Car Only Starts on Second Attempt with Performance E-85

[cavaldez23]

Hi guys/gals,

This is my first time posting here. I've searched for an answer but not sure if what I've come across will address my issue.

I have a 2015 chevy ss sedan with a LSA blower, fore fuel system (dual pump return style kit), etc. About two months ago, I had my tuner make some revisions to my tune, which included making some adjustments to the cold start. After picking up the car, it didn't have any issues with cold starts with e-85 from the local sunoco gas station which was around 75%. There is a company in my town that offers their "performance blend e-85" which I've used in the past a couple of times without any issue. After running out of the sunoco e-85, I had that company come fill up my car with their performance e-85. Their ethanol/alcohol content is at 86-87%, about 10% higher than what I had. Ever since my car was filled up with that fuel, it won't fire up on the first cold start attempt but always on the second attempt right after, and any time after that within the same day. However, if I go to start it the next day, it again won't start on the first attempt but on the second attempt, no problem. Here is the weird part. If I go to start the car after it's been sitting over night, like I said it won't start on the first attempt, however, if I don't attempt the second start right after but let it sit again till the next morning, it starts right up!!! Almost, like it knows the first attempt was the day before! This has me stumped!

I've tried adjusting the Cranking VE table by applying +10%, -10%, -15% (car wouldn't even start with this much removed), and no luck.

Fuel pressure is 60+ psi when cranking, so I don't think it's a fuel pressure issue. I have a return-style fuel system and as soon as the pump(s) turn off, the pressure bleeds but immediately pressurizes when the pump(s) turn on. It has always done this and never really had a cold start issue before until now.

I have a feeling that if I were to pump e-85 from my local sunoco gas station, it would go back to starting up on the first attempt like before. I haven't tried that yet since I was waiting to run out of this "performance e-85".

Has anyone come across this before? Could it be tune related or something else going on with my car?

Attached is the tune and a log file. Thanks in advance!

[verlon]

Seems like you have a vapor lock. Fuel pressure drops from 420kPa to 220kPa within 5 seconds between start attempts, you have something leaking in the fuel system.
As you described it no start condition occurs only on cold start after the engine has been warmed up.

Here is the weird part. If I go to start the car after it's been sitting over night, like I said it won't start on the first attempt, however, if I don't attempt the second start right after but let it sit again till the next morning, it starts right up!!! Almost, like it knows the first attempt was the day before! This has me stumped!

There was no engine warmup between start attempts and fuel hasn't boiled in the rail.

[edcmat-l1]

Instead of cranking it twice, try key on engine off twice with a few seconds between. Prime the system twice. See if it fires up then.

If it were mine, or my job to diagnose and fix, first thing I'd do is put a check valve in the system to eliminate that as a cause.

[cavaldez23]

Instead of cranking it twice, try key on engine off twice with a few seconds between. Prime the system twice. See if it fires up then.

If it were mine, or my job to diagnose and fix, first thing I'd do is put a check valve in the system to eliminate that as a cause.

I will give that a shot. I have only tried it before with keying the engine on once and then attempting to start it which results in a no start but start on second attempt.

The fuel fuel system I have installed does have a check value on the fuel send line next to the fuel filter. This is inline about 3 feet before the return style fuel pressure regulator.

[cavaldez23]

Seems like you have a vapor lock. Fuel pressure drops from 420kPa to 220kPa within 5 seconds between start attempts, you have something leaking in the fuel system.
As you described it no start condition occurs only on cold start after the engine has been warmed up.


There was no engine warmup between start attempts and fuel hasn't boiled in the rail.

Thanks for the feedback. I've been told that it is normal to see fuel pressure drop as soon as the pumps are turned off due to the return style fuel system I have installed. Even Fore Fuel System mentioned that in an email response to me when I questioned them. I do have their check value installed on the fuel send line and fuel pressure is reestablished immediately when pumps are turned out. I've never had this problem before until I had this "performance e-85" pumped in.

I'll look into the vapor lock. Thanks!

[edcmat-l1]

I will give that a shot. I have only tried it before with keying the engine on once and then attempting to start it which results in a no start but start on second attempt.

The fuel fuel system I have installed does have a check value on the fuel send line next to the fuel filter. This is inline about 3 feet before the return style fuel pressure regulator.

If it has a check valve it's not working if the fuel pressure drops off. That or the regulator is leaking by. If it's all working correctly it should hold whatever the reg is set to hold.

[Alvin]

These cars with push button start and a fuel system that bleeds back quick will do exactly like you describe.

[cavaldez23]

These cars with push button start and a fuel system that bleeds back quick will do exactly like you describe.

Can you elaborate further? Is the pressure drop/bleed normal with a return-style system or are you saying something else?

[Alvin]

Its pretty common with aftermarket regulators. The extra volume of the larger lines too take a little bit longer to pressurize too.

On cars with the push to start thing.. You don't have quite the control of turning the ignition on, letting it prime, then go to start like a car with a key can.

Other people are saying check valve. We do ton of swaps here.. For a while we used check valves I think made by FORE. They did their job and held pressure but come summer time there was a problem.

Fuel vaporizes *boils, create more volume, same space.. pressure goes up* in a hot rail. With the stock check valve they still bleed back over pressure, it seems anyway, with these check valves the fuel pressure gauge would be wrapped around and touching the other side of the needle stop. So if you shut these cars down hot and came back to start them again in 20 minutes they'd have over 100 psi in the rail. Injectors start failing to open around 90 PSI. The cars wouldn't' start until you bled the pressure down.

[cavaldez23]

Its pretty common with aftermarket regulators. The extra volume of the larger lines too take a little bit longer to pressurize too.

On cars with the push to start thing.. You don't have quite the control of turning the ignition on, letting it prime, then go to start like a car with a key can.

Other people are saying check valve. We do ton of swaps here.. For a while we used check valves I think made by FORE. They did their job and held pressure but come summer time there was a problem.

Fuel vaporizes *boils, create more volume, same space.. pressure goes up* in a hot rail. With the stock check valve they still bleed back over pressure, it seems anyway, with these check valves the fuel pressure gauge would be wrapped around and touching the other side of the needle stop. So if you shut these cars down hot and came back to start them again in 20 minutes they'd have over 100 psi in the rail. Injectors start failing to open around 90 PSI. The cars wouldn't' start until you bled the pressure down.

I appreciate your detailed response!

I've never seen my fuel pressure go that high when starting the car. I don't have any issues with warm/hot starts. I can start the car no problem after the initial cold start back to back and even a couple hours later. I only recently started running into the issue after filling up with this better e-85. I was thinking maybe there is some sort of issue with the commanded AFR vs alcohol % after a certain amount of higher alcohol content.

If I was experiencing fuel vaporization, I would think it would happen no matter where I sourced the e-85 from right and I would have an issue with warm/hot start up? What throws me off is that if I go to cold start the car first thing in the morning and it doesn't start, if I don't attempt the second start right away but let it sit again until the next day, it fires right up. Could it still be a result of fuel vaporization?

I'm going to pump e-85 from sunoco this working and see if my car behaves differently on cold starts with the lower alcohol content.

[Alvin]

How cold is it where your living?

The higher the alcohol the worse its going to run in a colder climate.

[cavaldez23]

How cold is it where your living?

The higher the alcohol the worse its going to run in a colder climate.

Right now is about 50-70F degrees in the morning.

Last month before the issue started, it was in the 30F, and the car had no problem starting with the lower alcohol% e85. I even have a video where it started right up on morning when it was 17F outside, my car was in the garage so maybe around 30F inside.

[cavaldez23]

Just an update. I reached out to Fore Innovations and asked them if it is normal for fuel pressure to drop with their fuel kit when the pump(s) are turned off.

Here is their response:
"It is normal and expected for the fuel pressure to drop when the pumps are off when large, flexible fuel lines are involved.

However, you should see the fuel pressure "snap" back to operating pressure as soon as the fuel pump is turned back on.

I hope that makes sense...please let me know if you have any other questions!"

[gtstorey]

Just from the engineering side, flexible lines should hold the pressure longer since they have some give to act as a spring as a small amounts of fuel bleeds through a check valve. I would expect non flexible lines to be the ones to bleed pressure off quicker. The only way I can see it being the other way is if flexible lines are less "tight" and bleed off pressure that way.

[Lakegoat]

You said it was bleeding down to 0 when you shut off the engine. The check valve is doing nothing. If you want it to hold pressure, mount it in the return line. Otherwise, turn the key on for 3 seconds and then start it so the pump has time to prime the whole fuel system. You shouldn't have that obstruction in your feed line anyway.

[GHuggins]

It looks to me like you have a couple of things going on just going by the one log file.

First your engine does fire. It just doesn't ever get going good before it dies. I summed this up to not enough fuel staying in the cylinder to get enough heat to keep the fuel burning and cam overlap causing fuel to go out the exhaust on top of not enough throttle input. Full E is hard to burn and takes some heat to get it going initially.

I changed starting ignition timing to help it ignite quicker. Added some open loop fueling. Added some startup air and changed your injection timing when cold.

Don't know if these will fix your issue since it did look like there were several tables that didn't look right to me. If it does then it'll give you an idea on a direction to go in.

[edcmat-l1]

You said it was bleeding down to 0 when you shut off the engine. The check valve is doing nothing. If you want it to hold pressure, mount it in the return line. Otherwise, turn the key on for 3 seconds and then start it so the pump has time to prime the whole fuel system. You shouldn't have that obstruction in your feed line anyway.

Check valve goes in the pressure side. The regulator is the return side check valve. It should hold whatever pressure it's set to. If it doesn't, it's leaking by.

[cavaldez23]

It looks to me like you have a couple of things going on just going by the one log file.

First your engine does fire. It just doesn't ever get going good before it dies. I summed this up to not enough fuel staying in the cylinder to get enough heat to keep the fuel burning and cam overlap causing fuel to go out the exhaust on top of not enough throttle input. Full E is hard to burn and takes some heat to get it going initially.

I changed starting ignition timing to help it ignite quicker. Added some open loop fueling. Added some startup air and changed your injection timing when cold.

Don't know if these will fix your issue since it did look like there were several tables that didn't look right to me. If it does then it'll give you an idea on a direction to go in.

Thank you Greg! I will try this and report back!

[Alvin]

Check valve goes in the pressure side. The regulator is the return side check valve. It should hold whatever pressure it's set to. If it doesn't, it's leaking by.

Often those aftermarket regulators bleed off.

[edcmat-l1]

Often those aftermarket regulators bleed off.

Yes I'm aware. Quick way to tell is have a helper shut the key off and pinch the return hose off. See if it stops leaking down. I see more bad aftermarket check valves or systems put together without them completely.