Archived injector pump timing

[MRowe]

Help! I am installing a rebuilt injector pump on an 89 5. 9 and I cannot get the tdc pin to engage the cam gear. (I dont think it is broken as I used it last winter when i replaced the head gasket). I used a drop indicator to bring no. 1 cylinder to tdc but the key on the pump is not exactly at 6 o'clock (around 6:35). The truck was running good until the pump started filling the crankcase with fuel. This motor is in my 93 GMC car carrier and is on 24/7 rotation for the state and local police so I cannot afford more downtime than necessary. My question is as long as no. 1 cyl is at tdc will the new pump be in correct time? Thanks MRowe

 

[Sticks]

Is the TDC by the mark on the crank pulley? There are 2 TDC's for #1. Top of the compression, and top of the exhaust.

 

[B.G. Smith]

The pump has to be aligned with the cam gear as you already know, I have a "el cheapo" manual which has some info on the 12 valve. With the pump out you are supposed to be able to remove the timing pin and look through the opening with a small bright flashlight and a mirror and see the hole in the cam gear for easier alignment. Put a new "o" ring on the pin assy. when you re-install. bg

 

[MRowe]

the crank is at the tdc of the compression stroke as both valves are closed

 

[B.G. Smith]

I agree but the pump is timed to the cam gear by using the timing pin. The cam gear is driven by the gear on the crank. Could there be enough wear in the gears to cause the gear to be one tooth off? Maybe the pump is not timed to the crank TDC? I don't know the answer to these questions. If it were me, I would rely on the alignment pin. bg

 

[MRowe]

Thanks, I was reluctant to remone the pump until i was sure it was lined up but after checking the posiltion of the key on the new pump i went ahead and was then able to pull the tdc pin and confirmed that it was in the right postition. Thanks again.

"It's alot of work to make a truck out of a GMC"