I have a '95 T100 SR5 4X4 with 82,000 on it and recently have had a starting problem.. When I start the engine, it takes several cranks and then turns over.. When I look out the passenger side mirror, I see a puff of black smoke when it finally starts.. I took it to a Toyota mechanic and he thought it was a problem with the plugs because they were well worn so he changed them with Toyota plugs and plug wires.. He was going to change the O2 sensor but wanted to replace the plugs to see if that would solve the problem.. Well, it didn't.. It's a big expense to change the O2 sensor.. Would replacing it resolve the starting issue?? Other than starting it up, it runs great! I did run some Lucas treatment in the gas tank and it fired right up every time for 2 tanks now back to the same problem...Got 19 mpg on the last trip with the Lucas in the tank.. Help!!!

oxygen sensor shouldnt cause a startup issue, check your voltage to the starter first, clean connections, tighten connections, do all the free stuff first...

I am not the most mechanically inclined, which is the reason I am trying to figure this problem out via this forum and save money paying the Toyota mechanic to guess.. Is it difficult to check the voltage to the starter?

i can't explain the smoke, that would have to be an exhaust leak. i'd check the voltage on the battery (since its hooked directly to the starter). recently my T100 was starting hard, and a new battery took care of it. autozone will test your battery for free.

Your symptoms pretty well match a fuel injection system loosing line pressure while sitting.

Typically, the fuel pump doesn't start pumping usually until the ignition starts pulsing from the engine cranking over. So the residual line pressure is what makes the fuel squirt out of the injectors correctly.

When the line pressure is low, the fuel injectors dribble instead of squirting. This gasoline doesn't burn, and the engine doesn't start.

With more cranking, the line pressure builds, the injectors start squirting instead of dribbling, and the engine finally catches.

It's usually a poor catch as it starts, the engine runs a little rough, and belches black smoke as the dribbled gasoline burns off in the cylinders and exhaust manifold.

So, I'd suggest a pressure check of the fuel rail.

That would make sense to me but the problem is very intermitent.. I had the plugs and plug wires changed right before a 650 mile trip.. Also added some Lucas treatment in the gas tank before the fill up to start the trip and it ran great on that tank and the next tank but now back to the same problem.. Most mornings it fires right up.. Seems to do it more if I drive it, stop briefly, then try to start again.. I would think after sitting all night, the pressure would bleed back and do it every morning..

The check engine light came on about a month ago and the code was for a bad cat converter.. I had the plugs and plug wires changed and the next day the light went out and never has come back on!? The Toyota mechanic hooked his handheld computer up and all readings were fine!!! He thought the O2 sensor was going bad but it did not code the O2 sensor and I didn't get how a bad O2 sensor had anything to do with starting the engine...

I forgot to add the fuel lines, fuel filter, fuel pump have all recently been replaced, in addition to the plugs, plug wires, air filter and cleaning the throttle body..

Frustrating!

You still might want to check the pressure in the lines. If the engine is warm and you stop and the pressure in the lines doesn't hold, the gas will vaporize and you essentially get vapor lock. Just a guess.

Well, I went down to Autozone and had the battery checked and it was fine.. They said the date on the battery was 11/06.. They seemed to think it was either the starter about to go or the cat converter, since it has already coded that before.. They said a bad cat converter will cause starting problems?????? Is that true??? They also said the starter looked original, the truck has 152,000 miles on it but only 82,000 miles on the engine.. If the starter has 152,000 it could be getting ready to go??

They said to run the truck at night and when I pull it in the driveway, look at the cat converter.. If it is red, it is clogged up and not running properly.. If it is normal, focus on the starter.. They all said it isn't the engine because it is quiet and smooth, like most Toyotas!!

Any opinions on that analysis from Autozone? I will have to take it to Toyota to get the fuel lines tested.. Trying not to chase money after this problem..

A bad cat is a plugged cat. Plugged cats get real hot so watch out for that. If they glow at night you are in deep doo doo. Cats cause brush fires.........

I just want to know if a clogged converter causes starting problems?? Do I have to wait for a code or something to just fail before I can fix the problem?