MavViper

iTrader: (1)

Was having issues getting my car started. It's a 305 TBI. I replaced the spark plugs, spark plug wires, distributor car, rotor. Still nothing. It's getting spark because I can spray gas into the throttle body and it will run until that gas is gone.

So it is a fuel issue. Fuel pump works, gives me enough pressure. I replaced the fuel filter, still doesn't start. I disconnected the fuel line going to the throttle body and fuel is pumping through there. I replaced the injectors and still nothing. Fuel barely drips out of the injectors, certainly not enough to start it.

Next time i am going to do, tomorrow that is, is test the injector connectors with a noid light to make sure they are getting a pulse. Anything else I should take a look at to see why it isn't running?

dimented24x7

iTrader: (2)

Does the fuel pump come on when you crank the engine?

MavViper

iTrader: (1)

yup

dimented24x7

iTrader: (2)

That says that the computer knows that the engine is turning, and is at least getting some signal from the dist. Still doesnt fully rule out a faulty module or some other problem.

Although Ive never heard of an 88 TBI with VATS, does this car have it? The other possibility is maybe the TPS is reporting high, and the car is going into flood clear mode. Try disconnecting it and see if the car will start then. There are other things that could do it, but theyre not as likely.

MavViper

iTrader: (1)

Doesn't have VATS. The key that I have has no chip in it and it started before when I first got the car. I'lltry disconnecting the TPS and try to start it

MavViper

iTrader: (1)

Nope, I pulled out the TPS and tried to start the car, still no go. I've had some people tell me that the oil pressure sensor, if faulty, would cause the computer not to tell the injectors to fire. But I've also had people tell me that's not the case. Could that be an issue?

dimented24x7

iTrader: (2)

If the fuel pump runs, then the fuel pump relay is good. The sender only serves as a backup for the fuel pump relay. If the car has good fuel pressure and spark, then its some signal issue or faulty injector drivers in the ECM. Can you datalog?

MavViper

iTrader: (1)

nope, wish I could. If it were faulty drivers, would it happen all of a sudden like this? Cause the weird thing is it worked about a week prior to me getting it painted, and then after getting it painted it stopped working. The body shop didn't touch the engine or the electronics.

MavViper

iTrader: (1)

Well I pulled the ECM out of another 88 TBI Camaro. When I hooked it up to my car it threw Code 21 which meant something was up with the TPS. I disconnected the TPS and tried to start and it would crank but not fire. When I hooked my old ECM up it threw no codes.

That normal?

Edit: *sigh* another problem it seems. When I turn the key to crank the engine nothing will happen. The temp guage will spike but that's it, nothing else. That may happen for a few times and then suddenly it will crank over again, but of course not start.

Ok, the fuel pump is priming fine and providing fuel to the throttle body. I had replaced the fuel filter. There is enough pressure going to the injectors. Fuel pressure regulator is fine. Replaced both injectors and gaskets. Changed the ECM. I haven't been able to check to see if the injectors are getting pulses or not due to no one I know or any store that has a noid light. I will have to make one but haven't had a chance really.

Are there any sensors that would cause the injectors not to fire? I noticed that on the original ECM that the injectors barely dripped any fuel, but with the new ECM that the right injector kinda sprayed a little bit but not enough to actually start the engine. I poured fuel into the throttle body and the car will start up no problem but will only run as long as I am dumping fuel into the throttle body.

I am getting fed up with this car not running. Even though I am strapped for cash right now I might just have it towed to my mechanic friend and have him figure it out and somehow pay him.

camaronewbie

In the pass fenderwell, tucked in beside the battery, there is a 20A fuse - have you checked that? Checked the 2 or so injector fuses in the fusebox?

The fuel pump relay only gets a signal from the ECM when key turned on - the pump priming is solely a function of the ECM and this relay. After the priming, the relay no longer sends current to the pump. For strting and running, the pump gets its electricity directly through the oil pressure sending unit. The OPSU will not prime the pump, and the relay/ECM will not run the pump after initial key on. Make sense?

Sounds like you are getting the signal to prime, but not getting the power for the pump to run. With the key on, you can check current at the fuel pump - there is a connector above the rear axle on the body. Sounds to me like a faulty OPSU. They are $30 at Autozone.

Hope any of that may help.

MavViper

iTrader: (1)

all of my fuses are fine, I doublechecked those.

What you are saying about the OPSU is that the relay/ecm will prime the pump and then it's the job of the OPSU to run the pump after that? I will definately check that out tomorrow. Is there anyway to check it rather than buying the part and installing it? Just wanna make sure it's that before spending more money.

camaronewbie

You can discoonect the plug to the OPSU and connect two of the 3 wires together, and you should hear the pump run - problem is I don't rememember which two wires. Maybe a search on here - or check Haynes for a schematic.

rocko350

check for a good ground from the thermostat bolt to the battery. a poor ground would do this. put = side of volt meter to battery hot and put - on battery neg to verify reading the put negative to the thermostat stud and have someone crank engine. if the meter spikes past 1.0 volts then bad engine/ecm ground. (ground drop test under load)

MavViper

iTrader: (1)

I'll definately try both tomorrow.

MavViper

iTrader: (1)

It's not the OPSU because from what I read that controls the fuel pressure when the car is running so it should have no effect when cranking.

There's only 2 things I can think of at this point. Either it's the computer (screw getting a used one) or somehow some animal chewed through the wiring to the injectors.

MavViper

iTrader: (1)

Well, it's not the computer. Got a brand new one in there and still the injectors aren't firing. I am at my wits end now

MavViper

iTrader: (1)

has to be a wiring issue, finally made a test light and when I hooked it up to the injector connections the light didn't do a thing.

Camaro101

Im having the exact same problem with my '91 RS 305 TBI. I cant get it to crank unless I prime it myself and I cant keep it running unless I keep feeding it fuel plus my engine doesnt turn over sometimes but show power on gauges and everything else but I can pull the key out for about 5 or 10 mins and the engine will turn over.(too bad it wont crank though). I can see the injectors dripping fuel when I try to start it and I heard thats all its suppose to do until it cranks then it turns into a mist. But after I manually prime it and the engine starts the injectors do nothing. My ECM is spittin out codes 12 and 53

Code 12:No TACH signal to ECM - system normal

Theres a few of these
Code 53:System over-voltage(ECM over 17.7 volts)
Code 53:Alternator voltage out of range
Code 53:Vehicle anti-theft (PASS-Key) circuit (5.0L TBI)

I have a Chiltons manual, a haynes manual, and a haynes techbook helping me and I still dont know whats up.

MavViper

iTrader: (1)

Have you tried a test light on the injectors?

305TBI

Read about your no start problem earlier this year. Wondering what your problem turned out to be. I have a similar problem with my 1991 Firebird Formula 305tbi. I have spark at the spark plugs (took one out and cranked the engine) and fuel from the injectors (saw good spray while cranking), but no engine start. This problem began after a hard rain the day before. I keep a cover on my car, but I suppose some water gets through. I hope you or others may have suggestions.

Thanks,
Don Moore

Camaro101

No test light yet but I did pull out the IAC and looked at it and it looked fine. I was gonna pressure test the fuel line but the gauge costs $40 and no one rents them out. Like I said when you turn the engine over the injectors let out drops of fuel then when I spray fuel in the TB and the engine starts the injectors stop.

MavViper

iTrader: (1)

From what I have read, the fuel pump should be pumping out between 9 and 14psi of pressure. If I were you I would disconnect the fuel line from the TBI and then have the fuel pump prime the system. If fuel shoots out then you know you have pressure. I did that with mine because usually fuel pumps go out slowly and not suddenly.

If it starts when you spray fuel into the TB then you know it's injector related. Have you tested the injectors for their resistance? They should be between 1 and 2 ohms.

Getting a test light is key though. You could even make one yourself by taking a 12v bulb and attaching wires to it. Then you hook up the wires to the injector and have someone crank the engine. If the light flashes, then you know the injectors are getting the pulses.

That's as far as I got with mine. I am getting no power to the injectors and thus the injectors aren't firing. I am not even getting any fuel through the injectors though I have confirmed fuel is getting to them. I've replaced the ECM.

beatercoprice

When I was working on my car I accidently left the A+B ALDL terminals jumpered with a paperclip, the car wouldnt start untill I removed it.

305TBI

You can buy a "GM TBI Electronic Fuel Injection Test Light" made by Pto-Gap tune up tools, part #3410, at some automotive shops. Cost is a couple bucks. You just unplug the connector from the TB and plug it into the test light.
Don Moore
----------
Thats "Pro-Gap"
Sorry.

MavViper

iTrader: (1)

Getting closer to fixing my problem. I wasn't able to do much testing to figuring out this past few days so today I finally got around to checking things.

Both injector connectors are getting power. I did this by connecting the test light to the hot wire on the connector and then grounding it on my engine block. The test light lite up. It did this for both injectors.

That means for whatever reason the ECM isn't telling the injectors to fire. I have a new ECM but here's the hitch. I am still using my old chip in there, which was the stock chip. Is it possible that the chip could be bad for some reason? My buddy gave me his chip but I have no clue whether it would work or not. His engine was the same as mine but the chip is an aftermarket one with the name "ADS SuperChip" on it. I'm going to post questions about that chip in the PROM forum since I figure I will get more answers over there.

My question for here is, what sensors or anything would prevent the injectors from firing? I am going to a local auto store tomorrow to get my ignition control module tested. Failing that what else might prevent the injectors from firing?

dimented24x7

iTrader: (2)

Faulty drivers, bad grounds at the distributer (both module as well as the distributer base and all points of contact must be clean to ensure a good ground path), faulty module, open circuit, lack of dist. reference pulses, possibly lack of cranking signal. Those are a few of the things that can cause no starts. Does the tach work when your cranking the engine?

MavViper

iTrader: (1)

yes, tach works, grounds are ok at the distributor. As mentioned before I'm going to get the module tested today.

89IrocZRagtop

I have the exact same problem. I have a 89 Camaro 305 TBI I was able to trace the problem to the fat wire harness plug at the fire wall. I have not fixed it yet but when it doesn't start I just grab on to the wire harness and give it a tug to the right , left, up, down and it starts everytime. The wire harness plug is located on the drivers side firewall. This has happened to me 3 times. I first replaced my ignition module and dist. cap & rotor and that did not help. I had spark & the fuel pump was pumping but the injectors would not spray gas.

MavViper

iTrader: (1)

Ermm which connector?

And the module tested out fine today so it's not that

89IrocZRagtop

It is the big fat one right where it goes through the firewall on the drivers side right below some relays. There is a bolt going through it.

89IrocZRagtop

You can try taking the bolt out and unplugging it and put some dielectric grease on it and plug it back in. The computer is sending the signal to the injectors but the power is not making it through the connector plug where it goes through the firewall. Either that or the distributor is sending signal to the computer and it is not making it through the firewall connector plug.

MavViper

iTrader: (1)

Well an update. Thought I had it almost fixed yesterday. I was getting fuel spray but the darn thing wouldn't start still. So I thought maybe I fouled the plugs or something so I checked and I wasn't getting spark. So today I replaced all of the spark plugs and wires. Reconnected everything and now I am getting no fuel out of the injectors.

It has to be some sort of short somewhere, my guess is at the ICM whether it be the connections behind the ICM or the connections going into the ICM.

Rod Behring

I had this problem once before with a Ford TBI and it turned out to be moisture inside the distributor cap. I took a hair dryer and dried it out and it fired right up. Apparently the distributor was not signaling the ECM to fire the injectors. Hopefully this can help you in your diagnosis. Good luck.

icarus402001

" Rod Behring". That's a good one. I like it.

Rod Behring

Thanks.

buell0303

I know exactly what it is, its your fuel regulator. the part that is on top of the injectors that bolts down on to them. Most of these seize up. on mine it did when i first got it and it would only run on the gas i poured in it. What you need to do is just replace that part. I bought mine from the dealer and paid 150.00. The new ones are much better. they changed the design which makes them not seize. there all preset from the factory to. Good luck!!

MavViper

iTrader: (1)

there anyway to fix it rather than having to buy a $150 part? Money is fairly tight given it's the holiday season, so I don't have that extra cash to buy it.

buell0303

Hey i have this one I'll sell you. i bought an extra TBI because i cracked a piece on it. it came with the fuel regulator. I know this one works. I tried it on my car. but then just put my new part back on. If you want it let me know. shot me a price. thanks erik

MavViper

iTrader: (1)

Don't think it's the fuel regulator anymore because after fiddling around with the distributor and the ignition control module I am now getting the injectors to fire and they are spraying fuel but it still won't fire up. I had replaced all of the sprak plugs and spark plug wires before. I am also getting spark too so I am clueless at this point.

1320-camaro-383

Wow that is a kick in the dink!Sounds like you have tryed almost everything.Lets see if you are now getting spark and you are getting fuel sounds like it shoul start unless you are not getting enough fuel.Have you tryed to pour gas in the throttle body to see if it will still run that way?If so I would have to say even if you are getting gas it might not be enough to start.Pour some in start it and see if you can keep it running by peddeling it.If it starts I would tend to think your regulator might be working but not correctlly,it might only be giving it a pownd or two of pressure.

MavViper

iTrader: (1)

sounds plausible. The thing the only real way to check that is to replace the fuel regulator, right? I'll see if my friend has his old one that I can try, if not I think I will just have to take it somewhere

1320-camaro-383

I have a throttle body off a 88.If you want the press reg off it you can have it just pay shipping.The only thing is it might take a while to get to you seeing that there is no mail for the next 2 days and you are accross the country.But the offer is open if you want it,I know it works it was removed about 6 months ago because it had one bad injector so I just went to the junk yard and bought a new one.Buy the way did you try pouring gas in it again and then peddleing it to see if you could keep it running?

swap350tbi

I had the same problem. When you first try to start your car do you get both injectors to fire twice. If no you are not getting the start signal. You always have 12 volts on the connector to the injectors but the computer applies a ground to them to make them fire. Check your connections at the computer. If you are not getting a gound no injector fire. What I did was place a towel under the injector to see if I got the start sig. make sure all of your connectors are connected and that all are good connections.
swap350tbi
fla.

TBITrucker

I had a similar issue with an '88 LO3

It turned out to be a defective pick up coil inside the distributor.

I had tested everything I could think of and still could not get it to run. When I popped off the cap to inspect the inside of the distributor I saw that the plastic around the pick up coil was cracked and broken, the connectors were grounding out on the base of the distributor.

The plastic was very deteriorated I think someone sprayed it with some sort of cleaner that was not plastic safe.

I had to take out the distributor to replace it but it was worth it because I found that all of my firewall ground straps were broken so I ended up fixing two things at once.

As far as you cranking problem check to make sure all the connections on your starter and solenoid are clean and tight, also don't rule out your ingition key switch, they can go bad and still "feel" fine when you turn the key.

buell0303

Hey I don't know if you have done this yet but check your vacume as well. My car had a problem after the fuel regulator where it lost vacume to the map sensor. It caused it to run like crap again. I ended up taking to a mechanic and he replaced all the gaskets in my tbi and fixed and routed all the vacum lines where they were supposed to be. 260 later but my car runs awsome now.

MavViper

iTrader: (1)

1320-camaro-383, I'll send you a PM definately.

The thing is, now the injectors are firing and there is fuel coming out of the injectors. I don't think it is enough to start it though because it's sort of like a fast drip. It's supposed to look like the conical spray that comes out of spray bottles, right? Like a mist sort of thing right?

bubba james

Its your ignition control module. Its located IN your distributer cap. If you look at your ignition coil you will see two plugs that go into it. You can follow one of the wires right to the back of your distributer cap where it plugs in. That is the sensor you need to replace. I had the same problem on my 89 rs. Its a 305 throttle body injection. Just take the module out and bring it to your local parts store and get it tested. I would put money on it that thats your problem

MavViper

iTrader: (1)

bubba james, I'll take that bet cause I've already had it tested and it tested out fine

1320-camaro-383

I removed the reg from the body,I just took the whole top off so that way you wont have to worry about a new gasket for the regulator,just remove the 5 or 6 torx screws and swap them out.Let me know what you want to do,like I said I should be able to get it to you for less than $5.00.If you want it priority maybe a tiny bit more.Id say it is worth a try.Merry Christmas

SLONOMO91RS

I am having the same problem so if you find it please let me know.