Narrowing down my start issue (84 4kq)

[Johnny B]

Well, I got some work accomplished on the 84 Friday and have some more specific start symptoms now on the car. Definitely narrowing things down!

First I'll say I noticed the starting issue is not just when cold, but always when starting (Even after sitting for say 30 seconds after the engine is hot). When the engine is warmed up, it SEEMS like the start issue isnt there (as it starts easily) but in reality, if you try to give it any throttle for the first 10 seconds it bogs. After the 8-10 seconds, all symptoms are gone and it drives as it should. During all of it the idle is rock solid. 

I started by doing a very thorough vac leak check with chemtool at idle, checked all essential bits including all formed vacuum tubing (X, ISV, Intake boot) and all the vac lines, all connectors, injectors, seals, intake manifold, TB, all vacuum related systems and found zero vacuum leaks. I installed the "X" & ISV silicone tubes from 034 and replaced all vacuum tubing under the hood clamping all connections. I re-checked the system with chemtool after the install and again, no vacuum leaks. 

I tested the idle & WOT switch at idle, both respond as they should. I pulled the DPR off the side of the fuel distributor to check for clogs, screens are clear. I then adjusted the metering plate screw by 1/8th of a turn towards the rich side. I restarted and same bog symptoms within the first 8-10 seconds (as the engine was still warm). I did notice after the adjustment the car feels a lot better while WOT, smoother idle, and was told by the PO it was 1/8th of a turn on the lean side of "11ma" for smog purposes, so a proper tune is definitely in order here (getting the harness bits from the yard tomorrow). I dont believe this is my starting issue as the symptoms remain the same this morning when cold and when warm. 

At this point I think Steve nailed it with a lack of residual fuel pressure after shut down. The fuel pump check valve is in the mail and will be arriving on Tuesday. Other then that I believe the only possible culprit would be the accumulator? Visually the fuel pump & accumulator look to be factory units, the filter looks new. Could it possibly be the fuel pressure regulator mounted in front of the fuel distributor causing this? My buddies 4kq is down for the next few months and he has no start issues, so I can swap the expensive bits from his for testing before spending any more money (or strike gold in the yard tomorrow). 

Thanks for the help everyone! 
Johnny