Hard Cold Start C4
Safety Car
Joined: Jul 2004
Posts: 3,845
Likes: 30
Originally Posted by 89C4
Had the same problems with my 89 about 2 years ago; went through the same things that your are doing now.
The problem turned out to be the ECM, it was converting the temp sensor signal higher that what it should have been thus disabling the "rich" injector pulse width needed to start a cold engine. The fact that you can get it started with a shot of starting fluid ( I did that too) makes it a reasonable conclusion.
Also, my idling was screwed up when I did get it started, and, my coolant fan would come on way too early, like 125 degrees.
After I replaced the ECM, all the hard start, idling, and fan come-on problems went away. The car ran like new.
I had the original 165 ECM and when I bought the new one it was already upgraded twice to part number 88999194. I paid $103 for the new one.
BTW, like SunCr said, you will need a scan tool of some sort to read the temp sensor output; I used WinALDL software with my laptop.
Hope this helps; I know what you are going thru: Been there, Done that.
The problem turned out to be the ECM, it was converting the temp sensor signal higher that what it should have been thus disabling the "rich" injector pulse width needed to start a cold engine. The fact that you can get it started with a shot of starting fluid ( I did that too) makes it a reasonable conclusion.
Also, my idling was screwed up when I did get it started, and, my coolant fan would come on way too early, like 125 degrees.
After I replaced the ECM, all the hard start, idling, and fan come-on problems went away. The car ran like new.
I had the original 165 ECM and when I bought the new one it was already upgraded twice to part number 88999194. I paid $103 for the new one.
BTW, like SunCr said, you will need a scan tool of some sort to read the temp sensor output; I used WinALDL software with my laptop.
Hope this helps; I know what you are going thru: Been there, Done that.
***oops, i tagged this on to the wrong post! oh well..(this is an 88)!
Last edited by Da Mail Man; Nov 25, 2006 at 02:26 PM.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
1990 doesn't have a CSV. Seems like you've replaced the pump etc. But with the pressure dropping off quickly you've either got a bad fuel pressure regulator or leaky injector(s). Above posts tell how to determine which. Good luck.
Advanced
Joined: Nov 2005
Posts: 54
Likes: 1
From: San Jose California
Originally Posted by jsmykl
HELP. I have a 1990 vette that I am having trouble figuring out why it will not start after sitting over night. Had it to 2 different Cheverolet dealers and they have not been able to fix it. I personally have changed the plugs, distributer cap & rotor and engine coolant temperature switch. The first dealership stated I had low fuel pressure 42 lbs, but it dropped of quickly when the pump shut off. I changed the fuel pump, pulsater, sock and and fuel filter. Still no luck, same symptoms. The second dealership stated the pressure was still low, asked what kind of pump was installed. I had bought a pump from auto zone, Bosh. The said that was the problem. Took out the bosh and I installed an AC Delco, bought from the dealership and did away with the pulsator. Still same problem. The ejectors have been tested and they tested good. Car runs perfect after starting and starts great when warmed up. The car starts imediately when cold if I give it a squirt of starting fluid so I am assuming it is fuel related, maybe bad pressure regulator?? Has any one run into this problem and been able to solve it. Thanks for any input.
...not sure whom this is directed at but, believe it is a previous poster. i have substituted 2 ecms and conditions remain the same. this morning i ran an auto x-ray on the car and the coolant sensor was approx that of the ambient air temp...i myself have replaced and checked both the old and new csv and it apprears to be working fine. i have voltage going to it while cranking cold. starting at cold temps is easy on most days but even after having reached operating temp after riding around all day, restarting requires the pedal to be held to the floor for a faster start-up.
***oops, i tagged this on to the wrong post! oh well..(this is an 88)!
***oops, i tagged this on to the wrong post! oh well..(this is an 88)!
Which one is it, it makes a difference.
Safety Car
Joined: Jul 2004
Posts: 3,845
Likes: 30
Originally Posted by VetBoy89II
Your orignal post stated it was a '90, now your last post states it's an '88 Which one is it, it makes a difference.
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