What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Q-jet hard start

black rust

black rust

1/2 ton status
Joined
Jun 29, 2007
Posts
563
Reaction score
0
Location
Beecher, IL
I recently rebuilt the q-jet on mt 85(carb, for some reason, is off of a 77 caddy). If the truck has been running recently or I take the carb off and put it back on it starts easily, but if if sits for a while, I have to pump the throttle 5-6 times and sometimes while its starting to get enough fuel to start. Once it is running, it runs fine, it just doesn't want to start. I have the idle mixture adjusted correctly, and I think the choke is adjusted correctly(anyway I can check). Any ideas on what my problem is?
 
The choke is bad . Either the coil in it , or the linkage binds . Maybe even the fast idle adjustment .

My choke quit 2 years ago after BB05 . I ain't worrying about it anymore , the truck is running pretty good after its warm , and I hate touching it .
 
Yeah, sounds to me like the choke isn't working right when the engine is cold. This is kind of hard to play with since once the engine even starts it throws choke adjustment off. But it's doable. You can fiddle with the choke cam after it sets (while adjusting the choke when it's cold) to disengage it, so you can see the effects of your changes.

Choke plate needs to (just barely) snap completely shut with one pump of the throttle, and needs to open about 1/8" with the choke pulloff, dead cold engine. When the engine is up to temp, after kicking the throttle down, the choke plate should be perfectly vertical. If the choke doesn't open all the way, typically you end up with a warm engine that idles too high.
 
That's weird. I didn't even touch the choke when I rebuilt it, and it started easily before the rebuild. I can run the engine for a few seconds and shut it off before it warms up, and it will still start easily. That was why I ruled the choke out. I'll try messing with it and see what I get. Thanks for the help
 
Since you have to pump it so much, sounds like it's lean, which if the choke isn't closed all the way, it likely is since there is more air getting in there.

Easier thing to check though, is pull the air cleaner before starting it (cold of course) and while the choke plate is open, look down the primaries and work the throttle. If no fuel sprays as you work the throttle, then there is no fuel in the float bowl, meaning you've likely got leaking well plugs, which is more likely if you didn't disassemble the choke assembly at all.
 
Just a guess, mine did that and turned out floates were bad.
 
dyeager535 said:
Since you have to pump it so much, sounds like it's lean, which if the choke isn't closed all the way, it likely is since there is more air getting in there.

Easier thing to check though, is pull the air cleaner before starting it (cold of course) and while the choke plate is open, look down the primaries and work the throttle. If no fuel sprays as you work the throttle, then there is no fuel in the float bowl, meaning you've likely got leaking well plugs, which is more likely if you didn't disassemble the choke assembly at all.
Click to expand...

I also vote for this as a first step. Not sure how long it would have to sit to leak down however.
 
Mine does the same thing. I don't have a choke hooked up. It has an electric choke that is not hooked up.

Once it fires up, starts with a click of the key. Cold start is a b!tch. The engine cranks almost the exact same length of time, every time on a cold start.
 
Update - I think I have another problem - not just the choke. My truck acts like there is no fuel on cold start after its been sitting for a few days.

After sitting for a week or so,
Cranked for a long time with no indication of a start. Then fires up.
All starts after are a click of the key
This has been the history since I bought the truck 2 years ago.

So Thursday - I started it, moved it out of the driveway and back into the driveway.
The truck sat all night
Next day - mid day, Fired right up and ran like a choke problem until it warmed a little.

Someone told me that they think that the fuel is leaking from the bowl when it sits.

Anyone have any ideas?
 
Thanks - I also did some searching and was able to find some pics.

HIJACK ON

Is the Edlebrock performer intake worth putting on a stock 350 with a Q-jet? I've got one sitting on the shelf that I got pretty cheap. I'm am wondering if it is worth the effort to do that when I fix the carb leak.

HIJACK OFF
 
You must log in or register to reply here.

Latest Posts

Top Bottom