Cleaned out the a/f and solinoid passage twice now

[Sh00bs]

3rd time she's conked out on me... will barely idle and I can free rev it but under load it just bogs
78 620, L20B

The past 2 times I was in my neighborhood and limped it home, this time I was a few streets down. Has a new fuel filter on it
I fixed the first two times by removing the idle solinoid and a/f screw, then blowing them out with carb cleaner, both ways
Runs fine for another 20-30 miles then the same thing happens..
Wtf
How can I make this permanently fixed ?

[datzenmike]

It bogs while driving under load? That sounds like the primary jet has a small blockage in it. It's hard to get at the jets so take the carburetor off first.

 

 

Take the front window or the metal plate with the small round window in it off the carburetor. Have a rag handy to soak up the spilling gas. Watch for very small parts that probably fall out from next to the float on the float hinge rod. Use carburetor spray to clean out the float chamber and wipe it clean with paper towel. 

 

Below the float chamber are two hex head plug covers. The one closest the valve cover or the one on the left is the primary, the right side is the secondary. I think a 12mm wrench will loosen it. Way up inside under the plug is the jet.

 

This is upside down so this is the secondary but you can see the brass jet up inside there.

 

You'll need a thin screwdriver to get it out.

 

 

Primaries are stamped 99-110 and secondaries are 160-170. DON'T mix them up. Spray the small orifice out with carb cleaner and flush out the hole it was in. Might as well do the secondary while you are at it.

[Sh00bs]

Before I do that, should I spray out the a/f and solinoid passageway first? ... for a third time lol since it worked the first 2 times

[datzenmike]

Won't hurt but don't forget this is only the idle circuit not driving under load primary. Cleaning out the float chamber and both jets might fix it permanent.

 

I had a 521 that you hit a bump and it would barely run. Shut it off for the count of 5 and restart and it runs fine. Eventually I got tired of it and took the primary jet out and there was a small flake of something in it. Hitting a big bump would block the jet but shutting off it would settle down out of the way.

[Sh00bs]

I gotcha. I'll get her pulled tomorrow and see if I can't clean it all out

[Sh00bs]

the more im thinking about it, all this stuff is 40 years old. i really dont want to have to keep going back and fixing it as things break - which i understand you ahve to do from time to time with 40 year old things. 

could anyone give me a good reason to not swap to a 32/36 and remove all the cali SMOG stuff ? being a '78 the intake and exhaust should NOT be connected i believe

i dont want to just do the age ole thing of "just tossing parts at it til it's fixed" but i mean shit, it was running GREAT on 3 cyl's until i started to diagnose my cyl 2 misfire, which turned into finding a damanged cam/rocker and putting a cam in it. running on all 4 now and a headache later im having carb problems - which i find weird being it was running so great on 3cyls. it sat for maybe 3 - 4weeks at most while i did the cam swap and had the front cover off to reset the timing chain 
in my head, less is more. less is simple. take the SMOG stuff all out (im in maryland, tagged historic we have no emissions testing or inspections) and put a 32/36 on her. gain a little performance but mostly make it easier to work on (Mike you mentioned in my last thread how much of a pain it is to get the stock carb off and you have to cut a 12mm wrench to do so) 
im looking at this guy 
https://www.californiadatsun.com/carburetor-parts/weber-32-36-dgev-electric-choke-carburetor-conversion.html

unless someone can really give me a reason i shouldnt. i LOVE old stuff, but when they start nickling and diming you every 50 miles or less, i dont want to clear my carb jets just to have something else come up with this 40 year old carb...  - whcih i get, it "shouldnt" lol but hey here we are right

[datzenmike]

Not California Datsun.

 

Try Pierce Manifolds.

 

The stock carburetor isn't worn out probably just dirt accumulated for years of driving it. This could be from lack of filter changes or several other causes that could also plague a new 32/36. I'm saying replacing a carburetor that may just need cleaning a/ is expensive and b/ doesn't get rid of the cause. I would clean the carburetor and change the filter for good measure.

 

Yes the '78-'80 L20B engines did not come with the co-joined manifolds. Only '75-'77 with U67 heads did.

[thisismatt]

If it runs fine for a while, maybe you have something blocking/choking the pickup at the tank?

[Sh00bs]

just changed the filter when i was doing the timing chain 2 weeks ago 

im going to clean the carb regardless, hopefully it's not too much of a pain to get off
i have jet cleaners, an ultra sonic machine and plenty of carb cleaner. about an hour and a half i'll be starting on it 

[banzai510(hainz)]

hawaiian tune up

run at 6 k for a second and put a rag over the carb and maybe it sucks the dirt thru the jets

 

I had a weber dgv and it would idle but above idle cut out. but at WOT it would be ok as the 2ndary was manual.

or if I drove with the choke on I made it home. I took the carb part and found a tiny rock blocking the main jet on bottom of the bowl.

I was lucky as webers are ezer to work on. Stock carbs are Rubix cubes in desguise so I would NOT take those apart I just give them away usually in pairs.

[Sh00bs]

the way Mike is describing it sounds like i dont have to take the carb off ? is this true

[banzai510(hainz)]

mike knows more than me on stock carbs

[thisismatt]

54 minutes ago, Sh00bs said:

just changed the filter when i was doing the timing chain 2 weeks ago 

im going to clean the carb regardless, hopefully it's not too much of a pain to get off
i have jet cleaners, an ultra sonic machine and plenty of carb cleaner. about an hour and a half i'll be starting on it 

 

The filter does nothing to help with a restricted feed line/tank pickup 🤷‍♂️

Edited June 7, 2021 by thisismatt

[Sh00bs]

3 minutes ago, thisismatt said:

 

The filter does nothing to help with a restricted feed line/tank pickup 🤷‍♂️

 

i completely understand that, however... after this has happened the first two times, i remove the a/f screw and the idle control solenoid, spray the passageways out with carb cleaner, and bam she runs fine again. 

i can let it sit for a day or more, start it up and the issue is still present. i appreciate the advice but i really dont believe that to be the issue 

Edited June 7, 2021 by Sh00bs

[thisismatt]

I see 👍

[Sh00bs]

After looking at it again, I'm gonna order a carb, remove all the California smog junk (yeah yeah I know, well it looks way better and a LOT less crap in the way when working in the bay) and see what happens. 

I've gotta remove it anyway or work around it to get the carb off anyway. Why does California suck? Lol look at all this extra garbage crowding the bay

Pulled the a/f screw and solinoid, blew them out again and bam she's good to go 

 

Any thoughts? Would spraying that passage way blow back the debris into the bowl and out of the jet? At least, temporarily freeing the jet

[banzai510(hainz)]

you really want to tear into all that?

 

ask Mike if one can go thru the front to clean out the bowl

that looks like a MOFO to get at anything

[thisismatt]

Nothing wrong with lowering tailpipe emissions. It's the draconian approach that sucks, where you can't change things even if you keep the emissions the same.

[datzenmike]

You can take the front of the float chamber off to clean in there, but VERY hard to get underneath it at the jet covers. Can't see them, have to feel for them. The jets are up up hill on an angle screwed into the bottom of the float chamber so you need a short screwdriver. Did it once but fuckit easier to do if off the car.

[bilzbobaggins]

I would take the latest fuel filter off and cut it open.  In your pic, it appears to be an opaque one you cant see thru.  If you are sucking up trash from the tank, you will be cleaning the carb non stop.  It will make the truck a chore and bore more so than a thrill and pleasure.  

 

You might just have a bit of trash that got that far in and everything else is good, or you might have a crusty death tank.  I have one in my 521 that I will eventually fix.  Still running of a 5 gallon jug in the bed.  Just gotta find the time to drop and coat my old tank.

 

Edit:  When in the hell did the clear fuel filters get stupid expensive?  

Edited June 8, 2021 by bilzbobaggins

[datzenmike]

There is something in the carburetor primary jet that gets dislodged when you clean out the idle circuit, but then falls back into place. As I said earlier I had a similar thing but would happen when you hit a bump. Shut the engine off and it would drop out of the way, start up and it was fine maybe for weeks if you stayed on pavement. Cleaned a small spec of something out of the jet and it was fine.

[Sh00bs]

the SMOG junk is just so much in the way it would make it even harder to pull the carb... 

yes i would like to remove the smog BS, i'll happily dig into it. gonna wait til i have the replacement carb though. Mike i've read a lot of your posts defending the stock carb, i do plan on keeping it and i'll be cleaning it as well, i just dont want to pull some of the smog stuff to get the carb off and then have to put it all back on. i now have a 19mm, carb cleaner, a 10mm and a flathead with me in case she breaks down haha i'm at about 4 mins to have the filter hat off w/all hoses, a/f screw out and solenoid out and cleaned with the carb cleaner. worst case i'll do it on the side of the road 

 

edit: any links for a quality clear filter ? 

Edited June 8, 2021 by Sh00bs

[banzai510(hainz)]

I run 2 filters on my 521 the stock one then a in line one bfore the pump

[bilzbobaggins]

Oreilys has the clear wix filters.  About 7 bux around here in Georgia.  Your results may vary.  I know I bought 6 off amazon for 1.50 each two years ago but cant find any that cheap anymore.

[Sh00bs]

bump. about 300 miles since i cleaned it for a 3rd time and she's still good! 

waiting on getting the gears back for my '91 jimny (went taller gears for better hwy driving rpm's) and i'll be pulling all the smog stuff off. 

since im not making a post though about it, she'll probably crap out on me today on the way home from work lol 

the 32/36 came in. im gonna hold off til this carb gives me issue's again though before pulling it