c50sooner

Yamae, thanks so much for taking the time to provide that level of very specific and very helpful technical analysis. I’m guessing you’re an engineer, and that kind of analysis is I’m sure worth a lot in the marketplace so thanks again, really appreciate your help. No doubt that will help many people begin to investigate their fuel delivery issues.

Your hypothesis was correct in that the chain was broken by the ECU, albeit for reasons that I caused myself!

I was working my way through the list that LScowboy provided, and it ended up being the MAF sensor. My experience is in carbureted motorcycle engines (which don’t care whether you have the intake on or off). After replacing the starter, I had the intake connector assembly disconnected from the throttle body to facilitate getting the starting fluid into the manifold. What I failed to realize was that with the intake assembly disconnected, the MAF sensor is out of the loop (which is of course obvious to me now why that won’t work).

So, just wanted to post the resolution in case it helps anybody in the future (always hate to read through a promising post that just trails off into nothing).

No intake connector assembly = No MAF = ECU sees no airflow = ECU cuts off fuel delivery = Engine No Worky

By the way, the LS starts so much better and smoother now with the new starter. Used to crank forever prior to catching, now it’s just one or two quick cranks and it fires right up. That replacement task is a bear, but it’s worthwhile and I’ve definitely gained a lot of knowledge and info in the process.

Again, thanks to all who responded, really appreciate you helping me avoid a costly visit to the repair shop!!

drs23

Thanks for posting your resolution. I'm sure it will be helpful to someone in the future.

Lavrishevo

iTrader: (1)

The LS400's like longer cranks. I really never have to crank mine twice because I let the starter engage long enough. It is better for your engine and for the the starters longevity to keep the starter engaged a bit longer, ensuring an engine start the first time vs repeated start attempts.

Yamae

c50sooner, Congratulations on your success to find out the exact cause. Your report will help others in the future. It was my pleasure that I could help you some.

I am a retired Japanese electronics engineer who once had worked in Southern California. That's why I understand English some but limited. I sometimes still work at auto repair shops as a volunteer. My patents give my wife some money and she does not complain me to help repair shop owners. I don't get any money from them but I am allowed to use their tools and equipments. I also can purchase parts inexpensively. I myself am a Celsior owner and I need to work on it time to time. I think you can imagine how I enjoy my retired life.

Automobiles now-a-days have ton of electronics inside and a person like me is sometimes useful at repair shops. Shop owners have been somewhat skeptical on me at the initial stage, but now they often call me asking for a help. One of the major issues for them is the ECU. They only replace the unit and pass the customer a big bill. I heard a customer complaining, "How can I pay that big money for my old car." That was a beginning of my action. I decided to repair ECUs for free.

When I was younger I was involved in developing scan tools for automobiles as well as designing electronics related equipments for automobiles and I know some about how the engine and other systems work. Other than ECUs, I found many of electronic or electric related issues that I can do for shop owners.

Anyway I will continue to watch the forum and I will post what I can suggest. As far as I watch, many people here are good at mechanical issues like those shop owners but ECUs and electronics related issues are other things for them. Regarding ECU capacitors, there was a guy LScowboyLS who responded me quickly although others were not fully responding. He and I talked on the phone for more than an hour and there started a good friendship. He has started the thread regarding ECU capacitors and he is now saving many people.

velandia

That's a very noble pursuit! You're the type of person that makes this world better for everyone. I hope to follow in your footsteps in my later years

velandia

I'm having the same problem with my wife's 99 LS400. It has trouble starting when it is cold (...and I mean California cold which is ~40F). If you keep trying to start it, eventually it does start and starts up strong. But, as in your case, later in the day it seems to start OK.

I'm searching the forum for similar problems and will start a thread if I can't find a similar thread.