hard start and puff

[Belsy]

My 90 has a long hard start symtom, cranks quite a while then starts with a stumble and a puff of smoke then clears out and runs fine. The motor was gone over and setup by SGC last year for the previous owner so everything has been touched recently and I hoped there was some opinions and fixes out there.
Thanks for any suggestions.
Gene in Fl.

[tccrab]

Originally Posted by gene

My 90 has a long hard start symtom, cranks quite a while then starts with a stumble and a puff of smoke then clears out and runs fine. The motor was gone over and setup by SGC last year for the previous owner so everything has been touched recently and I hoped there was some opinions and fixes out there.
Thanks for any suggestions.
Gene in Fl.

How long is quite a while?
How often do you start it?
Fuel injectors sometimes leak down over a period of time and fuel pools on the back of the valves. When you crank it, that fuel gets dumped into the cylinder and can cause a "mini flood condition" and thus produce extra smoke. And also the early year cars don't have valve stem seals so they tend to wic a little oil into the cylinder over time, also causing a puff of smoke at startup.

If your car was a daily driver you would probably not see the puff of smoke or experience the longer cranking caused by flooding of the cylinders from injector leak down.
Try starting the car every day for a week and see if the hard cranking condition gets any better.

[guinnessdood]

My car will start very poorly when it sits for a long time without being started....it acts like it's all loaded up with fuel...which it probably is...I still have the original injectors. Do you still have the original injectors or have they been replaced?

[Belsy]

Thanks for the response but this car will do this after 3 or 4 hours of sitting warm or cold and sometimes after sitting a few days then sometimes when it's cold start fine??? Not consistant yet mostly when warmed up and sitting for few hours!!

[Belsy]

Is the injectors leaking a possible cause and/or weak plugs? I was told there is a pressure valve of some kind at the fuel pump any confirm, as the fuel pressure drops (on gauge) after shut down.

[guinnessdood]

Originally Posted by gene

Is the injectors leaking a possible cause and/or weak plugs? I was told there is a pressure valve of some kind at the fuel pump any confirm, as the fuel pressure drops (on gauge) after shut down.

The injectors are suspect if they are the originals.

[rkreigh]

a really ez test is to pull the plugs and see if you have strong gas smell after sitting a while. you can also watch the fuel pressure and see if they are leaking. I agree it's likely the injectors are dripping like crazy and causing a flooded start.

the early injectors are a bit more failure prone and I'd check them first

good luck and keep us posted.

[blackjack]

according to what ive read here,and my own experience,the lt5 has never been known to be a quick start engine...mine is slow to start too,and ive come to get used to it,and accept it as a trade-off to performance and efficiency...it is something ive learn to live with...
bj

[tomtom72]

Originally Posted by gene

Is the injectors leaking a possible cause and/or weak plugs? I was told there is a pressure valve of some kind at the fuel pump any confirm, as the fuel pressure drops (on gauge) after shut down.

There is a thing called the "pulser" attached to the fuel pump in tank plumbing. That part, as I understand it, is supposed to prevent fuel from leaking back to the tank thru the feed line after shut down. But LT5's usually take more time to crank & fire up than conventional sb's. Mostly it's the ingnition system orienting itself before firing a spark.

The smoke could very well be injectors that are sticking open, as everyone has said. The other thing white smoke could mean is coolant leaking into the combustion chambers...I hope that isn't the case.

You could do a fuel pressure leak down test @ the fuel rail fitting and see what's up with the leak down rate. Or you might just run her and shut down, let it cool to stone cold and pull all the plugs and look for fuel.


Tom

Sorry, I forgot this. You did a leak down test and the results showed that the pulser is not working correctly! DUH on me! Mine isn't working right either. My work arround is when I crank, I turn the key to "on" and wait till the pumps stop and then go thru to "start". Maybe there are two issues: leaking injectors and a bad pulser?