Thread: I'm outta ideas... PLEASE HELP!!!

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hello everyone. im new here and im looking for help. i have a 46 ford with all origanal drivetrain, the 239 ran decent when i got it, then it started acting up, basicly what its doing is when the car get up to running temp (not hot) the car seems to loose spark and quit. if i let it sit for 15-20 mins it will start and run great till it gets up to temp and quits again. the part i dont get is i have replaced the following: DIS. CAP, ROTOR, POINTS, CONDENSER, RESISTOR, COIL, PLUGS, AND THE CARB, FUEL PUMP, FUEL TANK, AND ALL FUEL LINES, AND FILTERS. it has a brand new elec. pump and all the gas lines are no where near any heat, i was told it was vapor lock, but when the car dies it still has gas in the filter right behind the carb, and i can see its getting gas inside the carb, ALSO right when it dies i can jump out, pull a plug and it will have spark, but still refuse to start till it cools down a bit. seems to me if it has spark and fuel it should run right? not the case when im on the side of the road!!! this car has me baffled and im outta ideas, any help would be greatly apreciated. (hotrodwagon1@yahoo.com)

Maybe the gas tank has a sealed gas cap and is building pressure in the tank, then bleeds down and restarts. An engine needs fuel, spark and air to run, so it's one of them, lol. You only need fuel and spark to light it up an push it down the hill...
I would do the SBC swap.

I am with him ,non vented gas cap on older fuel systems does not work well,it allows a vac to form ..............if the gas cap has been replaced it`s probably non vented,the trucks with the gas tank in the cab have a hard time with those non vented caps too,they pressurize and leak vapor out the seals into the cab.

You could try and drill a very small hole in the cap to test it out ,at this point a new cap is cheap.....just drill it off of the tank ,so no shavings go into the tank or worse yet ....booooom.

how long has the car sat before you started driving it? using todays gas has ethonal in it which is not a bad thing but it is hell on old cars. had the same trouble with the studebaker lark i bought last month.i dropped the entire fuel system and replaced the lines with stainless steet and neopryem hose had the tank flushed out and sealed for today gas. the ethonal cleanes the fuel system and all that varnish has got to go somewhere,also remove the pump and check the dia. in the pump,if its a rebuildable tpye.the ethonal will soften the dia. it may look good but replace it.that is were i would start.good luck.i'd stay away from sbc.don't like them

x2 on tank venting also make sure fuel lines nowhere near exhaust... Try insulating line underhood... Mech pump or electric? How is airflow in engine compartment? Do you have fuel pressure gauge? I fought fuel problems long time related to all these...

Good luck

-Chris

"it has a brand new elec. pump"

Have you monitored the fuel pressure at the carb inlet? Those old carbs don't like any more than about 3 psi. The pump might be overpowering the needle and seat in the carb, leaking a little raw fuel into the motor that after a while, could overwhelm the motor and kill it. It might like the over-rich condition when cold, but when warmed up, not so much so. Tee off with your plumbing and run a fuel pressure line from the carb inlet to the cowl of the car, right in front of the windshield. Just mount it up there temporarily so you can see the actual pressure. Use a regulator in the line and drop fuel pressure to 3 psi or even 2 psi and see what happens. Don't cheap out with one of those fosdick poorly made regulators. Get a good one and mount it solidly in the driver's compartment.

More fuel pressure at the carb WILL NOT MAKE MORE HORSEPOWER. It will however, overpower the needle and seat and give you running/tuning nightmares such as you are experiencing here. The old stock stuff such as you have might like 2-3 psi. Most modern 4-bbls will operate best with 5 psi max.

All you have to remember is these 3 rules.
1. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER
2. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER
3. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER

I think you need to determine if the problem is electrical or fuel. You first say it is losing spark, then you start discussing fuel issues. Not a big deal to tie it down to one or the other. If it is spark, simply buy one of those $ 5 spark checkers that goes between the plug and the wire and see if that is what is going on. These flatheads didn't have the hottest ignition systems to start with, being only 6 volts, and if you factor in 61 years of age they can start to have some problems.

Flathead distributors were known to have problems when conditions were moist, and also when they get warm. One guess I would have is that something in the distributor is opening up when the temp goes up. You have thrown a lot of parts at it, but I think you may have to spring for a new distributor assembly, if indeed you find your spark is going away. I think Speedway and others sell new improved distributors for these, and when I get around to building the 46 flatmotor I have I am going to use one of their units for sure.

Next time it stops running do the spark check thing and then you will know for sure what is happening.

Don

This is not intended to hijack... but perhaps it will be of some benefit...
With a pressure regulator, is a return line required? This may sound like a dumb question, but if the fuel pump is putting out say.... 10 lbs of pressure, and the regulator knocks it down to 3 lbs, where does the other 7 lbs of pressure go? It seems like the pressure would just build up. Am I wrong?
I'm sure there is a completely simple explanation, but it escapes me.

Originally Posted by 65ny

This is not intended to hijack... but perhaps it will be of some benefit...
With a pressure regulator, is a return line required? This may sound like a dumb question, but if the fuel pump is putting out say.... 10 lbs of pressure, and the regulator knocks it down to 3 lbs, where does the other 7 lbs of pressure go? It seems like the pressure would just build up. Am I wrong?
I'm sure there is a completely simple explanation, but it escapes me.

no your right it can dead head the pump. if it need a small amount of fuel psi and over heats the pump if it has no bypass .free flow is much better you reg the bypass . i built some with a by pass .BUT my cars still have the old holley s with no returns

Hotrodwagon,

A bunch of years ago I had a very similar problem with a 46 Delivery I had. It would randomly quit once it was warmed up. I chased the problem for quite a while, messing with the fuel system mostly because it acted like it was running out of gas. Finally figured out that it was the stock 46 ignition switch thanks to an old time mechanic I happened to mention it to. Seems that the switch was weak and would slowly heat up and then lose contact. Replaced the switch and never had another problem.

Just another thing to check, if you're still running the stock switch.

I have the fuel pump issue on my truck, I have a blue holley pump and it has overheated my relay twice now. Problem is Blue pump pushes 12? psi, red pump pushes 6 psi. Fix, put the red pump spring in the blue pump, then pump doesn't overheat and destroy itself. Problem is spring is $12 +shipping, so I haven't enjoyed the thought of a $20 spring, when a new mechanical pump is $15, lol... Any tricks for this would help.

Another issue you might consider is crap in the tank. I chased and chased all kinds of ideas on my '48 Packard, and all it was was crap in the tank plugging the pickup. Car runs about a block or two, shuts off like you shut the key off. Let it sit for a little bit, and it fires right up. UNTIL enough suction is created to pull the crap back up the pickup, then it's off again. All it was was a little piece of fuzz in the tank.