Long cranking time

[emsherer]

I have an 85 K10,350,4speed,4x4. If I drive the truck every day it starts right up. If it sets for a week or longer it takes a real long time to start,lots of cranking over. I have been told I might need a check valve in the fuel line to keep fuel from draining back to the tank. I have also been told a paper filter in the quadrajet carb might have a built in check in it? Any ideas will be appreciated.

 

[1987 GMC Jimmy]

When you haven't ran it in a while, I'd get a little bit of gas to pour in the carb to prime it and see if it starts right up or still takes forever. If it still does, you know it's a fuel problem. If not, you know it's an ignition problem. I guess it could be an air problem, too, so I'd make sure you don't have any vacuum leaks first. Do you know what your timing is set at?

 

[MikeB]

There's' a problem with Q-jets leaking through a plug at the bottom of the float bowl.

Google "Q-jet leak" to find tons of info.

 

[Georgeb]

If your choke is set properly try starting it with this method.:
Pump 3 times, crank to the count of three, pump three times crank to the count of three. Repeat as required to get it started. Mine was the same way. If I had ran it the day before one pump was all it took.

 

[Craig 85]

I had a similar problem with my '79. It turned out my factory intake was warped near the EGR valve causing too much air.

 

[da_raabi]

There's' a problem with Q-jets leaking through a plug at the bottom of the float bowl.

Google "Q-jet leak" to find tons of info.

This would be my guess. It's apparently pretty common. These trucks never had a check valve in the fuel system like newer vehicles, instead they relied on the residual fuel in the float bowl. If the plugs in the bottom of the bowl are leaking then it won't have that. An aftermarket check valve could potentially band-aid the problem, but the real issue is likely the plugs. An at-home rebuild could probably fix it. I'd also be careful adding something like a check valve to the fuel system. It's another "something" to get gummed up by the crappy ethanol fuel we get today... but that's another soapbox.

 

[GregL]

Well plugs are leaking. Very common issue with the Rochester. Pull it apart, epoxy the well plugs, reassemble, problem solved.