Tried to start the '87 vert this am. It normally starts without depressing accelerator. After repeated tries turning key to start and it didn't I then fully depressed the accelerator to the floor and it started. BUT then it wouldn't stay lit when I let it go to idle. Repeated same with the same results. Me thinks its a fuel filter or fuel pump. It sat garaged this winter with occasional starting and runup to max temp. Any help in advice would be appreciated. Thanks, CAB

 

Check the fuel pressure.

 

Water in the fuel is more prevalent these days due to 10% ethanol in the fuel. Change the fuel filter yearly.

 

When you press the accelerator pedal, the ECM cuts off injector pulse until the engine is running. So, other way around. You're flooding the engine somehow. Maybe a leaking injector?

 

Sounds like a leaky injector could be flooding the engine.

 

My car does this after a long sit. I think it has to do with the battery drawdown voltage over time. Pull the neg bat cable off for a minute, restart it (even if it is running poorly) and drive it a little bit if possible. Works every time on my car. EDIT: By long sit, I am talking months. this has happened maybe 3 times in 20 years.

 

Yep...
start with fuel pressure test to SEE IF there is a filter problem.
IF the pressure is good and stable, then move to the fuel itself. Although I have recently seen fuel that was several YEARS old burn and run like it was bought this morning...its just not a good idea.

If the gas has been ok'd....next look at the fuel pump relay. Long cranking smacks of FPR issues where the back-up oil pressure switch comes into play. You might end up at the temp sensor too. ANY of the essential sensors under the hood can get dirty connections during storage. When the contacts are dirty the signal value changes...cold start-up is the single worst time for any sensor to be slightly out of spec...and make the eng hard to start. Once warm its fine. Cold...the sensor value (coolant temp) is marginal. If its 'off' the thing won't wanna start. because ALL these sensors are sending their data based on a level of resistance, even some grease on the elect contacts can change the values...and corrupt the signal.

Depressing the gas pedal does NOTHING to start a EFI car. The ONLY thing flooring the pedal does is to help with a flooded engine. TPS will see that. The Fuel system is designed to NOT supply fuel when cranking until the engine lites and runs on its own,...to prevent flooding. Designed that way. You get a 2 second "prime" of the pump...that charges the rails and then you have to get the engine to run or you don't get anymore fuel on THAT key rotation.
Once its running without the help of the starter,THEN it will let the pump run again and re-pressurize the system. Stepping on the gas while cranking is pure placebo effect. Gives your foot something to do until you're in gear.

 

Good info, thanks. My question still is, why won't it idle once I let up on the pedal? It just dies.

 

Can't drive it! It dies if I don't keep the pedal depressed to maintain fuel input.

 

I am going to start with this tomorrow. Picked up a fuel filter this pm. Once I figure how to get that installed at least I'll have that out of the problem equation.

 

Unless the filter is blocked 100%, fuel pressure will stay the same. He will lose volume, not pressure with a gummed up filter.

 

It is one thing to go on, and on, and on, and on in a post, but contradiction is quite another thing.

Clearly, depressing the pedal to the floor does do something! It enters into flood clear mode now doesn't it. So it does do something.

If it starts in flood clear mode it wouldn't seem in my little mind that we have a lack of fuel issue. It could be a bad TPS, CTS, injectors, and so on that is defaulting to max fuel that occurs when these devices go bad. Start by scanning for appropriate values, and ohm injectors, and feel each one for a click.

Think about what causes a flooding condition upon startup?

 

A ruptured FPR (Fuel Pressure Regulator) diaphragm will cause this problem.

Take the vacuum line off the FPR. Turn on the ignition without starting the engine. Check for fuel coming out of the FPR. If you see fuel the diaphragm is bad.

 

Replace the fuel filter o-rings at the same time. They don't come with the new filter. When you get the old filter out, pour the contents into a container for inspection to see if condensation exists. I would purge all fuel lines as well. If you have water in the fuel filter, you may have it in the tank as well. The tank is pretty easy to clean on a C4 from the top. Be sure to replace the sending unit gasket if you break the seal as a leaky gasket can draw water into the tank when driving in the rain. Also replace the fuel cap to make sure it is sealing properly. Make sure the fuel overflow tube is un-obstructed. Water can be drawn in through the fuel cap opening if water puddles in there.

 

Yes it will, so I have learned. This was my first thought as well.

 

I'd be leaning towards IAC.

 

Safety first!! Make sure any time you check for fuel with an open connection, you have a catch container and a fire extinguisher handy.

In theory S. Soden is correct about the constriction. As long as the fuel has somewhere to "stop" it will build equal pressure but if it is being used and the constriction is bad enough lower pressures can occur. Considering the actual small volume of the fuel system, this may not be true in the real world.

Try what Power porker suggests anddisconnect the battery terminal first. This will reset the ECM and may correct your issue. Reset the minimum idle speed. Check the IAC count. I also lean that way.

 

I fully agree with safety first. In my experience with checking the FPR, however, even if it is bad, very little fuel will come out. But I always have a rag in hand when I do it to catch anything that does come out.

I won't say it isn't the IAC, but his symptoms are pretty much identical to when my FPR failed.

 

Thanks. Of all the suggestions and different components that could fail I received the suggestion to disconnect the battery which resets the ECM worked. I have no idea what caused it to fail initially but the problem seems to have gone away....I hope!!

 

Thanks, of all the suggestions I received of problem components your suggestion of disconnecting the battery worked. The ECM was reset and it fired right up. I ran it for about 20 miles with no problem. The test will be tomorrow with a cold engine to see if it restarts. I had just had it running the day before this episode so not sure what demon possessed it a day later!!!