Hi guys, im new around here, i brought my '94 z28 m6 home on friday, its completely stock with 208,000.. i got a nice deal on it, and was ecstatic that it ran so perfectly, no rattles, squeaks, good oil pressure, everything. Well, ive been cruising around because its been so nice, ive put almost exactly 200 miles on the car since friday morning, and have just been so excited about it. Well, tonight, right after i drop my friend off, the car started acting up. i get about a quarter mile away from his house, put it in 5th gear, ease on to the gas, and the car starts to fall on its face.. push the clutch in, hit the gas, revs like nothing is wrong, still good oil pressure.. drop it in 4th, press the gas, same thing happens.. put it in neutral, revs fine. try again and same effect for 3rd and finally 2nd, i pull into a parking lot, and the thing dies as i roll to a stop. i try to start it, it fires a couple times, then nothing. wait about 10 mins.. wont start at all. i finally give up and call my friend, we get some jumpers and a flash light. nothing visibly wrong( i was thinking thrown rod.) check oil, no shavings.. try to start it, it runs for about 5 seconds and sounds like ****, bad misfiring, then dies and wont start again. had him take me home, and i get on here. With the car having so many miles, im thinking optispark.. is there anything else? fuel pump? im so upset i could just cry about this, ive wanted a z28 6spd since i was like 10 (18 now) and was so happy to finally have one. im going back to the car in the morning, is there a schraeder(sp) valve on either of the fuel rails to check fuel pressure? also, if it is an opti problem, how do i check to make sure?

thank you all for your help in advance.

josh

 

dont know what it might be, but if u wanna check the fuel pressure the valve is way, way in the back of the engine. it looks like a tire cap. it comes out at a bit of an angle towards the DS of the car.

 

alright, also, the car is sitting with about 1/8th of a tank in it.. i havent revved past 5k in it, nor have i gone over 75(highway) i have not abused it for these 200 miles ive owned it, when i test drove it last week, i had the car about an hour and put maybe 35 miles on it, and ran perfectly.. i just dont know what the hell is up..

 

The fuel guages in our cars are extremely unreliable. I actually ran out of gas when I first got my car when the guage said I was at a little below a quarter tank. I would say go and add a little gas to your tank just to rule that out as an issue.

 

i'll try that.. just went back to the car, still wont start, but wont randomly fire, either, and is throwing a ses code, any way to check those without a scanner? if not, its dead across the street from autozone.. i just dont like leaving it out all night.. its not really in a good part of town..

 

I REALLY hate saying this. It's the first thing the finger gets pointed to. Opti-Spark (Distributor). I would consider that a last resort. Get the basics checked first. Fuses, codes, fuel pressure, spark, grounds. Then, we'll go from there.

 

alright, i spent all night messing around with this. went back to the car with a 5 gallon gas tank.. put it in, took a bit, but it started, when i press the gas in neutral quickly, it will stumble and pop, when i press it more than say, 20% in gear, it will stumble and try to die. no ses light, so its gotta be the opti or other ignition parts, right? also, the car seemed to run pretty well on the way home, until it got warm...

 

got in the car today, ran fine in lower rpms.. plenty of power, until it gets to about 4500.. then it just doesnt want to rev and the power is gone.. i threw a check engine code, but autozone cant read it.. anybody know of any places that can read an obd1 car?

 

Check the fuel pressure. Once it runs out of gas the pump may be permanently damaged. Schrader valve is shown on Shoebox's photos:

http://shbox.com/1/fp_reg.jpg

You need an OBD-I scanner. You can find used Auto Xray units for under $100. There is also free, downloadable scan software for your laptop... just need to buy a cable. Actron, Auto Xray and others make OBD-I scanners - just make sure they are "real" scanners, and not the $30 "short-the-pins" units that claim they work on 94 LT1's but don't.

Last resort - a dealer can scan it. Even if the SES light is no longer on, the code is stored. The Opti will set codes for problems with the optical sensor (cam position), but not for problems on the high voltage side (cap/rotor).

 

thanks for the tip. i have another question though, i took the fuel pressure gauge off of our grand nationals fuel rail, removed the schraeder valve on my camaro, but the fitting must be slightly bigger on the camaro, because i cant get it on. im off to auto zone to get some fuel line and clamps..safe?

 

A fuel pressure gauge from autozone is 40$. Ask me how I know. HAHA

 

thing is, i dont want to go buy another one since i already have a working one.. i just need to know the fitting size on the end of the valve.. it should be 3/8th right? also, ses light is gone, that was my retarded self, i took the air intake off earlier to try to get a better look at the opti spark.. i forgot to plug the maf and the other plug back in. so, if it IS 3/8 fitting, should i get the russel stainless braided line? or what? also, thats a pretty sharp angle right away.. any pics of an install?

 

The Schrader valve is a -4AN connection, not 3/8".

 

thank you for that, think auto zone carries the fitting?

 

You need a hose to connect your fuel gauge (probably 3/8" NPT male) to the Scrader valve. That "hose", if you buy a fuel pressure test gauge, has a -4AN fitting on the end that goes to the Schrader valve, AND a pin that depresses the core of the Schrader valve. If you are just trying to hook a fuel pressure gauge up using standard fittings, you have to remove the core from the Schrader valve using a tire core valve tool.

Maybe you could find just the hose assembly for a pressure test setup, which also usually includes a small pressure relief button, so you don't drip fuel down the back of the engnie when you disconnect the hose.