My 86 has been stting up for the most part for a couple of years. Ever so often I would charge the battery and crank it and let it run. Some time back I had a problem with water in the gas tank. I have removed all the water but the engine would always run rough but would always crank. A couple of days ago, the battery would not hold enough charge to turn over the engine. I jumped it off and it ran fine except for the roughness (idled fine but cuts out when racing motor up.) After it ran a while, I cut it off and tried to crank it again to see if the battery had charged up. It only clicked telling me it was time to replace the battery. I replacerd the battery today (you know what a job that is). When I got through, The car turned over fine but wouldn't begin to fire up - not even a cough! I'm getting fire to the plug wires and fuel to the railing although I don't know what the pressure is. The thing that puzzles me is that it would run - I replace the battery and it won't run. Any ideas would be appreciated.

 

Spray some starter spray into the MAF and see if it will start momentarily. If so, you have water in the gas. Put some dry gas in the tank. You might have to drain the entire fuel system.

 

The starter spray will crank the engine for a moment or so. I siphoned all the gas and did not find any water in it. I thought I would check the fuel filter while the tank is empty. A Question: When I depress the pressure fitting on the fuel rail while the motor is being cranked I get just a slight oozing of fuel. Should I get a strong stream, or something more than a slight oozing? I should also mention that I get pretty good pressure buildup in the gas tank as evidenced by the whoozing when I open the cap.

 

Check fuel pressure.It could be coincidence that this problem is happening of you left or accidently disconnected something.Sounds to me like a injector problem if engine does run(poorly).Otherwise again check fuel pressure,ignition system,ohm injectors,& check for codes.Post findings

 

You should have a jet stream of fuel, when depressing the schrader valve. Pump should run for 2 seconds, when ignition is first turned on.
That should build up about 40 PSI.
Have you tested the fuel pump fuse, marked FR in the main fuse panel ?
http://members.shaw.ca/corvette86/Fu...iagnosis.pdfAs
As for the tank pressure, sounds like your EVAP system needs some work.
http://members.shaw.ca/corvette86/Ev...l%20System.pdf

 

Are you saying the fuel pump should run a couple of seconds with the ignition on but not cranking the motor? If so, when I just turn the ignition swith on (not cranking motor) I do not hear the fuel pump come on. I checked the FP fuse and it is good. The only thing I moved when I replaced the battery was the vacuum pump? located over the battery and moved the fender out some. There is an orange lead on the positive side of the battery cable - I checked it again and the inline fuse about 1' from the battery. I read in my Hayes manual about applying battery voltage to terminal G of the ALCL link under the instrument panel. Is this my next step (assuming I can find the ALCL link)? If so, can I run a wire directly from the positve side of the battery to terminal G? Is the FP fuse in the fuse box the only fuse to the fuel pump. I keep trying to make a connection with the fact that I jumped the car off, it ran ok except for the usual sputtering, and then after changing the battery a few days later it won't even try unless I spray the starter fluid. Sorry for all the questions but you guys are the experts and have been very helpful. Thanks for all your help!

 

Yes, the pump should run for 2 seconds with ignition on and no cranking.
The ALCL port is above your right knee/shin, when sitting in drivers seat.



Cranking should build enough pressure to activate the back up fuel pump power, via the oil pressure switch(goes to pump via same fuse in panel). Try powering "G" and report back. And read the link I gave you on fuel system diagnosis.

 

I'm confused about the A (ground) and B (diagnostic test terminals. The book said to connect battery to terminal G. Can I apply battery from a nearby terminal or do I need to run a wire from the battery? I couldn't access the links you gave me. One said web page not available and the other took me back to this page. Thanks for all the help!

 

Ignore what is written on the botom of pic, I posted the pic so you could see where the ALCL port is and what terminal is what. You are still going for terminal "G".

Don't know whats happening with my fuel system link, so I uploaded it to another of my sites.
http://dankai.shawwebspace.ca/asset/..._diagnosis.pdf

You need Adobe reader to open the files http://get.adobe.com/reader/

 

If you put +12v on terminal G of the ALDL the fuel pump will run continuosly. You can get +12v from your battery or from the cigarette lighter socket or anywhere else.

 

OK, when I turn the ignition switch on, I don't hear the fuel pump. When I put battery to the G terminal (ignition switch off), I can barely hear the pump - I seem to remember that it used to be louder. After turning the ignition switch on and leaving on, I get no flow at the schrader valve. After trying to crank the engine, I still get no flow at the schrader valve. When I put battery to the G terminal for a few seconds, I get a good flow from the schrader valve (I wouldn't describe it as a jet stream but good flow). Actually, I checked again after this post and did get a jet stream after the G terminal connect - I held it to the G teminal for a few more seconds than before.

Question: should the fuel system have enough pressure after doing the G terminal to crank the car? I realize the fuel pump is probably not working. I get a slight attemp to crank after the G terminal connect but no attempt at all with just a straight crank (not following the G term connect). Also, how does the fuel pump relay play into this - could it be bad? I don't hear a click or anything when I turn the ignition switch on. One last question: Would it hurt anything if I tried to crank the car while holding battery to the G terminal? I was wondering if that would tell me if the fuel pump was putting out enough pressure?

Thanks for the link! much better info than in my Hayes book.

 

The G terminal goes to the fuel pump motor through the normally closed fuel pump relay (relay not energized). You cannot hear the fuel pump relay click. Get on your sons bicycle and go to the nearest parts store and buy a fuel pressure gauge, they cost about $12 and finally find out if you have normal fuel pressure and if it holds up after the fuel pump turns off.
If you keep 12v on the G terminal and crank the car you will have constant fuel pressure and it should start if you don't have water in your gas.

 

It appears the fuel pump is not coming on at all through the ignition switch on or by cranking as evidenced by no fuel flow at the fuel rail, only when I use the G terminal. What would cause that?

 

When you begin to crank, the ECM turns on the fuel pump relay for 2 seconds and then turns it off. However, if the ECM receives pulses from the distributor, it will turn the fuel pump relay on. Also, when the oil pressure switch sees 4 psi, it will power the fuel pump (but not the fuel pump relay). If you crank the engine, the fuel pump should come on for at least 2 seconds .
Cranking and the fuel pump not coming on at all indicates possible trouble from the ECM, and/or the distributor (no distributor pulses and if no distributor pulses no spark either).
Jump 12v to the fuel pump fuse, its safe and this will force the fuel pump on continuously and then crank the engine to see if it will start and continue to run. Also, measure the fuel pressure to insure it is high enough and that the running fuel pump is working properly.

 

Thanks! I'll give that a shot. I appreciate both of you taking so much time to explain this to me. I'm pretty dumb when it comes to cars but have received a great deal of education on Corvetteforum.com.