Hello

Just got dyno tuned and my tuner says that the reason the car won't start immediately after sitting (once warmed up) is that the fuel inside the rail gets so hot it turns to vapor. The cure to this is to turn on the ignition twice, thus flushing the fuel lines out and getting rid of the hot fuel vapor. Once I do that, the car starts like normal. Also, if the car is cold, no problems starting at all. Just when its hot, and sits for a few minutes. If it is hot, I turn it off, and then right back on (say i run into the gas station and back out) it is fine. If i run it, turn it off, then let the car sit for 10-15 minutes, then try to start it; no beans on the first start/fuel pump prime. turn key off, turn it back on, prime the pump again, and she fires right up.


This is really annoying, and i find it hard on my vehicles electronics to keep turning the ignition on and off

Any remedies or cures? thanks!

 

Is a fuel pressure solenoid still installed and connected in your car?

 

I've been dealing with this same issue for awhile. Really embarassing at times when it won't start.

 

have you hooked up a fuel pressure tester? you might be losing pressure and priming it a couple of times pumps up the pressure enough to start.

 

I don't have an aftermarket fuel pressure solenoid. Is there an OEM one that I can look at data from through evoscan or romraider? Thanks for the help guys



Side note --> Can I run a switch to the fuel pump power supply and manually prime the system without turning the ignition on and off? Or will the switch screw up something between ecu and fuel pump? Thanks!

 

The OEM fuel pressure solenoid vents the fuel pressure regulator to atmosphere during hot start. This raises the fuel pressure in the entire fuel system back to the pump. The idea is to collapse any gas vapor bubbles that have formed from heat soak.

It is a common practice to remove the solenoid as many consider it useless. But, with your trouble, it might be a good idea to have one connected.

 

thank you

So i was wondering.. is this why i see a lot of evos with the lower portion of the hood vent removed? The grill is still there, just the vents are removed and its completely open.

Also, I do not have an exhaust heat shield, but my manifolds are coated by Grimmspeed.

Should I remove that vent from the hood and just leave the grill? I was also thinking about putting some heat shield on the fuel rail and lines in the engine bay

 

Well, if you haven't gotten the drift of what I am saying, if you don't have a fuel pressure solenoid, I'd try that first. Then, yeah, if that doesn't fix it, try other things that might cool the engine compartment or fuel rail.

 

Ok thank you! I'll go see what I've got in the engine bay

 

Just took a look at it and the FPS is still hooked up and appearing to be functional. Anyway I can test it? Anyone know what voltage it needs to activate? I can put it on the bench and double check.. i'm not getting any CEL's from it though so I assume its working correctly.


Maybe I should disconnect it and let the fuel flow through the system on start? I could see how that would basically do the same thing as priming it twice

 

If the FPS is present and plugged in I suspect it is working. It is not a complicated device. Therefore, I suggest something goofy with your fuel system. Evos don't generally have a hot start problem FPS or not.

The next thing I would do, if you wish to pursue this problem, is look for a fuel pressure gauge. I had one mounted permanently under the hood of my DSM and it wasn't expensive. That way you can see what fuel pressure is doing as the engine is started.

 

What are the temperatures like when/where you're driving?

We see vapor lock in fuel injected piston aircraft every now and again, but it happening on an Evo should be unlikely.

To give you an idea... we would typically see it on days where the ambient was over 90 degrees (so the ramp temperatures were probably into the 100's. The aircraft are air cooled, and it would be after a quick turn usually.

So... if your Evo is being driven HARD, and not given a good amount of time to cool down, I could see this happening, though it's unlikely.

Is this happening ALL the time? Even on a cool engine?

 

Yeah temps are usually over 90F and it only happens when the car is hot. If I drive it down the road in a normal fashion, not racing it or revving too high, it still does it after sitting for a few minutes (thermal soak takes place).

Lets say I drive it just as mentioned before, but don't let it sit for 5 min or so and avoid heatsoak - starts up just fine. Same for cold starts, no problem.


I think I'll pick up a fuel pressure gauge if I can't figure it out in the next few days. I removed my hood vent (left the grill behind) and will see if it still does it. FWIW, I don't have the heat shield on my manifold either. Maybe thats' it?

 

That does sound an awful lot like vapor lock.

Having that heat shield, and the vent louvers off won't hurt.

You aren't noticing any abnormal temp readings on your water gauge are you?

 

Sounds exactly like what was going on with my car, although it would never not start, just crank longer when it was hot.

People tried to say it was in the tune, and when i posted about it on here i never got any help to solve the problem