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F.ound O.n R.oad D.ead
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Discussion Starter · #1 ·
My buddys 89 4.3 tbi has a fuel pressure of 12 psi at idle and when he revvs it to Wot it drops to about 9, and with the return line clamps it stays still at 12 psi. his check valve is gone because with key on and truck off the pressure drops quick. but this does mean he does need a pump right? filter is good.
 

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goin broke but n style
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12,942 Posts
could be pressure regulator in TBI unit is bad.
 

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F.ound O.n R.oad D.ead
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451 Posts
Discussion Starter · #3 ·

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The TBI FPR is not a vacume activated type, AFAIK it trys to maintain a certian pressure no matter what. I would say either the FPR is shot or sticking..... Pump can always be a tad weak also, but you said it stayed 12PSI with return crimped, I would suspect with a strong pump it would have hit 14-15 or so......
 

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F.ound O.n R.oad D.ead
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451 Posts
Discussion Starter · #5 ·
yeah i figured it go up somme but didnt go up a bit and ive tryed 3 known working fpr and it does the same so pump time..again
 

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F.ound O.n R.oad D.ead
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451 Posts
Discussion Starter · #6 ·
one more question, i was replacing my timing chain because for some preventative maintenance and in the process i rotated the crank gear 1/2 a turn i know i cant just rotate it back to the position it was in so any tips on rotating it backwards? ive already removed all spark plugs but it wont budge
 
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