Hesitation at start

[wpurple]

Gots my first problem on my 99 Mounty that has me stumped. (5L)

In the morning when I back out of my driveway, then put it in drive it stumbles, just for a second. After that it never repeats the problem until the next day. I go to the end of my street (200') and start from a standstill and it is fine.

Thought maybe TPS but you would think that would be cause the problem to be there all or most of the time. No trouble codes either.

Thoughts?

TIA

 

[WillieTD]

Clean your IAC with carb cleaner. This is a common problem. I just did it last week because I had an idle problem at start up as well and it has been cured. Basically, you just flush out the IAC with carb cleaner and that will clear out the deposits and any dirt that has collected.

 

[wpurple]

Clean your IAC with carb cleaner. This is a common problem. I just did it last week because I had an idle problem at start up as well and it has been cured. Basically, you just flush out the IAC with carb cleaner and that will clear out the deposits and any dirt that has collected.

I will try it, but it does idle fine, it is just when you give it the gas to start accelerating does it sputter just for a second.

 

[boominXplorer]

dont use carb cleaner make sure you use electric parts cleaner. You can get it at all auto places

 

[WillieTD]

Mustang folks have been using carb cleaner for years, but I'm sure the electric cleaner will work, too.

I was also thinking spark plugs but it would continue doing it the entire time you are driving, not just when you first take off in the morning.

 

[wpurple]

I will try electrical (contact) cleaner first. I know you now suppose to use carb cleaner as it could remove the coating from the inside but I have heard from Ford dealers that they never had a problem, usually it is gunked up enough even after a good cleaning that the coating is coated with carbon anyways.

Did a complete tuneup including plugs a few months ago. Going to try the A/C in the morning too to see if that makes it stumble, my fathers F150 5L stumbled when the A/C was on and the IAC was dirty.

 

[the_tool_man]

Hi wpurple:

Another possibility is that you have a bad fuel pressure regulator diaphram. I had one go bad in a '93 Explorer I used to have and it did exactly the same thing. It allows a small amound of fuel to leak into the intake manifold, causing a rich condition upon startup. If left to worsen, and the diaphram ruptures, your intake manifold, cylinders and possibly exhaust can fill up with fuel the next time you try to start it. This could result in hydrolocking the engine or starting a fire. Fortunately for me, mine wasn't permanently damaged. I had to have the intake manifold and exhaust system removed and drained, and change the oil. I would check your regulator if I were you.

Regards,
John.

 

[bill dv]

I had the same problem cleaned my MAF sensor and the hesitation disappeared