89 c-4 very hard to start when cold
06-23-2019, 05:24 PM
#1
5th Gear
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89 c-4 very hard to start when cold
I just picked up my first vette. Pretty excited. So here is my issue. When cold she is very hard to get started. Once started runs rough and even backfire if to much gas peddle. But after couple minutes when warm runs VERY strong. Smells rich from exhaust. It did stumble twice when really hard acceleration. but runs great and quick otherwise. Guy I got from just put fuel pump in. I changed filter and put pressure guage on rail and ran38-40PSI. Any ideas what to check next? Has check engine light on. I have OBII scan tool but cont find a port on car for it.
06-23-2019, 06:56 PM
#2
Melting Slicks
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I just picked up my first vette. Pretty excited. So here is my issue. When cold she is very hard to get started. Once started runs rough and even backfire if to much gas peddle. But after couple minutes when warm runs VERY strong. Smells rich from exhaust. It did stumble twice when really hard acceleration. but runs great and quick otherwise. Guy I got from just put fuel pump in. I changed filter and put pressure guage on rail and ran38-40PSI. Any ideas what to check next? Has check engine light on. I have OBII scan tool but cont find a port on car for it.
Does your car have the original fuel injectors? If so, you may want to focus your attention on them...it is well documented that the Multec fuel injectors are at best problematic....and that's paying them a compliment. If you end up replacing them (and if they are original, you will) I would recommend going with a set of Bosch 3's.
06-23-2019, 07:44 PM
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Team Owner
06-23-2019, 08:06 PM
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Melting Slicks
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1989 is not OBDII, 1989 is OBDI (On Board Diagnostics I / II) OBDI was used in GM cars 1981 through 1996. OBDII came into play in 1997. There is a lot of information on the web that you can read to educate yourself on what each is an all of the differences.
aklim's picture above tells the story on how to identify a Multec injector. GM started installing them in 1989.
06-23-2019, 08:09 PM
#6
Team Owner
Rectangular one is OBD1 and Trapezoidal is OBD2
06-23-2019, 08:16 PM
#8
Team Owner
06-24-2019, 07:02 AM
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Team Owner
06-24-2019, 01:15 PM
#11
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Congrats on your new '89 Vette and welcome to the Forum. Is it a 6-speed manual or auto?
You have OBD1, like my '89. The connector is a little back under the dash pad to the right of the steering wheel.
To pull codes:
-jumper pins A & B, two upper right
-turn key to On, don't start the engine
-count the SES flashes: first three "12"s, followed by each trouble code flashed three times, terminating in three "12"s.
Does fuel pressure hold after you turn Off the Ign?
You might check manifold vacuum at idle.
Pull a spark plug or three and check condition. Also check wire condition.
What's the condition of the motor oil. If dirty change it before wailing on it too hard.
Good luck and enjoy.
You have OBD1, like my '89. The connector is a little back under the dash pad to the right of the steering wheel.
To pull codes:
-jumper pins A & B, two upper right
-turn key to On, don't start the engine
-count the SES flashes: first three "12"s, followed by each trouble code flashed three times, terminating in three "12"s.
Does fuel pressure hold after you turn Off the Ign?
You might check manifold vacuum at idle.
Pull a spark plug or three and check condition. Also check wire condition.
What's the condition of the motor oil. If dirty change it before wailing on it too hard.
Good luck and enjoy.
06-30-2019, 06:34 AM
#13
Melting Slicks
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One of the BEST investments you will make to support your car is to buy a FSM (Factory Service Manual). I can not emphasize enough how important having this manual is. It will take all of the guesswork out of diagnosing problems. Hard starts and engine stumble are covered in the book.
Go to the parts section and post a WTB thread for one. Check ebay. Do whatever you have to do to get one...you'll thank me later!!
Go to the parts section and post a WTB thread for one. Check ebay. Do whatever you have to do to get one...you'll thank me later!!
06-30-2019, 08:40 AM
#14
Team Owner
And next thing is a scanner that can read data and not just codes