My Corvette starts but hard to crank

[hdixon]

Hi everyone I am a new member to this group and hope I can get answer to some of the question that I have about my 1989 corvette. when my corvette sets overnight it is very hard to crank it starts but there are times when it will run down the battery down before it finally starts. I have replace the following fuel pump, spark plugs, distributor cap, rotor, new spark plug wires, fuel filter,also had the injectors replace a few years ago. I need help before I go broke.

Thanks.

 

[Rob]

Welcome to the Corvette Action Center! I'm going to move your thread into the C4 Tech forum for greater exposure.

 

[Midnight 99]

It sounds like one of the cells in your battery is weak. You should have it tested. A quick way to check is to swap batteries with another car to see if it does the same thing with the new battery. Although there is not as much parasitic draw in a C4 as there is in a C5 or C6 it is still there. I highly recommend a CTEK or Battery Tender for your car. I installed a battery tender quick connect on my brother-in-laws 86 convertible and did it so he can access it through the side cove (gill). He keeps it plugged in when he isn't driving it.

 

[ned pepper]

Hi everyone I am a new member to this group and hope I can get answer to some of the question that I have about my 1989 corvette. when my corvette sets overnight it is very hard to crank it starts but there are times when it will run down the battery down before it finally starts. I have replace the following fuel pump, spark plugs, distributor cap, rotor, new spark plug wires, fuel filter,also had the injectors replace a few years ago. I need help before I go broke.

Thanks.

it may be lean or rich, either will do this. if so, most likely rich due to injector leaking. the book says: try the "clear flood" method; hold pedal to the floor while cranking so that the ecm will lean out the injectors.
if it is "lean" it could be lack of fuel to the rails.
the fuel pump should energize for 2 seconds when you turn the key ON. is it? this is to prime the rails. if it is coming on, shut OFF, wait ten seconds, turn on again. do that several times so that the pump runs about 10 seconds. try to start. you have to wait 10 seconds of so between attempts to prime or the ecm will not turn pump on.

it is not likely the battery if it turns the engine for several seconds. my 90 starts in less than 2 seconds all the time. low ignition advance will do that also. should be set per the book, at 6 advance.
these are quick things to try. the symptom covers several pages in the FSM.

get back with the info and someone will jump in.

ned

 

[ned pepper]

added comment

I failed to mention that IF this is just an overnight or long time between starts issue, and I assume it starts fine -less than 3 secs crank otherwise- it points to a slightly leaking injector. a fuel pump can leak pressure back to the tank if the check valve is failing, but pump is new.

also, you have to "listen" for the 2 secs of prime time, because it is not that obvious.

there are sensors that can cause this but I believe they would also cause continuous problems, CTS (coolant temp) and MAP sensors (manifold absolute pressure) or MAF (rather than MAP) if you have that on an 89, not sure if you do. TPS, throttle position sensor, too, but would be a problem at all times.

also 2, the book says to check both fuel pump fuses. I think it will actually start on one but not run well, but check anyway.

if it is "LONG" crank, more than 4 seconds even when warm, it may be ignition related, such as timing.

"sensors-fuel-ignition," so says the book. but not in that order.

### I realized too late that I may have not understood the problem: is it "hard/slow cranking" or long crank without firing? if slow to crank, the battery may be too low, as someone mentioned, maybe something is ON that is supposed to be off, light in dash, etc. if it is slow rotation of engine then all my suggestions will not apply. the FSM says, first thing, that battery power must be adequate to spin engine at the proper RPM.