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390 motor mystery shut down...

Started by Joe L., July 14, 2009, 03:36:51 PM

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Joe L.

 :(....I recently attended an event in Reading, Pa., about a 2 hour ride mostly highway driving at 45-50 mph without any trouble.  A full tank of gas ( wow was that expennsive) and the 390 motor ran wonderful.  We parked for a few hours then headed home expecting a smooth drive.  After 10 minutes, we pulled into a Wawa to add a little gas, leaving her idle for few minutes when she stalls...Finished filling the tank, she won't restart...I have plenty of battery to crank her but she won't cooperate. All the fluids are good and she's not overheating...Everything was ck'd before we headed for home. Tried to start her again, but nothing. Took a look at the carburator (fuel problem ? ) and it appeared there wasn't any gas getting to the carb. Just then, an old-timer or my Cadillac guardian angel stopped by...I told him how my day was going...nice ride up but now this....After a few minutes, he says to pour cold water on the fuel line leading from the pump up to the glass fuel filter bowl. within a minute we now have gas filling up in the bowl and a few bubbles.  He said to give it 10 minutes more to cool down then try it.  Sure enough she started right up and after a quick look around, we pulled out and headed home.  About 30 minutes later we hit slower traffic and again she stalled and I glided her to the shoulder thinking...'again'?...So I repeated all my checks and again poured water over that fuel line with he same result.  10 minutes later we were headed for home, again. We did make it home. She has never acted this way before.  I have had her out on numerous rides all year round both cold and hot days, and this particular day was neither hot nor humid. I haven't had her out since due to a health concern of mine.  Any suggestions ?  What sticks in my mind is that line runs up from pump to carb and is close to the motor.  Is that contributing ? But why then?  What do you think??

Walter Youshock

CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

Otto Skorzeny

Yep. Walter is 100% correct.

Of all the trouble descriptions I have read on this forum that may be, might be, probably is, most likely is, vapor lock. This description leaves absolutely no doubt that vapor lock is the culprit. (most likely the real culprit is ethanol)

fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

Joe L.

Ahh, vapor lock...........ok now what !?    ( it was a good story, though....right? :)

Otto Skorzeny

Ethanol in gasoline has lowered the boiling point of fuel so cars that didn't used to experience vapor lock may now succumb to it.

Keep the fuel pump and line shielded or insulated from heat as much as possible. Reroute the line if necessary.

If that doesn't help, you may need to install an electric fuel pump.

Or just carry a cooler full of ice water in the trunk whenever you go someplace  and administer as required.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

35-709

We're seeing more and more of these posts.  An electric fuel pump back by the tank is pretty much the cure for vapor lock.
Geoff
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

Walter Youshock

Make sure your fuel system is compatible with ethanol and today's fuels--rebuild the pump, replace the flexible lines and anything rubber with new materials.  NAPA has replacement Weatherhead flexible lines.

Next, make sure your fuel pump is impervious to air.  Put a little teflon tape on the line fittings.  Like I stated before, my main problem was that the fuel filter body was warped and allowed air to be sucked into the filter section.  Once I reshaped the filter housing, it went away.
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

Joe L.

...Thank you, Walter, Otto and Geoff ...and especially that man that stopped to help me. I am going to insulate that line first and maybe relocate it so it doesnt get too hot. Any recommendations on the name-brand of the electric pump? 

Walter Youshock

Another old trick was to clip wooden clothespins on the steel line from the pump to the carb.  The wood would insulate the line from all the engine heat and they would also act as cooling fins.

I tried it a few times, but got tired of putting them on and taking them off. 
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

Misfit

Quote from: Joe L. on July 16, 2009, 11:47:34 AM
...Thank you, Walter, Otto and Geoff ...and especially that man that stopped to help me. I am going to insulate that line first and maybe relocate it so it doesnt get too hot. Any recommendations on the name-brand of the electric pump? 

Delco makes an excellent remote external pump for about $75.

Though if you sit in a parade idling for an hour, with the A/C on, in over 100oF air temps, it seemed even an electric pump couldn't stop the vapor locking on my '59. You could actually see the fuel boiling in the glass bowl.
I don't want to go higher than 6.5 psi on the pump. That might bypass the float seat and really cause a mess.

MisFit

jaxops

Joe,

  I wrapped my fuel pump and filter with heat resistant wrap that I can remove for car shows.  It helps a lot with all of the alcohol in the gasoline today.  Not a permanent solution though. 
1970 Buick Electra Convertible
1956 Cadillac Series 75 Limousine
1949 Cadillac Series 75 Imperial Limousine
1979 Lincoln Continental
AACA, Cadillac-LaSalle Club #24591, ASWOA