Warm Start Problems
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Senior User
Joined: May 2015
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From: Dallas, TX
Warm Start Problems
Having issues with the 93 bronco in my sig. (sorry I know this will be responded to faster on this side of the forum).
Checked fuel pressure and in range so not fuel pump and can hear it prime when I turn the truck on. Timing is at stock 10 degrees I went ahead and checked last night.
My issue only occurs on a warm start. Most of the times it will start (edit: accidentally put crank, the bronco cranks everytime no issues with starter whatsoever) just fine but sometimes it will back fire with in a few seconds of getting the engine turned over, sometimes it won't start at all. Let it sit for 20 mins and once it cools off it starts.
I was guessing ECT but was reading on the forums about a IAT? Have not tested/replaced either yet was hoping to hear from someone wiser than me first.
Oh and no codes. I pulled with my Innova reader and nothing pops up..... getting around 10 miles to the gallon which is expected with the small lift on it.
Checked fuel pressure and in range so not fuel pump and can hear it prime when I turn the truck on. Timing is at stock 10 degrees I went ahead and checked last night.
My issue only occurs on a warm start. Most of the times it will start (edit: accidentally put crank, the bronco cranks everytime no issues with starter whatsoever) just fine but sometimes it will back fire with in a few seconds of getting the engine turned over, sometimes it won't start at all. Let it sit for 20 mins and once it cools off it starts.
I was guessing ECT but was reading on the forums about a IAT? Have not tested/replaced either yet was hoping to hear from someone wiser than me first.
Oh and no codes. I pulled with my Innova reader and nothing pops up..... getting around 10 miles to the gallon which is expected with the small lift on it.
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Senior User
Joined: May 2015
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From: Dallas, TX
my bad should have been much more clear.
She cranks every time but has issues starting when engine is warm from time to time. Also when it does struggle to start it bogs down (like too much fuel) and when it does start it definitely smells rich from the tailpipe.
I am thinking the computer always is thinking the engine is cold on start but just a guess.
She cranks every time but has issues starting when engine is warm from time to time. Also when it does struggle to start it bogs down (like too much fuel) and when it does start it definitely smells rich from the tailpipe.
I am thinking the computer always is thinking the engine is cold on start but just a guess.
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From: Kentucky
Anything else means the code reader never connected to the computer.
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Senior User
Joined: May 2015
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From: Dallas, TX
You should at least get the System Pass code 111 for the KOEO tests if nothing failed. Then the Innova may display a Code 10, which is the separator flash between the KOEO code display and the start of the stored code (aka Continuous Memory) display.
Anything else means the code reader never connected to the computer.
Anything else means the code reader never connected to the computer.
Again apologies on my horrible forum question haha. - by no codes I mean all good with 111 for key on engine on test. No fault codes I should say not "no codes and nothing pops up".
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From: Dallas, TX
I will also add I just replaced vacuum lines with silicone lines. - by just replaced I mean 6 months ago. It does have the old style tin can reservoir so I can check vacuum pressure tomorrow if that might be it but it runs perfect once its started.
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Senior User
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From: Dallas, TX
I honestly didn't check that when I had the fuel gauge rented out from the parts store so not sure.... it started right up last week when I had the fuel gauge on her.
Anyway to tell without a gauge?
Anyway to tell without a gauge?
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From: Rhode Island
You can hear the fuel pumps when they're on. They should only run for 1 second when you turn the key on, then turn off.
See if the fuel pumps constantly run when truck gets into its refusing to start phase.
See if the fuel pumps constantly run when truck gets into its refusing to start phase.
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From: Dallas, TX
Had the starting issue again today. Made sure on the second attempt I had door open and radio off to hear the fuel pump prime. It kicked on for a second and then off. You can hear the buzz for sure but was definitely momentary and not constant so I think its priming right.
No doubt in my mind its dumping fuel for some reason on a warm start up and therefore flooding the engine. It smells super rich once it gets going.
I am going to put a vacuum gauge on it. Re-pull codes to be sure nothing in continuous memory since no CEL right now. Maybe the tin can is leaking... Then I may pull the ECT and IAT and clean them up and test them.
After some more reading I am not thinking ECT since it should throw a code at me right?
It only happens on a warm start. If engine is hot like I only ran into a store for a second then no issue. If engine is cold then no issue. If engine is warm as in has not been started in the last 20 mins then it will struggle like hell. Until you let it sit for another 10-20 then will start with issues but start.
No doubt in my mind its dumping fuel for some reason on a warm start up and therefore flooding the engine. It smells super rich once it gets going.
I am going to put a vacuum gauge on it. Re-pull codes to be sure nothing in continuous memory since no CEL right now. Maybe the tin can is leaking... Then I may pull the ECT and IAT and clean them up and test them.
After some more reading I am not thinking ECT since it should throw a code at me right?
It only happens on a warm start. If engine is hot like I only ran into a store for a second then no issue. If engine is cold then no issue. If engine is warm as in has not been started in the last 20 mins then it will struggle like hell. Until you let it sit for another 10-20 then will start with issues but start.
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From: Dallas, TX
Okay so this time around I did get some codes on the KOEO test.
Code 538
Code 411
Code 632 (this was user error on me forgot to push O/D button this time)
Engine off test gave me 111 again only got the codes with the running self test.
Code 538
Code 411
Code 632 (this was user error on me forgot to push O/D button this time)
Engine off test gave me 111 again only got the codes with the running self test.
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From: Dallas, TX
Okay looks like I might not have hit the accelerator at the right time during key on engine on test since looks like 538 might be that.
Whew. This issue has been a pain to track down...
Whew. This issue has been a pain to track down...
Thread Starter
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Senior User
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From: Dallas, TX
So looks like I am going to be cleaning and testing my IAC too when I check vacuum pressure...
At least it gave me something. Last time it didn't. I am starting to think I didn't do the key on engine on test right the first time.
At least it gave me something. Last time it didn't. I am starting to think I didn't do the key on engine on test right the first time.