Unable to get fuel from the tank to the fuel pump

[callahat]

I just replaced the fuel pump in my 48 Special Deluxe. I was sent the wrong gasket for the glass fuel bowl and attempted to substitute something else. Of course it didn't work but the point is the engine ran quite well although the fuel bowl leaked. I replaced the fuel bowl gasket and started the engine. It ran just fine but while I was under the car checking for leaks the engine stopped. I looked and the glass fuel bowl was empty. I removed the fuel line from the tank to the inlet side of the pump and blew air back into the tank. I could hear it bubbling so I knew air was at least getting back there.  I still cannot get any fuel to come out though. My next step will be to drop the tank and see if anything is blocking the outlet point inside of it. Does anyone know what could cause a running engine to stop like this and why I can’t now get fuel from the tank to the pump when I could before? Thanks.

[casper50]

if the line is clear from the tank to the pump and there's gas in the tank, then it's most likely the pump, new or not

Edited July 17, 2014 by casper50

[Barabbas]

FWI--I had a "new" fuel pump last about 30 seconds last fall, returned it to Rock Auto and used a rebuilt kit from Antique Auto parts Cellar on my old pump. 

[Don Coatney]

The fuel pump will not pump air. You most likely have a leak in the fuel line between the tank and the pump.

[_shel_ny]

You can try connecting the inlet side of the fuel pump to an alternate source of fuel ( 1 gallon gas can with a line stuck in it) to confirm pump operation.

If you get fuel that way then your pump is probably OK, and will need to look in the air/leak direction Don has pointed you.

 

If it does not pump fuel from an alternate source you may have fallen victim to the arm pivot pin failure.

 

Do you have a non-vented gas cap installed? Do you get fuel in the bowl with the cap off?

 

Wasn't bad before, can't be bad now.

Edited July 18, 2014 by shel_ny

[48ply1stcar]

1.  Start by removing the cap as Shel_ny stated.  When I bought my car in 1968 the prior owner put a after-market locking gas cap on.  I guess he couldn't afford to lose any of that 35 cent gas.  But the piont is that I ended up having an electric fuel pump installed because the pump was weak.  I removed the electric fuel pump and the non-vented gas cap 38 years later and the pump still works, I think.

 

2.  If that doesn't work try sucking the gas out of a gallon gas tank.

[linus6948]

When I had to redo my fuel system I had a similar problem getting fuel from the new tank thru the empty lines to the fuel pump. I used something I read on jalopy journal to use an air compressor line to gently pressurize your system and push fuel up to your pump. It worked like a charm, I removed the inlet line to the fuel pump and waited for the fuel to arrive. 

 

 

 

Paul

Edited July 18, 2014 by linus6948

[Lloyd]

When I was in high school I put a set of points and condenser in once, started it up and it idled rough. Checked the points twice, then the cap, then the plugs. All looked good. Took a look at the timing marks and they were jumping a bit. Must be a timing chain. Dropped the front cover, looked OK, went ahead and replaced the chain and cam gear anyway. Got it back together, started it up and it still had a miss. Occurred to me that it all started when I replaced the points and condenser. Popped the cap and while I was poking at the points I bumped the condenser. It was loose, I had forgot to tighten it down..

Not saying you might have forgot something but, taught me to go back to the last thing I did before it started having problems. If there wasn't anything wrong with all that other stuff before then probably aint nothing wrong with it now.

[Jeff Balazs]

The fuel pump will not pump air. You most likely have a leak in the fuel line between the tank and the pump.

Actually most diaphragm type pumps do not have a problem moving air ....... you just can't run on it. I suggest you have a blockage between the tank and the pump.

Jeff

[Plymouthy Adams]

the original poster has gotten some very good replies...lets wait and see how he takes and uses this information in troubleshooting and if he reports back the results of his efforts now armed with things to check..actually he has not come back to check his question for answers per the data base history log

Edited July 18, 2014 by Plymouthy Adams

[Young Ed]

One other thing we've ran into many times. The pumps have a hard time getting primed off the engine cranking. Running the engine while dripping gas into the carb until it pumps up will fix that.

[Don Coatney]

Actually most diaphragm type pumps do not have a problem moving air ....... you just can't run on it. I suggest you have a blockage between the tank and the pump.

Jeff

Path of least resistance. Pump will pump air before it pumps liquid as air is (somewhat like me at times) less dense.

[Lloyd]

How much air could a fuel pump pump if a fuel pump could pump air?

 

Honestly, don't know about fuel pumps but do know something about diagram pumps vs rotary or centrifugal pumps.

Rotary and centrifugal pumps need a prime, sort of an assistance between to seal the gap between the vanes and the housing although a centrifugal pump creates a suction at the inlet - still either one will not pick up a prime unless the pump chamber is full. A diagram pump does not need a prime. It will pull air until the product is pulled into the chamber. Self priming..

 

Since we are o the topic of fuel pumps, something I have wondered about.. What is the difference between a single action fuel pump and a double action fuel pump.?

[TodFitch]

Since we are o the topic of fuel pumps, something I have wondered about.. What is the difference between a single action fuel pump and a double action fuel pump.?

 

I believe that a double acting fuel pump has two parts: One to pump fuel and the second a vacuum pump for keeping the wipers moving when manifold vacuum is insufficient.

[callahat]

Wow this is a ton of information. I will print these answers and go back out and try each one. It may take several days depending on my small grand kids needs. I will report back though. Thanks again for the advice.

[linus6948]

During my fuel system redo I replaced my varnish clogged fuel pump with a NOS AC pump one of two AC`s  that I got with the car, there was even a receipt from 1980 when it was bought. The car ran for 10 mins. then quit, I hadn`t yet rebuilt the carb so I figured that was what stopped the car. I rebuilt the varnish and gunk clogged carb going by Mike`s Carburetor videos and when I primed the bowl the car started right up then quit. After doing this several times I called Mikes Carb and spoke to Mike and wanted to send my carb to him for a rebuild. Instead he made me tell him my whole story and he told me it was the fuel pump. I "gently" argued that it was a new one 10mins old so I disagreed and he "gently" snapped back at me that he trying to save me from an expensive carb rebuild and go out and replace my "new" fuel pump.

Well I`m old enough to listen and took his advice and he was right on the money, the second pump went in and she started right up, he also made the arrangements to have my carb dashpot rebuilt with one of his competitors in Fla. I can`t say enough good things about the man, a hell of a nice guy.

Edited July 18, 2014 by linus6948

[Lloyd]

I believe that a double acting fuel pump has two parts: One to pump fuel and the second a vacuum pump for keeping the wipers moving when manifold vacuum is insufficient.

No kidding. Never would have guessed it. Figured the double action had to be an upgrade from the single action.

So a double action pump has a vacuum connection as well.

[desoto1939]

 SO: Basically anyone contemplating buy a NOS fuel pump should consider the age of the Pump First.

The NOS old fuel pumps can be almost 60-70+ years old.  The old rubber diaphram willnot support the newer based gas with the ethinol.  They will still need to be rebuilt with a newer diaphram that will work with the newer gasolines. 

 

So if you can pick up even a rebuilt pump it more or less and I go with the more, that it still willneed to rebuilt becasue you do not know when it was rebuilt and the type of diaphram that was used, unless the current seller can tell you that it was rebuilt within the last year or so and also did not use a kit that was on soneones self for the past 50 years.  If you are buying from a reputable rebuilder then you have a good shot of being new materials.

 

I would only purchase a NOS pump and I mean OLD NOS pump just for backup parts only.  Instead of purcasing these pumps get a backup electric 6v inline pump as a fail safe.  Then get a brand new Airtex 73201 if replacing the old 588, (Airtex 73201 is the replacement pump for the AC588 that was used on our cars and trucks.). Have that in your truck or behind the seat in your truck.

 

Then you willbe good to go.

 

Rich HArtung

Desoto1939@aol.com

[Jeff Balazs]

One thing that has not been discussed here is the internal condition of the metal fuel line. When I tore the one out of my truck which had been sitting for many years it was full of scale chips and rust particles. I could easily see how this could pack up into a bend or fitting and either completely block flow or severely restrict it.. It you were to put air pressure on it from the pump side it might push it back into the tank...... or it could just move it back some only to have it stop up in the same spot again. Maybe act kinda like a check valve?

 

Jeff

[deathbound]

One thing that has not been discussed here is the internal condition of the metal fuel line. When I tore the one out of my truck which had been sitting for many years it was full of scale chips and rust particles. I could easily see how this could pack up into a bend or fitting and either completely block flow or severely restrict it.. It you were to put air pressure on it from the pump side it might push it back into the tank...... or it could just move it back some only to have it stop up in the same spot again. Maybe act kinda like a check valve?

 

Jeff

 

I believe in the first post, he removed the fuel line @the pump inlet & blew air through the line & heard bubbling in the tank.

[Jeff Balazs]

I believe in the first post, he removed the fuel line @the pump inlet & blew air through the line & heard bubbling in the tank.

Yes I saw this but that does not mean that the line is absolutely clear and clean of debris when fuel attempts to flow in the correct direction. All it would take is a few loose chips of debris that pack up against a rough spot in the line to create a blockage. Callahat should make certain that the fuel can actually flow all the way to the pump. One way to isolate the problem would be to try and run it off a temporary fuel supply......if that goes off without issue than you would know that either the fuel line or the tank is the culprit.

 

Jeff

[linus6948]

 SO: Basically anyone contemplating buy a NOS fuel pump should consider the age of the Pump First.

The NOS old fuel pumps can be almost 60-70+ years old.  The old rubber diaphram willnot support the newer based gas with the ethinol.  They will still need to be rebuilt with a newer diaphram that will work with the newer gasolines. 

 

So if you can pick up even a rebuilt pump it more or less and I go with the more, that it still willneed to rebuilt becasue you do not know when it was rebuilt and the type of diaphram that was used, unless the current seller can tell you that it was rebuilt within the last year or so and also did not use a kit that was on soneones self for the past 50 years.  If you are buying from a reputable rebuilder then you have a good shot of being new materials.

 

I would only purchase a NOS pump and I mean OLD NOS pump just for backup parts only.  Instead of purcasing these pumps get a backup electric 6v inline pump as a fail safe.  Then get a brand new Airtex 73201 if replacing the old 588, (Airtex 73201 is the replacement pump for the AC588 that was used on our cars and trucks.). Have that in your truck or behind the seat in your truck.

 

Then you willbe good to go.

 

Rich HArtung

Desoto1939@aol.com

Well Rich I can completely agree with this good advice as I have now been bitten twice by NOS AC Fuel Pumps purchased in 1980. The first one lasted 10mins and the second one

failed this morning after about 2 weeks of use, I have a new Airtex on the way from RockAuto, live and learn.

[48ply1stcar]

I bought my car 46-years-ago when it was 20-years-old.  I wouldn't buy a NOS mechancial part then and I see no reason to buy one now.

 

I guess I ony try to fix my car and not try to restore it.

[P15-D24]

It's really simple: If you disconnect the flex line at the pump and hold the outlet lower than the fuel tank, gas should easily flow out. (make sure you have a capture pan under it before you test). No flow, line is blocked. If you have (gravity) flow from the fuel line your pump has an issue.  

[callahat]

Ok guys I used a take off of 48ply1stcar. I broke the fuel line at the junction midway back to the tank and then at the tank itself. I blew air at each point to include the tank. There were no obstructions. I reconnected all the brake lines and attached a vacuum pump to the fuel line before the pump. Low and behold a couple of pumps and I had fuel coming out. I reattached the fuel line to the pump and she now runs like a dream again. Thank you to every one for your advice and assistance.