1990 Chevrolet Van idle fluctuation

Tiny
RDEVINO
  • MEMBER
  • 1990 CHEVROLET VAN
  • 4.3L
  • 6 CYL
  • 2WD
  • 160 MILES
Https://youtu.be/j4oTQO_QJlw

That address is a youtube vidoe of the engine running or not running i should say. Went to the store Tuesday mornig and when I cam out the car didn't want to run. I was able to limp it home by tapping the gass a little very often . got home going about 10 miles an hour if that. Wel it sounded like a vacuum problem so a long story short. I have done the following already.
Redid the intake manifold.
Rebuilt the throttle body and put brand new injectors on.
replaced the following parts.
Idle Air Control Valve
Distributor
Throttle Position Sensor
Engine Temp. Sensor
cap and rotor
I have checked the EGR valve it seems to be all good and it's only six months old


Symptom is it will start. But it labors to stay running. It fluctuates idle speed maybe even out for a bit but within about minute two at the most it will stall slowly getting more and more inconsistent. You can rev it and it seems to be tight but then you let go of the gas and it bogs down and stalls. Like I said I have rebuilt the throttle body but it still seems like it getting too much gas and the plugs are looking just a bit rich.
Saturday, July 25th, 2015 AT 12:47 PM

7 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuel pressure 9-11 psi if tbi and check for partially clogged egr passages
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Saturday, July 25th, 2015 AT 1:41 PM
Tiny
RDEVINO
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  • 4 POSTS
Already checked the EGR valve. The fuel pump is only a few months old and why would that make it get too much gas if the pump is weak shouldn't it be lean? Do you seriously think the fuel pump is giving to much pressure? Also I already changed the fuel filter.
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Saturday, July 25th, 2015 AT 2:08 PM
Tiny
HMAC300
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Who said anything about it being weak? If you have tbi which most vans did that year then I gave you correct fuel pressure. Maybe fuel pressure regulator is bad.
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Saturday, July 25th, 2015 AT 2:28 PM
Tiny
RDEVINO
  • MEMBER
  • 4 POSTS
Ok replaced the fuel pump. And the idle is consistent now and too high. I have an inline pressure gauge and it says it's getting 15 lbs at the throttle body. I don't have a tach but it sounds at least 500 rpm high. When I retard the timing enough to slow it down it won't accelerate right.
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Saturday, July 25th, 2015 AT 9:00 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Fuel pressure should be what I gave you earlier with 13 psi being max. Check the regulator may be bad or vacuum line disconnected if it has one.
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Sunday, July 26th, 2015 AT 4:00 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Alchck for a blown gasket at base of tbi unit.
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Sunday, July 26th, 2015 AT 4:00 PM
Tiny
RDEVINO
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  • 4 POSTS
It ended up having the wrong gasket for the TBI
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Sunday, July 26th, 2015 AT 4:04 PM

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