Changed Fuel Pump - Now Difficult to Start when hot.

[UKPR1]

Carburetor is a newly professionally rebuilt Autolite 2100. Duraspark conversion, new coil, dizzy, plugs, wire alternator and regulator. Was running and starting like a champ. Fuel was leaking from the fuel pump so I swapped that out today. First start was instantaneous just like it always used to be. I let it sit and idle for a while. Shut it off, went to start it after a few minutes and it didn't want to start! Holding the pedal down and cranking for 5-10 uncomfortable seconds and she'll final splutter to life. Used to start in the first 1=2 seconds - maybe 3 seconds when cold.
When it does come to life, it's in a cloud of smoke from the exhaust and the smell of unburnt fuel. Timing was set at around 30 degrees at idle. Retarding the idle back down to 10-12 degrees has no effect on the hard start. In pulling off the air cleaner, when the engine is just shut off, there is vapor that continues to rise from the carb for a minute or two. Once the engine gets started, it can run all day without hesitation.

So...what did I do wrong??? Such a feeling of defeat. I had gotten used to changing out parts and seeing an improvement. Changing out the fuel pump should have been a good thing. Instead I've taken a step or two back.

Thanks,

Geoff

[67 short box]

sounds like china strikes again. my little 240 with a new orielleys junk china fuel pump would flood the carb as high rpm. had to put a regulator on it.
just something to think about.

[jzjames]

Carburetor is a newly professionally rebuilt Autolite 2100.

Ok. Will take your word for it.
But it’s my immediate red flag.

[UKPR1]

The first rule of problem solving is asking...what changed? Hoped it wasn't the fuel pump because it was an absolute b*$(*%*( to install. Hoped that I wouldn't have to do that again for a long time. Carb was built by a reputable rebuilder right here in FL. Was running great before the pump was changed out. Wondering if I dislodged something that is now causing the carb to flood. Pump came with a brand new filter.

[UKPR1]

So in getting back to the principle of "what changed?" - I'm compelled to do as short box suggested and retrace my steps with the fuel pump. It's quite interesting/suspect that in REALLY researching fuel pumps (and not just ordering the Delphi from Amazon...) there seems to be many variations of pump in addition to none being available from the specialist sellers for my particular year (69) and engine (360). As much as I don't want to, I think I'll reinstall the old one today and see if I can replicate the issue. JZ - I may also send off the carb back to the rebuilders and have them take another look at it if after installing the old pump, the problem continues.

Geoff

[390FE1972]

Here are a couple options for the fuel pump (NAPA, and Dennis Carpenter)

https://www.napaonline.com/en/p/CFPB008 ... =fuel+pump
https://www.dennis-carpenter.com/trucks ... r-assembly

Regards

[Ren]

Maybe a properly rebuilt carburetor is compelling you to change your starting procedure.

Also, how on Earth did your initial ignition timing find it'self set at 30*?

If you find the fuel pump is difficult to install, briefly engage the starter so that the eccentric on the end of the cam is away from the arm on the pump.

[jzjames]

You could take the cover off your carb bowl and see if the float is sticking or rubbing on the side of the bowl.
This had happened to me.

[UKPR1]

JZ - I'll do that right now.

390 - thanks for the tips on sources.

Ren - thanks for the tip on mounting the pump. Timing started at 12 degrees and just ran better and pulled more and more vacuum until just over 30. then I trimmed it back a little. Could be just "my" 30...who knows it the timing marks are off!

Thanks for your help.

Geoff

[UKPR1]

Not so much SOLVED as everything back to normal.

I removed the float bowl cover and the fuel level looked normal, but with the engine off, when I depressed the float, fuel came shooting out of the needle at a very high pressure. I don't know what normal pressure is supposed to look like, but I reasoned that it was this high pressure that pushed fuel into the venturi area and caused all the vapor I had been observing with the engine just turned off.

Long story short - I removed said new fuel pump and replaced with the old pump and the car is easy to start once again.

Thanks for your input. Took me 30 mins this time around to remove and replace the pump.

Geoff

[jzjames]

Good luck!!
I suppose i is reasonable that new fuel pumps are wierd.