My 91 L98 intake gasket started leaking coolant a couple of months ago. After many hours new gaskets and new injectors were installed. No more leaks--but right away I noticed I had to crank the motor for several seconds before it would fire. Before I removed the intake this car never failed to start the first second I hit the starter. Now it doesn't make any difference if it sets five minutes or five weeks i have to crank it over probably 7 seconds before it fires. When it does start there is usally smoke appearing to be almost flooded. Any ideas? It's just too much of a coincidence that this happened the day I put it back together. I'm sure it's not the fuel pump or a fuel leak. All vacuum lines and sensors are plugged in. I used factory GM injectors. What could be making the car have to crank so long before firing? Seven seconds may not sound like that much but it's a world of difference from before. And if you're in a parking lot every one is looking like will it start or not?
Where do I start checking?

 

When you turn the key to the ON position do you hear the FP relay energize for 2-3 seconds? If you do I'd check the fuel pressure at the schrader valve...the smoke on start up may be because you have a leaky injector(s) yes, I know there new.

 

look at the fuel pump relay on the firewall right behind the left row of bolts that hold the manifold to the engine. if you tapped this relay slightly or pulled on the wire harness when you put it back together, the connector came out of the fuel pump relay. push it back in

 

I do hear the fuel pump when the key is turned on. I will have to get a gauge what should my pressure be at the rail? And should it stay pressurized or does it leak down with time? I assume you are talking the driver side of the firewall for the fuel relay? It was very tight working conditions. If I knocked a relay or wire loose--would it only affect starting? As the car seems to be running great after start! It just got slow to start after intake gasket install.
Thanks for the input.

 

i had the same problem. turned over a few times before firing. check for leaks at fuel connections. mine was the gas cap . it was not holding pressure. good luck

 

be sure and check the o-ring seal on your injectors...just went through this, and mine were leaking...not fuel, but you could just see a puff of vapor around the bungs...changed the o-rings, and she fired right up on the first second the key was turned...

 

I would double check what you did. It sounds like you left something unplugged if you find the fuel pressure holds. I should not drop more than 10psi in 30 minutes if the fuel system is up to par.

 

I also had a similar problem when the engine got warm. It would turn over maybe 2.5-3 seconds and then weakly fire up - kind of like it was coughing. I then replaced the spark plugs to NGK irridium and noticed the old ones were extremely worn and some even rusty ...they significantly helped my start up and the car runs like it should now, especially after upgrading the wires to Accel 8.8mm and changing dist cap/rotor.



Dave

 

when I bought my corvette, I was walking to the mailbox, and the new neighbor that just moved in was putting a for sale sign in the window of the vette. I inquired how much he was asking, he told me, and invited me to look it over. He opened the doors, hood, and hatch, told me all that he had had done, and told me $14,000.
I promise i'll make this short.
I asked him to start it up, and he said oh it doesn't run, but he assured me it didn't need much to fix it. I gave him my phone number and left.
The following saturday, he asked me how much i'd give him, and I said if it doesn't run, $85oo he said if you are here with a check within 3 hours, it's yours.
we pushed it down to my house, and I was going over things, and there was no oil in it.
So I put in a quart, and it still didn't show. I added 5 quarts b 4 the
dip stick read full. My wife came out of the house and said give me a ride.
I told her it didn't run, and she was upset. I got in the driver's seat, to show her, and it fired up after a bit of crankingRrRrRrRrRrRrRrRrRr
only later talking to a guy at the car show did I find out that the oil pressure switch is the secondary means of energizing the fuel pump.
I changed the fuel pump relay, and zing!!! started up every time!!

Sooo check the voltage at the pump, the relay may be high resistance,
or a bad ground at the pump causing it to run slow, not bulding up pressure as fast.
oh, the reason it didn't have any oil in it was because he changed oil, and only finger tightened the drain plug and in the process of moving, and not driving the car for 2 weeks, it all leaked out.
That's all I got but that relay saved me $5500

 

If you hear the fuel pump and it does make fuel pressure when the key is turned "on" the the FP relay should be good. You should see around 40 psi fuel pressure with a stock setup. Observe if the pressure drops. If so there is a leak somewhere and may be causing the hard start. I would focus on the fuel system, until you are satisfied that it is working correctly.

Try and hold the accelerator to the floor next time when cranking.

Good story coupeguy2001. (thumbs up)

Here is the fuel pump relay on a 86 and should be the same for 91.