Doublebase

Just yesterday my car intermitently has been doing an extended crank when I try to start it. It probably cranks twice as long as I'm used to. This has never happened in the three years I've owned the car and now it's happened three times in less than 24 hours. It doesn't happen all the time, but it's happened enough that I'm starting to worry.

Any my ideas what this could be? My battery is a year old...no issues in that department. No check engine lights. No drive ability problems.

I was was thinking perhaps a fuel pump? Maybe there's a check valve that's bleeding off fuel pressure and it takes longer to crank and start because of it? Or I was thinking crank sensor, but I'd have a check engine light on for that. Anyone have any experience with this?

Rhambler

Well, I wouldn't necessarily dismiss the battery outright because it's a year old.

From experience at my previous car's forum, people went nuts trying to figure out issues that were in fact caused by bad batteries, but dismissed that because the batteries were all relatively new.

From that experience, and my own experience of a battery lasting just shy of two years, I'm always leery of the hunks of junk batteries.

Other than that, it's typically starter related if it isn't battery.

yardie876

I second keeping the batter as a potential culprit. My battery of less than two years had a dead cell which caused long cranks, and elevated stress on me not knowing which crank was going to be the last. I had Lexus replace it since it was still under warranty.

Doublebase

The reason why I'm not pointing towards the battery is because the crank is excellent, it's not a slow or weak crank. It just seems to crank longer before starting. Could a week key fob battery do this? Maybe something wrong with the start button.

Z07

The symptoms are consistent with a fuel rail that is not staying full after shut down. This is caused by either a check valve in the fuel pump failing to close or an injector leaking.

I am new to the LS world but have seen this on other cars/SUVs.

You have rotation and I would wager you have compression. The only things to check are fuel, air and spark.

Try holding 1/4 throttle open while starting to see if the situation changes. If not rule out air and look to fuel and spark.

A spark test tool between a coil and a plug would show you if you are getting spark. A fuel pressure gauge would show you fuel pressure.

Take the above with a grain of salt as I do not have experience with an LS.

Littleguy

I've had previous Lexus vehicles do this and within a month or two the battery ends up being the issue. I even had one test good at Auto Zone then went to Lexus and it ended up being that one of the internal cells was dead and the Lexus battery tester found it.

Craig B

Are you running premium fuel? If not, it's low octane causing your vehicle to crank longer.

roadfrog

Since the starter turns over just as quickly and freely as ever, you can definitely rule out the battery. I agree that it sounds fuel related, but nothing to do with the type of fuel. I think you're on the right track in suspecting fuel pressure. Try this......push your start button without your foot on the brake to build fuel pressure. Then immediately start the engine. That could point towards fuel pump, fuel pressure, etc.

Doublebase

Talked to a diagnostic specialist today and asked him about my problem, he thought about it for two seconds and said fuel pump. I'll try to check the fuel pressure and see if it drops when the car is shut off.

Rhambler

Well before pulling fuel pumps or the fuel system, having the battery checked is such a small failsafe measure to take regardless if it's something else.

Another thing to be careful is that our engines are dual injected with two fuel pumps? I really don't know which one is used for starting, or maybe both assuming the engine performs under direct or port injection during startup. I'm not sure but if you can figure that out, assuming it is the fuel pump, you'll know which one.

Also spark plugs and air are the other two components in this equation.

Heck, before going to the depths of the fuel system, I would eliminate all the easy culprits first, battery, a bad batch gas, spark plugs, air filter, etc.

Doublebase

Battery is fine, checked it today. As far as the fuel pumps go I don't know which system is used for starting, but I assume it's the electric fuel pump seeing how mechanical pumps can't generate pressure without the engine running. And this is definitely an intermittent problem, it didn't do it once today in the four times I had to start my car...yesterday it did it twice and the day before twice. Maybe it's something that will just go away on its own, but my experience with cars tells me that won't be the case.

If it is the electric fuel pump I'm not sure if it's accessible by just removing the rear seat, or if the tank has to come down (I pray it's just the seat or through the trunk). Also if it is a check valve I'm wondering if I can change only that rather than the entire pump?

dlbuckls10

Be cautious if you are DIY job because you certainly don't wont to make things worse.

NotADood

Lexus Master Tech here, and that was my first thought. I've seen vehicles with rolled (leaking) fuel pump o-rings cause long starts because it takes the vehicle longer to build up adequate fuel pressure.

Doublebase

​​​​​​​Two questions if you don't mind...is the fuel pump under the seat and can I replace the o-rings? Or do I have to replace the entire pump? I imagine there's a check valve on the bottom, followed by a pressure regulator. I just don't know if it's something I can take apart...or if it's worth it.

Nospinzone

My vote is fouled spark plugs. How many miles do you have on them?

And 30 years ago I would have told you to check the points too!