Hot Start Problems
Thread Starter
|
Fleet Mechanic
Joined: Aug 2015
Posts: 1,838
Likes: 367
From: Candy Mountain
Hot Start Problems
Hey Folks, looking for ideas and suggestions.
Since I bought the truck in my signature, I have experienced the occasional rough idle on hot start. Typically, this has occurred in warmer weather and only when the truck has been shut down hot and restarted within 5 - 15 minutes. The rough idle always clears up as I drive away. The idle is worse under load, such as the AC compressor running. Edit [I have never had any starting or idle problems with this truck other than this condition.] Today it failed to start on the first crank twice. Started on the second try and idled very roughly for some time before it smoothed out. Minor annoyance moving into problem territory.
I had a few minutes on my lunch break and checked the manifold vacuum and for KOEO codes. Vacuum was a little weak until the idle cleared up and then it was strong. KOEO test returned a system pass and no stored codes.
My initial thought is a weak ignition coil, but I don't have any idle issues otherwise.
I just went through a whole set of diagnostics a few months ago chasing a lean code so I pretty confident in the vacuum system and fuel delivery system. I know vapor lock shouldn't occur in a fuel injected vehicle but a while ago I added heat insulation to the fuel supply line just in case. Oh well... The truck got a full tune up when I bought it, including new Ford coil, wires, plugs, rotor and cap among other things and I have only put 15,000 miles on the truck since then.
Thoughts and suggestions welcome. If I had any other running problems I would feel more confident about where to start...
Thanks!
Since I bought the truck in my signature, I have experienced the occasional rough idle on hot start. Typically, this has occurred in warmer weather and only when the truck has been shut down hot and restarted within 5 - 15 minutes. The rough idle always clears up as I drive away. The idle is worse under load, such as the AC compressor running. Edit [I have never had any starting or idle problems with this truck other than this condition.] Today it failed to start on the first crank twice. Started on the second try and idled very roughly for some time before it smoothed out. Minor annoyance moving into problem territory.
I had a few minutes on my lunch break and checked the manifold vacuum and for KOEO codes. Vacuum was a little weak until the idle cleared up and then it was strong. KOEO test returned a system pass and no stored codes.
My initial thought is a weak ignition coil, but I don't have any idle issues otherwise.
I just went through a whole set of diagnostics a few months ago chasing a lean code so I pretty confident in the vacuum system and fuel delivery system. I know vapor lock shouldn't occur in a fuel injected vehicle but a while ago I added heat insulation to the fuel supply line just in case. Oh well... The truck got a full tune up when I bought it, including new Ford coil, wires, plugs, rotor and cap among other things and I have only put 15,000 miles on the truck since then.
Thoughts and suggestions welcome. If I had any other running problems I would feel more confident about where to start...
Thanks!
Tuned
Joined: Sep 2014
Posts: 358
Likes: 7
From: Ky
Don't see the truck or engine, but nevertheless, you need a COMPLETE diagnosis of your ENTIRE fuel circuit.
Use factory procedures, don't cut corners, or you'll be guessing.
A "hot" start to the computer is similar to a "cold" start except fuel enrichment is leaner, as dictated by the temperature read by the ECT sensor.
Start with that, there are also A LOT of thread in the archives about problems of this nature, it can be extensive.
Use factory procedures, don't cut corners, or you'll be guessing.
A "hot" start to the computer is similar to a "cold" start except fuel enrichment is leaner, as dictated by the temperature read by the ECT sensor.
Start with that, there are also A LOT of thread in the archives about problems of this nature, it can be extensive.
Thread
Thread Starter
Forum
Replies
Last Post
Alan Valek
1987 - 1996 F150 & Larger F-Series Trucks
3
Sep 25, 2017 07:59 PM
R202INT
1987 - 1996 F150 & Larger F-Series Trucks
3
May 18, 2010 08:54 PM
B-Train 1973
1973 - 1979 F-100 & Larger F-Series Trucks
3
Apr 27, 2010 05:46 AM
Ezee4U2C
1987 - 1996 F150 & Larger F-Series Trucks
8
Feb 13, 2008 03:29 PM
