Car dying after 45-60 minutes of driving. Vapor lock?

[daryld]

Guys

My Cuda has died on my several times after driving it continuously for 45-60 minutes. It starts acting like it is running out of gas and then eventually dies. The pressure at the regulator has dropped to 40 psi and even as low as 20. Attempts to restart are useless as it just chokes and dies. I have to let the car sit generally for 30-40 minutes before I can start it again without issues. It will then run again for another 45 minutes before it dies again.

From everything I have read it appears that I am experiencing a vapor lock issue. This even happened when the motor was running 190 degrees while on the interstate. The issue seems to clear faster when the engine is running cooler versus taking a lot longer when the engine is consistently at 210-220 degrees like in traffic on a hot day. I am unsure at this time if the problem is a tank vent issue (seems unlikely), a fuel boiling in the fuel rail (more likely), a bad fuel regulator (possible) or a bad fuel filter (also possible but unlikely).

Have any of you experienced something similar after your Gen 3 swaps? I have a brand new Tanks Inc EFI tank and high flow in-tank bump rated at 630hp. It is turning on and appears to be working just fine. The regulator and billet fuel filter are cheap Chinese parts that could be faulty.

Any help or advice you can give me would be appreciated. I will try to replicate the problem this weekend. At that time I will open the gas cap and listen for sucking wind. I will also poor some water on the rails to see if boiling gas is an issue. If you guys have some other ideas please share.

Thank you

Daryl

[70chall440]

Probably need some details about the car/engine to provide better suggestions.

Are you running a return line on your fuel system? Is the tank vented? It could be an overheating fuel pump or potentially a clogged filter.

[1 Wild R/T]

When it dies pull the gas cap off & see if the yank is in a vacuum...

Vapor lock happens due to fuel boiling which it won't do when the fuel system is pressurized....  It's a carburetor problem, not fuel injection...... 

[JpRngr]

Definitely a fuel pressure problem. Fuel injected cars need 50-60PSI to run. The 20-40PSI is way too low for it to stay running. Is your gauge before or after the regulator? Need to check if it's caused by the pump or the regulator. Also, make sure you're getting good voltage to the pump.

Corey

[daryld]

Probably need some details about the car/engine to provide better suggestions.

Are you running a return line on your fuel system? Is the tank vented? It could be an overheating fuel pump or potentially a clogged filter.

So it is a 70 Cuda with a stock 2016 6.4 Hemi. The tank and pump are from tanksinc. The tank is vented but not sure if there is a pintch somewhere. Have to look and see. I am not running a return line because these engines do not require one and my hp is not high enough to require one. Do you suggest running one regardless so that unused fuel can return to the tank and cool during the process?

[daryld]

When it dies pull the gas cap off & see if the yank is in a vacuum...

Vapor lock happens due to fuel boiling which it won't do when the fuel system is pressurized....  It's a carburetor problem, not fuel injection......

I plan on doing this next time I have time in the car. The psi is dropping anywhere between 10 -30 psi at times so there is definitely an issue.

[daryld]

Definitely a fuel pressure problem. Fuel injected cars need 50-60PSI to run. The 20-40PSI is way too low for it to stay running. Is your gauge before or after the regulator? Need to check if it's caused by the pump or the regulator. Also, make sure you're getting good voltage to the pump.

Corey

The gauge is on the regulator which is on my firewall. The regulator is a cheap Chinses product which could be a problem. I have read that the flapper in these often go bad pretty quickly. Will probably replace the regulator and fuel filter with Aeromotive just to be safe. If the pump is over heating I am not sure why unless the vent is somehow pinched. It is wired correctly and working fine. The problem only occurs after driving 45-60 minutes. If I wait 15-30 minutes after it stills, the psi goes back up and the car runs fine, at least for another 45-60 minutes. The drop in psi does seem to be worse when the engine is running 210-220  during my drive time versus 190 on the interstate.

[70chall440]

I cannot speak for OEM fuel injection systems really, but I have 3 aftermarket EFI systems and every one uses a return line. I am not saying this is cause of your problems, but I think it would take some strain off your fuel system. It definitely needs to be vented. As to the pump, it is possible its a bad one or going bad, but I am running 2 Tanks Inc. systems and they work very well but I am running return lines on both.

Someone who has done and is using a Gen III system might have a better prospective on this.

[daryld]

I cannot speak for OEM fuel injection systems really, but I have 3 aftermarket EFI systems and every one uses a return line. I am not saying this is cause of your problems, but I think it would take some strain off your fuel system. It definitely needs to be vented. As to the pump, it is possible its a bad one or going bad, but I am running 2 Tanks Inc. systems and they work very well but I am running return lines on both.

Thanks for the info. I am considering running a return line to return the relieve the strain and give this fuel time to cool down. Appreciate the feedback.

Someone who has done and is using a Gen III system might have a better prospective on this.

[70chall440]

Good luck, you will get it done. Believe, I know all about gremlins; I am trying to get my 14 year project up and running and experiencing one issue after another. Had it running last night and discovered the water pump gasket was bad, that's after a leaking oil system which was after leaking brake lines.... Also have some valve train noise I have to investigate.

[twoterpilot]

how is the fuel line in the engine bay routed? and is it a metal line or a hose? I suspect the problem is the regulator.

[daryld]

how is the fuel line in the engine bay routed? and is it a metal line or a hose? I suspect the problem is the regulator.

Regulator is in the engine bay to the left like most. The hoses are braided nylon 6-an. I will be checking the lines this weekend to see if any are close to the headers but they are running behind the block.

[70chall440]

I can't say for sure but I doubt the fuel is boiling unless you have the line laying on the header. If it were me, I would be thinking its a venting issue especially without a return line. Of course it is always hard to say on a forum and it could be something completely different such as a bad coil or electrical issue overheating, although you did mention the regulator pressure fluctuation which points to a fuel problem.