View Full Version : hard starting 84

04-05-04, 08:56 AM
Got the vette out saturday rebuilt the throttle bodies,new plugs,It still takes a long time for it to start.any Ideas?Is there any way to check the coil?or maybe the voltage going to the plugs?

04-05-04, 05:00 PM
Just a guess, but...when you first turn the key to the on position, you should hear the fuel pump run for about two seconds. If you don't hear it run, the fuel pump relay may be bad. Then the only way the pump gets power is through the oil pressure switch after oil pressure build up. Which explains the long crank times.

04-05-04, 10:33 PM
have not check to hear the pump but I had the aircleaner off and I can see the injectors spraying while It`s cranking.I`m thinking I`m not getting enough juice to the plugs like maybe the coil is going bad.

04-06-04, 06:47 AM
Usually an ignition problem will not only affect starting, it will give you a problem while you're driving too. If not, hook a scan tool up to make sure that the sensor readings are OK. I would look at the MAP sensor voltage and the coolant temperature reading. Both of those inputs will affect injector pulse width.

04-06-04, 07:54 PM
have not check to hear the pump but I had the aircleaner off and I can see the injectors spraying while It`s cranking.I`m thinking I`m not getting enough juice to the plugs like maybe the coil is going bad.
During cranking the oil pressure switch will bypass the relay and directly energize the FP, but it still should run for a couple of seconds after turning ignition on but before starting. If its not doing this then it is not building up pressure before you start cranking, only after it has started cranking. This can cause longer than normal start-up time. Might also be a good idea to stick a FP gauge on there and see what the pressure looks like. When you turn the key on (before cranking) the gauge should jump up to somewhere between 9 and 13 PSI pretty quickly, and it should maintain that pressure while running.


04-07-04, 10:18 PM
can anyone tell me where the fuel pump relay is and how to tell if it is bad?

04-09-04, 03:45 PM
What coil do you want to check? The ignition coil or the pickup coil. Post and I will check my Helms. Generally speaking, if the coil is bad the car will not start. A weak battery will also cause hard starting. When did the problem begin, before or after the TB rebuild?

04-10-04, 10:18 PM
bought a new coil,plugs,cap,rotor,still starts hard,cranks forever,let it set and crank somemore and finally starts.battery is one yr.old and had it in my truck this past witer to keep it charged.the problem started before the throtlle body rebuild.

04-11-04, 12:55 PM
Did you check the fuel pressure like was mentioned? You could also have a weak pump too.

04-11-04, 10:10 PM
have not checked the fuel pressure yet,I will this week,I think I need at least 9lbs. right?
Anything less than that The pump is shot?

04-12-04, 06:40 AM
The correct spec is 9-12 psi. But if you don't have that, it doesn't mean the pump needs to be replaced. Before you buy a new one, check the rubber coupling from the pump output. Some times they leak or have a pin hole.

04-12-04, 10:00 PM
yes I think I`ll check that rubber line first because my understanding with fuel pumps either they work or they don`t,I`ll also check the filter and maybe the fuel pump relay any advice on the relay?

04-13-04, 06:58 AM
Yes, the relay should be one of your first checks. Make sure that it powers up for two seconds when you turn the key on. Before you do anything else, make sure that you at least have power to the pump.

If the relay doesn't power up...I'm here if you need help.

04-14-04, 09:39 PM
checked out the fuel pump.took it out,looked fine bought a new 85 pump,put that in replaced the fuel filter,hit the key,cranked ,cranked and cranked.
let it sit for 10mins.went out and cranked some more,finaly started.let it warm up shut it off and she fires up every time.got up this morning went out and cranked and cranked some more,started up and let it warm up.Came home for lunch and she fired right up,the temp was still around 100.new plugs,cap,rotor,fuel pump,filter.any other ideas to try?maybe wires?It almost seems like it flooding out.

04-15-04, 07:24 AM
Steve, I hate to sound like a broken record, but....is the pump working when you turn the key to the "ON" position? The pump should run for two or three seconds when you do this.

04-15-04, 07:36 AM
Steve I don't doubt your abilities but you may wanna find a person who really knows the Cross Fire Injection and have him set up the throttle bodies for you. I had mine done by someone who is very good with them and the car runs killer and starts on a dime. The Cross Fire is very sensitive to its settings so it pays to be right on.


04-16-04, 10:37 PM
yes I can here the fuel pump run when I turn the key to the on position,

04-17-04, 12:00 AM
Do you have symptoms of that? The '85 pump is for TPI, which requires much higher pressure. Also, I had a lot of problems with the TBs leaking after rebuilds; repeatedly. Perhaps yours are leaking and pooling fuel in the intake manifold.

Check for black smoke at the tailpipes when it finally fires. Were your old plugs fouled?

I wonder, if it IS flooding or pooling, if it'd start faster with the throttle open fully, giving more air for that gasoline.

04-17-04, 12:15 AM
thats what I think it`s doing is flooding but if I open the thottle it`s no better,the only way it will start is if I keep my foot off the gas.the old plugs were fouled and no black smoke,Tommarow I`ll check the injectors to see if there leaking,

04-17-04, 08:48 AM
Replacing the pump with an '85 unit is an extremely common "upgrade" for '84s. That's not the problem.

Based on your description it doesn't really sound like "flooding", but DO check for fuel leaking from injectors when ignition is on and engine not running. Like WhalePirot said, this is VERY common.

Need to check fuel pressure (don't see any numbers here yet), have TBs balanced (like MoeJr said...make sure someone who KNOWS how to adjust the CFI does it!), and check for major vacuum leaks (EGR valve stuck open could be a culprit).