89 start issues when cold?

[Gearhead88]

I have my dads 89 vet that will not start after it sets 24 hr. If I pour gas into TB it fires right up and will start all day long but in the AM again no start.
I have replaced the Fuel pump,fuel regulator, filter, sensor have plenty of oil pressure and great fuel pressure on the rail? Thoughts suggestions anything would help!

 

[DonB]

It sounds like there is NO cold start fuel enrichment. Since EFI doesn't have a choke to close and richen the mixture(like a carburetor) for cold start enrichment, there is another system used. It differs by model and year but, I seem to remember that the pre 1990 EFI systems had a additional enrichment injector that only supplied fuel when the engine was started cold.

That is where I would start looking. Since when you add some fuel into the system there-by enriching the incoming mixture it starts fine, cold.....You know everything else appears normal. COLD-START ENRICHMENT is your issue. The FSM would be a great resource here since CSE is a basic function controlled by the ECM by reading engine temp via the engine temperature sensor.

Good Luck. Keep us posted.

 

[Gearhead88]

Thanks Don I will look into that but I don't think there is another injector other than the 8. Someone mentioned that EFI on the #1 can sometimes be the start pulser also does that make any sense?

 

[DonB]

I know my '90 doesn't have the cold start valve system, but I thought the pre 1990's did. Here are a few pages from an TPI book I have.

 

[Gearhead88]

I know my '90 doesn't have the cold start valve system, but I thought the pre 1990's did. Here are a few pages from an TPI book I have.View attachment 23092View attachment 23093

Don I will dig deeper this weekend and let you know! Thanks