1983 R38 Wont start but will run ???

[Tripower389]

Hi Guys, ( already searched )

I have a 83 pickup, the trucks previous owner wasn't much of a mechanic and did more harm then good. I have been taking my time going over the truck and trying to piece Togother the wiring that was hacked and redo the vaccum lines. I have a FSM for 83 so i am pretty sure everything is going correctly.

My major problem is that the truck will not start but it will run. It was going good till i had to replace the origional carb when a seal in the carb went. I had a 85 carb that had been recently rebuilt, given to me. My truck was missing the plug for the 85's electric parts on the carb. I have them wired temporarily to run the eninge (the red wire to the choke is hot and should be on when the ignition is on, and off when the key is out. I already know that.). So what happens is the truck wont kick off on its own. Fuel has to be sprayed down the butterflies of the carb to get the engine to kick over. Once it has been running for a few seconds the fuel pump will supply the carb just fine. It just wont start on its own. Even after the engine has run if it is shut down it will not just fire up with out spraying fuel in there. I am betting there is something wrong with either vaccum to the carb. Or (not sure if this is correct.) if the accelertor pump is dead it will not work.My knowledge of these things is limited so any informaton you can give me would be great.

I do know for certain that it is not a case of a plugged fuel filter and im getting good spark.


- Jason

 

[Jukelemon]

So, you are saying that the vehicle will run, indefinitely, after you spray in fuel and even after being run i.e. driven, it will not start?

Does not make sense in terms of how the idle circuit works i.e. it is either there or not. It cannot be primed, for lack of better words, by spraying in fuel.

Describe in more detail from a-z, cold start to run to drive to warm start

 

[Tripower389]

OK to clarify on some things.....

If the vehcile was 100% togother. And fired off and was running yes it would continue to run. I know that the fuel lines are clear the pump is working properly the engine has spark and air. Now from this point if i shut the engine off and tried to restart the thing it will just spin and it might chug once but it won't fire off. Now if i get out of the truck and go spray gas down the carb hit the ignition it will run then start pumping fuel back through the system.

I cant describe a start to run to drive to warm start. I have had the thing running out of a jerry can because my fuel tank is a rust bucket. I know this doesn't sound great but i did run the vent line and return line back to the to the make shift tank. the truck does warm a but but there is no 02 sensor so it doesnt have a closed loop system.

I hope this helps clarify

- jason

 

[Jukelemon]

OK. I follow you now. Here are my thoughts then....you have created a vapor lock. If you have a vehicle that will start cold and run indefintiely, then your idle circuit is fine.

Do this...cold start it, let it run for a couple of minutes. Turn it off and then try to start it. It should not start...according to your description. Now, pull the fuel line off of the fuel filter end going to the carb. Now go back and try to start it.

Report back.

 

[Tripower389]

Ok I will try to do that I wont be able to work on the truck till Sunday evening then i will let you know what is happening.

- Jason

 

[Tripower389]

I posted this same problem on some other message boards. I was told that if the choked butterfly isn't closed the truck wont start. So i did notice that the butterfly is open so im going to try to fix that problem first. I'm going to go through the FSM and see what it tells me on that.

- Jason

 

[Jukelemon]

Should not be choked though after running. That would explain the issue on a cold start but not a warm start.

Just my opinion.

 

[Tripower389]

Hey Man,

I agree, i have a feeling it might have a few issues. I could always try one of the other 2 carbs i have.

- jason

 

[Tripower389]

Thanks For all your help !!!!

I turns out it was the butterfly on the choke had been reassembled incorrectly. I Didn't bother taking it all apart to correct the problem. I am guessing that there will be a few other issues with the unit, so i'd like more time to study the diagrams. I opted to switch to another (used) carb i had picked up at a Junk yard. So far the Thing is running good other then lower end noise. It also starts when its warm so i think i have the Fuel/Air system worked out.


I'm Doing a Build post for this truck in the buckeye birfield syndicate on the club boards.

https://forum.ih8mud.com/showthread.php?t=75554