Re: [AMC-List] Surging 401 update

["John Elle" <johnelle@xxxxxxxxx>]

Marty, 
Here are more thoughts on a thought by thought basis so I can read what
you wrote not what I wanted to read :-)
SNIP
.  Problem is still there...slightly worse after todays runs.  Here
is the latest:
-changed fuel filter (74 Jav/AMX doesn't have a fuel
return line on the filter).  I even cut the filter
open and it was very clean inside.
SNIP
Conclusion, fuel line not full of tank crud, neither probably is
carburetor
SNIP
-checked all of the lines from the tank and the pump
and there are no kinks (rubber lines were replaced
when engine rebuilt)
SNIP
Conclusion, fuel lines good assuming replaced all of the way back to the
tank.
SNIP
-Went out for a run and had surging problem again
(approx 3000 rpm)
SNIP
Observation, engine rpms up, possibly under a load such as acceleration
maybe!
SNIP
-pulled off and removed and plugged vacuum advance
-next run surging started even sooner so I pulled off
and reconnected vacuum advance
-ran engine up to 3200 rpm in neutral and no surging
-back on road and reconnecting vac advance had no
effect on early surging
SNIP
Appears to not be related to ignition as vacuum advance change would
effect timing and it did nothing. Not a strong test but certainly does
not point to ignition problem
SNIP
 (even noticed on exit at 20-25
mph that was a fairly steep climbing turn)
SNIP
Observation, rpm's up and possibly under a load again. Interesting!
SNIP
-got home and checked tranny fluid level and it's
right on
SNIP
Does not look as if transmission is slipping!
SNIP
-again ran engine to 3000+ rpm in neutral and no
surging
SNIP
Observation. RPM's up, but not under a load. This is a repeat item.
SNIP
-fuel pump is stock
SNIP
Well whaduaknow, I wonder if it is original or one with years on it????
SNIP
-removed the air filter and no indications of fuel
boiling/dripping into the carb
SNIP
Observation, doesn't look like flooding is a problem!
SNIP
-I'm running Shell 93 octane that was purchased the
same day as problem started
SNIP
YOU LUCKY DAWG! Best I can get here is 91 Octane. Can you say Ping!
SNIP
-Fuel line is rubber (vice metal) and runs up the
front of the engine
SNIP
It is 108F today, I never had a fuel line vaporization problem with any
AMC car with the fuel line run like the factory installed it. Does not
look like fuel vaporization is the problem
SNIP
-the floats have been set and rechecked several times
when working the boiling/dripping problem and the
inlet valves are new.
SNIP
 
Observation! Problem re-occurs when engine rpm's are up and under load.
Does not happen in neutral. The only time I have had that repeat itself
regularly was when the fuel pump was on the way out. Except of course
the one time it quit at an intersection with no warning what so ever and
left me sitting there.
If the fuel pump has some age on it and a couple of years is age my vote
goes for the fuel pump. This time anyway. 
 
John. 
 
 
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