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Re: 87 GMC Sierra R3500 7.4L TBI vacuum diagram
Quote:
Originally Posted by DieselSJ
Watched your video. Find out what is causing the CEL. Put a jumper between the A & B pins on the OBD connector (I use a bent paper clip) and turn the key to the Run position (do not start). Light will flash code 12 - one flash, short delay, then 2 flashes. It will do that 3x, then it will start giving codes in that same format - series of flashes, short delay, series of flashes, then a longer delay. We need to find out what is causing that immediate light to come on.
Meanwhile, change fuel filter. I found out mine was very sensitive to any restriction at all. That seems to have cleared up with upgrading to the EP381 pumps.
1 - change fuel filter
2 - get codes
3 - fix codes
4 - set timing and minimum idle speed
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I did that and made a video (on you tube) https://youtu.be/gwxRZxo7S5A
6 months ago I changed the fuel filter, intank fuel pumps and sending units (Spectra), and I installed fuel tanks (in excellent conditions)
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1972 GMC Sierra C2500, V8-350
1986 GMC Sierra C2500, V8-454
1986 GMC Sierra C2500, V8-LS1
1986 GMC Sierra K2500, V8-350
1987 GMC Sierra R3500, V8-454
1997 GMC Sierra K2500, V8-454
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