Join Date: Mar 2002
Location: Austin, TX, USA
Re: Poor Starting
I know my Dad has had a couple of S10 pickups with V6s that developed starting problems. If you went to crank it, it would take several seconds to hit and then would run rough for a few seconds before it would smooth out. On the other hand, if you crank it for a second or two, stop and crank again it would fire right up. I'm not sure he ever determined what caused it, but if yours behaves the same, perhaps we can narrow it down a bit.
I think GM stopped using cold start injectors in 97, but I'm not sure. A cold start injector problem seems like a possibility though if your engine has one.
Fuel pump problems could cause it also. The fuel pump is energized by a relay, but there is also an oil pressure switch in the circuit. I believe the oil pressure switch is supposed to cut off the fuel pump if you ever loose oil pressure. It could be that the relay or wiring is bad and the fuel pump doesn't develop pressure until the oil pressure comes up enough to make the switch.
Yet another possibility would be a bad crank position sensor (or ignition module). The ECM won't fire the plugs until the engine cranks over a couple of revolutions and the ECM sees crank / cam pulses. When you first turn on the key, the fuel pump should run for a second and then shut off. The ECM won't turn the pump on again until it sees those pulses and figures out where the timing is. A weak sensor could cause the ECM to delay turning on the fuel pump.
Does the car seem to work OK, once it is started, or does it run a bit rich? You might check your plugs to see if any are black and wet when compared to the others. If the fuel pressure regulator develops a leak in the diaphram, it will leak fuel into the vacuum line that controls the regulator and basically flood the engine. Starting will particularly affected - especially if the regulator has a small leak and feul builds up the first few minutes after the engine is shut down.
Lots of possibilities. Hopefully some of this will give you some things to look for.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI