As the title implies, I am having some trouble starting my car. Its been an ongoing problem. I started having starting issues ablut 2 months ago when I got my computer back from Ian. It wasnt anything that he did but when I got the computer back something was totally diffrent. I have never had to hit the throttle to start the car since Ive owned it for 5 years. Now if I dont hit the throttle at some point while turning the key, I wont start. Even doing that I chooses when it wants to start and when it dont. Seems like the colder the day, the lower the chances of it starting. I took it to the dealership and explained what happened. They kept it for a day or 2 and told me that I wasnt getting enough fual pressure and the IO needed a few fuel pump. I replaced the fuel pump with one from Racetronix. Nothing improved. I bought a new fuel filter and it started for about 2 weeks and now I am here...Dead again. Battery is a week old as well. The car runs perfect and thats why its som frustrating. It just wont start consistantly. Why do I now have to hit the throttle to start the car. I liked it alot more when I just turned the key and the car did the rest. This is kind of a weird deal. Ive checked my local dealership and a couple of other mechanics and Im still Dead. Anybody ever been through this? I just want the car to start like it used to, no more hitting the throttle to start it. Is there anything simple that might cause a car to start requiring some throttle for start up. This car is my dailey driver. Any thoughts, pointers or "I been theres" are welcomed and appreciated



My car and mods: 94 Z with Auto tranny, 2.73 gears
LT4 intake(twin 58mm), 58mm tb, ported MAF, K&N FIPK, MSD 6A ignition box, MSD coil, MSD plugs, Edelbrock mid-length Headers, Hooker Cat-back, HiFlow CAts, SFC, LCA, panhard bar, Poly bushings, TB bypass, Tune,

 

have you talked to ian?

 

Have you personally checked the fuel pressure? Checked the spark? Etc.?

 

I did talk to Ian. Hel said that this was something that he has never had a problem with. I instantly thought that it was something with the computer but, if Im the only problem out of 1000, then its got to be something else. I dont have a fuel pressure gauge, prolly a good time to buy one, I suppose. A new fuel pump and fuel filter have been in there about a month. The car would start but not a normal turn the key start up.... More like, turn it over, wait for the right time, let off the key and hit the throttle. I could get it to start that way but all shat stuff is unnecessary.

 

I would be willing to bet that it isnt getting enough fuel pressure because thats what they told me at the dealership. They said that it needed a new fuel pump because it wasnt creating enough pressure. I put a new fuel filter in 2 weeks after a trip to the dealership and it actually started semi-consistantly and eventually got me to the "Dead" perdicament that I am in now. It still started herky jerky each time I turned the key, even when it was starting....except when I was only out of the car for a short period of time. If I made a pit stop for a soda and came out a re-started the car it would start every time almost. Its a weird deal. Im very confused. Ive tried everything. Has any one experienced similar starting woes? What are some of the methods that were eventually used to fix the problems?

 

what fuel pressure regulator? stock or?

 

My fuel system is stock. I figured I would need a adjustable regulator kit that has a guage. I dont need anything wild.

 

I don't know about LT1's, but many fuel injected cars have a 'clear flood mode' that is activated if you hold part throttle while cranking. Do these cars include that feature? If so, seems like a clue as to the cause. Maybe leaking injectors could cause flooding if the car is off for very long?

I'd also check TPS sensor and especially TPS wiring. My car had a bad TPS connection, and even though the system 're-zeros' itself at ignition on, the random variation in voltage caused it to sometimes think the throttle was up to 13% open when it was actually closed.

 

NOT part throttle, that adds MORE fuel, "clear flood mode" is WOT while cranking

 

I havnt check the TPS yet. Is it a cheap sensor to replace? When I try to start the car, it sounds like its flooded. Is there any way to check fuel injectors to see? Im kinda stcuk and very limited on what I can so becasue now the car wont start and therefore caannot be driven to an expert. Start-up problems suck.

 

If you suspect the fuel system, try squirting fuel in the intake while someone cranks it over. If that doesn't work pull a few plugs and check for spark.

 

I will do that. I need to get it runnin really bad. There is snow all over the ground where I live so this should be fun

 

Qusetion.. is the fuel pump priming.. The fuel system is set up with 2 power sources for the fuel pump..

1. Fuel Pump Relay
2. Oil Pressure Safety Switch (Redundancey)

The fuel pump relay recieves a signal from the pcm to run the fuel pump for 2 seconds when the key is switched to on to prime the sytem. Then once the engine is running the pcm keeps the fuel pump relay engaged. All the while the oil pressure safety switch requires, well, just oil pressure to operate the fuel pump.

If the fuel pump relay is toasted or the pcm circuit is damaged either by a faulty wire, or a progaraming error, then the pump won't prime, thus causing the excessive cranking to build up enough pressure to kick on the fuel pump to start the car. Basically what happens, is the oil pressure safety switch needs approx 4-6 psi to trip thus closing the circuit and engaging the fuel pump.

The fuel system should still be pretty much primed when you first shut the engine off pretty much resulting in your easy start up frustrations when you stop for a drink, or gas.

 

Have you ever thought about a new starter? Mine was doing the same thing, replaced the starter and no problems.

 

I thougt about it but I turns fine. Im getting checked out at a diagnostic shop monday assuming that I can get it started. Thats for the info.
i didnt know that that was how that system worked.