Rough/weak start up issue. Diagnose?

[Stevo405]

Hello. I'm a very new owner of a fairly clean 06 SR5 4x4 with 120k miles. I am a member if other car forums and understand how the search function works. I have looked through many threads and have found some very good info concerning the issue I am having but I do have some questions that are specific to my situation.

Here is my current issue and any help will be greatly appreciated. I should also include that I am able to do most repair work myself. If it is over my head, I will take it to a shop.

Upon startup, the engine will crank for a couple of seconds and turn over. However, once it "starts" it is very weak and nearly stalls completely. It will then pick up the rpms and operate as normal. No issues while driving or idling.

Since I have noticed this problem, I have tried to prime the fuel pump by turning the ignition to on and waiting about 8 seconds. Then I turn it off and back to on to build fuel pressure up in the system. This still does not help the startup.

After it has been operating normally, I can turn it off and back on without the hesitation. However. If there is any significant amount if time between then the startup issue returns. By significant I mean 20 minutes.

Could this be a bad check valve that is not allowing FP to build up enough? A weak fuel pump? Can you replace just the fuel pump or do you have to have the entire assembly? Could plugs be the culprit? Any sensor that is know to cause this problem?

It runs and operates normally once it starts up

Thank you all

 

[NJshadow93]

What engine does your truck have? If it's the V6 your plugs should have been changed every 30k. Have you lost any coolant? Any lights on the dash? Hopefully it's not the headgasket.

 

[Stevo405]

It's the v6. I am changing the plugs today as I have no idea the last time they were changed.

No lights on the dash. No pending codes either. Coolant level is the same as it was yesterday before a 350 mile trip. I don't see any oil in the coolant or coolant in the oil. The car is not white smoking either so I don't believe it is burning coolant.

It drives great other than this issue. It has what seems like full power under throttle, No hesitation, smooth idle, 22 mpg avg on the trip yesterday.

Hopefully I can get this sorted out and start enjoying the new ride

 

[Swimmerboy2112]

I had this exact issue on my 02 Tacoma, turned out to be a vacuum leak. Check for any cracked lines or any connections that aren't firmly attached. Also it may be a good time to replace the PCV valve.

 

[Stevo405]

I will go ahead and replace the pcv valve and will give a thorough look over for vacuum leaks when I replace the spark plugs.

As far as spark plugs go, are the denso/Ngk iridium recommended? Or do most people go with the copper plugs and replace then more often? Would anyone be able to provide a part number?

 

[zonianbrat]

I'm curious what it is as mine does this. It did it a while back and I ran 91 octane gas and a bottle of sea foam through it on a 250 mile trip and it seemed to stop. It started doing it again yesterday though.

 

[Stevo405]

Alright. Here is what I found out about the car today. A toyota dealer in the area did a diagnosis for this exact problem in June 2013. They said either fuel pump, leaky injector or ECM. I am leaning toward fuel pump. I also found out the plugs were replaced and injectors "cleaned" in June of 2012.

Can I replace just the fuel pump or do I have to get the whole tank assembly? And do I have to drop the tank or is there an access panel in the cab?

 

[Stevo405]

Update:

Head gaskets, valve guide seals and water pump replaced. I still have the same issue. It turns out there was a bit of coolant leaking into the cylinder after the engine was turned off. A very small amount but enough to cause a small cloud of white smoke after a completely cold startup. Now I have to chase down this other issue.

Tomorrow I am taking it back to the dealer who did the work to check the fuel pressure. I am hoping for a fpr or pump issue as they are cheaper than new injectors.

Does anyone have experience with remanned injectors? Or experience replacing the fuel pump?

On a side note, I am going to push to have the dealer fix this problem on the house. I asked them multiple times if the head gaskets were the issue and if that would fix this startup problem. It appears that they have misdiagnosed the issue. After the money spent on this head gasket repair I feel they should be more than willing to work with me. Am I thinking clearly? They call them stealerships for a reason.

 

[Greydog]

There should be a fuel pressure regulator and also a damper. Perhaps replace both.

Sometimes you can find vacuum leaks using very small amounts of starter fluid spraying around hoses and fittings.

Cleaning injectors is fine, but you may want to have them removed and tested by a shop that can flow and function test and report results, just to rule out a leaking or weak injector.

Bummer on the HG job, good call on trying to get them to cover other repairs since they diagnosed.

Can you resistance test the coils too, perhaps one is throwing weak spark, so it's having a hard time starting when cold?

Give the plugs a good comparison, see which looks like an outlier, maybe that is the problem cylinder?

 

[Stevo405]

UPDATE AND SOLUTION.

As stated before, head gaskets, water pump and valve guide seals replaced. I do NOT think this was causing the startup issue. If coolant were leaking into one cylinder, I would more than likely have gotten a specific cylinder misfire code instead of the p0300 random multiple.

After the head gaskets didn’t fix my problem, I took the car back to the dealer. I have experienced fuel system issues before. I had a bad seal in the tank assembly on one previous vehicle and a bad FPR on another. When I took it back I specifically requested that they test the fuel pressure since I could not find any quick connect fitting to do it myself. The tech laughed at my request and told me that this would “tell me nothing” about why the car is having a hard start issue.

WHAT do you know, there is a problem with the fuel pressure holding once the car has been turned off! It’s a shame that I have to tell this “experienced” technician how to do his job. I asked him which side he thought the leak was coming from and he said it was in the tank. Did I believe him? No, I just knew I had a fuel system issue.

Headed to the junk yard and picked up a fuel pump assembly from a recently wrecked 08. It had been sitting for two weeks so I wasn’t too worried about contamination. It took most of a Saturday morning, but I got the new assembly in the tank (I say this like it’s a small job… It is not fun unless you have a lift. PM me if you need help). I started her up and BAM (not an explosion), no issues. Then I took it for a little spin around the block, brought it back, parked it and waited. I returned to the car and attempted to start….SAME PROBLEM.

Not the fuel pump… or check valve… at least it wasn’t terribly expensive for the tank assembly. On to the next thing. Now what else would leak down? Only one other thing, really: INJECTORS.

So at this point I am pretty pissed. I just spent time working on the car that I could have spent with my family that was in town only to have the same issue. Time to test the injectors.

I ran the car for a couple of minutes and shut it off. I let it sit for about 2 hours and pulled the plugs. ALL OF THE PLUGS had raw gasoline on them and fuel fouling from the rich A/F mixture. There is the problem. What is next? Back to the dealer.

I took it back to the dealer and described what I had found. Again, of course, they look at me like I have no idea what I am talking about. They will have the same tech “check it out.” Oh Great! I get a call that only one of the injectors is leaking and they will replace only one injector but I will have to pay for all of the others. $1100 parts and labor is your price.

Now I am a pretty quiet, chill, happy guy, but when you have already spend 2700 to fix the problem and they try to add on another 1100 to cover for their mistake, it is going down. I “spoke” with the service manager and director for about 15 minutes and that is all it took. Injectors replaced free to the customer because of a mistake in the initial diagnosis of the issue. Truck is fixed and runs normally.

Start-up problems? Do you have any smoke from the tailpipe? Black or White smoke? What is your fuel pressure? Does your fuel pressure immediately jump to 40.8-41.7 PSI? If so, then it is probably not your fuel pump. Check your plugs. Are they fouled? Let the car sit for a while and check your plugs. Raw fuel on them?

I should mention that these were warm starts. There had not been enough time for the gas to drain past the rings into the oil. On a cold start it would start up fine because there was no gas in the cylinder.

I hope this helps someone else save some money and time. Spend that time with your family. What is more important?

 

[DiskDoctr]

Nice writeup. Sorry for your problems, but appreciate you sharing them to help others avoid your headaches.

 

[radlynx]

Great findings!

UPDATE AND SOLUTION.

As stated before, head gaskets, water pump and valve guide seals replaced. I do NOT think this was causing the startup issue. If coolant were leaking into one cylinder, I would more than likely have gotten a specific cylinder misfire code instead of the p0300 random multiple.

After the head gaskets didn’t fix my problem, I took the car back to the dealer. I have experienced fuel system issues before. I had a bad seal in the tank assembly on one previous vehicle and a bad FPR on another. When I took it back I specifically requested that they test the fuel pressure since I could not find any quick connect fitting to do it myself. The tech laughed at my request and told me that this would “tell me nothing” about why the car is having a hard start issue.

WHAT do you know, there is a problem with the fuel pressure holding once the car has been turned off! It’s a shame that I have to tell this “experienced” technician how to do his job. I asked him which side he thought the leak was coming from and he said it was in the tank. Did I believe him? No, I just knew I had a fuel system issue.

Headed to the junk yard and picked up a fuel pump assembly from a recently wrecked 08. It had been sitting for two weeks so I wasn’t too worried about contamination. It took most of a Saturday morning, but I got the new assembly in the tank (I say this like it’s a small job… It is not fun unless you have a lift. PM me if you need help). I started her up and BAM (not an explosion), no issues. Then I took it for a little spin around the block, brought it back, parked it and waited. I returned to the car and attempted to start….SAME PROBLEM.

Not the fuel pump… or check valve… at least it wasn’t terribly expensive for the tank assembly. On to the next thing. Now what else would leak down? Only one other thing, really: INJECTORS.

So at this point I am pretty pissed. I just spent time working on the car that I could have spent with my family that was in town only to have the same issue. Time to test the injectors.

I ran the car for a couple of minutes and shut it off. I let it sit for about 2 hours and pulled the plugs. ALL OF THE PLUGS had raw gasoline on them and fuel fouling from the rich A/F mixture. There is the problem. What is next? Back to the dealer.

I took it back to the dealer and described what I had found. Again, of course, they look at me like I have no idea what I am talking about. They will have the same tech “check it out.” Oh Great! I get a call that only one of the injectors is leaking and they will replace only one injector but I will have to pay for all of the others. $1100 parts and labor is your price.

Now I am a pretty quiet, chill, happy guy, but when you have already spend 2700 to fix the problem and they try to add on another 1100 to cover for their mistake, it is going down. I “spoke” with the service manager and director for about 15 minutes and that is all it took. Injectors replaced free to the customer because of a mistake in the initial diagnosis of the issue. Truck is fixed and runs normally.

Start-up problems? Do you have any smoke from the tailpipe? Black or White smoke? What is your fuel pressure? Does your fuel pressure immediately jump to 40.8-41.7 PSI? If so, then it is probably not your fuel pump. Check your plugs. Are they fouled? Let the car sit for a while and check your plugs. Raw fuel on them?

I should mention that these were warm starts. There had not been enough time for the gas to drain past the rings into the oil. On a cold start it would start up fine because there was no gas in the cylinder.

I hope this helps someone else save some money and time. Spend that time with your family. What is more important?

 

[BlackWorksInc]

UPDATE AND SOLUTION.
...

I hope this helps someone else save some money and time. Spend that time with your family. What is more important?

Interesting, this is the first I have heard of leaking injectors on a 4th Gen, particularly at such a relatively low mileage (we have been seeing issues with with clogging injectors on some of our older Corollas and the 3rd Gens seem to have a hot injector failure issue at the 250k+ area from time to time)

I often get strange looks from my older co-workers who have worked on Toyotas for 10+years when I suggest "odd ball" problems, their typical response is "not on a Toyota" or "Not with these vehicles." Now I am not saying Toyota is the god car, nor am I saying they are crap; but sometimes when you've eliminated the easy stuff, you need to start looking at some of those "odd ball" issues.

Shame that this ended up being such a pain in the ass, checking the fuel pressure isn't hard. There's quick disconnects by the brake booster assembly.