Hard starts

[toobladink]

Hey guys, I've had this issue for a few years and I've just been ignoring it. But it's been bothering more and more lately, and I'd like to get it fixed before it starts getting cold again.

I pretty much have to start the car twice. The second time, it's almost immediately. I noticed that when I hold the gas pedal for about five seconds, it can start up first try about 80% of the time. If the engine is warmed up already, it also starts up first try. It gets really bad when it's cold, and sometimes I have to try three or even four times before it finally starts. It will have a really rough idle in super cold temps (single digits), but I feel like that's normal. Ever since I got a cone filter, whenever I have a really hard time starting it (battery was being used for something, it's cold, etc), it will give me a check engine light and it says both banks are lean.

I have the V6 SOHC. I've replaced the spark plugs and fuel filter. I've also used some injector cleaner thinking that would help a little bit, but it really isn't. The PCV valve was also recently replaced. I think it could be fuel related because of the engine codes. However, I also feel like it could just be some sensors. I've read that when O2 sensors wear out, you can run lean. Is this true? Should I replace them anyways? I'm at 170k and they've never been replaced.

What is a reasonable next step to properly diagnose this?

 

[donalds]

May be time for a pump check your fuel pressure
On a 2000 v6 it should be around 65 psi
Next time you start it
Before you try to start it cycle the key a couple of times to prime the system
Turn the key to run for a second then repeat then start on the 3rd turn
May have a bad check valve in the pump

Whatever you do don't just throw parts at it

 

[Fix4Dirt]

Hey guys, I've had this issue for a few years and I've just been ignoring it. But it's been bothering more and more lately, and I'd like to get it fixed before it starts getting cold again.

I pretty much have to start the car twice. The second time, it's almost immediately. I noticed that when I hold the gas pedal for about five seconds, it can start up first try about 80% of the time. If the engine is warmed up already, it also starts up first try. It gets really bad when it's cold, and sometimes I have to try three or even four times before it finally starts. It will have a really rough idle in super cold temps (single digits), but I feel like that's normal. Ever since I got a cone filter, whenever I have a really hard time starting it (battery was being used for something, it's cold, etc), it will give me a check engine light and it says both banks are lean.

I have the V6 SOHC. I've replaced the spark plugs and fuel filter. I've also used some injector cleaner thinking that would help a little bit, but it really isn't. The PCV valve was also recently replaced. I think it could be fuel related because of the engine codes. However, I also feel like it could just be some sensors. I've read that when O2 sensors wear out, you can run lean. Is this true? Should I replace them anyways? I'm at 170k and they've never been replaced.

What is a reasonable next step to properly diagnose this?

Usually I see when fuel pumps go bad it has issues when its hot more often than cold, but it could be that! I tend to see on old Fords they run richer over time rather than leaner. It could also be a gasket leak & when it gets hot it expands enough. Maybe the intake plenum gaskets? THose can be diagnosed with a smoker

 

[toobladink]

May be time for a pump check your fuel pressure
On a 2000 v6 it should be around 65 psi
Next time you start it
Before you try to start it cycle the key a couple of times to prime the system
Turn the key to run for a second then repeat then start on the 3rd turn
May have a bad check valve in the pump

Whatever you do don't just throw parts at it

Are there any other symptoms I would have with low fuel pump pressure? I haven't noticed anything else abnormal.

 

[donalds]

Lean codes
Hard start
Basically what you're saying

As @Fix4Dirt says intake gaskets are another avenue

 

[toobladink]

Okay i finally got around to testing pressure. Seems a little under 65, but can this small of a pressure difference really cause lean engine codes? These pictures are like a minute apart - when the car shuts off, pressure drops. Makes sense to me since the car is off lol. But is this too fast? I can’t smell fuel so i dont think i have a leak. Not willing to rule it out though if pressure is a little lower than it should be and if this is dropping abnormally fast.

I think my next step is going to be replacing the fuel filter, as I am getting close to my interval anyways. What else do you guys suggest I look at?

 

[toobladink]

I forgot to also share that this is the pressure when the key is on but engine is off. This seems like the culprit to me, is it even possible to start with this low of pressure or am I crazy?

EDIT: Okay i have discovered i did not bleed the tester and it probably had some air in it. We try again when i have some free time lol. Disregard for now! I’ll share an update hopefully within a week.

 

[wollimann]

is it even possible to start with this low of pressure or am I crazy?

You are not crazy and it's not possible to start with this low fuel pressure.
With the key on and engine off, the fuel pump runs for max 2 seconds and provide 60 PSI.
But the 60 PSI must stay for a while, maybe after 30 minutes the pressure falls down very slowly.

If the fuel pressure falls down rapidely (after key on engine off), there is a leak at the fuel pump assemly.
Maybe the pump is at it's end, maybe the short rubber hose is cracked or the fuel pressure regulator is bad.

Leaky fuel injector do not cause a rapid pressure fall, so i would say have a look inside the tank.

 

[410Fortune]

Your fuel pressure is fine
I have trucks where the pressure drops to zero in just a few minutes… they still start right up

The fuel pump primes when you first turn the key. This builds rail pressure. Cycle the key a couple of times if you want to get it to 64 psi before cranking the starter


With the sohc engine and lean codes 171 and 174 the culprit is intake o rings 99.999999% of the time

Fuel rail
Pressure spec is 64 psi running +/-

I don’t care if it is -15 degrees out the truck should not have a rough idle once started… Ever. This is not normal

Lean codes on both banks means the computer has detected a lack of fuel to air ratio and has attempted to dump extra fuel and is unable to compensate. Then you get lean codes. With a sohc engine this is because the intake plenum o rings have shrunk and dried up and you are sucking in un metered air at the upper and lower intake plenums

Checking fuel pressure is step one… 64psi running = that is not your issue.
Low fuel pressure at first start will cause a long crank… but as you can see the pressure builds very quickly with the key on and pump running

Your intake manifold has a upper and lower plenum.. all the o rings need to be replaced as well as a new egr o ring
Good time to re ring the injectors and replace the injector seats

I have fixed many many many sohc engines with 171 and 174 codes this way

Gaskets are under $40 and it takes a few hours to re seal the plenums
There is not a 97-02 sohc engine out there that does not need new intake gaskets.. yours dried up probably 5 years ago

 

[toobladink]

Gotcha. I think this might be out of my ability if I was improperly measuring fuel pressure with key on engine off (going to try again after work), but I'll have a look at some videos and see if I'm up for resealing once it warms up a bit more before I decide to take it to a shop.

What's the best way to tell that this is 100% my issue? Just open it up and see if the seals have cracking or rotting? I'm sure it's probably pretty brittle too.

 

[410Fortune]

If it has never been done they are toast

It literally takes me 15 minutes to take the upper plenum off and another 15 to do the lower
I have some tools that help me access the back screws
It’s not a difficult job
I charge $200 to do this for my friends plus parts. I bench check all 6 injectors, clean everything and replace injector seats. Clean everything like a surgeon, inspect all hoses and fittings clean the mas air flow sensor and replace the air filter all at once

Parts are cheap, the o rings used to be $15
They have gone up a bit
The hardest part of the job is digging the old rotten injector seats out of their holes with a pick and vacuum the. Cleaning the sealing surfaces

With a flashlight you can look at the base of your intakes where it meets the metal of the engine heads… there will be a buildup of soot around where air has been being sucked in

Again there is not a 97-02 sohc on the planet where the o rings are still good , it’s just not possible

 

[toobladink]

If it has never been done they are toast

It literally takes me 15 minutes to take the upper plenum off and another 15 to do the lower
I have some tools that help me access the back screws
It’s not a difficult job
I charge $200 to do this for my friends plus parts. I bench check all 6 injectors, clean everything and replace injector seats. Clean everything like a surgeon, inspect all hoses and fittings clean the mas air flow sensor and replace the air filter all at once

Parts are cheap, the o rings used to be $15
They have gone up a bit
The hardest part of the job is digging the old rotten injector seats out of their holes with a pick and vacuum the. Cleaning the sealing surfaces

With a flashlight you can look at the base of your intakes where it meets the metal of the engine heads… there will be a buildup of soot around where air has been being sucked in

Again there is not a 97-02 sohc on the planet where the o rings are still good , it’s just not possible

Do you do the injectors because once all that is off, it's pretty easy to access and is just a good thing to maintain? I imagine it's also nice to test and clean them to make sure the lean codes stay away. I've never done anything like that for my truck except for the occasional can of seafoam haha. It doesn't seem that bad, I'd just need to be patient if I try and do this. But what tools do you have to access the back screws? I pretty much just have a ratchet set and a wrench set right now, nothing else.

 

[410Fortune]

So I think they are torx 27 or 30 bit, I use 1/4”
Drive
The special tool is just a flexible drive makes it easier to get the back most two screws

A shop vac and lots of rags, razor blade scraper to clean the mating surfaces, alcohol or carb cleaner

Under the intake plenum is always a bunch of dirt debris and mouse nests (shop vac)

A strong pick is needed to unseat the hard plastic injector seats they are set down inside the aluminum head

All available at local harbor freight or tool store

 

[Turdle]

I highly suggest

Big plastic tub.
Purple power degreaser
Rubber gloves
Wire brush set with small bottle- tube brushes
New injector o rings
New intake gaskets

Torx bit socket set

Cooler
Ice
Beer


Make it a weekend. You'll get it all cleaned and sealed. My sis in law did it.

Edit

Gotta mention , don't forget to disconnect battery terminals when working in rhere

 

[eddiehudson]

Ever since I got a cone filter, whenever I have a really hard time starting it (battery was being used for something, it's cold, etc), it will give me a check engine light and it says both banks are lean.

What is a reasonable next step to properly diagnose this?

Did you try to replace the filter?

 

[BTR]

@toobladink - I have a 4.0L SOHC Job1 engine in my 2000 Explorer with 159,000 miles. I too have longstanding starting problems. For now, @410Fortune and @Turdle have you on the right track. Thus, I'd like to go back to your question about O2 sensors. I think 2 things apply to your question:

1. - My understanding is that the O2 sensors play no role during starts. They don't start reporting to the computer until they are heated up. Even on a hot start, they take some time to start reporting. I may be wrong, and if so, I'm sure @410Fortune and/or @Turdle will straighten me out.

2. - Replacing your 2 upstream O2 sensors (use Motorcraft based on the number/s stamped on your current sensors... assuming they are the OEM sensors) won't help your starts, but it will definitely help your gas mileage and maybe even your performance. Over time, O2 sensors can get lazy and/or less sensitive. I replaced mine and I can... literally... see my gas gauge needle moving down waaaaaay slower than it used to.

 

[Turdle]

Intake gaskets. Any other repairs are wasted time at this point . Opinion but this is a repeated forum trend.

O2s are indeed dead until they heat up. About 30 - 45 seconds after start up.


Get some baggies, and a sharpie also. Bolts in bag, sharpie to write on bag where they go. Take pics as you go. You'll be amazed how things fall back into place. Like you avoided it for no reason.