I ordered a CSFI to MPFI conversion spider for my 2000 blazer and ran into a problem installing it.

When I went to insert the injector cups into the injector boss in the intake manifold, they do not slide in at all.

The ID of the injector bosses in my intake manifold measure .525" +/- .002" on all of the holes and the OD of the plastic cup that the injector sits in measures .535" to .536" on all of them. The injector cups are too big to lock into place on my manifold. I am a machinist by trade so I am measuring them correctly.

So this makes me wonder if there is a difference between a MPFI replacement kit and a MPFI upgrade kit? Or maybe the injector bungs in my manifold were machined too small? Or the injector cups on my MPFI conversion kit are just oversized from where they are supposed to be?

Has anyone ran into this problem before?

 

Who makes the new spider you bought? Not that it necessarily makes any difference, but maybe somebody else has experience with that particular brand. I used an AC-Delco one with yellow injector tips, and it fit fine.

 

It is a Motorman kit, so I am unsure of the actual manufacturer.

I am way outside my return period on this, so returning isn't an option. I bought it this summer while the truck still ran okay, so I waited until now to do it when the truck got so bad that it needed to be done.

Is it hard to separate the plastic cups from the injector body? I see places to buy new injector tubes, so is it possible to pull the tubes off the injector body and replace them?

 

I don't know if that's possible or not. I would probably try to contact motorman and ask for a suggestion.

 

use a heat gun to soften the tubes, be careful and not get them to hot. Then pull straight away.