56 engine not running

[56 Buick]

Hoping someone may be able to assist. Engine was running fine and then started stumbling as if running out of fuel. This became worse until the engine stalled altogether and not run. Thinking it was the fuel pump, I have now rebuilt that. Carb was only rebuilt 6 months ago or so. Put the rebuilt fuel pump on the car and have tried to get it running. On initial start I squirted fuel down the throat of the car. Engine runs then dies when fuel runs out. Did this 10 or so times but no change. It appears there is at least some fuel at least in the accelerator pump because if I pump the accelerator I can see fuel stream out the 2 discharge nozzles at the top of the throat. Still the engine does the same run for a short time using the fuel in the throat/manifold and then stall. Any ideas?

 

Is it possible a float(s) are getting hung up somehow so the float level is low? But would this cause it to stop running as opposed to just stumbling?

 

Thanks, Drew

[56 Buick]

It is a Rochester 4GC. Just removed the 4 float level screws and I can see the floats are dry. So fuel getting to the accelerator pump but there is some issue with the floats. I will check the flow exiting from the fuel pump first and then I guess I will need to disassemble the carb.

[EmTee]

Have you checked the points and condenser?  Do you have spark?

 

"Engine runs then dies when fuel runs out. Did this 10 or so times but no change."

 

I missed this originally - I agree with Ben, an air leak in the suction line will interfere with fuel delivery.  Has the tank ever been cleaned or the sending unit ever been removed?

Edited March 5, 2022 by EmTee (see edit history)

[Ben Bruce aka First Born]

I have , over the years, had problems such as this.  Sometimes I would find a problem in the line from the tank to pump. Only need a tiny leak for the pump to lose suction.  Crack in a hose. Pin hole the line. To eliminate a possible pump problem, I have stuck a hose from pump suction into a gas can .

 

Good luck 

 Ben

[56 Buick]

Emtee, tank is only a few years old and I had the sending unit out a couple of years ago as the sending unit gasket was leaking. But there certainly could be material in the tank that could cause a blockage. Ben, I will try also try the gas can and see if that resolves the issue. Thanks guys.

[EmTee]

24 minutes ago, 56 Buick said:

But there certainly could be material in the tank that could cause a blockage.

Yes, that's what I was getting at...  Could be junk fouling the pickup.  If it runs successfully from an auxiliary can then it's time to drop the tank and investigate further.

[old-tank]

As a test, jump across the ballast resistor to see if it will keep running.  If no joy, check the dwell.

[avgwarhawk]

In my humble opinion, all points to a carb issue. If she is running with squirts of gas or flammable spray down the throat then I would say check the filter and floats. Possibly a small passage in that carb has debris. Remove it. Spray with carb cleaner in the small orifices, etc. Reinstall. See how she runs. 

Edited March 5, 2022 by avgwarhawk (see edit history)

[EmTee]

Needle valve may be sticking...

[KAD36]

How hot was the engine when this happened, what temp was it outside, does the engine start or run at all now or only if you force feed it fuel?  Does it run at any throttle position?

 

Am not sure how the fuel floats can be dry but the accelerator pump has fuel?  So the fuel bowl is dry also?  The pump, line integrity, needle valves all come to mind.  If this happened all of a sudden maybe something clogged a filter or an idle circuit or the fuel line rusted a pin hole.  Try isolating the line if the bowl is really dry, or check the pump pressure even if rebuilt if it will run just dribbling a little fuel down the carb.

 

If its getting gas without manually force feeding it but still not running move on to another system check.  If jumping across the ballast gets it to run for example, it suggests weak coil/low primary voltage/weak spark.

[56 Buick]

Thanks for all the replies. I used a gas can as suggested by Ben to bypass the tank and fuel line and she runs fine. I took a look at one of the fuel line filters and there is a lot of fine gunk and I only cleaned it the other day. It appears the issue was fuel starvation by clogged fuel filter. I can blow out the line and drop the tank to try to clean everything but I am curious whether these fine particles are possibly coming from the lining or inside of the fuel line disintegrating, is that a possibility? Looking at the fuel line I would say it is original to the car. I assume it is a steel line? It just seems odd the tank would be holding that much shit because the previous owner replaced the tank around 5 years ago with one of the Tank Inc units.

[avgwarhawk]

The tank and metal lines may have gotten some rust from ethanol gas. Can't say this is really the cause.   I would imagine the rubber hoses that make up the entire fueling system where replaced with new ethanol resistant hoses?  Possibly  bad dirty gas fill up at the pump. Probably not. Gas these days are quite clean. Just replaced a filter with 160k miles in use.  It really was not that dirty.  At least you have a cause.  Now to find out what is causing it. 

Edited March 6, 2022 by avgwarhawk (see edit history)

[tenugent]

Took the sending unit out of a 67 mustang that sat for 6 years,looked like it was dipped in mollases.Tank had alot of statement in it to.Replaced both.

[old-tank]

It is not likely that the lines are producing that much gunk.  Blow them out should be good enough.  Thanks to TanksInc for making replacement tanks available, but they are not the quality of the original.  If the car sat for extended periods condensation formed on the inside of the top of the tank starting corrosion.  First would be gray powder in the system from the zinc or galvanized coating then rust and I have seen even perforation from a totally neglected car after 3 years.

Drop the tank, flush it and use a mirror to look at the inside top.  You may need a new tank or coat the one you have.  Drive it regularly (daily or weekly) and any tank will last.

[56 Buick]

Thanks all. I will report back with what I find after dropping the tank.

[56 Buick]

I have dropped the tank and there is a lot of rust and debris in the tank. Should the fine debris be getting through the sending unit sock though? Because that looks like quite a thick sock that would catch a substantial amount of debris?

[old-tank]

My understanding is that the sock in the fuel tank is not a filter.  It's there to lessen the chance of fuel starvation when the gas sloshes away from the pickup.

[56 Buick]

That may explain why the fine debris is passing through it! Now the tank is empty it appears the rust is at the bottom of the tank where the fuel sits. I expected the rust to be at the top where the fuel doesn't get to regularly enough. I will get my mirror to further explore inside.

[56 Buick]

Using the borescope camera I actually cannot see any real rust inside the tank. I can see rust on the inside of the inlet tube but only on the bottom half i.e. where the fuel sits. Almost as if the fuel has eaten away the galv rust primer (paint) that Tanks Inc appear to use there. I am going to coat that area with some rust eater, wash out the tank and put it back. Then see what happens.

[avgwarhawk]

It is possible the small amount of rust was enough to cause a blocked filter just the one time and that would have been the end of it.  However, it was prudent to drop the tank for inspection and cleaning.  I suspect the problem will be resolved as a result. 

[JohnD1956]

I am not sure what "rust eater" coating consists of but it may be a good idea to make sure that it is not soluable in gas before putting it in the tank. 

 

It would not be cheap but I am certain the Gas Tank Renu process would be a good sealant.  Mine is holding out well for 19 years so far.

[56 Buick]

8 hours ago, avgwarhawk said:

It is possible the small amount of rust was enough to cause a blocked filter just the one time and that would have been the end of it. 

The rust in the inlet tube certainly has very fine particles which is what has been causing the problem, so I hope that is the extent of it.

 

And John, I too wondered about the after effects of the rust eater and whether that may cause something to dissolve in the fuel. There is often some kind of powdery coating left after the rust eater dries so I think all I can do is remove that powdery coating as much as possible.

 

Thanks all. Drew

[JohnD1956]

3 hours ago, 56 Buick said:

And John, I too wondered about the after effects of the rust eater and whether that may cause something to dissolve in the fuel. There is often some kind of powdery coating left after the rust eater dries so I think all I can do is remove that powdery coating as much as possible.

You  could coat a piece of bare metal, let it dry the appropriate amount of time, and then immerse it in a gasoline bath for a week and see what happens, if anything, to the coating.  I don't think you need a large piece of metal.  Something that fits in the bottom of a leftover food jar would be sufficient.

 

[avgwarhawk]

POR 15 gas tank sealant looks to be the product to use.  Many on this firumhave liked the POR products.

[KAD36]

Did the Bill Hirsch stuff after cleaning and washing out tank - holding up for 20+ years, no rust issues.  Unknown if it’s still same formula these days but it’s a data point.