Idle Solenoid Change Over

[RicardoJM]

I have an Aisin carb with a November 3, 1969 date code. I had been experienceing intermittent dieseling upon shut off. This weekend I checked the idle solenoid and it clicked, but it was a very week click. I removed the solenoid and found the arm was slightly bent.

I replaced the idle solenoid using one from from another Aisin carb, but could not find the date code on the other Aisin carb. I do know that it appears to be of the same vintage; 2 barrel, no ported vacuum, throttle cable. The idle solenoids appear to be the same. With the "new" idle solenoid the truck is turning off as soon as the key cuts power to the solenoid.

However, since installing the "new" idle solenoid the truck is very slow starting in the morning. The truck starts up fine during the day as I run around doing errands. In the morning I have to pump the gas while cranking to get it enough fuel to start running.

This got me to looking a bit closer at idle solenoids. On SOR, they show an idle solenoid for September of 69 through September of 72 and a different solenoid for September of 72 up until January of 75. I believe one of the reasons for the different parts has to do with the power connection for the idle solenoid on early trucks was the ignition coil and then it moved to the voltage regulator. Does anyone know if this is the only difference? Are the shaft lengths of the idle solenoids also different? Are the diameter of the shafts different? I did not check these items before making the swap.

Not knowing the exact vintage of the "new" idle solenoid I am wondering if I have put one in that is not correct and is a contributing factor to my morning starting issue.

 

[Pin_Head]

The idle solenoid shouldn't have anything to do with cold starts. Pumping the accelerator a couple of times is normally a good thing for cold starts. Long cranking isn't. What is the level of fuel in the bowl before you try to start it. Maybe it has to fill first, suggesting that the fuel is either evaporating or leaking out after you shut it off.

 

[RicardoJM]

What is the level of fuel in the bowl before you try to start it. Maybe it has to fill first, suggesting that the fuel is either evaporating or leaking out after you shut it off.

I've only had the problem yesterday and today. I will check the fuel level this afternoon after work and again tomorrow morning. I suspect it will be low, but have not yet confirmed this.

 

[FJ40Jim]

This got me to looking a bit closer at idle solenoids. On SOR, they show an idle solenoid for September of 69 through September of 72 and a different solenoid for September of 72 up until January of 75. I believe one of the reasons for the different parts has to do with the power connection for the idle solenoid on early trucks was the ignition coil and then it moved to the voltage regulator. Does anyone know if this is the only difference? Are the shaft lengths of the idle solenoids also different? Are the diameter of the shafts different? I did not check these items before making the swap.

Not knowing the exact vintage of the "new" idle solenoid I am wondering if I have put one in that is not correct and is a contributing factor to my morning starting issue.

No internal differences in the 70-74 idle solenoids. Only difference is the wire connector.

 

[RicardoJM]

No internal differences in the 70-74 idle solenoids. Only difference is the wire connector.

Thanks Jim, just to be detailed, this would include the 2 barrel carbs with date codes from September of 69 as well? The reason for my clarification is that the date code stamp on my carb is November of 69.

 

[RicardoJM]

Ok, this afternoon I looked at the fuel level in the carb window before starting. No fuel. I pumped the throttle until I could see the float start to rise. Jumped into the truck pulled the choke out a bit and it started right up. I'll check it again in the morning and then go from there.

 

[cruiserbrett]

pumping the throttle should lower the float level if the truck isnt running. If it is running, the fuel pump and float needle valve control filling, not the gas pedal.

 

[Pin_Head]

After it sits overnight and the bowl is empty, check for fuel in the bottom of the manifold with a flashlight. If you see a pool of fuel, it is siphoning out or creeping out via surface tension; if not it may be boiling off. It can siphon out of the idle fuel port, but only if the air vents are plugged and the solenoid cut off doesn't seal completely.

 

[RicardoJM]

Ok, this morning there was fuel in the bowl. I made three pumps with the throttle arm on the carb, closed the hood, got in the truck, pulled the choke out 3/4, gave the gas pedal 4 pumps and it started right up. In the first few seconds it seemed like it was going to die so I pumped the gas pedal a few times while simultaneously pushing the choke in to about 1/4 and then it was running at that choked high idle state. I kept it choked for a few blocks until the temperature started to come up and it ran just fine. It continues to turn off with no dieseling.

Cruiserbrett, I understand what you are saying. I did not have to crank the truck yesterday afternoon, so I must not have been correct in my assessment of there being no fuel in the bowl. I thought I was looking at the top of the float in the window. I'll continue to check the fuel level in the bowl before starting for the next several days.

My main reason for posting was to learn if there were physical differences (beyond the power wire) in the idle solenoid. As I reflect on the hard starting issue, it could be that with a good idle solenoid the start up behavior changed just slightly so that it now needs less choke and more pumps and it took me a couple of days to figure that out. That said, with a properly tuned system; ignition, dizzy, fuel delivery and carb there should be no "figuring out" needed.