Long crank when cold

03 4.7 Access cab, been having starting problems when truck sits for a while,recently replaced fuel pump filter and cleaned maf and throttle body and im guessing the system is not holding fuel in the system to keep it primed so what holds the fuel in the system to keep it primed? Is it an internal part in the pump?

 

Stupid question, have you had the battery tested?

Or are you saying the truck is turning over strong, constantly, until it finally catches and fires?

Have you done any other maintenance in the last 10k-15k miles other than what you just listed?

Whereabouts do you live, so we know whether corrosion may play a factor in your issue?

 

haven’t tested battery with a tester but every time it cranks strong untill it catches and fires

and haven’t done much other than oil change and fuel pump and strainer and fuel filter and cleaned maf and throttle body

and location is Hawai’i

 

How long does it take to start?

Having to crank for a while is normal on Toyotas. They don't start running until they detect that there is oil pressure built, which takes longer when cold. Mine takes a good 2-3 seconds of cranking to start when really cold, but starts every time.

 

Ok, so no timing belt change? (Should be done every 10k miles or 10 yrs)

Have you tried throwing a fuel pressure gauge on the line to watch the fuel pressure as you crank it over?

And to this point, it could easily be a sensor issue...

 

takes a while maybe like 5-6 seconds but here in Hawaii it doesn’t get colder than maybe 60 so the weather doesn’t really affect the engine

 

Hmm, yeah, gotcha. 5-6 seconds does seem really long to me.

 

How old are the spark plugs?

 

I bought the truck not to long ago but when I bought it it was running fine and previous owner did timing belt right before sale

 

Not to sure I’m guessing old I didn’t have the chance to pull them yet but I’m leaning toward fuel side like system not getting primed cause it only happens when it sits for a while but when warmed up it’ll start right back up in 1 or 2 cranks

 

To me it sounds like you need to check your fuel pressure.

Someone correct me if I’m wrong, but on startup, there’s some sort of switch that keeps the fuel pressure high and then once the truck has been running for a minute, it kicks back to a lower fuel pressure on idle. My thought is that control might not be working and it’s low all the time.

@shifty` isnt this something you know about or am I confusing it with something else?

If not that, I would think maybe the fuel pressure regulator or a leaky injector.

 

Do you know where I can get the adapter to test the pressures by chance?

 

You can borrow a kit from advanced auto. They have one with the banjo bolt to schrader valve adapter. I can’t remember offhand the make of it, but you can take a look online to find it.

 

Hmmm...fuel pump resistor?

 

The fact the timing belt was changed recently, if I were @Chkahi808 I would definitely check the crank position sensor harness on the front of the engine just to make sure it's properly secured and isn't being cut by a pulley or belt. It's required to keep the fuel pump alive after ignition. I don't think it would cause a delayed start, but ...

Definitely. It would immediately solve whether fuel delivery is the issue as OP has suggested. And get us a lot farther along. The fuel pump shouldn't turn on until either (A) the engine is actively cranking or (B) the crank position sensor tells the ECU the engine is running. It shouldn't be actively pumping when the key is in the ON position only. This is my recollection from the fuel circuit diagnostics page.

The "switch" you're talking about is the fuel pump relay. The purpose of the fuel pump relay is to change the power delivery to the fuel pump. Basically, the relay has two poles, one that feeds direct (full) power to the fuel pump, for full pressure. The other one sends power to the fuel pump resistor (opn/c?) which dumbs reduces the voltage, producing less fuel pressure. IIRC, it's the ECU that sends (or removes) the voltage trigger to to the relay which causes it to switch between the two.

But I don't know if the fuel pump is supposed to start off in the hi mode or low mode at ignition, I don't remember if it says this in the fuel pump circuit info I usually repost and I'm too lazy to look after the day I've had.

It's entirely possible. It's also possible to jumper-bypass the resistor easily. For an '03, I don't know if it's mounted to top of the driver side or passenger side fender, but I can help him find the resistor!

@Chkahi808 will find the resistor in one of these locations: https://www.tundras.com/threads/help-2006-stalled-and-won’t-start.117506/#post-3025323

@Chkahi808 can (and should) test the resistor using this info: https://www.tundras.com/threads/2006-double-cab-fuel-pump-no-power.36822/#post-2962132

Last thing I'll say. It's literally never been the fuel filter for anyone on this forum yet, it's the last thing I would ever expect. Don't bust your knuckles replacing that!

 

Fuel filter.......

 

Yeah, definitely not the fuel filter. I'd suspect the fuel pressure regulator before the filter.

 

Dunno… my crank gets shorter when it’s cold!

 

When Idling, resistor path is used, less current to fuel pump.



Good ole Ohms Law !

 

Thanks for pulling that.

So essentially, if reading what you highlighted and the two sentences prior:

• Engine start>Fuel pump stays in high speed (i.e. Tr1/not thru the resistor)
• After start>Fuel pump drops to low speed for idle (i.e. Tr2, thru the resistor)

And of course, this is assuming the ECU (/ECM) is actually feeding signal to the FP relay trigger.

I have a really tough time not confusing the open circuit relay and the resistor, and forget if you're not getting fuel or initial power to the FP, it could be b/c of c.opn

 

I just call it the pie chart cause I'm fat and like pie.

 

https://www.youtube.com/watch?v=s3Gdezyt8eY​

 

I hate relay logic with no initial state present on the relay circuit diagram (should state N.O. for normally open or N.C. for normally closed when the coil is uncharged next to each relay).

Edit: Unless the diagram is already showing the default uncharged state? I'll take another look.

 

Might recommend some lotion for the motion. Clean and dielectric grease everything you can. Reset the grounds. Cranking too long when its cold could result in blisters.

 

They tried to throw me for a loop way back when I was an ET baby that “Pie R Square”…BS I said, my moms pies are round ‍♂️

 

Yeah most all elec schematics are showing relays and their contacts(NO or NC) when no voltage is applied. For instance OPN(circuit open relay) has “NO” contacts. When OPN relay energizes, it then closes it’s contacts and sends current to fuel pump via NC contacts of Fuel Pump relay, which the drawing is not showing.(it has 2 sets of contacts, NO and NC)



back to the cheap seats I go

 

That's what I always said! Cake is square, not pie!

 

Sorry such a late response been busy with work but I’ve had the chance to change the resistor out with a know working one and it didn’t change anything

 

Cool, when you get time to throw a fuel pressure gauge on it to confirm if it's a pump turn-on delay issue, holler back.

 

Will do thanks for the help