So I had a #2 cyl. misfire problem with my '97 Blazer. I checked the obvious - the plug wires were switched and checked: still misfire; spark plugs checked for spark and #2 changed: still misfire; new distributer cap and rotor: still misfire. I have just replaced the fuel pressure regulator about 3 weeks ago and the fuel pump about 2 weeks ago. When looking at the #2 spark plug, it was somewhat dry ... leads me to think an injector problem.
Spark - check!
Air - check!
Fuel - I think is the problem.

The procedure seems easy enough. But are the parts going to be costly????

 

The updated MFI spider will cost you atleast $250. I have a really good relationship with the dealership close to me and was able to get it at GM cost plus delivery. Most places online sell the MFI spider for $300+. If you have an AC Delco retailer in your area (search on ACDelco.com), then you can probably pick it up cheaper than what an uncooperative dealer would charge.

I would recommend would be to run a few tanks of injector cleaner through it. I use Chevron w/ Techron injector cleaner on a routine basis on my vehicles and have had great results with it on other vehicles that came to me with problems. If that doesn't work, then you may try a professional injector cleaning. Also, with the appropriate scantool (tech2 or equivalent), you can run an injector flow test to determine if an injector is hanging open or not opening properly, but not everyone has access to such tools.

 

i replaced my spider on my 97 a few weeks ago. What a difference. I was losing fuel pressure and hard starting.. Anyways, if you decide to do the job these are the part numbers you will need. go to gmpartsdirect.com and you will get the best prices i think. Here's the part numbers:
12568332 - MFI Assembly
88894355 - Bracket
17113215 - Seal kit

THe whole job took less than 2 hours and was pretty straight forward. Just remove some coolantbecause i took off the upper hose assembly to gain more access. While i was there i replaced the thermostat. Coolant was seeping into the itake becasue i didnt drain some. Good luck.

 

The bracket and seal kit are unnecessary.

 

Well i disagree with that. You need new seals. You can get them at a local autostore but that is a must for a proper conversion. THe bracket is also a must since its a different design than the oem in 97. Take a look at the service bulletin.
http://members.shaw.ca/betterthanyou...g%20Poppet.htm

 

Well, maybe the bracket is different for a '97 which in this case is pertinent. For any '98+, the bracket does not have to be changed regardless of what the TSB states.

When I did the conversion to my old 2000, I didn't need anything additional beyond the MFI spider. I purchased the bracket mentioned in the TSB and compared it with the one in my engine. They were the same dimensionally and as such, I left the original installed. The new spider comes with all of the o-rings, spacers, and washers already installed. The upper plenum is an o-ring seal which doesn't require replacement when serviced so I still do notthink you need to purchase the whole seal kit (which services ALL o-rings in the spider for both v8/v6 and SCFI/MFI).

*EDIT* - I would like anyone with a '96-'97 SCFI motor doing this conversion to compare the spider bracket with the supposed updated version. I still do not think they changed anything other than the part number...

 

So then my next question would be - would it be more benefitial to replace ONE injector? Or the whole spider assembly?

 

If you only have one failing injector, it is cheaper, parts wise, to replace one injector. A single SCFI injector is in the realm of $80 last I checked.

Problem is, the work to get to that one injector is not a whole lot different than all out replacing the whole spider. Couple that with the fact that all of the injectors have seen the same conditions over their life and make an assumption on how long the rest will last and you can quickly justify replacing the whole spider.

There are other factors at play that sway me further into replacing the spider assembly as well.

But try a professional injector cleaning as described by the TSB posted above first and foremost. That should be done before thinking of replacing the injectors.

 

Thanks!

I will try the cleaner first. If that doesn't seem to work, I will go with the spider assembly.