Engine hesitates and backfires after driving an hour-

[edmayo]

After you got the pump back did you use a air/fuel ratio meter to set the mixture at normal operating temperature? I've never seen a rebuilt pump that din't need some adjustment for the particular car it was put on. After the car has been driven enough to get to operating temperature the thermostat housing should be hot enough that leaving you hand on it will cause pain, is yours that hot?

[Haasman]

This might not have anything to do with this, but is the tube from the heat exchanger to the MFI pump connected or missing?

[G69]

Thanks Ed,

I have been road testing and checking the spark plugs to set the air/fuel ratio.

I do not have a meter.

Yes my thermostat housing gets too hot to handle. I have new inner and outer paper hose connected to engine tin and rubber hose from SSI heat exchanger to bottom of engine tin.

[G69]

The hose is connected.

[edmayo]

Since you have no meter try this,,,adjust main rack 2 clks richer (ccw) and repeat test, if still not right go two more richer,,,if still not right STOP,,,, go back the 4 clks, your problem is elsewhere.

[G69]

One thing certain- The regulating check valve is toast. A new one should arrive tomorrow.

I disassembled the binding $140 'overflow' valve. The phenolic check valve was a mess. The steel spring was as new so the fuel hasn't seen a lot of water.

A bronze or even aluminum check valve element instead of that phenolic piece should last the life of the car (600 years????).

Without consistent fuel pressure to the injection pump I was lost- I'll post my results when I get back on the road hopefully tomorrow.

[edmayo]

The new one will have a plastic valve

[G69]

Yes plastic but modern. White instead of phenolic.

I installed the new "overflow" valve last night and took a little ride...

WoW! The car runs really solid.

The spark plugs have several personalities from all the different mixtures they suffered through with the bad overflow valve stuck half open and the MFI getting different fuel pressure at different throttle and load.

Dark and sooty on the perimeter and nice on the electrodes. BP7ES.

They have been in and out of the heads so many times! I choose a different cylinder each time I was swapping them out so often.
After today I'll buy new ones since the plug gaskets are shot- They likely have 140 miles lol.

I'm going to take a long ride now with my spark-plug socket, homemade low speed wrench, my homemade high speed screwdriver, hex-key in a flex tube, and what I forgot last time...

The 14mm open-end to roll out that one-year-only arm that prevents access to the high speed adjustment screw on the rack.
That little gem whacked my world for a few weeks.

It is a footnote in Check Measure and Adjust so 'no one to blame but me.

It really isn't a lot of trouble to pop the air box and make these adjustments.
Chasing my tail with the intermittent action of the overflow valve gave me 'opportunity' to get good at making the tedious-at-first high speed adjustment.


Thanks Ed. And thanks Early S.

[Haasman]

G69-

WoW! The car runs really solid.

Nice! Always great to get it right.