99 SUBURBAN FUEL PRESSURE PROBLEMS

  • Tiny
  • NEWT8243
  • 1999 GMC Suburban
  • V8
  • 4WD
  • automatic

I installed a new carter fuel pump in my 99 suburban. Two days later I cant get any fuel pressure built. I unhooked the return and turned the key on/off no fuel came out of the line which leads me to think the pressure relief valve is good. When I installed the new pump it came with a wiring conversion kit. The tails on the new wiring harness were pretty long so I cut them a bit, but I left more slack so I could hook the harness up easier than unhooking it was. Could the extra wire screw with the pump, or was I lucky enough to have just gotten a B.S. Pump? P.S.I is only at 51 +/- 2 lbs.

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Monday, December 6th, 2010 AT 12:15 AM

7 Replies

  • Tiny
  • rasmataz
  • Member

Your fuel pressure is low

4.3L, 5.0L & 5.7L 60-66psi (4.2-4.6)
4.8L, 5.3L, 6.0L & 7.4L 55-62psi (4.0-4

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Monday, December 6th, 2010 AT 12:26 AM
  • Tiny
  • NEWT8243
  • Member

O.K. But, why

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Monday, December 6th, 2010 AT 12:44 AM
  • Tiny
  • hmac300
  • Expert
  • 44,394 posts

You should change the fuel filter if haven't already. Also the harness should be replaced the full length of what was supplied. Make sure to solder the connections and use shrink wrap around them. Don't just crimp them on.

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Monday, December 6th, 2010 AT 1:00 AM
  • Tiny
  • NEWT8243
  • Member

Could the filter (new) cause low pressure?

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Monday, December 6th, 2010 AT 1:16 AM
  • Tiny
  • hmac300
  • Expert
  • 44,394 posts

If it were on backwards a fuel filter could cause that. The pump maynot have gotten on the clip real well also. The wires going to the pump are very fine and they can break if it wasn't put in right.

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Monday, December 6th, 2010 AT 1:29 AM
  • Tiny
  • NEWT8243
  • Member

I forgot to mention it ran for 2 days with some small cutouts then this morning after parking it in the drive just wouldn't start. Got spark.

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Monday, December 6th, 2010 AT 1:39 AM
  • Tiny
  • rasmataz
  • Member

Check the fuel pressure with a fuel pressure gauge and then comback with the readings so that we can further assist in this matter-You need to do some troubleshooting here-you're the eyes and ears here-Let us know

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Monday, December 6th, 2010 AT 4:19 AM

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