has anyone ever tried to eliminate the electronic mess that GM created in the '86 thru '89 C4's by removing the electronics, tuned ports, air flow system, vats, etc. and installing a standard intake manifold/carb setup with manual linkage? I have replaced everything related to the fuel/spark systems, (both mechanical and electronic), and 1988 4+3 still cranks but won't start intermittently! Last time out I got 10 starts in a row before it acted up and yes I can hear the fuel pump hum for 2 seconds then a little 1/2 second "vroom" as it tries to start with no success. waited 4 hours this time and still wouldn't start. Left overnight and it started right up. doesn't matter if engine is hot or cold it acts up regardless of temp. Been to GM dealer twice and now they are stumped! this vette had start problems in March of '89 and they replaced the cylinder lock assy and keys. I am the 3rd owner. bought it 2 months ago from a seller who knew the problem but didn't tell me. (it started fine when I test drove it then failed on me when I drove it home, after paying him $8,000 cash for it) In good concience I would never try to sell it to someone like it is. It is worthless as it sits! If I could retrofit the engine to a mechanical condition without the 'brains" that is my only thought, other than giving it away. it only has 73,000 miles on it and looks like new inside and out!

 

Yes, it's been done 1000's of times. I would do it if I couldn't solve the electrical issues but I'd rather fix the injection. What codes are you getting when it doesn't run?

 

After re reading your post it sounds like it could be a VATS problem. Search "VATS Bypass"

 

that would be easy to do but I thought vats related start problems did not allow the starter to turn over. my starter cranks like a raped ape! I'm having a hard time finding any threads that would be helpful for me to do a retrofit if that is what it comes to.
thanks!

 

SBC Chevy intake w/ carb. One 12v wire to the HEI. Aftermarket gauges. Not so hard.

 

If you have tried and failed to solve the problem, then it might be time to find a good Corvette mechanic (not the GM Dealer) in your area and have it done. Probably cost you less than the cost of converting to carb.

Since this is an off and on problem without a pattern, you might want to get a scanner and keep it plugged into the car and data log the car until this problem happens.

My guess would be 1) fuel 2) electrical (perhaps the control module in the distributor) 3) ECM.

 

will the manifold/carb setup sit under the hood without needing to modify the hood for clearance problems? Do you have to eliminate the ECM, ICM, air intake system and dash components ? If someone has done this please let me know what it would cost to have a mechanic do it for me as I don't have the expertise. If I did it I would probably want to install a performance cam to make up for the lost horsepower from no TPS.
thanks

 

Find a vette mechanic man. Cheaper than this... by far.

GM is NOT somewhere I would go for having a vette serviced!

 

replaced the ECM and ICM within past 3 weeks fuel pressure is fine and it is getting spark enough to make an attempt to start but then fails. Left it overnight and it started right up.....Grrrr! as I stated in my initial post everything that could be causing it has been either checked out "ok" or replaced both mechanical and electronic. It's like the "brains" are intermittently doing some weird signals that interfere with the starting process. It failed to start at the dealer and they found the ECM to be faulty but that did not fix the problem. I will bypass the VAT system and if that doesn't work I will try to find a mechanic that can retrofit a carburetor onto it and bypass the electronics but I'm having a hard time understanding how the throttle system will work without revising it with mechanical linkage etc.

 

Where are you? There may be a local 'vette expert in your area, ready to help. Sure hate to see a nice car butchered like that!

 

I'm in Willits , northern Calif. I've read some things on converting tpi to carb and it looks like you have to change fuel tank and fuel lines as well as fuel pump and dash instruments too? Also said the 4+3 transmission will not function properly. It sounds like a real cluster! If I can't resolve the no start problem I will have to either give it away or part it out. Just bought it 2 months ago and have 9k in it! It looks like a new floor model vette..... with ghost inside it...........too bad!

 

VATS can disable the injectors. No injector pulses, no spark. I had the same problem, starter spins but no start. If it doesn't start first try you have to wait (I think three minutes) for the VATS timer to reset. I disabled VATS in the PROM and no more problems.

 

Well it's not the VATS then. It will not start after 3 or 4 minutes. It doesn't start until the next day sometimes. sometimes 3 or 4 hours but never minutes. It would cost around 2k I'm guessing to have a side mechanic do a carb conversion with manifold, carb, nice air cleaner, distributor, fuel pump, regulator, & misc. items plus labor. For about another grand I could have him install a new cam, lifter and rocker set. that would up the engine to the 6500 rpm range and maybe add 5o HP or so.

 

A vette mechanic can fix it a hell alot less than 2k.

Dont forget the cost of a new hood in your carb conversion figure there either. That's another grand and change right there....that's not counting paint cost either.

You live in california..plenty of shops out there, performance shops and vette mechanics I'm sure.

 

Your posts are very frustrating. You sound as if you have no idea what the hell you are talking about. Are the injectors pulsing during the no start? Do you have spark? Have you pulled codes? Do all that and get back to us. Caribing this car at this point is idiocy. So is parting it.

 

If my posts sound frustrating it is because I am frustrated and you are right I don't know what I'm talking about. that is why I posted here so I could glean some helpful information. I know nothing about working on these machines. I've changed out a headlamp and replaced a coil....not much is it! If you read my post you will see I've had it to the dealer twice and they ran codes and determined it was the ecm and then the icm but that didn't solve the problem. furthermore after checking all of the service records from the individual that sold me the vehicle I see that he had start problems too and had taken it 3 times to a corvette restoration shop where they did extensive work on it including replacing 3 cat converters, distributor, wires plugs, all sensors, checked injectors, spark, fuel pressure and many other things with no resolution. The dealer I took it to said his techs were stumped, that they don't have any techs familiar with the older vettes and he doesn't even return my calls now. I am going to take it to a repair shop that has some good electrical people and give them my GM manual to help them next week and see if they can resolve the issue. If they can't then that doesn't leave many options does it?

 

Ok. Come down off the ledge. Fold up the "Repent- the End is near" sign. You need three things:

Test lamp (6-12v)
Digital multimeter
Factory Shop Manual
Total cost of these is about $75 if you have a Harbor Freight near you. The factory manual is $50 of that, get that on EBay. I would also probably buy a fuel pressure gauge as well, now that I think of it.

Get that. Drink a cold beer. Sit down and read section 5. And then get out to the car with the computer nearby and start testing and asking measured questions and providing meaningful feedback. We will get you through this. One other thing; I no longer make assumptions based on what parts have already been replaced. That has hurt me in the past.
You need three things; fuel pressure holding at 40 psi. Good spark. And lastly, injector pulse. During your no start condition, if you have all three, it is the injectors. But make no assumptions until you have tested everything!

 

I re read this. You have the factory manual already, you are way ahead. Starting drinking beer and reading.

I don't care if Gordon Killebrew diaged the car at this point. I take no one else's word for it based on where you are right now. Start with the basics. I have my suspicions but will reserve them for the moment. I just went through this with my dad's 86 and we fixed it.

 

I carbed my car for a couple of years. Ran ok but couldn't beat the fuel perculation problem, even with hood ducts. Back with a miniram and happy. By the way, the stock gauges all worked with the carb except for the mpg readout.

 

Anyway, we are here to help. NO CARB! I can answer PMs directly as well my man.