hot-start issue, cold-starts great! 85 308qv

hey guys, me and my father (also on the boards here) have been going through an extensive repair-a-thon on our vehicle. we've been having quite a show out of fixing one thing, and then finding another age related coincidental failure along the way.

at this moment, our issue is largely a hot-starting problem. we found a failed thermo-time switch recently, and replaced this sucker down in the valley as we were getting a terrible starting delay, and no signs the cold valve had been working. as it is, cold-start is working great.
we can take the car around the block, have a blast, get her really heated up, and pull her back on the drive and kill the engine (or stall... ) and then we're SOL, you can turn the motor over until you're as blue in the face as the car's paint color.

as per "use the search function" policies, we have repaired or verified the following:
-new dizzy caps/rotors/wires/plugs and gapped from the box correctly. plugs are OEM PN, no variance here with this.
-spark plug extenders? yea, those are new too.
-new injectors. i posted a bit ago here about rockauto having the matching PN for dirt cheap compared to other places yes, they're bosch.
-the fuel accumulator - no leaks, verified holds pressure. is OK. we would have more cold-start symptoms as well. no fuel comes from the drain pipe.
-fuel dizzy, works great when running, appears adjusted correctly, haven't screwed with the adjustment on the airbox EVER.
-cold start system -thank-god, doesn't exist on this car. there is no cold start air valve like birdman has details about.
-replaced any/all gaskets around the intake plenum and the hoses to the aux-air valve
-we smoke-tested the intake system. pulled off the driver side, farthest forwards vacuum hose, and plugged our smoke injector right to the nipple. only place we had smoke come out of is the line coming from the oil separator. if the smoke is passing through the manifold, and through the engine, it should be normal i imagine to see this after a little bit.

when we hot-start the vehicle, when it refuses to start, we have examined the engine compartment and the cis unit's metering plate. it does slightly pull down the metering plate enough, but the system does not buzz like the car does when cold-starting.
-even when we disconnect the safety-switch on the metering module, we get the buzz, but the vehicle still refuses to start.
-we are getting fuel. with a line disconnected, we have a strong-steady flow rate, even after the accumulator has spent it's load with the open line. we aren't talking just cracking a line, i'm talking with line off. we are getting a consistent flow and rate. this is further backed up by the vehicle being super responsive before the ignition is cut. it has a great power and tone as it did prior to these issues occuring.

we have spark (verified all cylinders via inductive tool)
we have air, with no detectable leaks via evap smoke system testing
we have fuel operating as should.

i would imagine any flywheel sensors wouldn't be the case here as the vehicle runs great prior to shutdown. faulty crank sensors would result in intermittent road operation i would imagine, by cutting the spark.

anyone got an idea?
maybe a batman spotlight with a bird image instead?
any insight would help at this point.

 

No leaking banjos on the entirety of the fuel system. I've been over, beneath, and inside of this engine compartment pretty thoroughly. Lol.

By check valve, are we talking about the one atop The fuel pump?

 

No, not that I'm aware of. Pipes come up the passenger side of the car around the quarter cheese grater, and under the air box to the fuel dizzy. No heat exposure there I could see being bad enough. It's all well spaced off from the engine.

 

We tried the repair kit first, one of the center piston rings was bad in the appropriate kit and bound it up. We ended up getting a tested and certified refurb. It's operating as it should, and we actually have pictures of it's rebuild internally as well as received the video of it passing a flow test with the old proper kdje bosch tools.

 

I had been directly avoiding starting fluid due to fear of backblow as can sometimes occur. Don't want to knock an adjuster or something out! I've only caught one car on fire in my life and I'd like to keep it that way

 

Also, Steve, my dad found a post of yours going into detail about the expansion tank coolant temp sensor having an influence on the digiplex retarding the ignition under different conditions. We have had it unplugged as well as jumpered via high tech paperclip, no difference there.

 

Previous to replacing some intake gaskets and hoses, it was definitely fowling up the plugs. I'll pull the set of new plugs, and blast/clean them later. I've got equipment for that. Laying a plug on engine ground or with spark testers does yield a spark impulse. Regularly I use an inductive tester instead of having to pull a plug out. After running for a bit, it should defoul the plugs though, you'd imagine ... I'll go at them all anyways

 

I'll check the plate.
After the car sits for approx one or two hours, the vehicle will crank to life just as strong as a newer modern car. So then I do t think I'll be pulling plugs with that in mind.

 

Updates!
I checked the metering plate. It is centered well, and moves correctly safely.
Per one of the recommendations, after the car was warmed up, I sprayed some accelerant under the plate, this had no affect to restarting.
From there, I disconnected the cold start valve and put my fuel pressure gauge inline.
Pressures after running are 70 PSI when pump active, holds no less than 40 PSI after 20 minutes, as per the workshop manual.

I had a hair rained thought earlier yesterday about the metering airbox. The car was a lot better to start after I replaced the hoses for the aux air device, and resealed around the cold-start valve. When I get home I'm removing the metering box and I'm going to re-seal the box halves. There was a slight difference in difficulty with the air filter off the car versus air filter in its box, I stalled correctly. I'm stepping closer and closer towards an over-lean issue where on hot start, it's just not building vacuum to successfully draw the metering plate to kick on the fuel pump and fuel accessories. The second you touch the metering plate, she whirrs and hums, same as removing the safety switch connector.

 

I have an analyzer at my house I've never used, for this purpose on a vw fox GL, also a CIS. sold the wreck before I ever tuned with it. I was trying to tell my father we should consider doing g that, but he's stuck on the paranoia of "it should be fine how it is!!! Do t mess with it!" But here we are. Lol

What results or ratios should I expect at cold or hot? Is there a specified chart to reference?

And since I'm at the airbox anywho right at this point, I think I'll confirm good metering unit seal by examining it. Couldn't hurt.

 

we have a fuel gauge at the line that goes straight out to the cold-start fuel injector. the measurements above were taken there, with the vehicle warmed up. i feel that with what the video goes into some detail of, we atleast have that correct.

earlier today, for the majority of the evening, until i just a little bit ago got cleaned up, i was "refurbishing" the metering unit the fuel dizzy sits atop. i removed the original seal between the box halves, the damn thing was just rock hard, no real sealing qualities to itself. scraped the f*er off, polished my surfaces, and created a custom-fit gasket out of the appropriate felpro gasket material. i've been doing a lot of custom gasket creation in a few air channel places lol

tomorrow i'll put the airbox back in the vehicle, and we'll give her a crank up to see how the ol' gal operates.

what are the preferred methods to remove the adjustment hole blockage? driling it out? is it a special threading, or just normal rightie tightie?

also, i'm not sure what you mean by moving the fuel cell's position. fuel cells in my book refer to the gas-tank, and that's only got one spot

so far this thread has been amazing. i feel definite progress with our repairs. gotta have this car operational by the 21'st, so that me and the then wifey can escape from our wedding reception!

 

I do have a cis compatible fuel gauge set. So what's the ideal position to install correctly for control? Between wur intake "ingress" port and the dizzy?

Also, it may be worth noting, we have a single diaphragm wur on this car. We do not have a vacuum port on the bottom or side of the unit