Testing Fuel Injectors

My girlfriend has a 1999 (I think) Chevy Malibu. The car's idle has been really bad and it's kind of chugging along. She took it to autozone and did a diagnostic on the error code and they said it's a fuel injector most likely. I read a few posts in here where other people are having that same issue and others have indicated it may be the fuel injectors. I have two questions.....

1. How do you go about testing the fuel injectors? Is there any web site that has instructions or has anyone done it before?

2. For all of those people that have had the bad idle on the Malibu, what has is turned out to be?

Thanks for the help
-Frank

When my intake gasket died on me I was getting a cylinder 2 misfire code ....can't remember the number off the top of my head. If you haven't had the gasket changed this may be your problem. Look for antifreeze leaks on the block and under the car. In my case, oil was also dumping into the coolant.

One way to test the injectors (electrically anyway, don't know how to test for actual flow) is to take an ohm meter on each injector (make sure you disconnect your battery and connectors to injectors first). They should all read about the same resistance...not sure the spec on these but I know my old Caravan read about 4.8 ohms on each injector.

I need to test injectors and am pleased that you covered most of my current ????? ex: disconnect battery & connectors first....I hope that you might tell me the next step to test. I must get this done ASAP Thanks....I have 87 ply voyager w/160K miles 3.0ltr.


One way to test the injectors (electrically anyway, don't know how to test for actual flow) is to take an ohm meter on each injector (make sure you disconnect your battery and connectors to injectors first). They should all read about the same resistance...not sure the spec on these but I know my old Caravan read about 4.8 ohms on each injector.

1) Disconnect battery.
2) Disconnect all electrical connectors to all injectors.
3) Set your ohm meter to the 10 ohm range
4) Measure the resistance across the 2 terminals on each injector and record your readings. All the readings should be close to each other. For instance, mine read 4.8, 4.8, 4.7 and 4.8.

That is definitely doable. I was close by guess....I took one off at a time & took reading, this is most helpful. What happens if the readings are off? What is the next step?



1) Disconnect battery.
2) Disconnect all electrical connectors to all injectors.
3) Set your ohm meter to the 10 ohm range
4) Measure the resistance across the 2 terminals on each injector and record your readings. All the readings should be close to each other. For instance, mine read 4.8, 4.8, 4.7 and 4.8.

Test done. Results:
inj 1 .015
inj 2 .015
inj 3 .015
inj 4 .015
inj 5 .004
inj 6 .015

injector 5 is the one that was replaced because fuel was not dripping but running out. What would next step be. My Chilton's manual has not been helpful in dealing with this matter.


That is definitely doable. I was close by guess....I took one off at a time & took reading, this is most helpful. What happens if the readings are off? What is the next step?

Okay I pulled an injector from #5 position from fuel rail picked up. The person that installed injector for me did not use one in same position as the one that had gone bad. Does that matter?

[I got that idea from someone's post the other day]. Anyway, that injector is testing at .015, the same as others. Can I assume it safe to install and check this out? Also, how are these cleaned?

[at this point I should be making lasagna & baking cake, but noooooo]







Test done. Results:
inj 1 .015
inj 2 .015
inj 3 .015
inj 4 .015
inj 5 .004
inj 6 .015

injector 5 is the one that was replaced because fuel was not dripping but running out. What would next step be. My Chilton's manual has not been helpful in dealing with this matter.

As long as it tests the same, it should be ok but your readings don't seem right. That is far too low of a resistance. Are you sure you've got it set to read resistance and not voltage?

There are only 2 ways to clean injectors...with a kit (like the dealer would) which costs about $150 or throw in a can of fuel injector cleaner. I prefer one called SeaFoam...works wonders.

where would I find SeaFoam?
Also I put another inj in and it will run longer but is kicking off at very high rpms. and I'll check vaccum lines but don't know why else this would happen.



As long as it tests the same, it should be ok but your readings don't seem right. That is far too low of a resistance. Are you sure you've got it set to read resistance and not voltage?

There are only 2 ways to clean injectors...with a kit (like the dealer would) which costs about $150 or throw in a can of fuel injector cleaner. I prefer one called SeaFoam...works wonders.

[sorry I was up until 5a and will have to leave shortly, for a couple hrs, then I can look at it.....if you could give some suggestions....I took digital photos where putting it back together to pay particular attention to getting it all back correctly

Oh! and meter was set to read ohms....it was set to 4k

As long as it tests the same, it should be ok but your readings don't seem right. That is far too low of a resistance. Are you sure you've got it set to read resistance and not voltage?

There are only 2 ways to clean injectors...with a kit (like the dealer would) which costs about $150 or throw in a can of fuel injector cleaner. I prefer one called SeaFoam...works wonders.

I buy it from my local Napa store, but it looks like it's available several places: http://www.seafoamsales.com/buy.htm