74 620 Idle Issue

[sanyantho]

Hi Guys,

           I am in need of help. My 74 620 has been running well for the last couple weeks. I am running all stock with a Weber 32/36 carb. I adjusted the idle mixture and speed screw per instruction and everything seem to be working fine. But yesterday, while riding to the store, when I came to a stop. My truck would not stay in idle and just die. The only way I can stop her from dying while in idle is to press the gas pedal and give her more gas. When I let off on the gas pedal, she would just die. Does anybody know where I should start checking? I am clueless.

 

Thanks,

Sanyantho

[bilzbobaggins]

Plugged idle jet?

[datzenmike]

Maybe a vacuum line fell off. There would be one on the side of the intake going up to the stock air filter that isn't used now and should be capped.

[sanyantho]

12 hours ago, bilzbobaggins said:

Plugged idle jet?

Can you walk me through the steps to check please?

[sanyantho]

7 hours ago, datzenmike said:

Maybe a vacuum line fell off. There would be one on the side of the intake going up to the stock air filter that isn't used now and should be capped.

Hi Mike, that vacuum line is capped. The only other line I see is from the intake to the brake mater cylinder. The screw for my choke ring somehow fell off, so I bought new screws and tighten them. I can see that my choke is not working properly. Can that be the cause? I have to reset the choke.

 

Thank you in advance for your help!

[datzenmike]

It might if the choke remains on when the engine is warmed up. It should be fully open.

[bilzbobaggins]

 

 

Here is a video on how to get them, its easy.  Your problem might be the choke tho.  How long has it been since you put the carb on?  Did you use any loctite on the adapter bolts and on the flange studs?(problem I have had multiple times, damn thing vibrating loose)  Do you have a clear fuel filter?  Is it full of rust?

[banzai510(hainz)]

truck the fuel filter is exposed to the elements. When I get a no idle I ck the idle jet for rust or dirt then check the distributor and intake or carb loose/

 

if a idle selinoid then make sure the wire is attached.

[sanyantho]

So I tighten the adapter bolts and the flange studs because they have loosen due to vibration. And I reset the choke, but she's still stalling on idle. My old fuel filter was clear and full of rust, so I bought another one a while back. The new fuel filter is white, so I can not tell if it's full of rust. She seems to be starving for fuel during idle. So I will check to see if the idle jets are clogged. Will report back.

 

Thanks Everybody for your help.

[sanyantho]

Update: I removed the primary and secondary idle jets and found that the primary was clogged with some debris. Also both of the rubber o rings was old and cracked. I am going to order some new o rings and clean the idle jets and passage. Thanks everybody for your help. I really appreciated it!

[banzai510(hainz)]

idle is primary and the culprit.

 

 

[sanyantho]

4 hours ago, banzai510(hainz) said:

idle is primary and the culprit.

Yessir! My truck is running good again after I clean the idle jet. Thanks again for your help everyone!

 

 

[banzai510(hainz)]

change out the fuel filter more often in the trucks. Water and dirt run down the gas tube.

 

or run the stock filter then a inline one

[datzenmike]

I change my fuel filter every two years, dirty or low mileage or not. Had one in my 620 that rattled when shook when I replaced. Took apart and the filter inside was detached. Probably filtered nothing. One of the perils of buying a cheap $3 filter. Worth paying $7 for the privileged of not ever being stranded or having to figure out and clean the carburetor or jets.