Mechanics

BUCKING WHILE DRIVING

1988 Jeep YJ • 213 miles

Ive got a 1988 jeep YJ with the 258 6cyl. And the ax 15 5 spd that I swapped in place of the peugeot POS tranny. Its been running really smooth lately up until tonight on my way home from work. It has done this a few times prior but would always stop after about 20 seconds or so, but it did it the whole way home. Commonly does it after I hit a puddle, or when its raining but it was dry today. Wanted to see if anyone else out here has had a similar problem and what they did to fix it.

it will respond smoothly to the gas when its in neutral but once I put it in gear and hit the gas it seems to just die than itll pick up and slam the entire jeep back and forth, similar to riding a bull or something. Definately causes a rough ride, and wont accelerate any faster than 25-30 or so.

any ideas? Im stumped.


Avatar
Grizzly93
March 7, 2012.



Sounds TOO lean.


Tiny
Fixitmr
Mar 7, 2012.
I put in a weber 38 in place of the stock carter BBD which was in need of replacement. And with that it called for a fuel pressure regulator, so I ordered one as welll as an inline gauge to test the accuracy of the regulator, well one of them is inaccurate. Weber suggested 2.5 PSI so I got it set to that on the regulator and the gauge only reads 1.5 psi. It reads that regardless of what I set the regulator at. Do you think it could be from that? Or the fuel/air misture set on the carb?


Tiny
Grizzly93
Mar 7, 2012.
You could force choke partially shut and try it?


Tiny
Fixitmr
Mar 7, 2012.
What would forcing the choke partially shut do in terms of testing it? Im not really following.


Tiny
Grizzly93
Mar 7, 2012.
Richen the mixture.


Tiny
Fixitmr
Mar 7, 2012.
Okay got it now. Duh. Lol. Would the mixture be different from neutral to being in gear?


Tiny
Grizzly93
Mar 7, 2012.
GRIZ

I HAD A WEBER DGEV INSTALLED ON MY CJ 5 PRIOR TO USING THE O2 SENSOR, OFFY INTAKE AND NOW 4 BBL HOLLEY 390

THE ONLY THING I HAD TO GO ON WAS THESE DRAG STRIPPERS OPINIONS AND ATTEMPTING TO "READ MY SPARK PLUGS"

THIS WAS A PROGRESSIVE CARB---ONE BBL UNTIL YOU GOT INTO IT, THEN THE 2ND BBL WOULD OPEN

I HAVE SPENT OVER $200 ON JETS AND CRAP FOR THE DGEV

I STRIPPED OUT 2 OF THE SCREW HOLES ON THE LID TO THE JETS, I WENT IN AT LEAST ONCE A DAY MESSING WITH IT. THE O2 THING MAY COULDA HELPED ME A LOT, IF I HAD KNOWN ABOUT IT

I WANNA KNOW SOMETHING, DOES THIS WRANGLER HAVE A RETURN TO THE TANK LIKE A CJ, USING THE 3 T. IT FUEL FILTER OR SIMILAR? MECHANICAL FUEL PUMP?

THIS IS MY THOUGHT ON YOUR DEAL. WITH INFO I HAVE NOW

ONLY BUCKS AT HIGHER SPEEDS?

AS IF FUEL BOWL IS RUNNING OUT?

FLOAT ADJUSTED RIGHT?

CHECK FUEL PRESSURE STRAIGHT OUT OF THE PUMP--NOT AS IT FLOWS THRU THE SYSTEM. THIS WILL LET YOU KNOW WHAT THE PUMP IS CAPABLE OF

MAKE ABSOLUTELY SURE THAT CRAP HAS NOT ENTERED YOUR REGULATOR, AND HAS IT STOPPED UP (BLOW BACKWARDS THRU IT, OR REPLACE IT IF YOU SUSPECT CONTAMINATION) AND THE K. NOB IS IN THE "POPPED UP" POSITION WHEN YOU HAVE IT SET ON A PRESSURE

HOW DO YOU KNOW FUEL PRESSURE? I HAVE A SMALL FUEL PRESSURE GAUGE ON MINE EVEN THOUGH IT PULSATES, THE HIGHEST IT READS IS THE PRESSURE BEING GENERATED

IF YOU HAVE A RETURN LINE, CAN YOU PINCH IT WITH PLIERS SLIGHTLY, TO BUILD PRESSURE REARWARD FROM IT?

IF THIS WORKS, MAYBE INSTALL A RESTRICTIVE BUSHING SHOVED INTO THE RETURN RUBBER HOSE---FOR INSTANCE, AN EXPENDED.22 CASING DRILLED OUT TO A SPECIFIC SIZE (EXPERIMENT), THAT WILL ALLOW FLOW, BUT BACK-PRESSURE AT THE SAME TIME?

OR EVEN INSTALL A SHORT TUBE YOU CAN SQUEEZE DOWN TO MAKE A SLIGHT PERMANENT RESTRICTION, MESS UP? SIMPLY REPLACE THE SHORT SECTION

OK---SHOOT DOWN MY THEORIES!

TELL ME YOU NEED ALL OF THESE WEBER JETS AT A REDUCED RATE, I SOLD THE CARB TO SOME POOR SOUL LONG AGO

WITH THE HOLLEY, MY STUFF IS AVAILABLE MORE LOCAL

THE MEDIC


Tiny
CJ MEDEVAC
Mar 7, 2012.
I MEANT TO ADD IN--ON BOTH OF MY JEEPS I HAVE THE SAME REGULATOR. ONLY MR. JEEP HAS THE LITTLE INLINE GAUGE.

I FOUND THAT THE REGULATOR IS PRETTY ACCURATE OWN ITS OWN, THE DIALED IN READING IS DARN CLOSE TO THE GAUGE READING.

WITH WILLY, 3.5 PSI IS WHAT THE CARB REQUIRES

IF I TURN THE REGULATOR ANY LOWER, AT HIGHER SPEEDS. IT BUCKS!

WHAT IS HAPPENING IS THE FUEL BOWL IS NOT GETTING ENOUGH FUEL INTO IT. ITS GETTING USED UP FASTER THAN REPLENISHED. THE FLOAT IS DOING NOTHING 'CEPT DANGLING, IN HOPES THAT FUEL WILL RAISE IT UP!

WITH THE BOWL BEING SO LOW, THE FUEL LEVEL IS NOT FILLING THE VENTURIES TO THE PROPER LEVEL. THE FUEL SORTA NORMALLY KEEPS THE VENTURIES REALLY CLOSE TO "SPILLING"---THEN AS AIR (VACUUM) RUSHES BY THE VENTURI THE FUEL "MISTS" FROM THEM (LIKE A PAINT GUN NOZZLE) THIS IS WHERE AIR/ FUEL MIXTURE BEGINS IN A CARB

IF THE FUEL IS LOW IN THE VENTURI----THE RUSHING AIR (VACUUM) HAS A REALLY HARD TIME S. UCKING THE FUEL UP AND OUT OF THE VENTURI.

KINDA THINK OF HOVERING YOUR STRAW REALLY CLOSE TO YOU SOFT DRINK THE S. UCKING THE STRAW---YOU GET SODA!

THEN BACKING OFF A BIT MORE, NOW YOU CAN'T S. UCK HARD ENOUGH TO GET THE SODA INTO THE STRAW

IF YOU PULL THE CHOKE, THAT IS IF YOU HAVE A MANUAL CHOKE! THIS MAY MAKE SUCTION GREATER, AND IT MAY PULL ON THE FUEL A LITTLE HARDER (S. UCKS THE STRAW HARDER) THIS IS NOT A FIX, BUT IF THE BUCKING SORTA SUBSIDES A LITTLE, TAKE IT TO THE BANK, FOR SOME REASON (PUMP, RESTRICTIONS, NOT ENOUGH BACK PRESSURE FROM RETURN LINE, INCORRECT CARB ADJ, ETC.) YOUR BOWL LEVEL IS TOO LOW

THE MEDIC


Tiny
CJ MEDEVAC
Mar 7, 2012.
Mixture should not be different, just workload. Lean is ok withno load but fails undr load.


Tiny
Fixitmr
Mar 7, 2012.
I turned the regulator up to 3.5 psi and it ran fine. Its weird though because it was running just fine for 2 months before this. It hasnt done it in awhile.

Medic, maybe ill do the O2 sensor piece on this one also since its my daily driver. Give me a better idea of my driviong habits and the efficiency of them. Might solve my 12 MPG.


Tiny
Grizzly93
Mar 7, 2012.
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