Ok. here is the problem. I bought this vette about a year ago (its an 89') and when we first bought it it ran good but would occasionally miss, not to noticeably, but non the less you could still feel it. Ever since then we would drive it a few times a month and the problem would get progressively worse. Over the last few months I discovered it had a code 42 and I also noticed that the coolant sensor nearby the header was also disconnected, so I re-hooked the sensor and reset the computer and the code seemed to go away and stay away, but I don't think that really had too much to do with it missing. So anyways today was the day we were gonna test drive it after clearing the code and hooking the sensor back up and what not, so the first bit of driving we did wasn't bad, which was about 15 minutes of driving. Then we parked went to eat lunch started it and kept driving for about another 15 minutes. When we started to get to the house we stopped at an intersection and we were waiting for the light to turn green and then all of a sudden the car started to sputter for a few seconds and then rpm dropped it it died all of a sudden as if it were out of gas, so I started it and same deal, it started and then began to sputter and died. So for the third time the light turned green and it was time to go so I started the car and again it sputtered but was running and I pinned the gas to the floor and nothing the car didn't even budge. So we pushed the car to a nearby driveway and we started to think that it was maybe the fuel filter going out because it made since for the car to act like this and do all this over a period of time if this was our problem. So we ran home grabbed all our tools and bought a new filter came back, dropped the x-brace and swapped the fuel filter and put everything back together, went to go crank it but nothing....the starter just turned the engine for a while but the car wouldn't start. then we towed it home and its sitting in the garage and it wont start at all. Also we did unhook the lines back by the fuel pump and when the engine turns it does spew gas everywhere, and when you turn the key just a little to turn the electrical on, the pump does pump but it only squirt a little gas and it only does it a couple seconds and then quits (not sure if this is good or bad).

Sorry for the essay guys, Im just a man that really wants his car back on the road. I really appreciate even the slightest help.

 

It is normal for the pump to stay on for only 2 seconds after ignition is turned to "on". Hook up a fuel pressure gauge to the schrader valve on the passenger side fuel rail and try to crank the car. The pressure should be around 39-42 psi.

 

also forgot to mention, before we changed the fuel filter the car would start easy but it would just either die or run and sound real bad (even when it ran for a few minutes in the lot when you would go to pin the gas to the floor it was completely unresponsive; I mean it wouldn't even leave 800rpm)

 

Start with the basics. Check fuel pressure and spark.

 

Auto engines require three things in order to start and continue to run and you need to check all three to learn what is missing for your engine to start. They need hot spark and spark at the right time, fuel and air and in the correct ratio, and cylinder compression. Use a timing light during cranking to see if timing is ok and if you have spark. Bring a grounded wire close to an unplugged spark plug wire boot during cranking to see if you have a snappy at least 1/2" spark, Measure fuel pressure, it should be 35-42 psi and it should hold up for at least 1/2 hour with the ign off. If pressure falls rapidly you may have leaky injector/s or a defective check valve in the fuel pressure regulator. Use a noid light (available from parts stores) on one injector plug on each cylinder bank during cranking to see if the injectors are being pulsed. You can make your own noid light with an LED (light emitting diode) in series with a 680 ohm resistor. The homemade light must be connected to the injector socket with the correct polarity, you can try it both ways. Last, measure compression.

 

thanks, I will play with it tomorrow but I still don't think it has to do with spark or air, because why would it stop all of a sudden after running perfectly fine for half in hour, and when I mean sudden I mean from when it started acting up and when it died it couldn't have been more than 50 feet (best I can sum it up is it acted like it was out of gas so we figured maybe it wasn't getting any so then we replaced the filter.

 

It sounds like there's not enough fuel getting to the engine. I would check the pressure first. It's most likely the pump, or the pump filter is clogged.

 

check the 4 pin connector behind the distributor that it's still connected.
The dist. sends a signal to the computer through that connector, and tells the computer when to switch on and off the fuel for each bank of cylinders.

 

I'm almost sure its not getting enough if any fuel, but the lines still pressurize with out the pump, it just means the engine has to suck all the fuel vs having it pushed to it via a pump, but when we unhooked the lines at the pump and cranked the car it would spew fuel everywhere. so if its fuel related I'm starting to think the problem is at the fuel filter or after it.

but one more thing, im worried that when we parked it in the lot and declared it was undrivable it was still able to start it gust ran **** poor and when you gave it gas it either wouldn't respond or die. It only wouldn't start after we replaced the filter when we thought that was our problem.

 

If you think it may be the fuel filter why don't you briefly bypass it with a piece of high pressure fuel hose and see how the car runs.

 

I am having the same problem with my 85 except it will start and can be be driven some but if you give it the gas it'll just stumble,ocassionally backfire and be unresponsive for a few seconds then suddenly accelerate and then go unreponsive again. It does this back and forth then at times seem to clear itself and will run for a little bit,then start all over. At this point the fuel pressure regulator has been changed(only made the problem worse) with an adjustable one. The fuel pump was changed about 4 months ago due to going bad and all was well for about 3 weeks then this stumbling and hesitation started. Will keep you up to speed as this drama unfolds maybe between the two of us we can solve this problem.

 

Fuel cannot be sucked to the injectors!!!!! It must be pumped there. You have evidence of fuel pressure but you have yet to measure the amount and if it holds up with the ignition off. You haven't checked for spark either, engines instantly quit when there is no spark. An injector/s that intermittently stick open will flood the engine and make it run rough and then quit. When it quits do you have black exhaust?
You need to spend your energy running the tests I posted instead of posting here, you will have a better chance of finding out what is wrong. Instead of guessing what is wrong, do some diagnosis!!!!

 

I will check, I just don't have a bunch of time, but back to the injectors; doesn't the engine create a vacuum when cranking which pulls the gas up to the injectors.

 

No it doesn't, When you turn the key to the "on" position,the pump pressurizes the system, then when you turn it to crank, the pump comes on again. These cars use pretty high pressure in the fuel system, and while it may be spraying fuel everywhere, it still may not be getting enough pressure to make the car accelerate. The pump went bad in my 86 and it started the very same thing. Also, take a note of what the oil pressure is when you turn the key to "on", I think hat has something to do with the engine being able to crank.

 

I think your right, because even after cranking for a while I noticed the tank wasn't pressurizing, meaning when you take the gas cap off there was no pressure that I noticed (kinda like when you open a bottle of soda) which would make since that the pump is starting to go out.

 

You need to understand the C4 fuel system. The fuel pump pressurizes the injectors through the fuel pressure regulator. The fuel pump has higher delivery capacity than required so the pressure regulator can do its job and excess pressure is bled back to the fuel tank. Removing the gas cap will reveal NO pressure because the fuel pump is merely circulating gasoline from the tank to the fuel pressure regulator and then back to the tank. The fuel injectors have a spring loaded valve in them that doesn't allow gasoline to pass through them until an electrical pulse on their coil occurs which lifts the valve (called a pintle) and the 40 psi causes the injector to spray a fine mist of gasoline. The intake manifold vacuum cannot act on the gas in the fuel rail which feeds gas to the injectors!

 

Ok. makes sense, then in that case when you turn the key (only electrical) the fuel pump should start pumping constantly not briefly like mine is.

 

No, yours is acting exactly as it should. It should only pressurize for about 2 seconds when you turn the key to on. But as I said earlier, it's probably getting some pressure, but not enough.

 

When you switch the ign to run, the fuel pump is turned on for 2 seconds by the computer. The fuel pump will turn on if the computer receives reference pulses from the distributor and it will turn on if the oil pressure exceeds 4 psi. So if you turn the ign to run, the fuel pump will run for 2 seconds and stop, then after waiting longer than 2 seconds, you begin cranking, the fuel pump will come back on because the distributor sends reference pulses to the computer.

 

Read these >>

http://members.shaw.ca/corvette86/Fu...l%20System.pdf

http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf