1990 L98 Fuel Injectors

[George D.]

I believe I have a fuel injector going bad on my 90 L98. The symptoms that lead me to this conclusion are rough idling and a miss (no codes were set). When driving in 6th gear at about 60 mph and letting off the gas you can hear a popping (backfire) and a clunking in the transmission due to the dual mass flywheel. I had similar symptoms last year and it was the number 4 injector gone bad.

I checked the OHMS resistance on all 8 injectors and 7 have about 17 ohms and the number 1 has about 10 ohms. I’m not sure this is an adequate test to determine if the injectors are good or bad. However, the one that was replaced last year has an ohm reading of 12. I also checked for vacuum leaks, fuel leaks, broken wires and all appears to be in good condition. I will also check out the fuel pressure to be sure that this isn’t a problem and will pull the plugs to see how they look. I don’t believe it is ignition related since the problem occurred when driving to the national meet.

If any one has any other suggestions for checking the injectors I would like to know what they are, but I don’t want to spend a pile of dough for test equipment.

I am going to do the repair myself, but I don’t have much experience with injector replacement and the service manual is very vague about how to replace the injectors. I plan on replacing all of them and the EGR valve (while I there). Is it necessary to drain the cooling system or can the throttle body be removed from the plenum without disconnecting the coolant lines? Does the fuel rail need to be disconnected from the fuel line or is here enough play in line to get the injectors out once the bolts are removed? Should the fuel rail O-ring be replaced? They are not leaking. Any suggestions to do this repair would be helpful.

Is there a book available that would help with diagnosis and how to replace the injectors?

Thanks

[Joe L.]

Re: 1990 L98 Fuel Injectors

George-----

Are you talking about a GM service manual or some other sort of manual? Usually, the GM manual will be very specific with regard to component replacement.

I do strongly suspect that the injector with the 10 ohm reading is bad. I also agree with your plan to replace all the injectors. You've had 2 go bad. So, the other 6 are probably not too far behind, especially if the car has a lot of miles under its belt.

The injectors you need are GM #17112285, aka Delco #217-292. GM list price is about $166/each. Rock bottom Delco parts system pricing will probably get them for about 1/2 that price.

[George D.]

Re: 1990 L98 Fuel Injectors

Joe,

Thanks for the response. I have the GM service manual with the white cover and it doesn't get into how to check or replace the injectors. It does tell you how to remove the intake manifold, but that would be over kill. Pehaps the red cover one is more detailed in this area. The car has about 85k miles. I have the injector part info. Do you know the part number for the EGR and is it still available from GM. Do you know if I can take the throtlle body off of the plenum without disconnecting the coolant lines.

As always thanks for your help.

Regards,

George

[Joe L.]

Re: 1990 L98 Fuel Injectors

George-----

EGR valve for your application is GM #17113456, aka Delco #214-5535. GM list is about 90 bucks.

I don't know if you actually need to remove the coolant lines in order to remove the throttle body. I've never done this on an L98.

[John S.]

Re: 1990 L98 Fuel Injectors

George; I had the same problem on my 1989 its only got 20K on it. I fisrt replaced a couple of injectors 10 years ago. Then I started having problems about 3 years ago so I replaced them all. I put Excell injectors in the car at the price of about $250.00. The car runs great. john

[John S.]

Re: 1990 L98 Fuel Injectors

George; I forgot to add I did the work myself. I beleive I had to take the coolant lines loose. The injectors that I bought had new O rings. Replacing the injectors is not a snap, but I just took my time, tore it apart one day and put it back together the next. john

[Jim T.]

Re: 1990 L98 Fuel Injectors

George I replaced some O-rings on my 85's injection rail system and did have to disconnect the fuel lines going to the rail. Be careful the lines are more than just slightly tightened. To get to the connections you will have to move the air conditioner compressor to gain access. Be patient, lots to remove to replace the injectors. On my 85 one or two plenum bolts had to be accessed from the opposite side.