Re: Vapor lock or vacuum in tank........
Clogged strainer/sock on fuel pickupin take and or maybe need a vented fuel cap and mech f-punmp ispulling a vacuum on the tanks then starving for fuel?
BTW,you can easily check fuel pump lobe on cam.
You can have someone spin motor over slowly by hand with plugs out while holding the f-pump rod by the sides to see just how much travel it has. But dont put pinger on end of rod asit could get piched hard or even broken whoile trying this out,you have to hold it by its sides to do that check.
If it bearly moves thats the issue but ifit hase a decent pump stroke then thats not the issue but the new elec f-pumps may be better ar sucking etc bandaing maybe a partially clogged strainer sock.
Any,here are some oher thought if the issue comes back.
Is it hot enough out at the times it dies and or is motor running hot ehough when it dies to make you suspect vapor lock?
Is this only happening at higher rpms when on it hard and not when just driving at normal cruise?
If you get the tank vented and its still doing it can the stock heavy f-pump rod & try a light weight fuel pump to see if the very heavy stock f-pump rod is floating the pump arm at higher rpms resulting in fuel starvation.
But again only try this if your sure the tank is vented properly and strainer sock in fuel tank is not clogged.
To test tank venting just get it to die on you and get out of car ASAP and remove the fuel cap to see if theres a vacuum being pulled on the tank when you remove the cap which you will hear right off the bat when you remove the fuel tank cap if thats the case.
If that happens the motor should also refire when you spin it over enough to pull fuel from tank to carb to refie it,it should run fine then untill it pulls vacuum on the tank again if thats the case. If yes get a vented cap or correct-fix the tank vent.
Or drill a small hole in the fuel tank cap and forget about it like i did over 30 yrs ago when the vent kept messing up and dropping fuel all over the hot exhaust pipes in my 69 chevelle.
Tank has vented fine since then with no issues with small hole in cap.have no fuel out the hole issues from the cap either. I fill the tank unitll the pump shuts down 1 time and thats it,i never fill to tippy top.
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)