Dry fuel filter??

[GBsPanhead]

So....I been doing preventative maintence on the '69 300. Last weekend I changed out the fuel filter, (plastic kind), and lines from pump out, to filter to carb. Started right up like she always does with engine barley having to crank/turn over before she would start. All was good. Went to start this morning, crank, and crank, and crank before she started. Hmmmmm. Worked on my gauges all day. At end of day, just happened to look at the fuel filter and was dry. Went to start, crank, and crank, an crank, then she fired off, no issues. Could see fuel in filter after she started, ran fine. Turn motor off, wait a couple minutes, started right up again. Like why is filter bleeding down after a few hours?

Researching here, going to put metal filters before and after pump, and most likely change pump while down there.

Question is what happened? Is fuel leaking back down lines? Hopefully not into motor some how. Oil smelled like oil, no gas smell in oil. All was good, started right up before I changed filter. Old filter was plastic too. Not sure why filter would be dry after sitting a few hours, and have a long crank while filter fills up, then starts.

One thing for sure I like about these old cars is no computers! No crank sensors, no fancy electronics to try and figure out!

Thanks for any insight!!

 

[70NEWYORKER]

How old is that pump? If the two one-way valves in the pump fail the line can drain back to the tank. Modern fuels eat original rubber fuel parts. Modern fuel also evaporates very easily, much more that the fuels from 50 years ago. After sitting for one week in the garage my car takes a solid 5-7 seconds of cranking before she fires....carb is bone dry and needs to be refilled. New fuel just disappears while parked.

 

[GBsPanhead]

Thanks for the reply! I was looking on RA site, saw a few different styles of pumps. I need to crawl under the car in the morning to look at the pump style. Not sure on age, car is new to me. Parts are not expensive, so will replace as a precaution. Will also look for an OEM one. ($$$)

I know too well these new formulated fuels. Wrecks havoc on my old Harley!!

Thanks again!

 

[69monaco]

Is it normal for the fuel filter to drain? | Moparts Question and Answer | Moparts Forums

 

[CBODY67]

Unless you are chasing concours show points, where date codes and such are important, do NOT put a NOS pump on an engine that'll see ANY ethanol-blend fuels, period. Reason is that the rubber formulation in the pump's rubber diaphragm needs to be the ethanol-resistant formulation rather than what was used in prior times.

Ethanol is a "cleaner/degreaser" agent and will dry/remove the oils out of the rubber itself, leaving only the (in the case of fuel line) internal fabric reinforcements holding things together, after it starts seeping/leaking. On mechanical fuel pump diaphrams, it can harden them and when they don't flex, they leak. Hopefully out of the "weep hole" in the housing rather than into the crankcase. Therefore, having a pump of recent manufacture is important, but even if the fuel line stays "dry" for longer periods, over time, failure can still result later on.

EVEN in a modern fuel-injected vehicle, with a rubber diaphragm in the fuel pressure regulator, ethanol can degrade that with time if the rubber is allowed to become dry from non-use of the vehicle (i.e., "low miles" for its model year).

As for the "dry" appearing fuel filter, this could happen well before we had ethanol fuel blends. When it happened with a "clear" plastic Fram filter on our '66 Newport 383, in the earlier '70s, I asked the old-line Chrysler service manager at the local dealership. He said he'd seen them with fuel in them (as I had) and also "dry" appearing. Dry appearing as the car was running! Didn't really worry about it as the car still operated normally, either way. Possibly ONE less thing to worry about when using the OEM Chrome filter instead? The chrome might also reflect ambient higher temps, too?

In putting an auxiliary "clear" fuel filter prior to the fuel pump, this can be done when there might be suspicion of "rust" in the fuel lines. To keep it from getting to the fuel pump, where valve damage might occur.

In some respects, it might be a consideration to get one of the older "Carter" style "repairable" fuel pumps rather than a unitized housing pump. BUT the price differential might be important! In our new world of ethanol'd fuels, that capability to disassemble might be important. Your determination on that. Might require some alteration to existing fuel feed/supply lines, as in a little time with some auto supply tubing lengths, a tubing cutter, and a tubing bending tool (not hare to do with a little practice, for a "factory look"). Polish it with some red ScotchBrite and it'll look almost like polished stainless or chrome!

CBODY67

 

[Yatzee]

So....I been doing preventative maintence on the '69 300. Last weekend I changed out the fuel filter, (plastic kind), and lines from pump out, to filter to carb. Started right up like she always does with engine barley having to crank/turn over before she would start. All was good. Went to start this morning, crank, and crank, and crank before she started. Hmmmmm. Worked on my gauges all day. At end of day, just happened to look at the fuel filter and was dry. Went to start, crank, and crank, an crank, then she fired off, no issues. Could see fuel in filter after she started, ran fine. Turn motor off, wait a couple minutes, started right up again. Like why is filter bleeding down after a few hours?

Researching here, going to put metal filters before and after pump, and most likely change pump while down there.

Question is what happened? Is fuel leaking back down lines? Hopefully not into motor some how. Oil smelled like oil, no gas smell in oil. All was good, started right up before I changed filter. Old filter was plastic too. Not sure why filter would be dry after sitting a few hours, and have a long crank while filter fills up, then starts.

One thing for sure I like about these old cars is no computers! No crank sensors, no fancy electronics to try and figure out!

Thanks for any insight!!

Not to worry because gravity is at work here. The fuel at the filter is draining back a bit because the tank is lower than the engine and liquids try to seek their own level. The position of the reed valves in the fuel pump dictate that one is open while the other is closed and the drain back seldom goes farther back than the fuel pump itself. Evaporation is unlikely because this is a closed system and before the fuel filter would evaporate dry, the fuel bowls at the carbeurator would have to be fairly empty and the internal float needles completely unseated. Even then it would take a few days for this to occur. The only way to verify evaporation would be to put a "one way" check valve in the fuel line just before the pump. It has been done on cars where slight drain back occurs all the way to the tank and it works very well making starting easier for cars that sit for a fair amount of time.

 

[CBODY67]

Drain-back from the carb would be nearly impossible as the needle/seat is above the normal fuel level in the float bowl, regardless of the type of carb. As with fuel barrel storage with the barrel being open, the lighter factions of the fuel will evaporate first, which might also be where the "octane" and "cold start" parts of the formulation might be. The carb's needle/seat would still work if the float level had closed them and fuel within the pump/carb lines had expanded very much in "hot soak" conditions, I suspect, especially the Viton-tipped needles. By the time that float bowl evaporation MIGHT have lowered the fuel level enough to allow more fuel past them, any residual pressure in the fuel pump probably had bleed-off.

Just some thoughts,
CBODY67

 

[GBsPanhead]

WOW! Thanks for all the good info!! CBody...I won't go OEM. After I posted that, I thought 'what about the rubber/materials' used way back when, and could be an issue.

I think I can get a new pump, and two filters for less than 40 bucks from RA. Going to order today, along with new battery cables.

I went out this morning to check the fuel pump style, looked at fuel filter, and it had fuel in it! Started right up with NO long cranking. I mean turn the key, and bam, she started right up.

Damn! Rain delay for NASCAR!

 

[marty koirtyohann]

So....I been doing preventative maintence on the '69 300. Last weekend I changed out the fuel filter, (plastic kind), and lines from pump out, to filter to carb. Started right up like she always does with engine barley having to crank/turn over before she would start. All was good. Went to start this morning, crank, and crank, and crank before she started. Hmmmmm. Worked on my gauges all day. At end of day, just happened to look at the fuel filter and was dry. Went to start, crank, and crank, an crank, then she fired off, no issues. Could see fuel in filter after she started, ran fine. Turn motor off, wait a couple minutes, started right up again. Like why is filter bleeding down after a few hours?

Researching here, going to put metal filters before and after pump, and most likely change pump while down there.

Question is what happened? Is fuel leaking back down lines? Hopefully not into motor some how. Oil smelled like oil, no gas smell in oil. All was good, started right up before I changed filter. Old filter was plastic too. Not sure why filter would be dry after sitting a few hours, and have a long crank while filter fills up, then starts.

One thing for sure I like about these old cars is no computers! No crank sensors, no fancy electronics to try and figure out!

Thanks for any insight!!

 

[marty koirtyohann]

well the gas would not go up hil into the carb unless its being pushed now the gas in the carb could drain into the motor (Q jets carbs on gms has that problem ) now one think it could be ? todays gas wit the ethanol boils @ lowr temps causeing a but I bet its draining back into the tank flooding problem (I have that on my 72 new Yorker )