Stumbles on quick acceleration

[rollingpinz]

Hello

If I stomp the gas quickly, it stumbles almost to the point of stalling. If I press gradually, even on a hill, it revs fine. All other driving aspects are fine and it starts right up like a dream.
I bought accelerator pump “cups”. I took the top off of the front carb. Two screws were broken. The “cup” on the accelerator pump looked fine. No cracks, it was flexible, and the same diameter as the new ones from SAV. The only oddity was the was the rod attached to the lever. It didn’t have the pinched “ears” or a cotter pin. It had external snap rings. Clearly, not original, but there was no binding. I replaced the broken screws and checked the rear carb. Same story minus the broken screws.
Any ideas? Thanks in advance.

[ChickenPinz]

Have you checked and confirmed your timing is where is should be?

[rollingpinz]

Hello

No. I’ll have to get a timing light. Is the idea that the timing is off just enough that it’s only on quick acceleration?

[rmel]

Just for yukes, and you my have done this already.

Remove the filter and Air Intake, with the bowls full and engine off, rapidly give the
linkage a full throw while looking down the throat of the Carbs. If you don't see a
healthy "squirt" of fuel a jet(s) are plugged up.

[rollingpinz]

Hello

Ok. The squirt from the accelerator pumps should enter the barres squirting from rear to front of the vehicle?

[Hugues]

you see them on this video,
https://youtube.com/shorts/Kp_mDAwnY1Q?feature=share

[rollingpinz]

Hello

Sorry about delay. It’s been sunny in so cal and I don’t like baking while I’m working on the pinz. My face sweat fogs up my old man glasses.
So I think the clogged accelerator jets are a likely cause because I’m certain that this truck sat for a while. If that is the case, how do I clear them. The exploded views that I have don’t really describe how the jets are in the carb. I’d like to think that after removing the top of the carb, I could just screw them out and avoid dismounting the entire carb.
A long time ago, I had a Yamaha TT600 and to clear some passages in the carb, I ran tag wire through. Would that work?
By the way, I haven’t checked for proper flow from accelerator pump yet because of previously mentioned sun and my engine cover has cracks so I try to move it as little as possible.

[ChickenPinz]

If you're in SoCal you can drive over to JimL's place and let him work on them. He'll dial them in on a test engine. Just one option if you don't want to solve it yourself.

[rmel]

The likely pair of jets are accessible on the Passengers side of the carb.
You should be able to see a pair of "Screw" heads (also with a Hex) on both
carbs. The Jets are behind these, each should have an O-ring so be careful
if you pull them.

The actual jets can be a bit of a PITA to remove -- they tend to stick. If you
carefully place a screwdriver inside the throat of the carb and give each a
little nudge they should come out -- and they are "keyed" so they only go in
one way with the pinhole pointing down. It's a real small hole for the fuel to
exit and they can get plugged. You can take a small sowing needle and get it
in there to dislodge any crud. Use Brake clean as to see if the path if open.

All the above said -- you should confirm these jets are clogged by looking down
the throat while you "goose" the accelerator. If you see a lot of fuel coming out
then this isn't your problem.

If your not comfortable messing with Carb's as Chickenpinz pointed out Jim L
will do nice to them, not a bad drive to San Bernardino.

[rollingpinz]

Hello

Thanks for the replies. Jim worked on my first pinz about 15 years ago and I plan on scheduling a fluids flush with him. Otherwise, I’m trying to do as much as I can and teach my son because he will inherit the pinz.
I will dig into it in the next few days. I don’t look forward to pulling things apart because it, otherwise, runs so well.

[rollingpinz]

Hello

Ok. So it was the accelerator pump jets. Full disclosure, I pulled the front carb and looked all over(inside) to see where the fuel squirts in. I watched the video several times. Then I read that last post more carefully. (I know …). I pulled the jets, cleared the blockage, remounted the front carb, pulled and cleared the jets from the rear carb, and, because I’m an idiot, I figured that had to be it, put it all back together only to find out there was no change. And the extra kick in the nuts, the fuel gauge stopped working. It lights, but reads empty.
So this morning, I took the top off of the rear carb and made sure the valve at the bottom of the accelerator pump moved freely. It resisted at first, but moves freely now. Then I pulled that little brass screw that is 90 degrees to the bottom of the a-pump(tired of typing accelerator. Damn. There it is again) and ran a wire through.
Now the stuttering problem seems to be fixed. Yeah me!
Before I put everything back together, does anyone have any ideas as to what might have happened to the fuel gauge? I can’t imagine how I could have disturbed anything relative to the gauge. But maybe someone has an idea.
Thanks for the help.

[Hugues]

Great, you learned a lot in the process.
As for your gauge, mine stops working sometimes, I tap on it with my palm and it comes back, bad contact I guess, I'm a little lazy to look into it, worth a try.

[eric82000]

Hello everyone
My fuel gauge isn't working right either!
I removed the tank
My problem was a bad crimping of the ground wire on the gauge head
inside the aluminum tube, the float sliding wires had a faulty electrical connection with the ground of the gauge head, and added a series resistance to the fuel height measurement circuit.
And resulted in an erroneous fuel level display on the dashboard.

Greetings from France
Eric

Translated with Deep

original version
Bonjour à tous
Ma jauge à carburant ne fonctionne pas bien non plus!
j'ai déposé le réservoir
Mon le problème était un mauvais sertissage du fil de masse sur la tête de la jauge
à l'intérieur du tube en aluminium, les fils de coulissement du flotteur avaient une liaison électrique défectueuse avec la masse de la tête de jauge, et ajouter une résistance série au circuit de mesure de hauteur de carburant.
Et entrainait un affichage erroné du niveau de carburant au tableau de bord.

Salut de France
Eric