fuel pump mounted on the block itself it will have the diedicated lobe on the cam..for those engines where the pump is mounted on the timing chain cover these are usually driven by an eccentric mounted on the cam gear and are replacable

[BloodyKnuckles]

I think the coil was only briefly mentioned in this thread. Bad ones will act up when they get hot, as we know. I wonder if you've got an extra you could switch in just for kicks. I had one go bad on my old Toyota pickup (which I'm still driving 23 years later, by the way) and once I let it cool down it not only operated normally, it also tested good with an ohm meter. But once I got the engine up to temp, all hell would break loose.

by the way, just came to think of it:

i had the same problem with an old opel once, wouldn't start when hot

but came to life immediately when it sat for a while.

back then i found out it was the coil.

The coil would be considers but after the engine is hot there is no gas in the carb or fuel line from the pump. The pump bowl is full but it won't pump to the carb when hot. When it's cool it will fire and run, no problem.

BloodyKnuckles

[Alshere59]

Well I don't see it mentioned but have you checked to see what your temps are? Temperature gages are not very reliable IMHO. Seems to be related to under hood temperatures from what I am reading. Wonder what they are. Radiator blocked etc.. Mine always goes up allot after I shut it off and some on the highway as well. Its cheap and easy to look at.

[55 Fargo]

Well I don't see it mentioned but have you checked to see what your temps are? Temperature gages are not very reliable IMHO. Seems to be related to under hood temperatures from what I am reading. Wonder what they are. Radiator blocked etc.. Mine always goes up allot after I shut it off and some on the highway as well. Its cheap and easy to look at.

I dunno about this, yes if your engine coolant temp is close or at 200, then things start to happen.

You can get these conditions at 170-180 degrees engine temp, especially when the engine are underhood, is as hot as the ole gas BBQ.

I hope Bloodyknuckles finds the problem, but why not just run the electric fuel pump with a return line, especially if it is working, thats what I would do.

All these engines jump up in the temp department when you shut them off, I just came back from a ride, engine temp 160, it rose to 170 when shut off for 10 minutes, but as soon as I started the engine it cooled down to 150. So rise in engine temp when shut off is completely normal.

I choose to run my engine with a 160 t/stat, and it stays at this temp even at 80 f, at 90 and above she will climb to about 170 or so, and then the underhood temps really rise too.

I think those that have converted to 12 volt systems, get these engines spinning better, when is hot outside. I still run 6 volt, and have no immediate plan to convert...........Fred

[Joe Flanagan]

The nice thing about a worn out cam lobe is that it would explain everything. The bad thing about a worn out cam lobe is . . . a worn out cam lobe.

[Niel Hoback]

A worn cam lobe would produce the same results hot or cold. I believe the complaint was about hot operation?

[JoelOkie]

The nice thing about a worn out cam lobe is that it would explain everything. The bad thing about a worn out cam lobe is . . . a worn out cam lobe.

I wonder how many miles you have to drive to log enough time on an engine to wear one out.

[JoelOkie]

The coil would be considers but after the engine is hot there is no gas in the carb or fuel line from the pump. The pump bowl is full but it won't pump to the carb when hot. When it's cool it will fire and run, no problem.

BloodyKnuckles

Sounds like the float is sticking when it gets hot and won't let the gas through the needle valve.

[55 Fargo]

I wonder how many miles you have to drive to log enough time on an engine to wear one out.

diddo, no doubt, would be tough to wear that one down. But hey, I think everyone is trying to come up with a rational idea of what is taking place for the blood man.

I totally agree with your earlier post Joel, on the procedure for starting a hot flathead engine........

[JoelOkie]

no doubt Fred...It would be good if there was a guy or two that lived near enough to go over and help check everything in person.

[Don G 1947]

3rd lobe over from your finger. The one that looks round in your picture.

Don