Engine sputters

Tiny
SNYDER69
  • MEMBER
  • 1987 CHEVROLET CELEBRITY
  • 142,000 MILES
The car put out a code of 43. I had replaced the ECm and knock sensor. I was able to zero the code and the engine runs a little smoother but it still has the sputter to it. Did not notice any vacuum leaks and I have new plugs and wires. What else could it be?
Monday, January 17th, 2011 AT 12:16 PM

12 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Your saying you no longer have the code? Use a gage and check fuel pressure.
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Monday, January 17th, 2011 AT 6:45 PM
Tiny
SNYDER69
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  • 7 POSTS
That's correct I no longer have a code. What should the pressure be around 42?
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Monday, January 17th, 2011 AT 6:51 PM
Tiny
JDL
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28--36 psi for mfi.
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Monday, January 17th, 2011 AT 6:58 PM
Tiny
SNYDER69
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If the pressure is below spec would it be the fuel pump would need replacing? Also could it be dirty injectors?
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Monday, January 17th, 2011 AT 7:14 PM
Tiny
JDL
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How about the fuel filter? Don't take any lines loose without being sure there is no pressure on the system. Check the pressure spec first, before worrying about the pump.

You could do a cylinder balance test, engine running, kill cylinders, one at a time, pay attention to the rpm drop when cylinder is killed. If no rpm drop with cylinder that you killed, that cylinder is dead. Could be fuel--spark--compression. For testing, if you kill spark at the cylinder, be quick, so you don't flood anything.
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Monday, January 17th, 2011 AT 7:28 PM
Tiny
SNYDER69
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  • 7 POSTS
I did the cylinder balance test and found 3 and 6 were not working. I checked the spark on both and it wasn't a nice blue like it should be. I am thinking it is a weak coil pack, it happens to run both of those cylinders. I will purchase a new and try that. Thank you very much for your help! Hopefully this is the problem.
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Tuesday, January 18th, 2011 AT 11:54 AM
Tiny
JDL
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Good job, hope that fixes it.
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Tuesday, January 18th, 2011 AT 5:07 PM
Tiny
SNYDER69
  • MEMBER
  • 7 POSTS
I installed the coil pack and it runs like a race car. Now I have another problem. My cooling fan is not turning on. I check my fuses there ok. Is there maybe a resistor that may need replacing? What else do I check?
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Wednesday, January 19th, 2011 AT 12:08 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Use jumper wires from fan to battery, voltage and ground. See if fan will run? You should use an inline fuse on the jumper. If fan still won't run, replace fan motor.

The fan relay location is in the picture. With relay packs, those relays may be all the same? If you think the fan relay might be an issue, swap it out with ac relay, for testing.
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Wednesday, January 19th, 2011 AT 4:34 PM
Tiny
SNYDER69
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Great I will that out and let you know. Thanks!
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Wednesday, January 19th, 2011 AT 5:01 PM
Tiny
SNYDER69
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Run jumper to fan, it works. Switched out the relay fan still does not turn on.
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Thursday, January 20th, 2011 AT 5:09 PM
Tiny
JDL
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On some models if you turn on the ac, the fan will turn on. If you unplug the coolant temp sensor, the fan may run. If you use a jumper wire on the A & B terminals at the data link connector, like your going to check codes, key on, no crank, the fan may run. Anything?

I have seen faulty fans that would run intermittently. Can you check for voltage and ground at the fan connector, when you think it should be running?
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Thursday, January 20th, 2011 AT 5:55 PM

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