Thread: Hard Starting Issues When Hot

Hi all i have been working on this issue for quite some time. I have a starting issue when the car is hot and in direct sunlight. As we all know the B15's have been plagued with a flawed fuel system. I have been doing some research and even took apart the fuel pump piece by piece to see where any issues could arise. Upon disassembling the fuel pump i noticed that Nissan integrated the fuel pressure regulator and the check valve into one unit. There is nothing "wrong" with this design but after age the spring that retains the digraph valve closed becomes weak and thus causes fuel pressure to leak when the car is off.

In most fuel injection applications there is a necessity to have existing fuel pressure to feed the injectors when starting so the fuel pump does not have to do all the work in filling the fuel line with gas. When the check valve is faulty fuel leaks out and replaces its volume with air. Air in an engine is like a stomach full of beer :P this can lead to starting issues upon your first crank of the engine.

I noticed that there was a post on the forum where someone put a check valve close to the injectors but there really i have not seen anyone say if it worked or not. So i decided to custom make a braided fuel line with an external check valve and place it closest to the fuel pump thinking it will allow more fuel to be pressurized in the line.

Below are some pictures of what i did...



The result from this repair made a small improvement in my particular case with the starting issues. Now with this device in place i can start ruling our issues in the fuel system. Putting a large check valve now rules out the fuel pump's check valve since it is isolated from the equation. The next step was to replace the fuel pump relay.

The fuel pump relay is activated by the ECM when the key is turned to ON for about 3 seconds to charge the fuel pump and then turns off. Then once the ECM receives a rotation signal from the crank position sensor the relay comes back on and stays on while the car is running.

Once i replaced this relay the car has been working allot better. I have to test more to see whats going on but this seems to have fixed the issue. Any feedback is welcomed. From what i see buying the fuel pump repair kit doesn't actually fix the problem sadly.

i just prime the fuel, keyON 2-3 seconds, start motor. starts everytime hot and when just turned off, 250,000+ miles.

i just prime the fuel, keyON 2-3 seconds, start motor. starts everytime hot and when just turned off, 250,000+ miles

Thank You. But i have always done that before i start the car ever since i have owned it but now with some of the replacements i have done the issue has basically gone away. Before this became an issue i was always priming the car before starting and then after a while it stopped working. Hopefully this is more of a long term solution. I am not as fortunate to have problem free miles so i try my best to be one step ahead of the car.

just saying, cause most people dont, and then say wtf.

hopefully you solved your problem, i have read people saying a check valve worked using the previous write-up. i have yet to get there, so i pray thats the long-term solution is this simple

Haha your right about that. And just like you said i hope that the long term solution stays simple.