&#039;59 American FH: fuel pump mystery

Thanks(0)

Quote

Topic: '59 American FH: fuel pump mystery
Posted: Jul/19/2017 at 12:09pm

-Yesterday, I went to start this car: no fuel to carb. After trying many things (besides changing to another pump), I hooked up a gas can and hose to the fuel pump inlet. The pump would not pull the gas until I 'primed' the line by getting a flow established by suction. Once the hose had flow, I hooked up to the pump inlet, the pump worked fine. Once the pump began working, I reconnected the line to the car gas tank and the pump worked as usual.

-Today, it starts just fine.

-This seems to be a summertime phenomena, and it occurs if I have not driven the car for a couple of days, perhaps a week. It also happens on my other '59 American, too. That pump, though, seems to have enough strength to pull the gas from the tank, although I do not let that one sit as long (I use it much more often).

-We've had weeks of 95+ heat. Presumably the gasoline has evaporated out of the carb, pump and lines.

-While I could begin a habit of starting each car each day to get fuel flow established, I would really like to know if there is something wrong with the one pump.

-The 'pulsating' diaphragm on this particular pump was disintegrated last summer. This is the diaphragm on the top of the pump, just above the check valves. I replaced it with a non-fabric-reinforced buna-n rubber piece I cut to fit; this diaphragm is now a bit domed and I should get the right raw material from McMaster Carr to make a replacement. For now, it works.

-The gas tank was removed and coated with a bake-on by a reputable outfit here; the product is called 'Gas Tank ReNu' and is warranted.

I hate to just replace parts to see if that will work. It may be that another pump will just do the same thing.

Any thoughts? Experiences?

Thanks, in advance!

As usual,

Pete

tyrodtom

AMC Addicted

Joined: Sep/14/2007
Location: Virginia
Status: Offline
Points: 6213

Post Options

Quote tyrodtom

Thanks(1)

Quote

Posted: Jul/19/2017 at 12:35pm

The check valve in the pump isn't closing tight, it letting the fuel in the line drain back to the tank .

Taking the pump apart again, and removing and cleaning both check valves might help, or if you can get new ones replace them.

66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.

tufcj

Supporter of TheAMCForum

Supporter of TheAMCForum

Joined: Jul/10/2007
Location: Watkins, CO
Status: Offline
Points: 4086

Post Options

Quote tufcj

Thanks(0)

Quote

Posted: Jul/19/2017 at 1:07pm

If it's a vacuum wiper pump, I have a rebuild kit with neoprene diaphragms. I bought it for a pump that ended up not being rebuildable due to other internal damage. Kit was $69 + shipping, I'd let it go for less.

Bob
tufcj

69 AMX
74 Javelin AMX
67 Rogue

If you need a tool and don't buy it...
you'll eventually pay for it...
and not have it.
Henry Ford

pwreimers

AMC Apprentice

Joined: Dec/16/2012
Location: Salt Lake City
Status: Offline
Points: 101

Post Options

Thanks(0)

Quote

Posted: Jul/19/2017 at 3:27pm

tyrodtom wrote:

The check valve in the pump isn't closing tight, it letting the fuel in the line drain back to the tank .

Taking the pump apart again, and removing and cleaning both check valves might help, or if you can get new ones replace them.

That's a great idea. It looks like I've got some work to do. I just wish it wasn't 95 degrees out there! Maybe I can test that by putting an inline check valve on the fuel line, just upstream of the pump.

farna

Supporter of TheAMCForum

Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19676

Post Options

Quote farna

Thanks(0)

Quote

Posted: Jul/20/2017 at 6:54am

The in-line check valve should work. I think I'd put it in the line between tank and pump though, close to the pump.

Frank Swygert

pwreimers

AMC Apprentice

Joined: Dec/16/2012
Location: Salt Lake City
Status: Offline
Points: 101

Post Options

Thanks(0)

Quote

Posted: Jul/21/2017 at 12:19am

Well, this did not work out. Here's the check valve I used, from Grainger: https://www.grainger.com/product/GRAINGER-APPROVED-1-4-Ball-Cone-Spring-Check-4DHY9

It cracks at 1 psi, is made of nylon with a buna-n seat & ss ball. $5 is a very fair price.

I installed it just upstream of the fuel pump inlet in the problem car, which worked at idle. Installed in the workhorse car, same result.

A little later I moved the problem car and it stalled out. I have to return to that.

I needed to get groceries and took workhorse out, which stalled within a couple of miles. I removed the check valve and it ran as usual.

All I can figure is these pumps can't handle that upstream 1 psi load.

$10 to find that out isn't a real problem, but it's a little surprising.

Maybe it's fuel pump rebuilding time?

Honestly, the idea of disconnecting the fuel pump line while the motor runs, and timing how long it takes to fill a one quart jar, scares the beejeesus out of me. Is there another way to test the pump performance?

As usual,

Mystified but determined Pete

Edited by pwreimers - Jul/21/2017 at 1:02am

tyrodtom

AMC Addicted

Joined: Sep/14/2007
Location: Virginia
Status: Offline
Points: 6213

Post Options

Quote tyrodtom

Thanks(0)

Quote

Posted: Jul/21/2017 at 8:40am

You can do the fuel pump test while it's cranking, it won't take long to fill a 1 quart jar.

Use someone inside to turn the switch, or get a remote start switch that hooks to the solenoid, only $10-$15 at NAPA.

66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.

tomj

AMC Addicted

Joined: Jan/27/2010
Location: earth
Status: Offline
Points: 7544

Post Options

Quote tomj

Thanks(0)

Quote

Posted: Jul/21/2017 at 11:11pm

i'd just bite the bullet and rebuild the pump (though i too enjoy and learn from experimentation). its unlikely that only that one checkvalve is dead. you only need to build them every decade or two or three.

that pump should put out 3 - 7psi which ought to overcome the 1 psi. i found that two check valves in series interact in weird ways. found that out with LPG where the pressures are much higher.

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

pwreimers

AMC Apprentice

Joined: Dec/16/2012
Location: Salt Lake City
Status: Offline
Points: 101

Post Options

Thanks(0)

Quote

Posted: Jul/22/2017 at 12:06am

tyrodtom wrote:

You can do the fuel pump test while it's cranking, it won't take long to fill a 1 quart jar.

Use someone inside to turn the switch...

I am a bit embarrassed; your post encouraged me to re-read the TSM, which I should have done in the first place. BTDT? They have two tests and the flow rate one sounds much safer than my imagination!

tomj wrote:

i'd just bite the bullet and rebuild the pump (though i too enjoy and learn from experimentation). its unlikely that only that one checkvalve is dead. you only need to build them every decade or two or three.

that pump should put out 3 - 7psi which ought to overcome the 1 psi. i found that two check valves in series interact in weird ways. found that out with LPG where the pressures are much higher.

I never thought about being in the flow path between two check valves. It would be interactive, no doubt; they would have strange manifestations: one opens, the other closes...

Sometimes experimentation seems the hard way; hopefully it gives definitive results, whereby only one conclusion becomes known. A good experiment eliminates unknowns properly.

You're right: it's just plain rebuilding time...I'll do the flow and pressure tests, though, just to see. I just like that stuff!

I do not understand the 'pulsating diaphragm' sitting above the check valves on top of the fuel pump. Does that diaphragm really need to be anything more than a seal to prevent flow from one side to the other? Isn't the flow path on the other side of the check valves?

Thank you!

Pete

Edited by pwreimers - Jul/22/2017 at 12:14am

pwreimers

AMC Apprentice

Joined: Dec/16/2012
Location: Salt Lake City
Status: Offline
Points: 101

Post Options