Slow Start on Cold Engine Worse with Ambient Heat (1 Viewer)

[NearJetties]

My FJ62 has started slowly since I got it and I’m finally getting around to trying to fix it.

symptoms:
When the engine is cold it normally takes 3-4 seconds of cranking to start but it’s been much worse with this prolonged humid 95 degree weather. Lately it takes 5-7 seconds and sometimes a second attempt.

When it does start it stumbles like it needs you to pump the pedal. Almost immediately it runs normally with or without the additional load of the AC.

If the engine is warm it fires in less than 1 second no matter what the ambient temperature is.

what I’ve done:
-cleaned and tested the cold start injector (fired plenty of fuel into a cup this weekend)
-new battery and starter cables
-PO did a full tuneup with plugs, wires, etc. in the last 5 years but not many miles
-marvel mystery oil fuel treatment

What should I trouble shoot or replace next?

In most threads the common fix is the cold start injector. Is it possible it’s dribbling rather than atomizing the fuel?

Fuel regulator, fuel dampener, fuel pickup filter/sock, and cleaning the injectors have been mentioned but none seem to be a definite solution.

thanks in advance

 

[Rockkreek]

I'm having same issues for many years and have tried the same fixes,so I'm interested in ideas too.it has never not started but in summer it takes twice in the afternoon when its hotter..

 

[Michael Hanson]

Hi, If the cold start is leaking your going to have problems starting. Have it cleaned at a fuel injector business. Mike

 

[NearJetties]

Hi, If the cold start is leaking your going to have problems starting. Have it cleaned at a fuel injector business. Mike

it’s not leaking. It’s just unclear if it’s atomizing properly. Regardless, I should consider getting it cleaned and tested professionally.

 

[Seth S]

I’d test check the temperature sensor that the efi uses.

 

[NearJetties]

I’d test check the temperature sensor that the efi uses.

so the cold start timer isn’t the only coolant sensor that affects the EFI? Didn’t realize that.

 

[Seth S]

Efi is just a bunch of sensors that feed data into a black box full of excel spreadsheets....basically. So an input from each sensor gets used to calculate a value and cross referenced to a data table and when all is said and done results in the fuel injector firing duration.

so you need to know:
1. Either how much air is coming into the engine or the density of the air in the intake manifold (map, airflow or air mass meter)

2. the temperature of the engine (Temp sensor)
3. How much Unburned fuel is in the exhaust (O2 sensor)
4. Throttle position (TPS)

sometimes there are additional sensors but those are the core ones

A bad or out of spec temp sensor can trick the system into thinking it’s too hot or too cold and that can lead to a no start or delayed start issue. You could try unplugging the sensor and seeing if the truck starts any differently. I would t leave it unplugged but do it as a test measure.

other issues are vacuum or air leaks that cause issues on every car known.

 

[NearJetties]

Just replaced all the vacuum lines with silicone so definitely going to check the temp sensor out.

 

[NearJetties]

I’ve since changed the coolant temperature sensor, fuel pressure regulator, and fuel damper all with Toyota/Denso parts.

The truck has better power and the mpg is up—the coolant temp sensor made a huge difference despite no CEL.

.....but I still have the cold start issue. It actually seems worse with more of a stumble

what next?

I’m think of sending the CSI to WitchHunter Performance to be reman’d. not excited about having the truck down but it’s relatively inexpensive. I still have a hunch it’s drizzling fuel rather than misting it.

After the injector cleaning I’m thinking fuel filter. I’m not inclined to drop the tank and deal with the fuel pump/sock at this point.

anything else electrical to look at? TPS? Coil?

I’m very happy I did the other things even though it didn’t solve the problem I was after.

 

[Seth S]

I didnt see it mentioned....have you adjusted the valve clearance and have you verified the base timing is set to 7 degrees?

 

[SteveH]

Be sure all the hoses from the air cleaner to the throttle body are uncracked and well sealed.

 

[NearJetties]

I didnt see it mentioned....have you adjusted the valve clearance and have you verified the base timing is set to 7 degrees?

Be sure all the hoses from the air cleaner to the throttle body are uncracked and well sealed.

will look into those and a valve adjustment is on my to do list. I’ll likely have to enlist a friend to check the timing but will peek at the FSM.

 

[red66toy]

will look into those and a valve adjustment is in my to do list. I’ll likely have to enlist a friend to check the timing but will peek at the FSM.

I am interested to hear a solution to this. I also have some long starts on hot days after it’s been sitting a while. It drives me crazy. I have new sensors, injectors, damper and pressure regulator, fuel filter, vacuum lines, spark plug wires, cap and rotor, and valves set. My AFM passes FSM tests, NOS IACV, TPS in spec, I still need to check timing. Going to shoot for 9/10- degrees BTDC, I read that bumping up a couple degrees over factory spec helps a lot with general performance on these engines. Not sure about starting though.

Additionally: One thing I have yet to replace is the fuel pump.. but fuel pressures have always been in spec and the truck runs great overall, just these hard starts.

 

[Joe Campos]

I am definitely watching this thread...I have had the same issue since I got my 62!

 

[red66toy]

While my fuel pressures are within spec, I wonder if the pumps get tired over time and take longer to build up the pressure quick enough to meet demand on initial starts? Maybe that is not a thing, just thinking out loud.

 

[Seth S]

Does the stock system have a check valve in the supply line to prevent drain back? I know some cars do. Not sure about LC’s

 

[Joe Campos]

I had a smoke test done and my exhaust/intake gaskets need to be replaced. Hope that is the cause for mine.
A) because I already cleaned out the cold start injector
B) because I don't want to have to drop the tank and change out the pump.

 

[NearJetties]

I had a smoke test done and my exhaust/intake gaskets need to be replaced. Hope that is the cause for mine.
A) because I already cleaned out the cold start injector
B) because I don't want to have to drop the tank and change out the pump.

did you have a high idle from the intake gaskets being bad? Mine is dead on the nose.

 

[Joe Campos]

did you have a high idle from the intake gaskets being bad? Mine is dead on the nose.

Nope, no high idle. Mine idles normal.
When I crank, mine will act like its going to start but then dies immediately. Then, it takes a few cranks to start like there is not enough fuel getting there.

 

[SteveH]

You might try sniffing the exhaust right after it starts to see if it smells rich or (not rich).