05 4.7 V8 has intermittent extended crank time on cold/hot starts.

[Utah_4runner]

Hey everyone, I'm new to the forum here and new to Toyotas as well which is why I need some extra help.

The problem is that my 4runner has long crank time intermittently. It doesn't matter whether it is hot or cold, or if it is a cold start or starting it within five minutes of turning it off I will either have a super quick start or a super long start. The longest it has taken is probably 7 seconds of cranking before it will start. It always starts, but its starting to worry me because I don't want something to fail and leave me stranded.

The battery tests good, the alternator tests good, the starter is cranking strong, I have tested the fuel pressure regulator with a vacuum gauge and it holds pressure, and the fuel pump relay is good.

I hooked up a fuel pressure gauge today and got these results. When I turn the key to on (not starting the vehicle) it sits at 0. When the vehicle is started the pressure goes up to 42 psi. After turning off the car the pressure drops to 38 psi, and stays above 35 psi for 5 minutes. I am used to GM vehicles, which prime the whole fuel system when the key turns to on. Is it normal that my 4runner stays at 0 when I turn the key to on? Shouldn't turning the key prime the fuel rails and get the system up to pressure?

If the pump is operating how it is supposed to, do you have any ideas of what could be wrong? Can the fuel pressure damper fail? Could it be a bad ground like 03-04 Tacomas had a problem with?

Another thing to note is that there are no fault codes that come on while driving, BUT if I turn the key to on, wait 10 seconds, then repeat twice, the ECU throws 3 fault codes. The codes are P0441 (Evap system incorrect purge flow), P0455 (Large evap system leak), and P0456 (Small evap system leak. These only come on if I "prime" the system 3 times and then start the vehicle. I get the codes as well as the VSC and traction control light. When it happens I am able to clear them and they don't come back on until I do what is described above.

I've looked around the forums and haven't found anything quite like this. Any help is greatly appreciated. Thanks!

 

[Utah_4runner]

Note: I also just did a 3 part sea foam treatment, and then replaced the spark plugs with NGK laser iridiums.

 

[Billynath1988]

clean the MAF and throttle body.. check wiring.. also could be Crank position sensor. disconnect battery for a few hours and reset the computer. Id start with that easier stuff.

 

[Utah_4runner]

clean the MAF and throttle body.. check wiring.. also could be Crank position sensor. disconnect battery for a few hours and reset the computer. Id start with that easier stuff.

I'll try those out in a few hours and let you know if there is any progress. The MAF seemed really clean when I looked at it a couple of weeks ago, I'll clean it anyway.

 

[Utah_4runner]

Today I cleaned the throttle body, cleaned the MAF sensor, and had the battery disconnected for several hours to let the computer reset. The first few starts after that were great, but I'm right back to where I was with intermittent long cranking. I have never had any of the symptoms of a failing camshaft or crankshaft position sensor, so I really don't think it is that... plus those are too hard to get to anyway. Any other ideas of things I could try? Does anyone know if it is normal for the fuel rail pressure to be at 0 when I turn the key to on multiple times?

 

[Billynath1988]

hm.. not sure about the fuel pressure reading.. run a load test on the battery?

 

[Utah_4runner]

hm.. not sure about the fuel pressure reading.. run a load test on the battery?

Battery came out good as well. I think it would have to be the fuel pump or a bad ground possibly. Have you, or anyone else ever had to replace a fuel pump? What were your symptoms with the 4runner?

 

[Billynath1988]

I never really had this issue on my 05 v8. I know when the batterys get weak it makes the truck do weird stuff. I personally haven't had to or seen anyone else replace a fuel pump on these. You said it throws a code right? I do know these trucks can have evap system issues if you overfill the tank to much and it leaks fuel into the charcoal canister but Idk if this would be a symptom of that or not. .. check PCV valve.. 02 sensors.. ect..

 

[BlackWorksInc]

Every now and then the 4th gen cranks a little longer that it usually does... I never did figure out why. It's somewhat present on other vehicles I've worked on as well, could just be an anomaly where the ECM didn't like the crank/cam correlation and wanted another revolution to make sure... hard to say unless it's consistent.

 

[Utah_4runner]

Yeah, it throws three codes, but not while operating, just if I triple prime the fuel system (which I just found doesn't work) without starting the vehicle. I didn't know that the newer 4runners had a fuel pump access port until now, so I pulled up the carpet and listened carefully as I had someone turn the key to on, and then start it. It doesn't start pushing fuel until it goes on, so it doesn't prime anything like it is supposed to. I think i'll replace the fuel pump and see if it fixes it. Hopefully that'll fix it.

 

[Utah_4runner]

Every now and then the 4th gen cranks a little longer that it usually does... I never did figure out why. It's somewhat present on other vehicles I've worked on as well, could just be an anomaly where the ECM didn't like the crank/cam correlation and wanted another revolution to make sure... hard to say unless it's consistent.

Sorry BlackWorksInc, I didn't see your post until after I just posted. It is off and on, but cranks long at least daily, and just seems too long at times to be an anomaly. It cranks long enough at times that I feel like i'm in some old beater!

 

[BlackWorksInc]

Sorry BlackWorksInc, I didn't see your post until after I just posted. It is off and on, but cranks long at least daily, and just seems too long at times to be an anomaly. It cranks long enough at times that I feel like i'm in some old beater!

Hmm... how's the starter sound?

 

[Phils4th]

Easily hot wire the fuel pump at the relay so it runs with the key on. Try to duplicate your cranking issue. But if it cranks long when the manifold is still under pressure, I'd doubt its fuel related. I'd say it has to do with your codes that you pulled. That evap canister uses engine vacuum to purge fuel vapors. If there is a vacuum leak anywhere in that system, it will start slow and crank long. Look over the part and any other vacuum hoses and connections that could leak. You could also try and block the evap system off from the engine, it may be the evap canister itself. Look over the gas cap for a proper seal and fit.

 

[Utah_4runner]

Hmm... how's the starter sound?

The Starter is cranking very strong.

Easily hot wire the fuel pump at the relay so it runs with the key on. Try to duplicate your cranking issue. But if it cranks long when the manifold is still under pressure, I'd doubt its fuel related. I'd say it has to do with your codes that you pulled. That evap canister uses engine vacuum to purge fuel vapors. If there is a vacuum leak anywhere in that system, it will start slow and crank long. Look over the part and any other vacuum hoses and connections that could leak. You could also try and block the evap system off from the engine, it may be the evap canister itself. Look over the gas cap for a proper seal and fit.

What do you mean when you say hot wire the fuel pump? I'll have to dig into the evap system some more I guess. My OCD does make me bump the gas up to the next dollar, so I could have overfilled at some point. Anyone have common failure points with the evap system where I could start?

 

[86mcss]

Do a compression test on each and get back to us with the results.

 

[Billynath1988]

Im still leaning towards a sensor issue. along the lines of what blackworks inc said. Do you have all OEM sensors in there? plugs, coils injectors.... usually a fuel pump works or it doesn't ... When these trucks start the ecm has to take instant readings from the primary sensors to start the truck, if one isnt oem or isnt working 100% for whatever reading it might take an extra second to start but its not enough or its at the wrong time to throw a specific code.. id say your issue is somewhere between a sensor and the evap codes your getting. its hard to diagnose this kind of thing on the internet lol.

 

[Phils4th]

The Starter is cranking very strong.



What do you mean when you say hot wire the fuel pump? I'll have to dig into the evap system some more I guess. My OCD does make me bump the gas up to the next dollar, so I could have overfilled at some point. Anyone have common failure points with the evap system where I could start?

Find the fuel pump relay and the wiring diagram. Find the pin that goes directly to the fuel pump and run a wire from the battery positive to the pin. Fuel pump will constantly run. Try and start the truck and see if it has the long cranking still.

 

[Phils4th]

Check over the evap system and all vacuum hoses for leaks first. If it's a crank/cam sensor issue, you can only diagnose with the obd computer, and since it's not throwing any of those codes, it will need to be taken to a shop and have it run on an oscilloscope to view the crank/cam signal to find the problem. They should also be able to view the coil packs discharge with the same thing. Tho I feel you have a small vacuum leak. When the leak is big enough, it won't even start. You can find a tricky vacuum leak by using a small propane torch that's unlit and waving it around all vacuum lines and components. The propane will be sucked up by the leak and you'll notice a slight rpm change when the propane gets sucked in. You can also use carb cleaner and gently spray with the red straw the connection and wait for a rpm change. This let's you know there is a vacuum leak somewhere in there. It's best to do on a cool engine and be careful where you spray since carb cleaner can flash on hot exhaust. A cool engine will also change rpm as it warms up so be sure the connection has a leak by testing it multiple times.

 

[Utah_4runner]

I checked all of the vacuum lines and the evap system today and couldn't find any leaks at all. I had my bluetooth scanner hooked up, so I was watching the RPM values the whole time and they were steady. With this though, doesn't the car have to be running higher RPM's to cycle the evap system? I feel like I read somewhere that it opens up at higher speeds, but maybe I'm wrong.

I also tried to get those codes to come up again all day today, and can't. I'm wondering if it happened within a couple of days of me overfilling the gas tank a bit. So... maybe I can rule out any issues with the EVAP system?

I'd like to try jumpering the fuel pump relay, but it is intermittent so I'm not sure how I could tell whether or not it is working. Maybe I'll try to set something up for that though.

 

[nevada]

Yeah, it throws three codes, but not while operating, just if I triple prime the fuel system (which I just found doesn't work) without starting the vehicle. I didn't know that the newer 4runners had a fuel pump access port until now, so I pulled up the carpet and listened carefully as I had someone turn the key to on, and then start it. It doesn't start pushing fuel until it goes on, so it doesn't prime anything like it is supposed to. I think i'll replace the fuel pump and see if it fixes it. Hopefully that'll fix it.

I am unsure how the 4th gen fuel pump works. though, I do know, the 1st gen 4runner would not activate the fuel pump unless the engine was cranking. perhaps the 4th gen does something similar?