I have an 86 Iroc with the 305 TPI. Recently it just shut off on me while driving, It turns out it hydrolocked.

The engine was flooded with gas. It doesn't turn on at all, it just makes a clank sound sometimes. So I removed the plugs and turned it over and it pushed out a lot of gas.

Then I put everything back up, added some gas and what do you know, it hydrolocked again. Although, it did crank a little.

So I'm in a budget and am trying to figure out exactly what it could be. Don't want to buy what i don't need. Thanks in advance.

 

Do you have spark? Looks like injectors are giving gas. On the other hand, have you checked fuel pressure. Check your bleed down. Injectors should hold pressure after shutoff. I'm sure someone with a TPI will chime in shortly.

 

I have spark, but no tools to check the other stuff.

 

Cheap way to see if fuel pressure is holding - WEAR EYE PROTECTION - Prime the fuel pump. Find the fuel pressure nipple on the fuel rail and depress the needle. If it sprays out, you have pressure, if not, and you have your original injectors, they may be leaking into your cylinders. Be careful, you may be looking at 40+psi at the rail.

 

Is it one cylinder or all cylinders that are filling with fuel? After you check for spark, if it's one cylinder look into the injector being stuck open. If it is all cylinders, take a test light and check if the injector harness is getting power and ground anytime the key is on. the injectors should have power anytime the key is in the on position. The ECM sends the ground. If the ground side is ALWAYS grounded, look into a damaged wire (exposing it to a ground, pinched or something of the like) or a bad ECM. If it's all cylinders getting too much fuel AND the injector harness doesn't have constant ground, it's probably the fuel regulator, or the outside chance of all injectors sticking.

 

It pushed gas through two or three cylinders on the passenger side. I disconnected the injector connectors and checked them with the key on and both pins on all injectors lit power, but i got clicks from the 4 injector cables on the driver side.

 

With the injector harness unplugged, do the three injectors still pour gas into the engine? Probably leaking injectors. JMO.

 

How do i unplug the harness? Or do you mean the injector connector that connects to the injector?

 

Inclined to agree with bigal, probably those passenger side injectors. Good chance if they're originals they're all about had it. If you change one, change them all.

 

They could be the originals since my car has 94k original miles, but if it matters it all happened after i got my cat removed for a straight pipe.

 

The exhaust shouldn't make any difference unless they damaged some wiring in the process. The cat is a long ways away from any wiring so I think you're safe.

 

You say you have spark. Did you test using a spark plug? Or did you actually test KV capacity. Just because spark will jump a plug gap sitting in open air doesn't mean it will fire in a wet cylinder. A no special tools method for testing KV is to insert a 1/4" phillips screwdriver into the plug end of a wire and hold the screwdriver 1" away from a solid engine ground while you have a helper crank the engine. You should get a blue snapping arc. If the spark won't jump at least 3/4" gap, you need to look at cap and rotor, plug wires. Can't remember if 86 is still large cap internal coil HEI. If so, pull the cap and look for damage or deterioration.

If the KV tests okay one hole, try another hole. Test KV on the holes that flooded with fuel the quickest. If KV checks out, remove the 2 injector fuses from the IP fuse panel and spark plugs from all cylinders. Disconnect the power lead to the coil, or HEI cap. Crank the engine and/or let it sit for a while to let the cylinders dry out.

Prime the pump as needed so that you pressurize the system for at about 1 minute. Now have a helper crank the engine and look for fuel spray from any plug holes. You may need to play with this for a minute to be sure but any fuel in any cylinder during this test is a leaking injector.

 

They were all wet when I took them out. Thinking about just replacing all the injectors, but need to know if I'll need to replace the ECM or fuel regulator. Car is currently sitting with no plugs and distributor disconnected.

 

I don't think he did. I was watching him most of the time. He just cut the cat and installed a pipe. He said made a small hole on either the pipe or something else to prevent the engine light from turning on.

 

The injectors are most certainly due to be replaced, even if they aren't the main cause of this problem. For a quick test of the ECM's injector driver, you can use a noid light or a 12 volt test light. Use a paper clip in the ground clamp of the light to touch one terminal and the tip of the light to touch the other while a helper cranks the engine. The light needs to flash. Be sure to check the regulator for fuel coming from the vacuum port with the system under pressure.

I don't know what someone might have "made a hole in" to keep the CEL from turning on. Sounds a little scary to me. The 86 doesn't do a catalyst self test and shouldn't set any fault code for having the cat removed. The 86 doesn't even have a code for the catalyst. No cat causes a very small increase in air flow, which will effect fuel trims, but not enough to set a code.

Honestly, while we might think we get some improved performance having the cat removed, mostly because of the change in exhaust tone, unless the cat was restricted, the actual power increase on a stock engine is negligible. David Vizard in his Exhaust Science Demystified article explains how a large high flow cat can actually serve as a pressure wave termination box and increase power in the upper rpm range.

The main reason we may want to delete the catalyst on any high performance car is if the engine build includes an aggressive cam that increases exhaust emissions and might overheat or otherwise plug up the catalyst.

 

Not sure if it's the same, but earlier I had all the injector connectors disconnected and I had the key on and tested the two pins o each connector and they all lit.

 

OP, make sure you're doing like this. That'll tell you for sure if you need more than injectors.

 

Anyway one of you Can provide pictures of how and where exactly to do this? I'm new to all this still learning.

 

Here's a tutorial.

You can do this exact same thing with just a test light. The clamp of the test light you'll need to touch one of the pins in the harness. That's hard to do without a paper clip or something thin and small. The test light probe will need to touch the other pin in the injector harness. Then crank. The test light should flash.


Since TPI is batch fire injection you will not need to test each injector plug individually.

 

My car hasn't started since it turned off, could I still do it by just turning it over without the spark plugs and distributor disconnected?

 

Doesn't need to run. Just needs to crank. The distributor will need the module wires hooked up (that's what tells the ecm the crank is turning) but the spark plug wires aren't needed.

 

Ok so I'll hook the distributor up. So i just stick the paper clip on the injector connector one end touching each pin. Then with the tester light i touch the paper clip and have someone crank the car?

 

The paper clip needs to touch ONE injector harness pin. DO NOT TOUCH BOTH WITH THE PAPER CLIP. Bite the paper clip with the test light clamp. The paper clip should now be touching the pin and the clamp of the test light. Then touch the second injector harness pin with the test light probe. Have someone crank the engine. Light should blink.


One pin is a positive, the other is grounded by the ECM. That's the circuit that makes the light turn on.

 

With the key on both pins lit on all eight injector connectors. I just touch them with my test light, but all my driver side injector connectors clicked when i touched them with the test light.

 

That only makes sense if you are grounding the test light at a engine or chassis ground to test the pins. You need to test the injector circuit only so you don't want a chassis ground you want the pin on the injector harness as your ground for your test light. Am I making sense?

 

Ok, so my test light only has one wire which is what locks to a ground. Are you saying to put the ground of the test light on one of the pins and touch the other pin with the test light?

 

I get it now, but does it matter what pin?

 

Now you have it. And no, the test light doesn't care if the electrons are flowing from probe to clamp or clamp to probe. So you can hook it up either way and it'll still work the same.

 

Yes, one pin is the + and one pin is the -. As noted: You don't want to short the two pins together (fry the ECM). Fortunately an incandescent bulb doesn't care if current is flowing left-to-right or right-to-left, just that there is +12v at one side and ground at the other.

Just to recap as stated above, the two injector wires are:
+12v - whenever the ignition key is in RUN and/or CRANK, a constant +12v will be supplied to the positive wire.
Ground - when in CRANK, or in RUN and the ECM senses the engine is running, from the distributor, the negative wire will get grounded in pulses, completing the circuit, and firing the injector.

It might be easier to only test one pin at a time on the injector plug.

A) Find the + wire. Note, it SHOULD be the same side of the plug on each injector connector.

1. turn key to run.
2. attach test light to good GROUND
3. touch each terminal in the plug:
   • One should light up, that is your positive.
   • The other terminal is the circuit to the ECM that you (also) want to test.

B) Find/test the - wire:

1. you will need to CRANK the engine for this test, as the ECM won't fire the injectors when the key is just sitting in RUN.
2. attach test light to +12v battery POSITIVE
3. touch a terminal and CRANK.
4. The positive terminal should NOT light your test light... +12v-to-+12v does not complete a circuit to light the light.
5. Touch the negative terminal...
   • while still in RUN, does the light light? steady? If so, that means the wiring harness is shorted to ground, or your ECM injector driver is fried to ground... Unplug ECM and re-test to identify wiring vs ECM.
   • CRANK the engine, and the light should FLASH.

I suppose it is also possible a torn FPR diaphram is flowing gas into the plenum, shooting across, and flooding at least cylinders 5 & 7.

 

If it matters, my car doesn't turn on at the moment. I grounded my test light and poked both of the pins on each injector connector and they both lit on all 8 connectors.

 

For one contact of each connector, it should. But not both...
If you had ANY of the injectors on a bank still plugged in, the ECM/grounding connector was at a floating voltage... the (very low current) power flowed through a still-plugged-in injector, to the ground wire and had enough voltage potential to trigger your test light.

Try again with all 4 injectors per side unplugged.

 

When I tested it all my injector connectors were disconnected. Not sure if that's how I was supposed to do it, but on one connector I sticked a paper clip through one pin and clamped it with the test light ground. Then with the tip of the test light I touched the other pin. Is that right?

 

That is correct. And the test light lit? On all of them? Test light lit solid, not flashing?

If so, that sounds like a problem... the constant +12v is correct, and it is the ECM on/off grounding that controls injector flow. BUT, if the injectors are always grounded, then they are flowing full blast all the time... hence your flooding/hydro-lock.

Unplug the ECM and test at the injectors again.

• If test light still lights up, then a chaffed/pinched wire is contacting ground.
• If the test light does NOT light, then the ECM drivers are fried, and you need a new ECM.

 

I need to crank with this method correct? Or just key on? And which pin do I touch and which pin do I ground from the two? Left or right?

 

Going back to your original statement, you have 3 injectors leaking. IF, you had a short on the ECM side, ALL your injectors would be spewing fuel, not just 3. When you touched the ground side of the injector connector, on the drivers side with injectors still connected, you completed the circuit to ground through your test light, hence the injectors "clicking". Could you have just 1 ECM driver shorted? I suppose, but then all 4 injectors would be leaking fuel. 1 bad injector could take out the driver so you should at least check that injector with an ohm meter. Should be around 14 ohms. This would be the injector that doesn't pour gas into the engine. If your test light lit when clamped to ground and touching the pins on the injector harness (both pins on each injector), then you are not grounded and the ECM driver circuit should be ok. Connect your test light to +12 volts and probe the injector connectors. You should get NO light on any of the wires, proving there is no short to ground causing your injectors to be open. This is just another more simple way to test for a short using a test light. HTH!


Do this test with key "on", does not need to be cranking. Cranking only required to see if ECM pulses injectors as in MoJoes test above in post 29.

 

Ok so with the key on I'm getting light on one pin and nothing on the other. Which one gets the paper clip and which one gets touched with the test light?

 

Also, when you say 12v do you mean to clamp my test light ground to the negative battery? THEN, with the key on, touch both pins on injector connectors, and they shouldn't lit?

 

Was your test light connected to positive (+12v)? Or to ground?

You need to understand what you are doing, not just poking this and that. You are telling us only half of what you are doing, and we cannot determine what you are doing, therefore what the results mean.

Your test light lights up when you have positive voltage on one side, and ground on the other, to complete the electrical circuit.
+ to + does not have a voltage drop across your test light... no light.
- to - does not have a voltage drop... no light.
+ to an open circuit will not provide a "loop" for the current to flow... no light.
- to an open circuit ... same thing... no light.

You need "+ to -" on a complete circuit to get a light.

All injectors unplugged.
Key to RUN.
Test #1 - light connected to ground. This is to identify the + circuit and make sure it is working.
Test each pin of one injector plug.

• One pin should light (+ pin to ground). This is your + circuit.
• The pin other should not light (- pin to ground or open circuit to ground). This is your - circuit.

Test #2 - switch your test light to + side of the battery... now we are trying to find if the - circuit is grounded or open.
Test each pin of the same injector plug.

• The pin that lit last time, should now NOT light... + to + does not light up.
• The other pin is the ECM/ground pin. Does it light?
  • No - that is good. The wiring/ECM is not grounding the wire. The ECM grounds in pulses when triggering the injector.... which is does NOT do when in the key is in the RUN position while the engine is not turning.
  • Yes - that is bad. Either the harness is shorted to ground somewhere. Or the ECM driver is shorted to ground. If this is the case, we can help you perform other troubleshooting.

Repeat this test for each injector plug. Since this is batch fire, you should get the same results for each injector on the left or right side of the engine.

 

Ground = 0v = negative side of circuit or negative terminate on battery and is abbreviated as "-".

The Positive side of a typical car battery is +12v. So those terms are used in place of each other... positive side of battery = +12v.

Are you using a simple test light?

• If you put the test light clamp on the battery ground, and the tip on the battery positive terminal, it lights up... Right?
• Now, if you put the clamp on the POSITIVE terminal, and the tip on the GROUND terminal, does it also light up?

If so, your light does not tell the difference between +- and -+. This is called polarity. Some test devices are polarity sensitive, and will give different results if hooked up forwards or backwards.

 

Ok, I did test 1 and test 2 and it checked out perfectly. So does that mean my ECM is good?

 

MoJoe makes a good point. There is a lot of confusion which needs to be cleared up. If you follow the test outlined above, by MoJoe, and have questions about the procedure, ask but do not start probing wires and saying this lights but that doesn't. It just adds to the confusion as do too many voices telling you what to do. So, with that said, MoJoe has a good handle on this and is very good at explaining the procedures. I would follow his suggestions very carefully and you will get this figured out. Again, follow the procedure as outlined and ask questions about the procedure if need be. Post results only when you are satisfied with your testing procedure, repeating it if necessary. GL!

 

I agree. He's very knowledgeable, but obviously I'm not and I sometimes get confused with certain words you guys use. I don't know much about cars, but that last message he posted was i understand it 100%. I apologize for my lack of knowledge.

 

No problem, we all had to learn at some point. I was alluding to the confusion of multiple responses (mine included). That is why I stated you should follow one persons responses and gave the go ahead to MoJoe, he is very knowledgeable and explained things very well. GL!

 

Well luckily i understanded his last message. So test 1 and test 2 came out great.

 

So does that leave my ECM out of the picture?

 

I guess I'll answer this one. Yes, your ECM appears to be OK. Your focus should be on the injectors. Unfortunately, there is no real way to test them without the proper equipment. That is why it was stressed that you perform the above test to eliminate a short or your ECM as the problem. Satisfied that you don't have a short or the ECM is not causing your problem, you should get a new set of injectors. Southbay is a sponsor here and has great reviews from all that have used their services. HTH!

 

Thank you. What about the fuel pressure regulator? I'm currently removing the intake, but any idea how many screws this thing has in total? I already took out 14 and I'm still having trouble removing the pletum or whatever it's called.

 

When you removed the vacuum line from the fuel pressure regulator, did it have gas in it? If no, then it is probably ok. If there is gas in the vacuum line then your fuel pressure regulator diaphragm is punctured and needs to be replaced.
Why are you removing the plenum? To pull the injectors, you need only unbolt the fuel rails. If you need to pull the plenum off, the gaskets will be stuck and make it hard to remove. Loosen the runners at the manifold base. Once the bolts are loose at the manifold and the bolts are all removed from the plenum, you should be able to push the top of the runners away from the plenum and allow the gaskets to break loose. This will allow you to remove the plenum. Once you remove the plenum, you will need to clean all the mating surfaces and install new gaskets. Again, why are you removing the plenum?

 

Don't you have to remove it to get to the regulator and to replace injectors? I already got it out though.

 

Yep, you're right. I am used to a HSR which has the fuel rails on the out sides of the runners and can be removed separately. How is the fuel pressure regulator? Was there any gas in it?