My truck starts slow. If it hasn't bee ran in awile, say a hour, it takes a few seconds for the engine to start. If I turn it off and wait a few minutes, then start it up, it fires immediately. Are the TBI's designed this way or is something wrong?

 

I have always had a similar problem with my TBI engines. Here is what I have found out, the engine isn't getting fuel. When it sits for a period of time the fuel evaporates out of the intake, the intake ports, etc. It takes the fuel pump several seconds to build up fuel pressure. I was curious one day and hooked a fuel pressure gauge to my G20, let it sit overnight, the next morning I grabbed the gauge and hit the key. After about 3-4 seconds of cranking the fuel pressure jumped up and the engine fired. The engine will not start until it gets fuel, the TBI system lacks a drain-back valve in the pump, therefore the fuel will return to the tank. It takes 3-4 seconds to get fuel to the TBI. Once I knew what the problem was, it didn't bother me too much. Later as I moded my 305 I needed a high volume/pressure fuel pump. I swapped to a TPI pump in the TBI tank. The TPI pump has a residual pressure check valve, unlike the TBI, it now fires up with a hit of the key.

This is a cold start-up for me now.

YouTube - 350 TBI

 

im used to it

 

OK, thanks for clearing this up. It has always done this, but I never paid much attention. I just recently put in a new crate engine, and I was wondering about the wear and tear.

Is the TPI pump a bolt-in project or did you have to do some modifications? I wonder why GM didn't put a simple check valve in these things?