Re: 94 JGC Hard Start
Any chance it might be some condensation in the computer or relay box? It would make sense that it only happened when it was cold. If you can put a volt meter on it, you could make sure that the relay was getting voltage instantly and that the pump had power to the feed side of the relay. You could probably (if you wanted to stand out in the cold) even measure the time from key activation to relay activation. That would give you some good ammo against the pump theory and maybe give you enough info to get a new relay. I don't know how much those relays cost though (if it was inexpensive I would almost replace it anyway). The other thought I had was maybe a clogged fuel filter. It would cause an intermittent problem maybe enhanced by the fuel being thicker? (I'm reaching there, but if you haven't changed it in a while, it sure wouldn't hurt).
Is the fuel pump controlled by the ignition switch or the Engine Management System? I know GM systems the fuel pump isn't controlled by the computer. That would sure simplify trouble shooting (and make repair possibilities less expensive).
Have you bought the TSM yet? If you can spare the $100.00 it would give a listing of the engine codes, that would help analyze the source of the problem. Maybe one of the guys on the Mid-Sized board has one, or you could call another dealer and ask one of the service guys to tell you what it means (they might not tell you, but it never hurts to ask).
Have you ever had the fuel sytem cleaned or do you use premium gas? I know you said you could hear the pump start, but extremely dirty injectors could cause a computer fault especially during ethanol months. If its a throttle body type injection, it might not be too hard to pull the throttle body and clean it. I don't think I would mess with a port fuel injection system as there is a lot of possibility for leaks, but if you're comfortable with it, you could pull and clean the intake, fuel rail, and replace the injectors (depending on cost). Even if this isn't the source of the problem, it is a good idea on a vehicle that is getting on in years, might help you narrow down possibilities.
Just some thoughts. I hope that helps.
Phillip J. Van Why
1985 Jeep Grand Wagoneer