How do I test my injectors?

[mrweelr]

I'm still getting knock retard with 100 octane in the tank and I'm thinking it's either the early MEMCAL or my injectors are not flowing right. Is there any way to test the injectors while they're in the truck? If I remember correctly, the process involves checking the resistance of each injector with a voltmeter. The #1 injector is also making a pronounced ticking sound that varies with engine RPM. I already ran two bottles of RedLine injector cleaner through the truck and it didn't help reduce knock. The plugs look normal as well.

_________________
Jeremy
GMC Syclone #434
Yamaha R1 #1525

<font size=-1>[ This Message was edited by: mrweelr on 2002-02-10 23:48 ]</font>

 

[jwaller]

you cant really test them in the truck....resistance testing only shows you a small part of the puzzle....pull them and have them flow tested, matched and cleaned.....its the only way to go....should cost about 100 bones

 

[mrweelr]

OK, thanks. How much are brand new injectors from GM? What about the 50 lb. injectors from AR autosports? The reason I ask is because I'm planning on going with an ultimate chip and PTE 52 turbo setup soon so I'd hate to waste the money if I should just upgrade them anyway. What do you suggest?

 

[Tooky]

Jeez Jeremy I really hope you figure this one out because I have the EXACT same problems and symptoms as you.. I ran 100 octane and I still got knock so I feel my injectors are possibly the source as well. I haven't gotten around to having them tested yet tho. :sad:

 

[Falco]

There is an other way to test them in the truck. You should use an injector tester to switch on an injector to a precise amount of time and check the pressure drop on the fuel rail. If you do this for all the injectors, you can compare the results.

Anyway, the injector tester around $50 if I'm right, so maybe pull them out and do what John said is the way to go.

HTH,

 

[RAACCR]

If you need good set of stock injectors, Ive got some with only 9k miles on 'em. Let me know.
Rob
syclonerob@prodigy.net

 

[Blake]

http://www.mytoolstore.com/toolaid/diagn02.html#37500
Here's how you check to see if one or two are lean. Hook this up to the injector, put on your fuel pressure guage at the rail, have this device pulse each injector for a specific time and record the pressure drop for each injector. Compare all 6 and it will tell which one(s) are clogged(not as much pressure drop as the rest) or sticking open longer than it should be(too much of a pressure drop)
Blake
I'm buying one of these myself

<font size=-1>[ This Message was edited by: Blake on 2002-02-14 15:45 ]</font>

 

[Blake]

http://www.mightyap.com/Data/OTL1298.pdf
Here's another link (pdf) that tells when you should replace. It suggests that if it is a lean injector, clean it. If it is rich, replace it. 3 psi difference between injectors is normal.
Blake
Hope it helps and saves some money maybe

<font size=-1>[ This Message was edited by: Blake on 2002-02-14 21:23 ]</font>

 

[JoeLutz]

On 2002-02-14 15:26, Blake wrote:
http://www.mytoolstore.com/toolaid/diagn02.html#37500
Here's how you check to see if one or two are lean. Hook this up to the injector, put on your fuel pressure guage at the rail, have this device pulse each injector for a specific time and record the pressure drop for each injector. Compare all 6 and it will tell which one(s) are clogged(not as much pressure drop as the rest) or sticking open longer than it should be(too much of a pressure drop)
Blake
I'm buying one of these myself

I think that may only work with a stock pump that still has the check valve. With an aftermarket pump such as walbro where the valve has been replaced by a rubber hose, the pressure will start leaking down as soon as you turn off the pump. Correct me if I'm wrong.

 

[Blake]

Your thinking of the pulsator. That is the part you throw in the garbage. It leaks under the higher pressures of the walbro. It isn't a checkvalve, it has two chambers surrounded by silicone that absorb the noise of the fuel pump. There is no positive seal with the pulsator. This is what you replace with the short section of hose in the kit. Every in tank pump has a check valve. I have a walbro on my Typhoon, behaves just like a stocker except it can handle higher demand for volume and pressure.
Blake

 

[mrweelr]

Hey Blake, thanks for the tip :smile: I'll order one of those or find someone in my area who already has one. Can someone tell me how much a new set of injectors through http://gmpartsdirect.com is?

 

[JoeLutz]

On 2002-02-14 21:18, Blake wrote:
Your thinking of the pulsator. That is the part you throw in the garbage. It leaks under the higher pressures of the walbro. It isn't a checkvalve, it has two chambers surrounded by silicone that absorb the noise of the fuel pump. There is no positive seal with the pulsator. This is what you replace with the short section of hose in the kit. Every in tank pump has a check valve. I have a walbro on my Typhoon, behaves just like a stocker except it can handle higher demand for volume and pressure.
Blake

Thanks man, for some reason I was thinking the pulsator had a check valve in it.