I don't think I am getting fuel through my injectors and am trying to check them.

I pulled the connector off the top of an injector and both wires to that plug have 12 volts on them (key on, engine off). Is that right ?

Also, how do you fire the injectors manually, which terminals are power and earth ?.

Hope someone can help me out

Thanks
Rhys

 

Rather check resistance on them. You can#t really "fire" them manually, because they receive power pulses within ms ranges.
If resistance is bad, then you know you won't be receiving the correct amount of fuel.
Check the boards for resistance values.

Another way would be to put the fuel rail into a large container and fturn the ignition key. Then you'd see whether they all have the same spray pattern.
Just be very careful with that. You wouldn't want that spray to ignite!

 

injectors are supplied a constant 12v+ on one lead and the ecm grounds the other side to fire the injector.

do not attempt to ground the injectors manually as u cannot do it fast enough and can overheat/burnout the coil inside the injector

 

Okay. I checked the resistance of all the injectors last night. They were all about 12.6ohm ish, so should all be okay.

I did find one messed up plug. the metal retainer clip was in the wrong place and so I dont think it was clipped on to the injector properly. I fixed that and now it is clipped on properly.

Would one disconnected injector cause none of them to fire ?

I'm hoping that was my problem. Will try starting it when I get home from work today (was too late to try last night)

 

Time to shop for new injectors

 

What?

12.6 ohms is pretty much right on spec for high-Z injectors.

No, if just one is disconnected, it will be just that injector that will not work.

Also, you can manually trigger them, but for very short periods of time. Basically just tap one of the connections very briefly to actuate the injector.

Yes, both sides of the connector will have 12V when there is at least one other injector plugged in, with key on engine off. I've described why several times before, so you can search for that if you really want an explaination why.

The injectors do not have a particular polarity, that is is either terminal could be positive or ground to actuate the injector.

 

Sorry my bad, I thought they were like the multechs

 

If they don't make a clicking sound when they're supposed to be firing they're probably clogged. The easiest visual test is like someone else said to remove the rail from the intake and crank the engine to check if they're spraying.

If the injectors are clogged beyond DIY cleaning you might be able to find a known working used set on here for pretty cheap. I've had people suggest soaking clogged injectors in gasoline or fuel injection cleaner overnight.

 

I have a full set of known working injectors + rails etc on my old engine that I could swap in, so I'm okay for swapping in parts.

Before I go through all the hassle of removing all the injectors, I find it funny that not even one injector is firing (car does not even catch at all).

Couple of questions I hope one of you guys could help me out with:

1. Would the injector still click even if it is clogged and not spraying ?.

2. Is there some way to test there is a ground pulse going to the injectors (with a test light or DVM). Which wire should I check on the injector harness.

Thanks for all your help so far guys.

 

You're positive that your not getting fuel in the cylinders? Hows the fuel pressure look? What do the plugs look like on all the cylinders?

Make sure that fuel pressure is primed really good and not dropping to much while cranking on the start.

If there clogged it common if the car sat for a bit and the gas is turned a tad varnished.

 

There is pressure at the schrader valve, however I dont have a gauge so I don't know how much (enough to shoot it in the air). Fuel Pump primes when I turn the key (also re-primes after cranking)

I pulled a plug after cranking and it was bone dry.
Car does not catch at all, not even slightly.
Engine has been sitting in someones garage for about 10 years after being re-built but he never ran it after he rebuilt it.

I am definately getting spark. Engine started when I shot starter fluid down the throttle body (and stopped as soon as it used up the starter fluid)

I think I am at the point of pulling the fuel rail, however before I did that I wanted to at least make sure there is a signal being sent to pulse the injectors. Once I verify it is not electrical I will pull the rail and swap over to my know running injectors.

Thanks,
Rhys

 

Sounds like clogged injectors for sure. A year ago I swapped an engine that had been sitting for 3 years, and when I went to start it, none of the injectors were firing, even though they all appeared nearly brand new (engine was from an 06). I ended up getting the injectors cleaned but it would have been cheaper to buy another set.

 

So there is a high chance that it is clogged injectors. Funny that it would be all of them.
I'm guessing my cold start could potentially be blocked too and I should change that also.

Before I start pulling parts, does anyone know if there is a way to test the circuit to make sure that they are getting a pulse. I only have a test light and a DVM

 

Im not saying that you dont have enough fuel pressure but can you tell the difference between 25psi and 43 psi when its gas shooting out?

 

Yes , There is a very simple and inexpensive device called a "Noid Light"

You unplug an injector , plug in the noid light in between the injector and the harness , and the noid light should blink while cranking the starter in attempt to start the engine . If the niod light flashes in a good distinct pattern indicating proper injector electrical circuit , well then yea , now you can suspect clogged injectors (provided you have used a pressure gauge to assure proper fuel rail pressure and have viable , not age fouled fuel).

 

If there was only 25 PSI of fuel pressure, would the engine at least catch ?

I will go and buy a noid light and test the injector signal.

Thanks,
Rhys

 

You'd think that an engine would run on 25 PSIG fuel pressure, but it won't.

Really to diagnose this knowing actual pressure would help.

If the plugs are bone dry after cranking, then either the injectors are not firing, meaning electrically not driven or they are clogged.

The fact that the fuel pumps runs while cranking indicates that the ECM is getting DRP signal from ICM, so you don't need to look into that system.

 

its hard to say if the engine would run well atleast idle , when i first put my twin turbo iroc together it would idle but do nothing else, put a fuel presure gauge on it and it had around 16-17 psi of fuel presure


even if it doesnt run it should still sputter like its trying to start ,chances are the injectors arent firing at all

get a noid light and check for the pulse at the injectors if u have one its then u need to test fuel presure and go from there

 

Yes I've even had a car that idled on the CSI for a few seconds when cold. Even with low fuel pressure but injectors firing there should be at the very least popping here and there.

 

You can also back prob the blue or green wire at the six point connector under the throttle body, get an auto ranging dvom with the sliding bar under the voltage reading. Put the red lead and the back probe and the black to ground. Dvom is not as fast as a scope but an auto range can help.it will show 12v once cranking the auto range bar will rise and drop fast indicating ECM driver grounding the injectors.

You can also pull a license plate or turn signal 194 bulb and straighten the pins into legs and stick them in an injector connector to see if it flashes. You only have to check one injector on each bank, each bank is a parallel circuit controlled by the same driver.so 1,3,5 has one driver and 2,4,6 have another driver.

 

Bought a Noid light set, pulled one of the injectors and cranked it. Noid light flashed, not as fast as I thought, sort of flashed like a turn signal. I'm guessing thats right ?.

So I am going to swap fuel rails and injectors out. Off to the garage I go......

 

an led from radioshack and the right resitor should also work as a noidlight

i would think one of the 194 bulbs could fry the injector driver

 

The Noid light sets use a 194 type bulb. They generally draw less current than an injector.

 

really? i always thought they were l.e.d.'s

 

So I swapped the rails, Injectors and cold start injector.

One thing left to do is to turn those funny little clips - any tips on how to turn those back to the locked position ? {edit: On the way to work this morning I figured out why those clips are hard to push back, probably cos I bolted down the rail - will loosen that off and then turn the clips tonight when I get back home}

 

You may be able to borrow a fuel pressure gauge from Advance Auto, Autozone, etc. They loan tools to customer. Probably a good idea to check the fuel pressure even if it runs after installing new/rebuilt injectors. Enjoy the driving experience once you get it running. My V6 Bird is the funniest driving car I've ever owned.

 

Cold start injector? Is this a v6 or a 5.0/5.7 tpi? Or have I over looked a cold start injector on my v6?

 

Because 3.1L dont have one

 

RESOLVED

Yes, it was the injectors. Put my old known running set on my new to me engine and it fired right up.

The non working ones I took out looked clean as a whistle - everything was squeaky clean - rail and everything. Funny that not even one of them fired (the engine just cranked with no popping or anything).

Anyway, runs now. Just gotta put the nose and hood back on the car and time to take it for a test run...... its only been 3 years in bits in the garage.

Thanks everyone for your help

 

Ya my last set of clogged injectors looked brand new still but had just been sitting too long. Glad to hear that you got your car running.

 

Hate to bring this from the dead. but Im looking for the Resistance values in the injectors. Found that 12-13 is good. On our Batch Fired Injector cars. one failed injector can screw them all. As I just replaced ONE injector and it runs like a champ but im changing them all day after tmrw.

I was driving along and it totally died. i decided to unplug one inj. at a time and try cranking it. and Bam i found a dead one.... got it to the shop on 5cyl. and started a tear down.... I noticed the one inj. was at 6 ohms rest at 12.2-12.8 and i wanted to find a spec. sooooooooooo just for future ref. just ohm all the inj's. replace the bad one and think for future ref. to replace them all..........

 

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

 

Its bad practice to replace just one imo. Take the extra time get a good set from south bay for about 100ish. And be done with it.


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How about spraying starter fluid into the intake to see if it starts up faster? This will help pinpoint if its a fuel delivery problem or not.

 

all u guys who use starter fluid i dont think u relize how dangerous it actually is, starter fluid should only be used when absolutly necasary to get an engine started, like for example my dodge intrepid will not start when the temp gets below 10* in the winter, then i would use it , eventually i just stuck a 100 watt halogen work light under the car facing the oil pan at night and it would start up in the morning

 

Explain how its dangerous. the spark could come back up the intake from the cylinders and blow up the can. Ijs.


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It can hurt the internals and even wear the rings/cylinder/piston. you could be spraying mass ether in the car and it will run with a much richer mixture when you try to keep it running, like alky it can wash down the cylinders if too much is going in. I never saw a point in using the stuff. I just have a spray bottle full of gas and use that when I think there is a fueling issue present. And god forbid the car backfires when your trying to keep it running. That stuffs has a larger window for exsplosion limits close to methanol but the lel is much lower then methanol. The UEL of ether is higher then gas. 36% is the UEL. Gasoline...100 octane has a UEL of 7.6%. The LEL is some what close within 1% I like a small window of explosion limits when im trying to start a car that may backfire since im now the fuel injector.

 

I wont even use that stuff on our diesels at the shop. we have cases and cases of the stuff in stock and you would not belive how many people buy that stuff. i used it on a lawn mower once just to see what would happen used half the can and it locked up. Just put gas in a pop bottle and poke a hole in the top and squirt it in. if it back fires and catches the cap on fire at least you can throw it.

 

Thanks for sharing your trick with the soda bottle. It's a keeper.