saskdan97

I bought a 95 z28 for my son and I to play with 5.7 Lt1. Engine rebuilt last year by previous owner. One of the first projects we tackled was dealing with lag and stalling. After reading posts on here (thank you) I changed the optispark and wow it runs grea! But....before I did this it would start almost without effort. Now that the job is done (changed optispark, water pump and replace radiator) the car has a few new problems. The low radiator fluid level light is on although the fluid level is up and the car has to turnover for about 5 seconds before starting. Once running there it runs great. If I turn it off and start it again is a hard starter even when warm. One additional piece of information is that it we ran out of gas a few days before the project and I was wondering if by letting it run out of gas that I might have sucked up some junk for the bottom of the tank? Thank You for any and all advice.

Injuneer

Running out of fuel will often overheat the stock pump and damage it.

Check your fuel pressure. Turn the key to on, and read the pressure when the pump shuts down. Should be above 40psi. Watch how fast the pressure drops. Should not drop more than 5psi in 10 minutes. If the pressure drops quickly, it will cause an extended starts. PRessure loss can be caused by a faulty check valve in the pump, a leaking fuel pressure regulator, leaking injectors or leaking lines, including the flex hose in the tank.

Another way to check is to cycle the key several times before turning it to "start". If it starts faster, you've also confirmed a problem with loss of pressure after the pump primes.

If it isn't a pressure loss problem, look at the coolant temp sensor in the water pump housing and verify it is operating correctly. The PCM has to know the engine temp accurately in order to set the correct A/F ratio for starting the engine.

The low coolant sensor is a very common problem. Could be crud built up in the sensor, or the more common problem - coolant has penetrated the sensor housing and corroded the printed circuit board. You can try cleaning the sensor, but usually it needs replacement. You are verifying the coolant level in the radiator (where the sensor is located), and not in the reservoir, correct?

Here's a site with an amazing amount of info on the LT1 engine, and the 95 model in particular. He has info on the coolant level sensor, the coolant temp sensor, the fuel pump, etc. Best LT1 site on the internet.

4th Gen LT1 F-Body Tech Aids

saskdan97

Thank you Fred! I'll look into what you suggest right away and get back to you. I do have a list of problems in addition to what I've mentioned above but want to tackle one at a time. This car was neglected and has a long laundry list. One important one is that the ODM will not give us codes and I'm trying to sort that out. I thought I found a ground problem but it was not the ground to the PCM or ODM like I was hoping. Would my car run if the PCM was not working correctly. I have tried to have the ODM scanned three times - twice by Oriley's and once by a local transam/camaro shop where I live. The camaro mechanic thought it could be a ground issue for the ODM. I'm still investigating. In regards to the water temp sensor you mentioned on the water pump....I know where it is and is there a way that I could test the sensor before buying a new one?

saskdan97

and yes to your question lol...I'm checking the radiator for level not the reservoir.

parkers Z28

If you have not looked at the 4th gen link that Fred posted check it out
look at components location view. it has pictures where all the sensors are located
And a lot of other helpful things Great feature !!! welcome to camaro Z28 &merry Christmas to
you and your family

saskdan97

Thank You and Merry Christmas. I will check the site out right away.

saskdan97

okay, I changed the fuel pressure regulator and checked the fuel pressure with a guage and turning key to on but not turning over. The pressure reading I get is around 60 psi while pump primes. Once the pump turns off it the pressure drops immediately to zero. I repeated the process with the same results. I had to mess with the injectors to get to the fuel pressure regulator and am concerned that I may have unseated the injectors but I thought I did a good job putting them all back in place. I do not smell gas around injectors. I really do not want to replace the fuel pump unless I really have to. Is there a test I can do to see if the pressure loss is related to injector leakage. I would not have thought an immediate pressure loss to zero would have been caused by a leaky injector?

help please...Dan

Injuneer

Did you check the fuel pressure and bleed down time BEFORE you replaced the fuel pressure regulator? If so, what were the results? If not, why did you decide to replace the FPR?

What replacement FPR did you buy? No way it should be set at 60psi. Is it adjustable? If so, any chance it's the AFPR made by Aeromotive?

Pull the rails up, leaving the injectors intact in the rail. Turn the key to pressure the fuel system (do not try and start engine). Look for drips. I mentioned four possible causes of rapid pressure loss. Did you consider the other three, beside leaking injectors?