I'm a newbie to this forum and to the 1988 Samurai JX that I recently picked up.



It has a Weber DVAG 32/36 carb and the exhaust looks to me like it is over sized (2") but other than that I believe it is stock.  It runs great except after it warms up when I give it full throttle it cuts out.  I'm thinking it is cutting out just about the time the second barrel of the carb opens.  There is a mixture gauge on the dash that is telling me it is running extremely lean when the problem occurs.  (I don't know if the meter is aftermarket or stock with this model).  If I'm reading the plugs right they agree with the mixture gauge, they are white.

I've done the basic tune up stuff:
New plugs, wires, rotor, cap, fuel filter.  All of the vacuum lines look good.  Two of them were mis-connected per the vacuum line diagram under the hood and in the manual but it makes no difference in the performance if I leave them where they were or route them per the diagram.

Ideas anyone?  Any ideas would be greatly appreciated.

(I hope this is not a no-no but I'm going to post this in two discussion threads:  Repair & Performance because I'm not sure where it belongs.)

Check the secondary jet for some blockage, that mixture meter is
not stock, and it's great that you have one because it tells you a lot
about how the engine is running, and you don't want lean for an engine
that is working hard, that will run it hot and wear it out faster.

Best power on gasoline is about 12.5:1 AFR, I have seen as high as 11:1
but this is rich, you want about 12-13:1 under full load and a cruise of about
14-15:1, stotich (sp?) is 14.7:1 so if your mixture meter is like mine with
the LEDs, when your foot is down hard it should read rich with the greed
lights, at cruise it should read yellow lights and lean is red lights.

If the secondary jet is clear, then you need a bigger one, and you will need
to also find out what jets should be in that carb, a classic VW type shop should
be able to help with the jets and proper jetting and adjustment for that carb.

Weber carburetors are a jet adjusted carb, there is a limited range of adjustment
and from what I heard, the screws for adjustment are air screws not fuel screws
so less is more, less air more fuel, sort of backwards to the normal way the screws
work on other carb's but I haven't messed with a weber for 25 years, so get a tuners
opinion on setting up the Weber to run best

Good Luck
Wild

check your down pipe on your exhaust, if it is the original it is a double wall pipe and the inside pipe will collapse and cut off your exhaust and do what your talking about.

Also check the fuel lines coming up the the fuel pump.  Seen them crack and leak when under load.

Thanks for the input everybody.  You were right on the money Wildgoody!  I'm a lot closer now.  The primary jet was a 130 with a 100 for the secondary.  I found a 140, put it in the primary and the 130 in the secondary.  Much better! With my foot down at a lower RPM I'm still bogging some but at 3000 & above she's pulling pretty good. 

According to the meter I'm all over the place but with my foot down I'm still pretty solid in the red lean area, not as far in the red and she has power now.  I'm feeling much better about it.

I found a guy at a VW shop that will fine tune it for me when I get my pennies saved up.

Now all I have to do is try to reroute the exhaust to see if I can get it out of the cab some so the wife will ride with me.  I'm thinking I need to take it out the side instead of straight out the back so it doesn't curl in.  But that is a different discussion.

Thanks for the input everybody !   

Great to hear you are finding the problem.

The primary side is usually smaller than the secondary, and the
jets should be sized similarly, I would see about putting the 140
in the secondary side. and the 130 or the 100 in the primary side,
this should fatten up the secondary, but it probably is still too small
if you are on the lean side

Wild

In a quick internet search I found this info for jet sizes and his engine
was running really well, and wanted to give credit to his tuner

Primary Jets
Main: 140
Air Corrector: 145
Idle: 60

Secondary Jets
Main: 170
Air Corrector: 175
Idle: 55

These should get you running good, if not a little fat on the fuel, you can
reduce sizes from there if it's too much

Wild

Here is the actual post, there is a little more info that you may want to see
that I didn't catch the first time I read it

Weber 32/36 DGV Jetting

I have had many requests for the carb jetting used on my stock and slightly tired '73 2002 motor since I have often waxed lyrical about the smooth operation at any RPM and the complete absence of deadspots and bog on acceleration from a stop. So here they are. Credit for these settings goes to Creighton Demarest.

Primary Jets
Main: 140
Air Corrector: 145
Idle: 60

Secondary Jets
Main: 170
Air Corrector: 175
Idle: 55

In addition, plug the small brass high-speed enrichment orifice in the top cover of the carb since this extra, coarse fuel supply is not needed with this jetting. This mod may have solved a problem I had with clouds of black smoke on WOT. I used a carefully-sized round toothpick to plug the hole. I cut it to length so that it is held tightly in place when the top cover of the carb was secured, no epoxy or sealant is necessary.

I have recently found that using 55pri/50sec idle jets works well for me and may be just a little easier on fuel consumption.

Overall, I have found that fuel consumption has not increased noticeably, except perhaps from the extra "testing" of throttle response I now do. Effects on emissions compliance are unknown at this time but I doubt it is very severe and certainly not likely a problem at idle. Slighlty smaller main jets, perhaps 130 and 160, would probably bring the loaded CO back in line with minimal performance loss.

Usual disclaimers apply, your mileage may vary, yadda x3.

Thanks Wild.

I was actually thinking the same thing about rotating the primary (140) and the secondary (130) only because the mixture meter is telling me I pretty rich until the secondary kicks in and then it pegs to lean if I am below 3000 rpm.  AT 4000 + rpm and I kick it because I need just a bit more power it drops to lean for a few seconds and then you can feel it sputters for an instant and then take off.  The meter reads right along with the feel.  When it sputters it is dead lean then when I feel the power I also see it jump up there to stoich.

I'm wondering though if I dare go as large as the 170 your source suggested.  I live at 8000 feet and most of my 4 wheeling is at 10,000 to 11,000 +.  I think I'll roll the two and see how that works.  One step at a time they say.

The next thing I have to figure out if possible is what to do about it flooding (or whatever is happening) when I'm in real rough terrain.  I've found that if I go over too much rough terrain to fast it floods out (or something) and I have to floor it to wake it back up.  I killed it dead a few times but usually flooring it quick enough will make it recover.  I guess that is why fuel injection works so much better.

I have to say again Wild.  You've been great!  You've given me some great advice!  Right on target.

I love this thing.  Not bad for a $400 investment!  (Plus $100 for a new battery and $150 for a soft top that doesn't fit quite right).

Not quite a high powered Jeep and not quite an ATV.  Somewhere in between.....

You might look into dropping the jet sizes by 10, run a 130 in the primary
and a 160 in the secondary, I didn't realize you were at a high altitude, and
you might also see what the Weber powered VW guys are doing for their
jets at the high altitude