ChevyFreek

ok i have the 2.8, it has spark, air but no fuel. so i went and replaced the fuel pump, now i know i have a good fuel pump. car still wont start but when i quit turning over the motor i get a hissing sound from the top under the intake where the fuel injectors are. now i am wondering if their is a way to clean them or test them or do i have to replace them all?

sofakingdom

iTrader: (1)

Shoot some starting fluid into the plenum and see if it starts.

If it does, you might have a fuel system problem. If not, it's something else.

Do some troubleshooting; stay out of "maybe it's this maybe it's that" hell, and be LOGICAL. Costs a whole lot less that way.

OrangeBird

iTrader: (1)

I would think it highly unlikely that all six injectors went bad all at once , and the hissing gives me an idea of something I'd check . If the starting fluid doesn't make it start for a few seconds , and your sure you've got a good spark at the right time , the cat may be so clogged as to keep it from running .

I have seen in the past , where a clogged cat gave the exact same symptom , the hissing being the release of pressure in the exhaust system after you stop cranking the engine . Since the pressure can't flow out the normal way (through the exhaust system) it bleeds off by pushing back through the engine when ya let go of the key , and can be heard escaping the engine from the vacinity of the intake manifold .

Were it mine , after I had checked the spark and fuel delivery and made certain they are proper , I'd disconnect the exhaust system from the cat and see if it starts . And for god's sake , As the other guy in this thread has said , DON'T buy and replace any more parts till ya do a proper diagnosis of why it wont run ! You could run up quite a parts bill by changing components till it starts !

Any monkey can slap new parts in till they get lucky and and runs . A real mechanic will do specific checks and tests to diagnose exactly which part has failed , and change only the failed part ! , , , , Now , since I know your a smart guy (just by the fact that you came here to ask) , get out there and make certain of what it is that's keeping your engine from starting , and then go replace that part .....

ChevyFreek

Well, me and my father have been, thats how we figured it was the pump, but its not. it wont start off of starting fluid, or hasn't lately, it did back fire one after i put the new pump in tho. after turning the motor over and pulling the plugs their is no fuel on them at all quite dry, thats what leads us to think its injectors, any way i can test them?

ChevyFreek

so that hissing sound happens when i turn on the key to cycle the pump and also a clicking sound is coming from that area, sounds like fast repetitive clicks, i hope this will help anybody that can help.

ASE doc

The clicking is most likely your IAC valve positioning itself and it's perfectly normal. The way I test injectors is first to test the control circuit. Do this using a noid light. You can buy noids at the local parts store. Find the one for Bosch injectors(the one that plugs into your injector connector). Unfortunately, to test for signal at the injectors on a 2.8, you pretty much need to remove the upper intake. You can test at the injector harness connector but you really need a lab scope to determine whether the signal pattern is okay. The noid light will simply flash if the control signal is okay. Test at least one injector on each bank since they are controlled by two separate drivers. If you get no signal, suspect the crank reference circuit from the ignition module to the ECM.

You can roughly test the crank reference signal with a DVOM. It is a 5V square wave (on/off) signal and will look like 2.5 volts on a DVOM while cranking.

Also, I see no mention of a fuel pressure test. Have you verified that your new fuel pump is actually working? You may have a fuel pump control circuit issue.

ChevyFreek

ok well i do know that its putting out fuel cause i forgot to tighten the line all the way so fuel kinda sprayed, lol. could it be my line is pluged or something, its been dow for almost 3 weeks and iam very tired of bumming rides but ill look into what you said, thank you ASE DOC.

TwinTurboROC

That sounds like a ICM in the distributor. No spark (didnt start with starting fluid) and no fuel on the plugs.

Check your fuses first.

Check to see if you have spark. Either with a spark tester.
- or if you don't have a tester take a spark plug out of the head, plug it into the spark plug wire and place it on the valve cover. Have someone crank the car and look at the spark plug to see if you see a spark. DO NOT TOUCH IT OR THE MOTOR WHILE YOUR CRANKING.

Check your injector connected. You can backprobe the wires with a DVOM or test light. DVOM prefered.

Turn the key on for this one. This test is done at the injector harness with it connected. It is ok to slightly pierce the injector wire with the tip of the probe or test light. Be carefull and dont poke yourself in the finger.

Connect the test light to Negative or ground. Next probe the black/pink(one side of the motors injectors) or the black/light green wire(the opposite side injectors). Your looking for 12 volts (battery voltage really) or the test light to turn on. Next test the wires on the opposite bank. Those are the power feeds.

After that take your test light and connect it to the POSITIVE batt side and then while someone is cranking the car probe black wire on one side (the other side is black/white) of the block with the test light or DVOM. You should see a signal as your cranking.

Just some quick test to avoid going in the wrong direction. Stay calm and dont panic.

ALSO
Did you disconnect the lines by the wheel to access the fuel pump? And if so did you make sure to connect them back the right way. Ive seen people goof the feed and return lines so your car is trying to feed fuel backwards.

ChevyFreek

well i tested it for spark, with a screw driver and grounding it. Iam very positive i put the lines back properly cause i took pics for a reference and they're all different size lines so it was easy to match back up. i am planning on going to the parts store tomorrow and getting the testing equipment so hopefully i can get her back on the road. Sorry for picnicking, just really frustrated haven't had a problem i haven't been able to fix fairly quickly until this, the days are nice and i would love to drive with the t-tops off soon.

ASE doc

I think is very likely that, as Twin Turbo is saying, it is your ICM. I have seen several cases where the digital converter/amplifier in the ICM failed, dropping the crank ref signal to the ECM. The coil will still fire since it's charged by the analog signal from the ICM. Follow Twin turbo's advice and verify injector pulse. If you have no injector pulse, then look at the crank reference pulse from the ICM. One quick test I have used in the past is to first disconnect the 4 wire connector from the distributor. I don't know for sure which distributor you have, but I'm assuming it's the same small cap, external coil design used on the V8s, just with only 6 plug wires. With the key on, use a 12v test light, connected to Batt+ to quickly tap the purple/white wire of the connector. If the ECM and injector circuits are okay, you hear the injectors click. The fuel pump will also activate for a second or two. DO NOT do this more than a few times and DO NOT hold the power to this circuit for more than a 1/2 second tap. You will fry the ECM.

I have used this test in the past for a quick verification that the ECM was getting power and that the injector drivers were okay. If this test gives positive results and you have spark, you are good to replace the ICM.

ChevyFreek

Tonight i found out why i had no fuel, my lines were vapored locked. that and when i brought it to TDC the rotor was pointing at plug 6, next day or two i will be picking up a new timing chain and putting that on. Thank you everybody for your help knowledge and advice!

TwinTurboROC

ok so now your sure you have fuel pressure? and injector pulse? What about the timing chain? is it streched? is it broken?

ASE doc

Hold the phone! You know that on a small block chevy, which is a four stroke engine, #1 TDC only comes every other rotation of the crank. On the rotation in between, #6 is at TDC. I'm thinking you just have the engine at #6 TDC. Please verify compression/no compression before you tear down the engine for nothing.

joelsnorton

Bump, quick bookmark thanks.