I have a 1989 Dodge Ram Van B250 TBI 5.2L 318ci engine. It takes about 10-15 seconds of cranking to start the engine. After it gets hot sometimes it never starts. I'm getting afraid of taking it anywhere I have to trust it to start.
My question is about how to make the fuel system work better.
If I pitch a spoonful of gas into the carb while cranking, it instantly starts. If I short the outputs of the ASD relay so the fuel pump runs continuously and then crank the engine it instantly starts. I can see that fuel does not spray into the carb for quite a while after starting cranking, and it starts when the injectors start squirting fuel.
Why does the fuel take so long to get to the injectors? Does it siphon back down while sitting and take a while to get back to the carb? I'm wondering if air in the fuel line is why it behaves worse once hot.
I tested fuel pressure at the fuel pressure regulator at the carb and it comes up to 14 psi, but really slowly (taking about 10 seconds). Once up to pressure, it's solid and the pressure regulator dumps fuel back to the tank. Safety tangent: I tried to hold my thumb over the output of the fuel return line to see if it was misbehaving and when it came up to pressure, van started and fuel came spraying out like a thumb over a hose. Yowza! Won't check things that way again.
Anyhow, I checked pressure at the output of the fuel filter - and the input to the fuel filter (from the fuel tank pump). Pressures behaved the same as I measured at the carb, but replaced the fuel filter anyhow. I also pulled down the gas tank and replaced the fuel pump.
Question: Can fuel somehow drain back down from the carb when the engine quits - leaving air in the last 5' of line or so from the fuel filter? Does that matter? Is the fuel regulator suppose to allow a backfeed of air or is it suppose to stop backflow? Any ideas appreciated!
[added] Replaced the fuel pressure regulator at the carburetor body. Same issues remain. This problem has me stumped. Everything from the pump to the regulator has been replaced. Pressure checks are the same at all points in the system (nothing is plugged). I could sure use some help...