C5 Hard Start Problem
Thread Starter
Heel & Toe
Joined: Nov 2019
Posts: 16
Likes: 2
From: New Castle, DE
C5 Hard Start Problem
my 2001 with 45k on it cranks and tries to start but conks out. my fuel psi on the key only surges to 58 then settles at 51 with no bleed down
at 1 minute. when i try to start it it almost starts but then settles at 55 psi. if i play with the pedal it will eventually start. these symptoms
seem to have no engine temperature variable.
i think the next step might be to clean the throttle plate area before more invasive solutions like replacing the fuel filter/ regulator, or worse,
the fuel pump. i've already tried the techron.
i'd appreciate any ideas. thanks very much.
at 1 minute. when i try to start it it almost starts but then settles at 55 psi. if i play with the pedal it will eventually start. these symptoms
seem to have no engine temperature variable.
i think the next step might be to clean the throttle plate area before more invasive solutions like replacing the fuel filter/ regulator, or worse,
the fuel pump. i've already tried the techron.
i'd appreciate any ideas. thanks very much.
Instructor
Joined: Feb 2002
Posts: 249
Likes: 10
From: Mesa AZ
My car did that when I first got it. It had not been driven often. I used SeaFoam, in a higher concentration
than recommended. Driving for hours non-stop also helped, IMO. About 12 hours in 2 months fixed it.
than recommended. Driving for hours non-stop also helped, IMO. About 12 hours in 2 months fixed it.
Administrator
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Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
Merry Xmas !!...as was mentioned...check for any DTC's !!!...your "01 fuel rail pressure like mine should be 55-62 key ON so you're 4 psi low right there and may be the problem !!...don't know if you have a scan tool but that would also help in a diagnosis...there are some data PIDS I can have you look at with key on that be help you...if you don't know when the fuel filter/pressure regulator was changed I'd do that first...don't know if you are good with electrical though...you can pick up a cheap amp clamp at Harbor Freight and check your fuel pump current draw...my "01 draws around 6 amps at idle...and you can look at pump power and grounds...also compare your ECT temp gauge in the morning vs. the outside air temp...should be real close...also a bad cam sensor can cause "hard starts"...another thing to check is the TPS sensor circuit...there are 2 signal wires that if the voltage is to high with key on can cause this issue !!
Last edited by C5 Diag; Dec 27, 2019 at 03:36 AM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 326
From: CA.
St. Jude Donor '13-'14-'15
I would suspect your MAF sensor----
Do you have a cold air intake that is oiled ?
This is a problem as new technology no one uses oiled air filters As the oil will foul the MAF sensor and whatever the MAF reading was when the engine was shut off (LTFT'D) will remain when started again Clean your MAF sensor with brakeclean---
Try this Dis connect a battery lead over night-- after cleaning the MAF-see if this helps dis connecting the battery will re set the fuel trims
2ndly If you have an access to a scanner see what your 02 voltage averages are after the engine is warmed or switches to closed loop
Correctly operating 02's should have a voltage average from .400 to .550 millivolts
-The higher the average the richer the closed loop fueling and vice versa---This will also affect re starts--This is a brief explanation however it is more complex than this---
Many variables and mods can affect hard starting--
Do you have a cold air intake that is oiled ?
This is a problem as new technology no one uses oiled air filters As the oil will foul the MAF sensor and whatever the MAF reading was when the engine was shut off (LTFT'D) will remain when started again Clean your MAF sensor with brakeclean---
Try this Dis connect a battery lead over night-- after cleaning the MAF-see if this helps dis connecting the battery will re set the fuel trims
2ndly If you have an access to a scanner see what your 02 voltage averages are after the engine is warmed or switches to closed loop
Correctly operating 02's should have a voltage average from .400 to .550 millivolts
-The higher the average the richer the closed loop fueling and vice versa---This will also affect re starts--This is a brief explanation however it is more complex than this---
Many variables and mods can affect hard starting--
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
I try not to throw parts at problems...but, when was the last time you changed your fuel filter? Clean your MAF and your throttle body. That should make a difference….get back to us.
Drifting
Joined: Nov 2017
Posts: 1,371
Likes: 291
You'll have to post the diagnostic codes (or state that you have no codes) if you want something more than wild speculation.
But, speaking of wild speculation... I had an issue last summer where mine would fire up and then just die. It turned out that the ground connection on the driver's side of the crankcase was loose. Several codes were present due to bad sensor grounds - MAF, low oil level (it had just been topped off), and a couple others. Tightening the ground fixed everything.
But, speaking of wild speculation... I had an issue last summer where mine would fire up and then just die. It turned out that the ground connection on the driver's side of the crankcase was loose. Several codes were present due to bad sensor grounds - MAF, low oil level (it had just been topped off), and a couple others. Tightening the ground fixed everything.
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