JNRSingh

So I have a 91 Camaro z28 305 TPI...recently the car was driving very poorly and I found that 4 fuel injectors were bad so I replaced all 8 with 19lbs Bosch IIIs from South Bay fuel injector co. The car ran alot better but would at times start chugging like a diesel engine and stall out unless I drove with a foot on the brake and the gas pedal. So I looked at the fuel system for issues, and replaced the fuel filter and the fuel line from the filter to the tank was also replaced. I did not find any leaks in the fuel system. After this, the car continued its erratic behavior but at times would behave 100% normal and idle extremely smoothly. To rule out other possibilities of this issue, I changed the rotor, distributor cap, and spark plug wires and I cleaned the existing spark plugs with a small wire brush and re-installed them. I started the car and immediately it started (where before I would need to crank it a few times and floor the gas pedal). It idled high as it should initially then after a minute the idle decreased and the car ran steadily for about 7 mins. Then the engine suddenly stopped, so I quickly turned the car key to the off position. When I tried restarting the car, it would crank strongly but not start, and pressing the gas pedal had absolutely no effect while cranking. When I looked at the exhaust there was alot of powdery carbon dust on the floor, soot that I literally brushed out of my garage with a broom. Also after cranking I hear a metallic tapping sound coming from the engine after the ignition is turned off and I can't find where it is coming from. I removed both valve covers and listened to try n tell if it was valves but could not tell.

Why is the car not even starting now?

To fix the initial "diesel" rough idle behavior I compiled a list of possibilities based on searches from this site:
1. I need a heated o2 sensor as I have shorty headers
2. Vacuum leak (haven't found any)
3. a bad engine temp sensor?
4. A bad ecm
5. a bad ecm fuse (I didn't find any bad fuses by the underside driver area)

Could any of these be the reason the car isn't starting?
Please help

Thanks in advance!

Edwardgp

How old were the plugs that you cleaned and what did they look like when you first took them out? How is the fuel pressure? How old is the fuel pump? Fuel pressure regulator?

JNRSingh

The plugs are about two years old and looked black when removed...none were wet or anything... just coated with carbon all the same way...I do not have a gauge to check fuel pressure...I will try and get one asap....the fuel pump is an edelbrock performance pump that was put in a year ago...I am not sure about the fuel pressure regulator...i have owned the car 7 years and haven't changed it in that time...an ideas what unusual ticking might be?

Thanks!

vetteoz

iTrader: (13)

https://www.thirdgen.org/forums/tech...formation.html



Doing that cuts off the fuel to the engine

https://www.thirdgen.org/forums/tech...s-dumbies.html

A common noise as the lifters bleed down or even as the headers are cooling off

JNRSingh

Hey vetteoz, thanks for the advice, I updated my profile a bit...I could not test for the codes because my check engine light/ses light among other do not work, I don't know why and all my fuses in the fuse area under the steering wheel are fine...the noise could be the lifters, but not the exhaust because the engine is cold and will not start thus the exhaust isn't heating/cooling and pinging...

an update on my unresolved situation:
I had a spare fuel pressure regulator, so I replaced the old one, checked for leaks, didn't have any, but the car would crank but not start...so it is not the fuel pressure regulator...also the old one seemed ok, the diaphragm looked worn so it would have needed replacing soon anyway...I also checked the fuel pump by removing the relay and connecting the orange and gray wire and I heard it hum and heard gas spraying sounds by the engine so it must be pumping...I then checked the relay by switching it with another good relay, but it did not change anything so I think the fuel pump relay is fine...in between cranking the car at one point it started with some difficult with the swapped relay and ran as smoothly as ever and idled solidly...the exhaust was white but that may have been because it is 26 degrees where I am at that time and the exhaust was warm...I turned the car off and tried starting it again but it would not start so i put the old relay back in...

I am yet to get a fuel pressure gauge to test the pressure......

any suggestions so far based on my findings?

vetteoz

iTrader: (13)

is the bulb good ?

Until you confirm the fuel pressure and that the injectors spraying ,not much to go on .............

JNRSingh

I suspect the bulb may be bad...I am not sure how to get to it though....

I think I am loosing fuel pressure based on a simple test...when I remove the gas tank cap after attempting to start the car, there seems to be no pressure in the system as their is no suction sound when removing the cap as there usually is...but I know this is a very poor test without a gauge etc...

I am suspecting the issue is a leaking/stuck open injector...I suspect this because my oil level rose a tiny tiny bit and smells a little like gas...

How could I test for a shorted open injector with a multimeter? What can I do before having to pull the fuel rails off again? I am hoping its an electrical issue, but perhaps some rust from the full line connections got into the line while i was reconnecting them after the injector swap...?

Lynn1990IRocZ

you can check in injectors electrical integrity by unplugging them and using a multimeter set the the resistance setting and checking across the 2 injector terminals, im not 100 percent sure but I think the spec is around 12 ohms but regardless all the injectors should show the same amount of resistance, the only way to know if the injector pintle is stuck open physically is pull the rail with the injectors connected and prime the system and check for leaks

JNRSingh

Ok so here is my progress so far:

Lynn1990IrocZ thanks for your advice, but all my injectors are above 12 ohms. So I pulled the fuel rails with the fuel lines and injectors connected to it and pressurized the fuel system by removing the fuel pump relay and jumping the power wire and powering the fuel pump. I attached a fuel pressure gauge to the schrader valve and with the pump running continuously I had 42 psi fuel pressure. I then removed power from the pump and within 15 seconds the pressured dropped from 44 to 20 then a bit later almost to 0. I had placed rags under the injectors and inspected them, but none were leaking. Thus I do not think there is an issue with my injectors leaking. I then connected back the fuel rail and ran the pump. Here is my pressure data:

44 psi - pump running constantly
drop rapidly from 44 to 20 psi then 0 - pump off
constant pressure/ no drop - fuel supply line clamped shut right after pump is turned off
drop rapidly from 44 to 20 psi then 0 - fuel return line clamped right after pump is offed

Does this mean bad fuel pump check valve? Could I put in an inline check valve so I don't have to drop the tank to get to the fuel pump?

I then changed the ignition control module (the old one's bolts etc were very corroded) for a BWD aftermarket ICM. I then tried to start the car and with some difficulty it started. It started spinning slow then I woke it up with the gas pedal and idled like a champ. A minute later it started to chug like a diesel engine and just stalled. The idle fuel pressure was around a constant 34 psi and when the engine was revved it would flick up a bit then return to running at 34 psi. I can restart the car and keep it running by applying gas but I don't wanna do this and damage my engine and possibly foul spark plugs etc.

What is causing this chugging? Is it a possible bad fuel pump check valve? Is it a sensor issue like o2 or MAP sensors? Do I need a heated o2 sensor as I have shorty headers? Are the fuel injectors misbehaving at random due to clogs in them? Any ideas?

Thanks!

vetteoz

iTrader: (13)

A bad check valve will effect the prime and hold pressure but should have no effect if the pump is running

I would be questioning why you have 44 psi on prime but only 34 @ idle? Should be closer to 39
Does the idle pressure change if you disconnect the vac line to the reg?

JNRSingh

Ok so I took a step forward and now I have taken the same amount back...the car is not starting at all now. I installed an inline check valve right after my fuel filter as it was the closest spot I could reach from under the car to the tank without upsetting to many things. This didn't help the system hold its fuel pressure as it should, but it definitely slowed down the pressure loss after priming. I also installed a heated 02 sensor and wired it to the wire for the smog pump as I had removed it a few years back. When I cranked the engine, the car started and ran fine for the two minutes I had it on. I then turned it off. Then next day I try to start the car and the battery is dead. I check it with a voltmeter and it reads 10 volts. The battery is only a few weeks old so it should be fine, so I suspected a parasitic short. So I connected the battery to a charger/maintainer and overnight it was up at around 12.5/13 volts. When I tried starting the car, it would crank strong but not start. It would barely attempt to start at times, but the pulleys would spin slower than when the starter is cranking. So now the car isn't starting at all and I am back to square one. I also confirmed that there was no short as the battery held its charge for up to 3 days and then I tried starting the car.

Any idea? I would say maybe bad alternator but even if the alternator was bad wouldn't the car at least start with the fully charged battery? Fuel is flowing because the fuel rails prime as indicated by the pressure gauge I have on the schrader valve. Could the spark plugs have fouled again?

blue iroc

JNRsingh, Did you ever resolve your cars starting problem? If so what was the problem?

JNRSingh

blue iroc, I have been busy lately and have not resolved the issue yet. I plan to tackle it next month with the help of a friend and will post my results. My goal is to get the car fixed, insured and registered by June.

Jcase350

Im also interested to see whatvyou find out. Im having a similar problem. Thanks

rusty vango

fix the CEL issue and check your codes. you MAY have a bad MAF and or relays. this could be your problem

JNRSingh

Thanks Rusty Vango, I will try and get that CEL fixed ASAP. Also blue iroc and Jcase350 I think I have found the primary issue.

Yesterday I began working on the car again and the battery had held a charge over a few months so that was good and I tried starting it to no avail. Checked the oil and it was way over the upper limit. Emptied some out and found there seemed to be gasoline in the oil. Pulled the spark plugs and found plugs 2 and 6 wet with gas. Smelled like gas and when I blew on it it evaporated so I concluded it was gas. To confirm I lowered a piece of plastic rope into each cylinder and cylinder 2 saturated the rope with gas and cylinder 6 I had a bit but not as much as #2. I believe this is causing the no start issue and I'm hoping no damage was done to the engine because of this liquid in the cylinder condition. I suspect the injectors are sticking open or something and after trying to start the car after cranking an shutting it off I heard clicking from the passenger side of the engine so I am guessing that was the injectors leaking the fuel into the cylinders. I guess this leaking happens randomly as when I pulled the injectors and pressurized the rails as suggested by Lynn1990IRocZ there were no leaks.

SouthBay Fuel Injectors, who sold me the injectors last year, suspected that my fuel lines my have been contaminated and caused a blockage in my injectors. A gentleman named Frank over there said they would clean my injectors free of charge and was very understanding of my situation as my car is old and fuel lines could have gotten some rust in them during the installation process. So I sent them my injectors today and will update this thread as soon as I get them back and install them.

Jcase350

Could be fouled plugs. Are you sure your not supposed to have 22lb injectors?

JNRSingh

Yea I cleaned off the plugs using a little dremel wire brush tool on a drill gun last night as I had them out. I have a 305 5.0L engine so I have 19lb injectors, I believe the 22s are for 350s, but please correct me if I am wrong.

Jcase350

Are u using AC Delco plugs? I had 2 fouled out that were brand new and didnt even know it...still ran good...had to end up putting it in the shop to figure it out. You may be right about the injectors. I have a 350 with 22 lb injectors. Orginally I had bought 19lb injectors and it took me a while to figure out I had the wrong size....no thanks to Jegs! I am having an idle surge problem now im trying to figure out...about to go grab the shotgun and take it out back. Let me know what you find out about yours.

southbay08

you are correct.
19lb for 305
22lb for 350

We'll let you know what we find after we put them on the bench. Hope you included your phone #

zero13

i had some starting/continuing to run problems after a great day of riding...so i was stumped..didnt do nearly the things you did...but it was the coolant temp switch near water pump..line/connector was corroded,hence the intermittent start....cured my problem,and was a cheap fix...

Jcase350

Hey Zero was the idle surging at all on u or would it just not start for ya?.

JNRSingh

Jcase350 , yea I am running ACDelcos. And yea JEGS does not describe their products accurately, I've had similar compatibility issues with them. Check your idle air control (IAC) valve on your throttle body. If that goes bad you will have idling issues but doesn't affect the car while driving/while you're on the gas pedal.

Thanks southbay08, I appreciate it and look forward to hearing from you when you receive and test the injectors.

zero13 yea thanks that could contribute to my issues, I'll check it out.

red rock

iTrader: (2)

Quote:The plugs are about two years old and looked black when removed...none were wet or anything... just coated with carbon all the same way...

Have you tried new plugs?

zero13

difficult to start..but when it did i had to pepper the gas to keep it afloat...but eventually it would just die...i was told if the sensor is bad.it compensates for the false codes and tries to accommodate by adjusting fuel according to temp.....so your problems could very well be similar....i was glad cuz it coulda been huge problem..

JNRSingh

red rock I will first see if the injector issue solves my issue then pull a few plugs to see their condition after that fix. Eventually I will change the plugs. Do you recommend any particular type/brand? I'm using an MSD street fire ignition box that fires the spark plug quickly multiple times per cycle. Thanks!

red rock

iTrader: (2)

I was thinking maybe you had some bad plugs, as far as brand, anything that's new and gapped properly would be good. Changing plugs can be a pain, i have to change some from the top and some from underneath. Keep at it till ya get it.

JNRSingh

Ok so just an update on what is going on:

I received the injectors back from Southbay and they all were cleaned and in working order. I re-installed them and also changed the spark plus for good measure. The car started and ran, but after five minutes of idling, it would cut off. However, if i started it and started driving right away, the car ran fine, but would randomly start running extremely rich and their would be a significant lack of power and if my foot was off the gas it would stall out. To try to troubleshoot/resolve these issues I did the following:

- Removed the charcoal canister all together as the solenoid was bad
- Replaced the distributor as the reluctor magnet had multiple cracks
(new coil, ignition control module, rotor etc and timing set)
- I tested the coolant temp sensor operation by heating it up and seeing the resistance decrease on my multimeter
- I also checked the wire for corrosion and cracks etc and connected a 100k ohm resistor to simulate coolant at around 50deg and that did not help.

The issue persisted and one morning my engine flooded and I couldn't even start the car yet again, so I did the following:

- tested every wire in the harness to the ecm from the ecm to the sensor or what not for continuity and all checked out
- checked all fuses

Then I followed the instructions in this post:
https://www.thirdgen.org/forums/tpi/...-flooding.html

and everything in terms of the injector wiring based on that post seemed fine.

The car started after I unplugged all the injectors and the fuel pump relay then died once the flooding was cleared, so I am definitely getting spark.

I am suspecting the ecm may be bad and may be flooding the engine. I will keep trying with this car and will update as I make progress but am open to any suggestions/tips.

FBOMB90

Possibly a throttle position sensor? I had an 86 IROC that would stall out when hot, but would stay running if I two footed it at a red light. It wound up being a dead spot in the TPS. Good luck, hope this helps.

miguelc561

Me and you.are having the same.problems but my car is carbed. My car always.starts tho but has mind.of.its.own. been battling it.for a.year 2000 dollars later. Same problems. Shops cant.figure it out

88Trans-am

im having the same issue.. car ran fine sunday, came out to do some tuning yesterday and wont start.. if i floor the pedal it will start and rev up but die and choke out.. my resistance in the injectors are all the same, i have spark....this sucks

blue iroc

JNRsingh, my iroc started great for a while. All I did was wiggle the key and primed fuel pump for a quick second. It's was working great until it stalled one day at the house. Now I'm back to square one. Now on a cold motor it will start but sputters, hangs around 650 rpms and slowly climbs up to 1,000 rpms. If I step on the throttle it will help getting the rpms up quicker. Iroc stalled because electrical tape was blocking 3/4 of maf sensor screen. It wasn't getting air. How it got there, I don't know. I checked out iac and tps, both checked out good.
Now for the weird thing. If I remove maf sensor (maf still plugged in) and air duct, the car will start normal. Like if nothing was ever wrong. On the next cold start, with everything in place I start the car, again sputters to life. What's the problem?

Thanks in advance.

rusty vango

you,sir. have a dead MAF

blue iroc

Thanks Rusty. Starting problems only happens on initial start of the day or when car has been sitting for long time. Afterwards I'm able to start it without any problems just as long motor is warm. Like pressure loss. It had happened before several months ago, same brand new sensor.

I'm thinking that when car stalled, forced to start, and ran it I might have screwed up something.

rusty vango

you could also have a fuel problem .like zero pressure after sitting. do a fuel pressure test.tape the gauge to the windshield and go for a drive,checking as you go. then shut it off. if the pressure drops to zero almost immediately. you either have leaking injectors or that pulsator thing in the tank has failed. you could also have a fuel pump on its way out. if you aren't showing any codes. this is even more likely

miguelc561

I got this problem fixed. But my car still runs horrible. The exact same sane as beforr i repkaced the head gasket

ASE doc

JNRSingh, since the last thing you did was plugs and wires before the engine became a no start, I would go back over what you did. Check the coil wire for arcing to ground at the coil frame. Check the 2 connectors at the distributor and at the coil for corrosion and good connection. Your problem could be the MAF sensor. To eliminate it as a suspect, try unplugging it with the key off. Then try starting the car with no MAF input. The ECM will operate on default fuel and if the engine starts, you have MAF system issues. ECMs rarely fail.

blue iroc

I wondered if the maf is the problem. When I remove the maf, but still leave it plugged in, the car starts great on 1st cold start of the day. Afterwards it starts great throughout the day. I know about unplugging maf test. I tried two other maf's and had same results. I had the problem before until one day it's started not doing it. Until this past week.

blue iroc

JNRsingh, I finally got the car to start on first try without sputtering. I took off iac valve and cleaned it again, even though it looked clean. This time I also lubricated iac by using wd40. This really helped and hope this helps you.

Is there something else I can use beside wd40?

JNRSingh

Ok gentlemen, I have finally resolved the issue! Thank you to everyone who contributed to this post!

I checked the coolant temp sensor by comparing its resistance at different temperatures to that of a new one. There was a consistent 100 ohm difference, and I replaced the old one with the new one for good measure, but this made no difference.

Next, I electrically tested the throttle position sensor and it was consistent throughout the little armatures motion, indicating it was fine, but I had a spare new one and changed it for good measure and will keep the old one as a spare. This also made no difference.

Then I changed the map sensor as it was over 20 yrs old. I was unsure how to really electrically test it, but I assume it was ok because even after I changed it I still had no luck starting.

I also took ASE doc’s advice and checked for arcing around the coil. There was a bit of intermittent arcing in the dark when I cranked the motor with the starter, so I changed the plug boot. That resolved the arcing issue, but did not help with the starting issue.

Finally I decided to swap out the ECM for a reman ECM. The car started within seconds of the first crank and ran like a champion after that. Thus, I concluded the original ecm had failed in some way. Based on the cars behavior, my guess is that there was some sort of intermittent short causing one or more of the injectors to fire non-stop and flood the engine. Looking at the board it looks fine, so perhaps something wrong internally in one of the ICs. Anyhow, I’m glad that it has been sorted out and I drove the car about 500 miles since then to ensure when I give this good news I’m not crying wolf. I guess random issues like this with the ecm are quite hard to detect! My advice is to borrow a friend’s ecm and try it in your car if you think it might be the culprit.

Sorry all for my delayed response. ASE doc, thanks for the arcing check tip, but as for the MAF sensor, my car wasn’t equipped with one from the factory and as such blue iroc I do not know what are the symptoms/issues associated with their failure. And blue iroc, the best thing to clean the iac with is throttle body/choke cleaner, and wd40 would work ok for a short time as a lubricant. From my own experience, although I had cleaned and lubed my IAC valve, it still failed days after, my advice is to replace it if it is old/never has been changed as it might be faulty. One way to determine if the iac valve is bad is to very very lightly have your foot on the gas pedal when you start the car and keep it there. If it starts and runs fine with your foot keeping the throttle body open a tiny bit, chances are the IAC valve has failed. A temporary solution would be to open your throttle more with the idle set screw. I hope this helps. If it isn't the IAC valve, change your fuel filter if you have not in a while and check your fuel pressure. Before you start the car, turn the key to ignition with out cranking, count to two seconds (allowing the fuel pump to prime before you start), then crank and see if that helps.

Again, thanks to all who have contributed with their input! I took everyone’s advice and couldn’t have done it without you all!

blue iroc

JNRsingh, thanks for update and happy you resolved your problem. Since I lubricated iac valve, I have not had any cold start issues. I think I need to buy some graphite lubricant and use that instead of wd40.