Cold Start Prob. w 84 4KSQ, Still

[Ameer Antar]

most likely it is your cold start valve system not actuating. It also could 
be the warm up regulator in addition. Or maybe the mixture is out of 
adjustment. A cheat to help you start for now would be to richen the 
mixture w/ a 3mm allen wrench at the air-flow meter. Turning it clock-wise 
richens the mixture. This will make the engine run rich when warm and 
create more unburned gas and poor performance and economy. Also this 
shortens the life of the O2 sensor. So don't leave this as a permanent fix.

First thing, test the cold-start valve. Disconnect the harness from the 
valve and check the voltage or put a test lamp on the connector while you 
crank the engine when it's below 70F. It should light for a moment and go 
out. If not, then something is not telling the valve to open [probably 
wiring]. If so, then the valve might not be working right. Take off the 
valve from the manifold w/ an allen wrench, and leave the wire and fuel 
line connected. Hold it over a glass or somewhere not dangerous, and crank 
the engine. It should squirt fuel for a few seconds. If the voltage is ok 
at the harness, but no fuel, the valve is bad.

Second, make sure the warm-up regulator is working right. Check for 12V at 
its harness when the engine is on. Then check the resistance of the valve. 
It should be 17-21 ohms. If that's all good, you need to get a CIS fuel 
pressure tester. You can get one from JC Whitney that's $55. That's the 
cheapest I've found. The kit explains how the control pressure should be 
tested. When warm, the control pressure should rise to about double the 
cold value, but specs are in the Bentley.

Unless someone has played w/ the mixture, that should not be the problem. 
Also you would notice a lean mixture even when warm, causing hot running 
and loss of power. Good luck, and let us know what you find out.
-ameer antar

'84 5kT...190k miles