'97 Blazer hard to start when hot... not when cold

[imnprsd]

I find it odd that my '97 blazer, 4x4, is harder to start when it's hot vs when it's cold. In the morning it starts immediately, but after I have been driving it a while... turn the engine off to go to a store for example, when I return it's harder to start.

It's almost like it's flooded... And when push down on the gas pedle it starts fine. Any ideas? I did a full tune up, but that did not change anything, and prior to that I flushed the fuel rail.

[perrokonan]

i posted in another thread that i had the same problem but in my case it ended up being the gas pump now it always starts on the first try right away

[BlazerLT]

Originally Posted by imnprsd

I find it odd that my '97 blazer, 4x4, is harder to start when it's hot vs when it's cold. In the morning it starts immediately, but after I have been driving it a while... turn the engine off to go to a store for example, when I return it's harder to start.

It's almost like it's flooded... And when push down on the gas pedle it starts fine. Any ideas? I did a full tune up, but that did not change anything, and prior to that I flushed the fuel rail.

What did this tuneup include?

[imnprsd]

Originally Posted by BlazerLT

What did this tuneup include?

The tune-up consisted of the following: AC-plugs, Sorenson wires, cap, roter. And just a few weeks prior to the tune-up I replaced the fuel pump (because the old one was making an even louder noise than usual), and I had the fuel rail flushed. Mind you, the starting problem has always been there -- when it's hot -- and none of the above mentioned things had a pro or con affect on the engine being slow to start when it get hot.

Someone mentioned to me that the fuel pump solenoid might be the problem if we are talking about a temperture dependent part as being the root cause of the problem, but I think that is a long shot. What do you think?

I also replaced the engine sensor (on the top-front of the engine) where the upper water hose attaches, as someone suggested this is the sensor which affects the mixture or priming functions that are controlled by the PCM, but I don't know if that is true. I only know it was a $15 part so I ttied that... with no affect as you might expect.

Also, for clarification, the engine will start right away (when it's hot) if I depress the gas peddle 3" or so; i.e., not just a little but a lot! ...Sorry, but that's the only other piece of information I can share with you.

This blazer has 120,000 miles, 4.3L, 4x4. Any ideas you have would be helpful.

[imnprsd]

Originally Posted by BlazerLT

What did this tuneup include?

The tune-up consisted of the following: AC-plugs, Sorenson wires, cap, roter. And just a few weeks prior to the tune-up I replaced the fuel pump (because the old one was making an even louder noise than usual), and I had the fuel rail flushed. Mind you, the starting problem has always been there -- when it's hot -- and none of the above mentioned things had a pro or con affect on the engine being slow to start when it get hot.

Someone mentioned to me that the fuel pump solenoid might be the problem if we are talking about a temperture dependent part as being the root cause of the problem, but I think that is a long shot. What do you think?

I also replaced the engine sensor (on the top-front of the engine) where the upper water hose attaches, as someone suggested this is the sensor which affects the mixture or priming functions that are controlled by the PCM, but I don't know if that is true. I only know it was a $15 part so I ttied that... with no affect as you might expect.

Also, for clarification, the engine will start right away (when it's hot) if I depress the gas peddle 3" or so; i.e., not just a little but a lot! ...Sorry, but that's the only other piece of information I can share with you.

This blazer has 120,000 miles, 4.3L, 4x4. Any ideas you have would be helpful.

[imnprsd]

ccc

[BlazerLT]

Originally Posted by imnprsd

The tune-up consisted of the following: AC-plugs, Sorenson wires, cap, roter. And just a few weeks prior to the tune-up I replaced the fuel pump (because the old one was making an even louder noise than usual), and I had the fuel rail flushed. Mind you, the starting problem has always been there -- when it's hot -- and none of the above mentioned things had a pro or con affect on the engine being slow to start when it get hot.

Someone mentioned to me that the fuel pump solenoid might be the problem if we are talking about a temperture dependent part as being the root cause of the problem, but I think that is a long shot. What do you think?

I also replaced the engine sensor (on the top-front of the engine) where the upper water hose attaches, as someone suggested this is the sensor which affects the mixture or priming functions that are controlled by the PCM, but I don't know if that is true. I only know it was a $15 part so I ttied that... with no affect as you might expect.

Also, for clarification, the engine will start right away (when it's hot) if I depress the gas peddle 3" or so; i.e., not just a little but a lot! ...Sorry, but that's the only other piece of information I can share with you.

This blazer has 120,000 miles, 4.3L, 4x4. Any ideas you have would be helpful.

1.) Check fuel pressure with key to the on position before start.

2.) Did you replace the fuel filter?

[imnprsd]

Yes... I replaced the fuel filter and the checked the fuel pressure. It's 64 psi and then drops to 59psi moments after the key is turned.

...Do you think the fuel regulator could be leaking? I'm just guessing, of course, but I'm thinking that if I have to depress the gas pedel to get a positive start, that what I am doing is adding air to compensate for too much fuel. Does this sound like a possibility?

What do you think about the possibility of the fuel solenoid being the problem? ...And for the record I did replace the ignition switch/harness about 3 months ago.

The only other possible symptom might be this: when the mechanic was cleaning the throttle body, I commented on the whistling sound...and he openned up the buterfly to stop the noise. I'm not sure, but I don't think the starting problem existed before this. Therefore, I'm wondering if that might be the problem or possibly the MAP sensor got damaged. Note: my SRS light does not come on.

Mark

[BlazerLT]

If you hear the pump prime when you put the key to the first position, the solenoid is fine.

[imnprsd]

...Any other ideas? I agree the solenoid is probably not the problem...

...But why does the engine start right away (when it's hot) if I depress the gas pedel 3" or more?

PS: My gas mileage is 16 city and 19.5 hwy (driving at 70 MPH).

[BlazerLT]

I would check and clean your idle air control valve and the hole it inserts into.