Trouble on initial starting..please help

[jersey280]

Hey guys,

 

Own a 78 280z. I am having the issue of a "cold start", when its not "cold".

 

Whenever I want to start the car initially for the day, it takes me 4-5 good rounds of cranking to get her going. This happens at any temperature outside. I feel like the fuel pump may be shutting off once I begin cranking? 

 

Any ideas what may be causing this?

 

Thanks in advance!

[Mike33Stig]

Try unplugging the oil pressure sensor. This should trigger the fuel pump to turn on and stay on as a test. 

[jersey280]

Great idea thanks! I will get around to that shortly. If this works, any idea what may be causing the pump to stop pumping during the turn over? 

[grannyknot]

19 hours ago, jersey280 said:

I feel like the fuel pump may be shutting off once I begin cranking? 

 

Any ideas what may be causing this?

You need to find out if that is actually happening, get a friend to crank the engine while you take a voltage reading at the pump.

[jonbill]

cold start isn't what happens when its cold outside and you start your car. 

ANY outside temperature is a lot colder than the running temperature of the engine, and it needs fuel and timing adjustments while it warms up.

so suspect a temp sensor somewhere. 

[NewZed]

On 10/2/2021 at 5:54 PM, jersey280 said:

Whenever I want to start the car initially for the day, it takes me 4-5 good rounds of cranking to get her going

 

The suggestions about the pump are good.  But your symptoms sound a lot like pressure is bleeding off overnight.  Do you have a factory FPR or aftermarket?  The typical aftermarket regulators all bleed down quickly.

 

You can check all of the possibilities by attaching a fuel pressure gauge and watching it.

[AydinZ71]

If you are able to rule-out fuel pressure, try checking/replacing your ignition system consumables and replacement parts. Cap, rotor, plugs, wires, coil. Check your ignition timing to make sure it has not wandered. 
 

in my case, most times I have had poor cold-start was because my Spark had weakened or become inconsistent. This is most obvious when the car is cold. Once she is up and running, a poor/inconsistent spark can improve as the ignition parts and plug warm. 

[jersey280]

Thanks for all the suggestions guys. Newzed, I have an aftermarket FPR, without a check valve currently. I suspected this may cause an issue, but I always allow 30 seconds(ish) before cranking for the pump to prime. Other than that, ive replaced all senors related with NOS and adjusted timing/replaced cap rotors ect (she runs great when I get her going).