Hi all. I’m rather new to the forum and third gens. I bought a 92 TA vert with a LB9 305 TPI and auto trans in November. It ran fine for a month and then one day one my way home from work it died and wouldn’t restart. I was on the highway going 70 mph and with no change on the gas pedal from me the car died. The fuel pump is still priming to this day so I ruled it out as the problem. On January 11th, I changed the fuel filter. It ran for 20 minutes and warmed up well. I stopped engine for 10 minutes and then it wouldn’t restart. It threw codes 34 and 42. So on the 19th of January I changed the plugs, wires, cap and rotor. It ran good at idle with “service engine soon” light on. The engine started, ran well and warmed up, then I shut it off and restarted it 5 minutes later while warm and it started strongly. I shut it off and disconnected the battery to erase the codes (which didn’t work). I reconnected the battery 30 minutes later and the car ran rough for a few seconds and died, then wouldn’t start and stay running. “Service engine soon” light still on.

After all that, work got busy and I didn’t have much time to work on it. On the 28th of March I changed the MAP sensor, MAT sensor, EGR valve, EGR solenoid, vacuum check valve, all vacuum hoses under the plenum, ECM, PROM, PCV valve, PCV valve grommet, and yes I even changed the gas cap because the old one was looking rough. The car cranked but would not start. My fuel system APPEARS to be working properly, but I don’t have much experience with TPI or fuel injection in general. With it still not running and ignition seeming to be the problem, I changed the ignition coil on the 29th with not much better results. Then yesterday I changed the distributor and it seemed to try harder to start, so I gave it some gas and it ran really rough and terrible as long as I gave it gas. As soon as I let off the pedal it died, which left me with a dead battery now so I guess some jumper cables or a battery charger are in order.

I really love the car and would like it to be my daily driver but I cant get it running right. Any assistance you guys can give would be awesome, besides suggesting to get a new engine because it’s a 305. Its numbers-matching and it sounded good when it ran good and it has enough pep for me for now so I would just like to get it running again if possible. Again, any help you all can give will be much appreciated.

 

i had i similar prob when i repined my car from maf to sd 730 i found that my ECM was not out putting the 5v reference signal, i had killed the ecm voltage regulator i guess cuz i wired the map in wrong and basically grounded the 5v, check for 5v signal at the TPS and MAP, i had another ECM and just swapped my chip and it fixed it. i would check for 5v. good luck

 

Alright, here's an update. The lack of starting doesn't appear to be the battery. I get 12V from it on the multimeter and I tried to jump it today with no success. It won't even crank now. When I turn the key it clicks and the dash lights flicker in sequence with the clicking sound. Is it possible that I burned out the starter or starter solenoid, or both? Now I don't know if the original problem is anywhere near fixed and if I possibly have a new problem on top of the original. Can anyone help?

83Fast4Door - Would the 5V ground problem that you were having have any effect like my cars current issues? I don't know if thats my problem because I'm not picking up any 5V at the MAP or TPS, but I'm not sure I'm checking them right. Did you unplug them and check the male end of each sensors wiring harness? I don't have much experience with working on computerized cars. Does anyone have any idea what the problem could be?

 

Wow you're determined to get this thing running - that's good. So far you've thrown a lot of parts at it and it still won't run. I think it is possible that you burned out your starter because you've been running that thing for a long time.

Just like an old carbed engine, you still need to determine what's missing, spark or fuel?

But to answer your immediate question, I have an idea based on your findings. With the key on, the grey wires on both your MAP and TPS sensors should have 5 volts.

 

I appreciate the comments and tips guys. I am definitely determined. I haven't had a vert since high school, and I haven't had a V-8 for about 10 years, so I really like the TA.

Since I picked up a multimeter this past weekend, I'm going to start checking all kinds of electrical connections. I'm going to start with the MAP and TPS, then onto the spark plugs and wires, then the fuel injectors and the harnesses that go to them. I hope the culprit is not a massive job, like the engine or transmission being seized. I'll probably replace the starter in the next couple of weeks. Does it sound like maybe the battery could possibly be dying too? If there is a ground somewhere, would that be reason enough for the car to not start? Or would it just run like crap after it started?

Again, thank you for any help and tips ahead of time.

 

Here's an update. This past weekend I replaced the starter. I went through the wire harness for the ignition and couldn't find any obvious issues. Since it threw code 42 at me the last time and I had already bought the part last week, I put in a new ignition switch as well. During that fun operation I either broke or discovered the already broken cruise control brake release switch and ordered that. It came in today but I wont have the opportunity to install it until next week (that damn job keeps getting in the way). I also checked for 5V to the MAP and the TPS and with the key on they both had 5V. I'm keeping my fingers crossed that the ignition switch was the issue, otherwise it'll be back to the drawing board. I'll start checking for spark and compression if I don't have success next week.

 

Have you looked into the ignition module?

 

I have. I was going to buy a new ignition control module when I bought the distributor, but the distributor came with a new module already attached. So at this point, the only reason I can think of for the code 42 would be a well-hidden ground (which I already looked for and couldn't find), or the ignition switch. I believe I've changed every other ignition component. I'll be able to find out for sure next week. Am I missing something?

 

Here's an update. Today I finished putting in the cruise control brake release switch and the ignition switch. With a new starter also in place, I thought I'd be home free. I was definitely wrong. I got the same results as before only the starter felt A LOT stronger; cranking with no starting until I tried to give it a little gas, which kicked it over extremely rough and only ran as long as I gave it a little gas and then died as soon as I let off the pedal. There was a strong fuel odor too. I got frustrated for a little bit and then after a break, I went back to basics and tested the fuel injectors. #1 had 16 ohms, but #3 had 11 ohms and #5 only had 9 ohms. No need to test any more. So, after I order and install a whole new injector set, I wil try again.

My questions are: Would I smell a strong fuel odor when trying to start if my injectors are bad? Does it seem like bad injectors could be the underlying problem to begin with?

Thank you for any help and opinions.

 

An update from the weekend. Saturday I changed all the injectors and the fuel pressure regulator. The injectors were pretty dirty and a bunch of them didn't even get close to 14 ohms. The fuel pressure regulator was TERRIBLE. Theres no way it was doing anything. I also put a new battery in. I ended with the same results as stated in post #1. It would run extremely rough and struggle as long as I gave it a little gas and then die as soon as I let off. The fuel pump makes the sound like its priming but I'm not sure how much pressure (if any) is getting the the fuel rail. My next step is going to be getting a fuel pressure test tool and see what I've got at the fuel rail. To cover my bases, I will probably also check all my newly installed spark plugs to make sure they're all getting spark. At this point, I'm thinking I got a bad tank of gas and it hosed up a bunch of my fuel system. If the fuel pressure isn't what it should be, I plan to syphon the gas out of the tank and drop it so I can inspect everything. At the least, I will probably replace the pump and strainer while I have access to them.

My current questions are: What are the symptoms of a bad sending unit? Would the pump still sound like it was priming and maybe not actually be pushing fuel to the engine?

EDIT: I also forgot to mention that I'm only getting code 12. Both codes 34 and 42 are gone, but it's still not running.

 

How did it go?

 

A bad sending unit usually gives you a wonky fuel gauge or a very in accurate fuel gauge. like it reads full till you have an eighth left and then it works you also need a sending unit

Yes that is in fact possible. It has happened to me and ever since I check fuel presure to determine something is wrong pre injectors. the only thing left is a fuel pump. I mean you changed the ignition system, and swapped the injectors. so the only thing left is the pump. you have to put a gauge on it and see what the PSI is. It sounds like your starting to get closer though. you will be happy when she is running and its the right time of the year to have the top down.

Just remember if this stuff needs to be changed use a quaility pump and sending unit so you only have to do it once

 

Unfortunately it didn't go yet. My job requires me to be gone for days at a time so I won't have time to test the fuel pressure until probably this coming Thursday or Friday. Thank you for your interest. I will update as soon as I test it.

I felt like a mega rookie at first because it felt like I was just throwing parts at it. I feel much better now that I am aquiring diagnostic tools to make dialing in on the problem easier (and cheaper too). I must say that all the parts I changed REEEEEALLY needed to be changed anyways. Most of the stuff I took off was total garbage. I wonder how the car was even running when I bought it. It felt under powered and the gas mileage was terrible, but I liked it. Even after all the issues it has, I'm glad I bought it. I had no idea of the low production numbers until after I bought it. As soon as I get the major issues worked out, it should have decent power and pretty decent gas mileage too.

I can't wait to get her running. Fortunately enough, I live in San Diego so its convertible-time most of the year. I figure if I do end up needing to drop the tank to change the pump and sending unit, I'm also going to change the strainer and I'm even thinking about getting a new tank too if the inside of my current tank looks like trash. Then I really won't have to worry about fuel problems for a long time.

Thank you for your interest and help guys. I appreciate it very much.

 

So today I finally got around to checking my fuel pressure. When it primes, it shoots up to 43 psi. It only holds for maybe 2 or 3 seconds after the pump shuts off and then it quickly dwindles down to around 5 to 10 psi and after a minute or so its down to nothing. I used the bleed valve on the tool to take a look at the fuel and it looks good. there doesnt appear to be any contaminants or water. My wife and I checked all over the fuel system for leaks and there were none.

I'm sure there has to be a check-valve of some sort that has gone bad either in the sending unit or the pump itself. Thats the only way I can explain the pressure drop immediately after priming, but with no fuel leaks. Either way, I believe todays test leaves me with changing either the sending unit or the pump. Since I'm going to drop the tank anyways, I'm going to change everything; the pump, sending unit, strainer, and tank.

My question of the day is: Does my car (92 LB9) have a fuel pulsator attached to the sending unit and/or pump? I just want to know so I can order everything ahead of time.

 

Well, congrats, it sounds like you are getting much closer to fixing it. I know what you mean by getting frustrated lol i think we can all relate there.

Did you/could you check fuel pressure while running?

I replaced my tank, pump, sending unit, fuel filter & strainer, all the gaskets, even filler neck and gas cap all at once. I was having a simliar (although it sounds less severe) problem as yours. After this, the engine runs like a champ and i ALREADY need new rear tires

Hopefully this fixes yours!

 

Sounds like a vac leak idle bad when u give it gas. Do it bog down bad when u give it a lot of gas.

 

Now the key is to figure out where you losing the presure, its either a pump, a check valve, of the injectors are bleeding down quick

 

if not firing order, how bout voltage regulator, aka alternator or the throttle position sensor?
I too am having similar issues with not running after changing coil, plugs, wires, cap & rotor

 

When I got my car is ran good for the most part, A stumble now and then, a buck here and there. I thought is just needed a tune up as it still had the 25 year old plugs, wires, cap and rotor, fuel filter was older too. So after a about a week of owning the car an only putting about 70 miles on it the car started running real bad after the fuel fitler and MAF was clened. I took it to a shop and had the plugs, wires, cap and rotor replaced with the parts I bought-I ran out of time to do them. Anyways my CEL never cam on, but the car almost did not make it the 1.5 miles to the shop and a few times I had to push it the 10 feet into the garage. They plugged in the scan tool and there was no comunication-bad PROM chip. They checked the fuel PSI and it was good. So we got a used PCM and PROM and they said it started and ran great, but when they went to drive it-it died out and bucked-almost as bad as before. They tested the fuel PSI longer this time and as the fuel pump heated up it would cut out and PSI would drop off. So after the new PROM, tune up and fuel pump my car runs like new. You might have a bad fuel pump.

 

Unfortunately I didn't check it while running before the big bridge incident happenned, and now it wont run at all so I can't check it. I'm pretty positive that I need at least a pump so I think replacing everything back there will solve the big issue. Hopefully I can keep from needing new rear tires too quickly.

It just won't run so I wish I could tell you. With any luck, after I replace the tank and sending unit and pump and strainer I'll be able to tell you for sure that it doesn't bog down when I give it gas. LOL!

I'm hoping its not the injectors, considering I just replaced them. I don't think Southbay Injectors would let me down.

I've checked and double checked my firing order and wires so I'm positive thats not the problem. I did some serious research into this and I don't believe the throttle position sensor is my problem. I feel pretty strongly that the fuel pressure is the main issue. It tries reeeeeally hard to start, but it feels like its starved of air or fuel. It's definitely not air, so fuel would make sense especially with the pressure issue.

I'm really hoping that this will fix my issue. It seems like it will. With all the stuff I've replaced, I'm expecting this rig to run like it just rolled off the lot 20 years ago once I get it purring again. HA! I'm expecting significantly more power and better gas mileage too.

Thanks for all the interest and support everyone. I will update you as soon as I get time to do the work. My wife and I have another baby on the way so we're prepping our house and getting ready for his arrival. Thats my priority right now, but the TA will get some more attention from me soon enough.

 

what about the ignition control module

 

I actually changed the distributor at the end of March. It came with a new cap, rotor, and ignition control module. I have replaced every part of the ignition system I can think of. I changed the plugs, wires, cap, rotor, distributor, ignition control module, ignition coil, and even the ignition switch on top of the steering column in the dash. The only part I know of in the ignition system I haven't changed is the actual key switch.

At this point I know the fuel pressure is a problem, I just can't be 100% positive that its THE problem. If I replace the tank, fill tube, pump, sending unit, and strainer and the car still doesn't run, then I'm going to utilize the new spark test tool I picked up when I bought the fuel pressure test tool. I'm keeping my fingers crossed that I don't have to use it though.

 

Sorry i wasn't aware of the distributor change. I am strongly leaning towards fueling, and since you have new injectors I suspect the pump. Just do it the right way and drop the tank so you don't cut a hole in your floor

 

Oh yeah, I'm definitely going to drop the tank. I'm planning on replacing the tank and the fill tube anyways. I can't knock people who cut the hole in the floor because that would make the change out easier. I just figure if I'm going to change everything anyways, I might as well drop it all the right way and keep myself from cutting the whole. With any luck, I won't have to drop the tank again for a long time. I might even replace the tank straps too just for good measure.

 

Im on the edge of my seat here reading your situation. I have a 90 Formula 350 giving me the same problem. No codes at all. Just wont stay running, like its losing fuel. Runs on starting fluid. I got to the bottom of your thread hoping for a solution!!!! Please keep posting you results. Its well appreciated

 

I wish I could say I'm the only one with this problem. It will be at least a few weeks until I get a chance to do much more on it because we're prepping for our next baby, but I will keep posting for sure. Have you checked your fuel pressure at the fuel rail yet? If not, I highly suggest you invest in the $30 tool and check it. I was trying to avoid buying diagnostic tools for a while and I know my car would be running already if I had just started with test tools. It was a mistake, but all the stuff I changed REALLY needed to be changed anyways. I knew I had a problem as soon as I checked my fuel pressure.

You should aquire the tool and test your pressure, then come back to this thread and post your findings as well. Maybe if we are both having the same problem with the same part and we fix it and post our results in this thread, we can help some other third-genners when they have this issue.

 

If it makes you guys feel any better I think my fuel presure regulator has a ripped diaphram and I really don't feel like pulling the plenum at the moment but I need to do to it because I can't pass inspection right now. So mine runs but won't pass inspection. THEY ARE ALL PROJECTS!!!!

 

You should definitely take the time to pull the plenum and change it. I did and it was a lot easier than changing the fuel injectors, I can tell ya that! LOL! I'm excited to get it up and running again. I know that with all the labor I've put into it and all the parts I've changed, it's gunna run like a champ as soon as I finish off the fuel system. I'm so happy with the T/A that I think I'm going to get a 3rd gen Camaro for my oldest son when he's the right age. He's only 9 now, so I have some time.

 

Yeah I typed that and then did it

 

So I guess the big question is: did it pass smog?

 

I've been following this thread because I have a similar problem Tested the fuel pressure at rail and it was only 10PSI. No wonder it won't run. The fuel pump is only six months old, but it seems like the most likely cause. Other threads have recommended the Bosch pump. Also the Walbro 225 was mentioned. Any thoughts on a replacement pump that will be better than the OEM?

 

Thats a very good question. Since I'm not ready to tackle this project yet I haven't really done the research. I'm VERY interested to see what some of the guys on here have to say on the subject of fuel pumps. There's a whole lot of knowledge on this forum and I know I'd love to hear anyones personal experiences, good and bad, with any brand of fuel pumps.

 

Yes but barely. I think the cheap aftermarket cat thats on it is on its way out. So to remedy that potential problem I have ordered Hooker emission compliant headers with y-pipe, a catco high flow 3 inch in 3 inch out cat and a Borla adjustable exhaust its going to sound so sweet

I have always had great luck with replacing the fuel pump with a AC Delco unit. I know its expensive BUT you won't have to do it again

 

I must agree, it's going to sound friggin awesome. It'll probably chirp tires better too.

Thanks for the heads up on the pump. Believe it or not, I found the AC Delco pump online for like $60, which doesn't seem too bad compared to the Cardone's pump at $51. AC Delco it is!

 

EDIT: This was a double message.

 

So I've been thinking about the symptoms that my car has and doing more research. I haven't ordered any more parts yet and because I have another baby on the way, I'd like to spend money where I need to. $190 for a new sending unit doesn't sound like a good spend if I don't need it. So I have a new question for all you fuel experts out there.

In your personal opinions and judging from the initial problem in post #1 and my fuel pressure findings in post #14, do you guys think I need a new sending unit or could it possibly just be the pump and strainer?

I haven't been able to find if the check valve I mentioned earlier in the thread is in the sending unit or the actual pump. I'm wondering if I need a new sending unit or if I should clean the one that I have and replace the pump and strainer?

 

the only thing the sending unit does is operate the fuel gauge. so if you think you don't need a correct fuel gauge you don't need to spend the money on it

 

Well alrighty then. My fuel gauge works just fine so I'll just be going with a good pump and strainer to get her running again. I'm gunna check my fuel pressure again when I get all done with it. I'm really hoping this does the trick so I can move onto other issues like brakes. First I gotta get it running before I worry about stopping.

 

I just want to be clear on this issue. Is there anything that will cause a low pressure reading (10 PSI in my case) at the fuel rail besides a fuel pump? I replaced the fuel filter, and the tank is full of premium gas. I want to fix this issue as soon as I can, but have not found a clear answer.(yes I did search). I'll throw the $$ at it, if it is the problem. I'd appreciate your expert input!

 

there is only a couple things that can cause low fuel presure. Here they are: Clogged Fuel Filter, Clogged Fuel Line, Bad Fuel Preasure Regultor (normally this causes abnormally high preasure) and a bad Fuel Pump.

If you have gone through the system but have seen no results it is time to drop the tank and do the pump

 

So yesterday I dropped the tank and replaced the fuel pump and strainer. Fuel pressure is 43 psi at the rail with no loss of pressure after primed, so the fuel problem is fixed. If you can believe it, the car still won't start! So now I'm exploring other avenues.

It has the security system with the removable kill-key under the driver side of the dash. I have pulled the battery a lot and the car went a couple of months without battery power. I hear that you are supposed to disable security systems before you remove the battery. I don't know how to disable it and now that the battery has been removed without disabling the security system, how would I reset it so the car will run? I know this might not be the problem, but I'm grasping at straws at this point.

I can't find any electrical shorts. All sensors that I tested had proper resistance and/or voltage. Fuel system is definitely good. Now I'm at the point where I'm going to check for spark (even though the entire ignition system is new) and then I'll aquire a compression check tool and check that too. Aside from checking those things, I'm down to the following question: Would the security system, the inflatable restraint system, the oil pressure sensor, or the throttle position sensor keep the car from starting?

 

If you don't care about the security system and its aftermarket what you can do it try to find the control box which in usually stuffed under the dash somewhere and cut the power or ground wires to disable it. I have done it before when the aftermarket alarms go stupid and the person doesn't have a remote. If it has a weather pack connector at the box just unplug it.

 

Unfortunately it doesn't have an aftermarket alarm. It's equipped with the VATS. After doing some reading online, it seems that the VATS could potentially be the culprit, but who knows at this point. Does it seem possible to any of you that the VATS system could be giving me my problem? I've already checked both keys and the orange wire down at the wire harness connector. Both keys and the harness are good with 4.75 Ohms. So if it is the VATS, the problem has to be between the harness connector and the TDM. Does anyone have experience with this terrible system and possibly have any suggestions? I haven't seen anything from the security light, past the first few seconds that it stays on when trying to start the engine. I've never noticed before, if it comes on when starting before I had this mega problem.

I really like this car and want it to run right. I've owned it for 7 months and it only ran for the first month. I've always been a fan of third gens and this is my first one. I'm bordering on wanting to get rid of it and looking for something older with less electrical junk in it. Normally I wouldn't want to just take the easy street, but I'm getting pretty frustrated with it. I hope I can resolve the issue and get it running soon.

 

I wasn't aware you were speaking VAT's. I thought you were saying aftermarket. Unfourtunatly the only way to dump vats is to have a chip burned. VAT's is good when it works right, but when it doesn't it can be a pain. I have personally never had a VAT's issue so I really can't tell you how to start diagnosing. maybe Ascdoc will see this and chime in because hes really good with this kinda of stuff

 

How about the fuel pump relay? I dont think i saw that in your list of parts that were changed.

 

just out of curiousity what kind of condition is the chip in the key? If its all worn down it might not make the resistance it needs to let the car start. just a thought

 

I didn't change it yet. Doesn't the fuel pump relay send power to the pump? It primes, gets good pressure, and maintains it now that I changed the pump and strainer. What would be the symptoms of the relay going bad?

I didn't think the chips in the keys looked great but I tested them both and got 4.75 for one and 4.72 for the other. Then with the key in the ignition, tested each key down at the wire harness connector and got the same readings.

I'm thinking my best bet at this point is to just start taking my dash apart and try to find any grounds or damaged wiring. While its apart, I'm going to get a VATS bypass module and hope that fixes the problem. I'm also going to put the dash back together with some reeeeeally clean pieces I got off a guy who wrecked his 91 TA.

 

Actually test that wire all the way to the ECM and see if your reading is consistant. You can buy the bypass module but I am not familiar how that works, I would assume that it tricks the ecm into thinking the VATS is always clear to start.

 

Will do. I'll be home tomorrow and I'm going to start testing and tracing ALL my electrical systems. It's going to be a huge project I'm thinking, but I'm kinda looking forward to it. With any luck, I'll fix the problem extremely cheap by finding a ground and repairing it. I think thats probably VERY wishful thinking, but a guy can dream.

 

Either that or a bad wire. You could also try checking in the inner fender where the harness goes through the fender and make sure there aren't any chewed up wires in there