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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I have a 1989 Firebird 2.8l that cranks but won't start. Was running fine the last time I drove it but suddenly won't start. It had a tune up like a year ago, spark plugs, wires, cap and rotor replaced. When I try to crank, it keeps cranking but won't start. I hit the gas a bit too and can smell gas from the engine bay but still no start. So maybe it's not getting spark? Sometimes the security light would come on when trying to start but that did not happen this time and when it does, it doesn't even crank at all anyway so maybe not that. I do keep the battery negative cable disconnected in the winter so have to reconnect that every time I want to drive it.
What are some things to check to try to figure out what's going on?
I haven't had a chance to look at it yet. Will have a chance on Friday. It's a little chilly but will check connections and fuses. Was just wondering if anyone had any other ideas for things to check besides the simple stuff. Or if it's some common problem.
I haven't had a chance to look at it yet. Will have a chance on Friday. It's a little chilly but will check connections and fuses. Was just wondering if anyone had any other ideas for things to check besides the simple stuff. Or if it's some common problem.
Shoot some starting fluid into the TB. Try to start it.
One of 2 things will happen: either it'll start and run for a second or 2, or it won't.
If it runs a bit then dies, you have a fuel problem.
If it still doesn't run, you have a spark problem.
Use some logic instead of "maybe it's this maybe it's that". Works better than posting crap on the Internet before you've actually DONE ANYTHING for yourself. After all, it's just a car. About as simple as it gets.
Forgive me for not checking earlier. Was just thinking I could get some tips on how to diag. Like with the starting fluid suggestion. But isn't starting fluid only for carbureted engines?
So I checked the related fuses under the dash such as crank, ign, f/p, eng, and ign. All of them looked fine. Checked the distributor wires and everything looks like it's connected fine. When I put the key in ignition, I can hear the fuel pump whining. I try to crank and it doesn't sound like it's starting at all. Not even struggling. There's a certain sound every now and then but I think that's just my starter skipping a tooth. Tried giving it some gas. I noticed after doing this that fuel started dripping out of my air intake right where the mass airflow sensor is. In the picture it's where the red arrow is. Is this what they call flooding? I've pumped the fuel pedal before when it had trouble starting but it never leaked like that. I think it's safe to say it's getting fuel.
There's a few relay in the engine bay along the driver side and like 1 along passenger. Are any of those related to spark? Actually I think there's 1 under the dash behind a gooey wall that I had to replace once as well.
Sorry I didn't start this post off correctly guys.
Pull a spark plug, see if it’s wet. If fuel fouled check for spark. If no spark check for power at the coil and icm while cranking. Check acv from pu to icm. Not to hard to diagnose. I doubt it’s something as easy as something unplugged.
Ummmm.... it's FUEL. Is gasoline any different for FI vs carb? Starting fluid isn't either. (sorry for the bad pun there... starting fluid is actually ETHER )
fuel started dripping out of my air intake... Is this what they call flooding?
Yes, may well be.
Might be a good idea to pop the air filter lid or whatever one of those things has, and maybe that crinkly air tube, off, and see if there's liquid fuel in there. If so, wipe as much of it out of there as you can, dispose of the fuel-soaked paper towel or whatever SAFELY, and try again.
Giving a fuel-injected engine throttle when starting is a BIG no-no. It doesn't pump a shot of fuel into the intake like a carb would, anyway. All it does is confuse the ECM. You're supposed to just turn the key. It's programmed to give the engine the right amount of throttle opening and fuel based on the ambient temp, engine temp, etc.
None of the relays has anything to do with spark. Best way to see if you have that is, unplug a wire from one of the spark plugs, plug it onto another spark plug, and have your assistant crank the engine while you hold the shell of that plug solidly up against something grounded, such as the intake manifold, but not touching the plug itself with your hand (unless you enjoy getting shocked). You should be able to hear it even if it's too bright around you to see it.
For the most part code list is the same for obd1, variations between maf and map codes. The process was the same for retrieving codes from 83-94 gm obd1. If you can count to 12 you might have a chance reading the blinks.
I don’t think any code will help you with the no start
This is true. They'll help with a runs-like-crap, butt the car will virtually ALWAYS start, no matter how messed up the ECM's situation in the world is. Might run like crap after it starts, butt it'll start.
Get the car to run. Then scan the codes. Some will go away on their own after some number of run-off cycles; some are best cleared by disconnecting the neg batt cable and waiting about 5 minutes before hooking it back up.
Yes OBD1 codes are the same for any GM car, subject to the different meanings that some of them have for carb vs TBI vs port injection and such as that. Body type doesn't matter in the slightest; the ECM couldn't care less what wrinkles and stickerzzzz the sheet metal it's wrapped in has on it.
Ok so for the spark test, can I attach an alligator clip wire to the test spark plug, then attach the other end to the frame of the car. Then I can put the plug by the window so I can actually see if it sparks. No difference if ground it to the frame or the engine right?
And I'm thinking I should probably disable the fuel injection while doing the test. Just pulling the fuses that say F/P and INJ should be good? Or is there also a cable I can unplug?
So was able to get a friend to come help me check for spark. We grounded the plug to the frame we both observed a white spark coming from a known good plug from a few wires. Also, I had removed the air cleaner hoses from the throttle body and the air cleaner box to let the gas air out.It sat like this for a few days. However we observed that when cranking for not very long at all, that gas seems to be dripping out of the throttle body right by where the idle position sensor is. Also noticed it's a little wet by where the EGR valve is. Seems a little abnormal. Could it be a sign of running too rich? It's really cold and we're expecting a lot of snow the next few days so won't be able to do much more for a bit.
Is it dangerous to start the car in this condition? Or will pulling the vacuum line help if that is the issue?
No, it ain't gonna start being so flooded that fuel is dripping out of the throttlebody......
What your gonna do is, put all the fuses back, so that the fuel pump will be able to do the two second prime when you turn the key from off to run.
Then you will disconnect the vacuum line from the fuel pressure regulator to the throttlebody. It's the plastic/rubber block thing with two black plastic pieces of tubing going to it that's plugged into the back of the throttlebody.
With that tubing block thing unplugged, turn the key from off to run (but not start!). If fuel shoots out of the smaller black tubing, replace your fuel pressure regulator diaphragm.
See in this pic the round circle labeled "Fuel Reg"? See how it's vacuum line goes to the back of the TB? At the TB is where you'll disconnect it for this test.
Last edited by OrangeBird; Feb 11, 2025 at 04:32 PM.
Yes, that’s it. If fuel comes out of the line. Pull the plenum and replace the fpr diaphragm. Change your oil and you might have to swap out your fuel fouled spark plugs.
Last edited by Tuned Performance; Feb 23, 2025 at 08:42 AM.
I thought I remember the two pieces of plastic tubing as being different sizes but I guess my memory is faulty there. No matter, you'll unplug the plastic (rubber?) block holding those two pieces of tubing into the TB and then do the two second prime thing. If you see ANY fuel come from one of those pieces of tubing your regulator's diaphragm is shot (ripped)
Be careful pulling that tubing block outta the TB, those pieces of tubing are VERY brittle and like to snap like uncooked spaghetti
I pulled a little hard on the tubing. Hope I didn't break it. But yes I just tried what you suggested. But I only unplugged the leftmost hose. The other goes into the egr solenoid I believe. Anyways, a stream of fuel shot like 10 feet in front of the car.
Ok so I need to remove the plenum to get to the fpr. Throttle body probably needs to come off too. Probably need new plenum gaskets too huh? Something I've seen in a few places is that the fpr is not serviceable and not to open it. The fpr looks like it has a circular top with bolts going around it. Is the diaphragm under that circular part? Is there a trick to opening this up and replacing it? Or is that warning not as grave as it seems?
Ok so I replaced the fpr diaphragm. I heeded the warnings in other posts and let it soak in PB blaster overnight. Came out nice and easy. Tightened it all back up and then I verified that no more fuel is coming out of the vacuum line.
However when I tried to start it up, it would not start. Cranked on it for a little bit but no luck. Probably my plugs are soaked in gas? Can I clean them with some kind of spray cleaner? It doesn't help that it's 10 degrees out right now.
Just take them out and if they're wet, let them dry. Gasoline evaporates pretty quickly on its own when out in the open. Dump out and/or dry up any leftover fuel hanging out in the intake tract as much as you can.
Alright I'll try that next. I had the intake tubing apart for a few days and pulled everything all the way to the air filter. Didn't see any more fuel in there.
After taking out the plugs and cleaning them up a bit, it started, but had to crank it for like 10 to 15 seconds. Ran like crap. Tried starting it again and it also took 10 to 15 seconds to start. Seemed like it was running ok, but probably wouldn't be a bad idea to replace these plugs anyway.
Yes, that’s it. If fuel comes out of the line. Pull the plenum and replace the fpr diaphragm. Change your oil and you might have to swap out your fuel fouled spark plugs.
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