hard start
Thread Starter
8th Gear
Joined: May 2012
Posts: 8
Likes: 0
From: akeley minnesota
hard start
This is a question relating to code po705. There are times on a warm engine when restarting, the engine cranks as if there was no fuel pressure.
The code comes up intermittently and if I don't cancel it, it will go away. This is the only code that ever comes up. My question, can this trans range switch have anything to do with my starting problem? I have replaced the fuel pump and inspected the fuel pressure regulator and nothing has changed the starting. I will add that when it is slow to start, I quit cranking and immediately go back to start and it starts right now.
The transmission does take its time going into gear from neutral, but never indicated a problem with shifts or does any slipping. The fluid is clean and of good color with no odor.
Do I have 1 problem or 2? That is another thought.
The code comes up intermittently and if I don't cancel it, it will go away. This is the only code that ever comes up. My question, can this trans range switch have anything to do with my starting problem? I have replaced the fuel pump and inspected the fuel pressure regulator and nothing has changed the starting. I will add that when it is slow to start, I quit cranking and immediately go back to start and it starts right now.
The transmission does take its time going into gear from neutral, but never indicated a problem with shifts or does any slipping. The fluid is clean and of good color with no odor.
Do I have 1 problem or 2? That is another thought.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You have not provided the year of the C5 and what MODs if any do you you have.
You have accomplished fuel system repairs but have not indicated if you monitor the fuel pressure prior to cold start and at first KEY ON.
What is the fuel pressure when the engine hard starts?
BC
You have accomplished fuel system repairs but have not indicated if you monitor the fuel pressure prior to cold start and at first KEY ON.
What is the fuel pressure when the engine hard starts?
BC
Thread Starter
8th Gear
Joined: May 2012
Posts: 8
Likes: 0
From: akeley minnesota
hard start
The car is a 1998 and stock to my knowedge. I checked pressure on a cold engine and had 60 psi. When I went to crank and the engine started ( normally) the pressure maintained at about 50+ psi. After a good warm up I shut it off and came back about 1/2 hour later, went right to crank and the pressure didn't come up. I released the key and went back to start and got pressure right away and engine start. Pressure about 50 psi running warm. The car has never left me stranded, but it would be nice to fix this. There are no codes at present and like I mentioned the only code I ever get is po705.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
A C5 has NO "idle air control" circuit- because of the drive by wire throttle--So the idle air ( at start-up) is set by opening up the throttle blade slightly--
The usual suspect for slow starting engines (DBW) is a dirty throttle body----Try taking the intake and airbridge off and sparying it with T-Body cleaner or Brake-clean-
careful not to bend the blade--open it up an clean it with a wet rag----Most likely it has some coal like black residue in it
PS: A way to determine if it's indeed just a dirty T-Body-- --- Before cleaning------Try starting it with your foot on the throttle just a little -- If it starts eaiser---that's your problem !
The usual suspect for slow starting engines (DBW) is a dirty throttle body----Try taking the intake and airbridge off and sparying it with T-Body cleaner or Brake-clean-
careful not to bend the blade--open it up an clean it with a wet rag----Most likely it has some coal like black residue in it
PS: A way to determine if it's indeed just a dirty T-Body-- --- Before cleaning------Try starting it with your foot on the throttle just a little -- If it starts eaiser---that's your problem !
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I "THINK" I have an answer to your issue. If you saw an issue with fuel pressure when you switched the Ignition on, you very well could have a burnt/corroded/defective contact inside your IGNITION SWITCH. Take a close look at this schematic and look at the "HOT IN ON & START" feed. That comes from the ignition switch.
Burnt contacts are very common in the C5. Heres a post that details a very easy self DYI Fix: C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Let us know what you find. You can measure the ignition powered fuse to ground and see if there is a delay or significant reduction in the measured voltage to pin it down.
Bill
Burnt contacts are very common in the C5. Heres a post that details a very easy self DYI Fix: C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
Let us know what you find. You can measure the ignition powered fuse to ground and see if there is a delay or significant reduction in the measured voltage to pin it down.
Bill
Last edited by Bill Curlee; Jan 9, 2013 at 05:57 PM.
