1996 Toyota Previa Cold start flooding symptom

I have never held it open when first cranking. Only after I notice that it is not going to start. Is that what you meant? I can try it, I have not started it since Sunday.

After the holiday, I went out and pulled the throttle body off the vehicle. I removed the IAC and cleaned it and the throttle plate with carb cleaner and a toothbrush. I also put a light lubricant on the 2 shielded bearings that the IAC shaft has. I did the ohm test on the 2 circuits of the IAC motor, and they checked good. I also verified operation of the IAC by applying battery voltage to the 2 circuits, and watching it open and close. After installing the throttle back onto the van, it started right up. I was happy. I put the engine cover/floor back on and installed the passenger seat. I went out today to make sure it was good, and it would not start again.

This time during the first revolution it nearly locked up. I want to say it hydrolocked. It did crank over though and spun freely after that. It did not start. I could smell gas, I think from the tail pipe. No matter what position I put the throttle pedal, it would not start. I was able to get it started by unplugging the fuel pump relay by the battery, cranking it until it cleared, then I hook up the relay and it starts. I drove it around for a while and got whitish steam out the tail pipe. It did go away after a few miles of driving. I did not smell the sweetness of coolant in the exhaust, so I think it is just massive amounts fuel burning up in the converter.

I am fairly sure this year of van did away with the cold start injector. Is this true? I keep thinking fuel is settling in the cylinders or a cylinder after sitting, but that sounds a little far fetched, especially after having the injectors cleaned.

I do have a basic fuel injection grade gauge, but I don't have all the adapters. I will look at what it would take. Are you thinking that the injectors may be dripping into the intake runners? I wonder if the whole rail will come off with the injectors, then I could physically see the business end of them under pressure. These are the type of injector that go into a bore in an aluminum rail. I think it may come loose without detaching any fuel components.

I pulled the injector rail, leaving it attached, and saw no drips. I also pulled the plugs so when I initially cranked it I could see why the thing was hydro locking. I got lots of coolant out of the #4 cylinder. I ran down to the parts store, and rented a coolant system pressure tester. After pressurizing the coolant I got no major leak down. I cranked the engine to clear all the coolant out of #4, put it all back together, and it started up great. All this time the coolant must have fouled the #4 plug enough to cause it not to start, which in turn let the other plugs get fuel fouled, and cause it to really not start.

Does this sound right? Is there any other reason than a bad head gasket or cracked head that would cause the #4 cylinder to fill with coolant?

I did pull the intake tube off the manifold to check for coolant. I read somewhere about the breather hose having a coolant line run inside of it, and that those fail and leak coolant into the engine. If that was the case, I think that I would have seen a major drop in coolant pressure on the tester, and I would have coolant in that intake hose.

Thanks for all your help, and sticking with me during my diagnosis.