I have a 1991 LS 400 and it runs great. On the first crank of the day, it is slow to crank and will sometimes spit back thru the carb. All cranks the rest of the day are fine and it runs very good. It is just on the first crank of the day that I have this problem.
Does anyone have an idea of what my problem may be?
Von Hamrick
Winston-Salem, NC

 

The LS400 does not have a carburetor.... just saying.... Could be the battery thats slowly going....

 

That statement dates me. Yes, I know it does not have a carb. The battery turns the engine very fast so I have ruled out the battery. Is there some kind of electical device that is used only when the engine is cold?

 

I suggest you to check the voltage of the battery terminal while the engine is starting. Is it keeping higher than 10.5V? If not, the internal resistance of the battery is higher than normal.

Are the contacts of the battery terminals in a good condition? Sometimes those can not be fully checked by your eyes when the microscopic corrosion is caused. Brush them up and see the difference.

I also worry about the engine oil. Is the viscosity OK? Isn't it too hard?

 

Maybe the coldstart injector malfunctioning.

 

Thanks Cobalt91. I am going to replace the cold cranking injector when I have time. Is it hard to replace? I am not a mechanic but I have some mechanical ability.

 

I have been fighting the cold start problem with my 91 LS400 for sometime now. Before I was going to rep;ace the cold start injector, I decided to check the fuel pressure. When I turn on the switch, I get no (0) fuel pressure. After I hit the starter, the fuel pressure picks up and stays up after the engine is switched off. I can not figure out why the fuel pressure does not come up when I turn on the switch. It would seem to me that the fuel pressure should pick up when the switch is turned on (before the engine is cranked). When I hit the starter, the pressure picks up. Does anyone have any idea why the fuel would not prime up when I turn the switch on. Maybe my cold start injector is not bad and the problem is the system is not throwing a prime until I hit the starter.
I would appreciate any suggestions.
Thanks,
Von Hamrick
Winston-Salem, NC

 

I replaced the cold start injector and it now cranks fine in the mornings. This was quite a job. Had to take the vary top intake part off to get to it. After doing the job and on second thought I believe I would try to clean the old cold start injector. If you take the thortle body off, you can see this injector in the middle of the opening. You can reach the old injector well enough to clean it. To test it, turn on the switch and bunp the starter. If the injector is spraying gasoline, it is working. I found that the fuel pump was not activated until the starter is bumped.
THANKS TO COBALT 91 FOR YOUR HELP.
Von Hamrick
Winston-Salem, NC

 

I have replaced the cold start injector in my car and it solved my problem. As for the fuel pressure, I can confirm that the fuel pressure does not pick up when you turn on the switch. You have to bump the starter to get the fuel pressure up.
Von Hamrick
Winston-Salem, NC

 

i would say ur starter is starting to fail...have it checked for high amp draw. mine did the exact same thing..also have ur battery and alternator checked while ur at it

 

Thanks Python. My Lexus has 185,000 miles on it and the starter was replaced by the Lexus dealer in July, 1998 at 113,693 miles. The autonator was replaced by the dealer in May,1997at 94,398 miles. The Battery was replaced in October,2010 at 169,022 miles. It cranks and runs great now.
I love my Lexus,
Von Hamrick

 

Thanks Python. My Lexus has 185,000 miles on it and the starter was replaced by the Lexus dealer in July, 1998 at 113,693 miles. The alternator was replaced by the dealer in May,1997at 94,398 miles. The Battery was replaced in October,2010 at 169,022 miles. It cranks and runs great now.
I love my Lexus,
Von Hamrick

 

Yep...