Noses over at WOT when at operating temperature

Checked fuel pressure at operating temperature?

 

It would surely be useful :Brow:

 

i believe that vapor lock is due to excessive heat. i haven't ever had a car do it but that is what i think will do it. install a pressure gauge first.

 

I'm not saying it is but-
There could be a lot of crap in the tank, and collecting around the screen while the pump is sucking.
Falling away from the screen when you stop the engine.
To test it, create the condition, pull over shut it off for a minute, start it and see what happens. I put a magnet in my tank and swished it around to see
how much rust there was in there, none.
maybe your tank is new! Good luck. Always go with the easiest solutions first, is what i tell myself..:blast:

 

Not quite sure the of reason it does that. However, my engine has a permanent fuel pressure gauge and it reads a few pounds higher when the engine is cold versus hot. Maybe is something to do with the heat on the pumps regulator causes the pressure difference.

If I was you, I'd find a rubber section of the return line and put a pair of vise grips on it. See if that makes any difference.

 

I would check the fuel line condition all the way to the tank.
Had a issue like yours that was a half way pinched off 3/8 hose
connecting the tank. Just another idea...good luck

 

Smarty... in 1976 I had a '66 LeMans. 326 2bbl.

It would nose over just like yours. Can't remember if it did it when cold or not, but the rubber line from the tank to the metal fuel line along the frame was dry rotted.

Check that. Could be that when cold the rubber hasn't expanded enough to let too much air in. Yet when warm, it expands and lets air get in.

 

FIRST: Make sure there is plenty of fuel in the tank. Not being smart here, just covering the bases. Cant tell you how many bogs, vapor locks, bad carbs, bad fuel pumps etc I have cured by adding more fuel. o No:

SECOND: Check the tank vent! If no tank vent, then check the cap, it should be vented. If the vent is plugged, then the longer the car runs, the more reverse pressure (suction) the tank will have. Easy way to check this is to run it a while and then remove the fuel cap. If it sucks in air when you remove it, then guess what?

Then:

Check fuel line from tank to carb.
If you have a choke on the carb, make sure it isnt closing for some reason under throttle when warmed up.
Check the carb inlet filter, if its clean then throw it away and get a free flowing in line filter. If its dirty, do the same thing. :laugh: Put the inline filter in the fuel line somewhere under the driver side door.

Then get back to us! :3gears:

 

This is in line with fuel pressure, My 70 GSX would not make it to the 1/4 without bogging and surging (spelling). An old Buick guy told me to block off the return line from the fuel pump to the tank at the fuel pump. DID the trick , the return line was acting like a bleedoff , reducing the pressure ! Car went 11.70's after the fix !

 

I had the same problem thought I had checked everything.

When I lifted the body off the frame I found the the steel supply line where it goes over the frame was bent almost closed.

 

To test the system I ran the car down the road without using the fuel line or fuel tank. I put a 2.5 gallon tank on the passenger floor board and ran fuel line through the firewall. If you leave the spout on the can 3/8 line fits snug. This was after changing pumps going through the carb a fuel filter and blowing air back through the line. Also I dont use a return line on this car.

 

Adam -

Is the filter sock still on the pickup in the tank? When these fall apart they will cause starvation - and they all fall apart eventually.

 

You can remove the sock ONLY if you install a filter before the pump. It needs to be a hi-flow filter designed to be a "before pump" filter.

 

Socks are still available from GM. You need to find out if it's a 5/16ths or a 3/8ths line inside the tank.

Tom T.

 

Let's think outside the box.

Coil?

Throw a new NAPA IC12 (NOT #IC12SB) coil on there and see what you get. They're cheap.