Fuel Flow issue.

[keithb7]

I had never worked on a mechanical fuel pump before. I knew little to nothing about them. Until I had one acting up. I bought a new fuel pump, as mentioned the pin fell out on me. Then I thought, I can do better than this. I had a few old tired worn out fuel pumps kicking around. Some car folks gave me their old cores. A couple cores came with boxes of spare parts that I came with old Mopar Cars that I bought. I bought a new seal kit. I tore one pump apart and rebuilt it. First time in there and the rebuild was a success. Easy-peasy. Later my '38 Chrysler came with a dual action fuel pump. Fuel pump on the bottom, vacuum pump on top.  It needed rebuild too. I ordered the rebuild kit from Then & Now and tackled that pump too. I was unsure how it would all work out, being as I have never been into a dual action pump before either. I had little idea how the vacuum pump worked. Again, success right out of the gate. Fired right up and have been running great ever since.  I still have about 6-7 spare old fuel pump cores. Maybe I should consider rebuilding them all and selling them.

 

The moral of the story is, try rebuilding a pump core. It's not hard. Read up a bit to learn the theory while you are rebuilding it. You'll have it all figured out and be an expert in no time!

Edited September 24, 2022 by keithb7

[keithb7]

Glass bowl down. So you can remove it and clean out all the sediment.

 

[OUTFXD]

7 minutes ago, keithb7 said:

try rebuilding a pump core. It's not hard. Read up a bit to learn the theory while you are rebuilding it. You'll have it all figured out and be an expert in no time!

 

I originally planed or rebuilding my old core.  Then I found out the Rebuild kit wasnt for the fuel pump I had (Unbeknownst to me someone had replaced it with an aftermarket pump),  so I ordered a new pump.  Thats where we are now.

[Sniper]

Yes

 

lol

 

Mine is glass bowl down. 

[johnp]

had the pin fall out on my pump . had to have the car towed home . next pump put j b weld on  both sides of pin so far good.

 

John

[soth122003]

On 9/23/2022 at 1:37 PM, OUTFXD said:

Both great ideas!  Luckily I have a cheap bore scope that attaches to my phone that till give me an idea of the state of the interior of the tank. We have a good compressor system to blow out the line to clear it.

While blowing air through there can clear some of the debris, it will by-pass some of it due to path of least resistance. You might try a section of line filled with Acetone or carb cleaner and blow that back thru the filter. Think water erosion. The liquid will not flow as fast as the air and will probably clear more gunk out than air alone. It is an oil lite filter and most of the rust is from the tank. I cleaned my tank by using this method as well as a section of chain and some cleaning solution and sloshing it around for about 1/2 an hour. Cleaned the tank real good and haven't had any problems in over 9 years.

 

Joe Lee

 

Joe Lee

[OUTFXD]

Took the fuel pump off and took it apart.  All parts present and operational.

 

Ordered a fuel check valve as a temp fix.

 

Question is.  Should I put the check valve before the fuel pump, Between the fuel pump and the Fuel filter, or between the Fuel filter and the Carb?

[Sam Buchanan]

What is the purpose of the check valve?

[OUTFXD]

2 minutes ago, Sam Buchanan said:

What is the purpose of the check valve?

Currently she runs in a permanent lean state.  and when she is shut off hot.  I will come back to an empty fuel system(see through fuel filter is empty)  and it takes a considerable time cranking the engine to get the fuel back up to the carb. 

 

My theory at this point is a plug in the fuel pick up causing the lean state,  and I guess the fuel is flowing back to the tank.  Until I can pull/replace the tank,  Putting a check valve would eliminate any back flow keeping fuel in the carb. 

 

Then I started thinking "But if I kept the fuel pump primed...."   and decided to ask the experts.

[Sam Buchanan]

The fuel pump has check valves (that's how it pumps fuel), not sure fuel could flow backwards through the pump unless the pump is defective, and sounds like it may be. 

Edited September 28, 2022 by Sam Buchanan

[OUTFXD]

1 minute ago, Sam Buchanan said:

The fuel pump has check valves (that's how it pumps fuel), not sure fuel could flow backwards through the pump unless the pump is defective, and sounds like it may be. 

That was my initial thought,  It is a new pump but I pulled it and took it apart and all seemed to be in order.   Honestly at this point I am just throwing stuff at the wall and seeing what sticks.

[Sniper]

It's not going to siphon fuel put of the bowl.  So there should be enough in there to start the engine and run it long enough for the pump to do it's thing.

 

Now if you bowl is empty, the issue is something else, not fuel flowing back to the tank from the carb.

[Los_Control]

I wonder if you fill the fuel tank if it leaks or you smell gas fumes? ..... Think we all agree the tank is rusty.

 

What is possible is to drop the fuel tank down & really inspect it good .... you will need to do this anyways to search for a replacement .... not a waste of time.

Then if you feel comfortable with the condition of the tank, You can possibly use muriatic acid in it and clean it. Flush it clean it several times ...use some JB weld to plug the pin holes in it ... flush it some more ...... You may get 6-9 months from it before you have more issues. .... Or it could be a complete flop.

 

Big scaly rust will plug a fuel line.      At this stage of deterioration, the small fine rust particles will pass right through your filter plugging your carburetor.

Your needle or seat on the float may not work smoothly anymore because of the fine powder rust ... It can only get worse from here.

 

I personally would want a new fuel tank ..... I'm blessed enough to have one sitting on a shelf waiting to be installed.

Next best option for a workaround, I might look for a fuel cell you could install in the trunk to get you by while looking for the proper tank.

 

I would rather use a metal boat fuel tank strapped down with straps .... then run a rusty gas tank.

 

A rusty fuel tank is like  **********  Fill in the blank. ..... Nothing you can do will make it better.

You pull that tank, toss it to the curb .... You find a new way to supply fuel to your engine.

 

 

 

 

[soth122003]

19 hours ago, OUTFXD said:

Currently she runs in a permanent lean state.  and when she is shut off hot.  I will come back to an empty fuel system(see through fuel filter is empty)  and it takes a considerable time cranking the engine to get the fuel back up to the carb. 

A lot of us have that problem, whether from losing the prime from heating of the fuel lines from the engine or letting it set and it slowly leaks back to the tank over time. The biggest reason for this IMHO is the ethanol fuel. A lot of us have installed a fuel filter and a prime pump at the tank to ease or over come this issue. My car does the exact same thing as yours OUTFXD. Installing the prime pump and the filter was easy and it solved the problem of cranking forever just to get gas to the carb. I just get in my car and hit the prime switch for about 5 seconds and presto, the car starts up quick.

 

Joe Lee.

[greg g]

Running lean is not a carb problem, it's a vacuum leak some where between the throttle butterfly  and the block.  Needing the choke partially on, c9mpensates, but isn't the fix.  You need to find the leak and address it. Worn throttle shaft bushings, bad carb to manifold seal, bad manifold to block seals, intake manifold leak, bad line to windshield wiper motor, are places air can enter below the carburetors mixing areas.

 

Did you ever put a vacuum gauge on 6our engine?  It can tell you a lot about your engine, and help troubleshoot  your problem. 

[OUTFXD]

So.  I used a compressed air airgun to blow fuel back to the tank and hopefully unplug the pick up sock.

 

I then drained the fuel from the tank and noticed a fair amount of grit in the fuel.  I strained the fuel through a coffee filter and a paint strainer.

 

Put everything back together. drove to a fuel station the next town over,  Fueled up.  Drove home (about 20 miles round trip).  She was running better and better,  I could even completely open the choke.

 

picked my buddy up and drove to town.  Slowed down and took a 90 degree left and the motor shut down.  Just turned off.   I coasted to the shoulder of the road and looked under the hood.  Fuel filter empty.  No amount of coaxing could get fuel through the fuel pump.  A kind passer bye noticed that the bottom of the fuel filter was coated in black grit.

 

We managed to flat tow my car home and I have ordered a brand new fuel tank.

[Los_Control]

Glad to hear it. I live on a retirement fixed income ... It can be tough to come up with extra money to buy hotrod parts. .... It is possible to spend a few $$  & have a tank cleaned & sealed .... There is a chance it will fail ... the cost is about the same as a new tank.. I would only use this if my vehicle did not have a replacement tank available.

 

A new gas tank is not as sexy as a new set of wheels ... but it is a needed item.

[OUTFXD]

On 9/30/2022 at 1:37 PM, greg g said:

Did you ever put a vacuum gauge on 6our engine?  It can tell you a lot about your engine, and help troubleshoot  your problem

I have NOT put a vacuum gauge on the engine.  It didnt have this problem before I went through the carb.  In fact it had the opposite problem.   Pull the choke full on .  Turn the engine over.  as soon as the first cylinder fires Close the chock fast!  She would idle rough for 10-15 seconds then clear out and run fine.  The spark plugs showed black sooty ash indicating a rich mixture.

 

I rebuilt the carb and been having issues ever since.  as with everything else, I think I am fighting multipull issues.

[Sam Buchanan]

It is helpful to just address one issue at a time. When you get the tank replace EVERYTHING in the fuel system up to the carb. That eliminates one problem and may clear up other problems. It is impossible to troubleshoot drivability problems if the engine isn't getting proper fuel flow.

[clarkede]

I had a similar problem with my 1948 Plymouth a few years ago where the fuel tank lining was chipping out and clogging the carburetor. I became quite skilled at pulling the carburetor apart on the side of the road cleaning out the jets and reassembling to get back home. I started to do a lining lining repair of the tank, but after the car sat for a few years where I didn't trust it,  I decided to just buy a new tank and I installed flexible fuel lines from the tank to the fuel pump.  I also rebuilt the carburetor and added a clear fuel filter so i can see what the fuel looks like. (The old original stone filter looks cool but the grit would just go right trig it)

I am so glad I did this... it now runs great and I don't worry about breaking down for a fuel problem. 

[OUTFXD]

Ordered a new tank.  In preparation for the new tank I removed the old tank, which necessitated draining 10 gallons of fuel from the old tank.

 

With gas aimed at $6 a gallon and me on a fixed income,  I was not about to throw that much fuel away. So I strained it.

 

First I used a pain strainer,  Which removed a fair amount of vegative matter, Pine needles, and Wood shavings.

Edited October 8, 2022 by OUTFXD

[OUTFXD]

Next I strained it with Ye ol coffee filter.  Tword the end I noticed the coffee filter was flowing fuel at a mear trickle.

 

When I checked the coffee filter.  It was choked up with a very fine powder.  when wet it was kind of black, when dry it was a light grey that was near invisible.

Edited October 8, 2022 by OUTFXD

[OUTFXD]

my current theory is that it was left in the woods without a fuel cap for several years,  then drug into an active shop  where it sat without a cap for several years.

[OUTFXD]

I took a look inside the tank with  a cheap bore  scope.  Sadly it was out of focus but it shined light in such a way that  I could see inside the tank.

 

There was a bit of black grit, a bunch of light grey powder some pine needles and a small flips head screw.  Also the fuel pick up had patches of white/grey all over it (I assume from corn syrup gas)

[Sam Buchanan]

That tank was never going to work, you made a good decision!