Neighbor's car, 1990, smog-pump replaced with pully, someone installed larger injectors, leaking intake gaskets (swapped around), came into my radar as a no-start 100% of the time.

Started with fuel pump, it was ugly, pressure was weak in the 30s and wouldn't hold, replaced the pump. Replaced the fuel filter, it was plugged, couldn't blow through it. Rebuilt the fuel regulator and the fuel system now holds mid-40 PSI all night long and during start, so I'm confident fuel system is sorted out now. MAP sensor had a broken pin in the connector and that was preventing starting, which it does now, learned a thing about the 1989/1990 speed-density <G> or was it 90/91? Side note, what are the chances of a pin inside the connector breaking? That is why I'm leery of what other hands have done to this poor car. Not that it really matters, but mileage is low 60k. Distributor was removed and looks fine, nothing worn.

When the car runs it's HEAVY rich, burn your eyes black smoke rich. It will start and idle and go above idle but with it being rich its not running 100% as it should. After X number of minutes, the car will die and it will not start for anything, until the next day, sometimes in a few hours. Ether shot into the intake, no hit. Was the computer reprogrammed to handle the bigger injectors, unknown, but the owner did drive it this way for a summer without too many issues.

No check engine/SES light, but I pulled the following highlighted eight codes from it. I'm not one to jump on the ECM as the problem but this is nuts. Code 53, I put a DMM on the alternator and never saw anything above 14.x so I'm doubting it saw that code, let alone the rest of them, BUT I'm not just not sure and not pulling my hair out. Its not my car and its history is really unknown, but others people have had their hands on this causing problems, such as the intake leak due to reversed gaskets. Seems like I fix one problem and discover yet another. New plugs installed early on, but now they look like they've been driven hard for years, and they are wet. IAC was heavily carboned and looked bad, so it was replaced as well. The smog pump had a connector and its just laying there now,

Anybody been here before? Any solutions or suggestions? Any help is MOST appreciated as this problem child has been bugging me for a few weeks now.

 

A kind helping neighbor.
You will need to collaborate with your neighbors C4 TPI.
That intake can be tricky if not familiar especially the intake to runner bolts. Did you both correct the vacuum leak? Vacuum gauge reading.
It would appear you have restored pressure
(1) prime = KO no start. should snap the pressure to 40lbs - 45lbs, (2) idle should be constant 43lbs, (3) slow gradual rev to approx 2k should be 43lbs 45lbs. Engine off that pressure should stay approx 1 hour.

Help us understand why did the owner install larger injectors. Especially unknown lbs/ hr, pulse width.
This would "require" a PROM tune!
INJ part number?
What mods on this car. that require larger INJ?

 

Vacuum leak is fixed, verified by spraying ether around the intake, leak is now gone.

I have no idea who installed the larger injectors, car was bought this way. I mentioned a retune would be required and the owner knew nothing of what was done. No other mods that I can see, other than the smog/air pump is gone.

With the fuel pressure holding 45 psi all night I'm confident with the fuel. With vacuum leaks gone around the intake runners I'm content there. It starts RIGHT up when it wants and when it dies it turns over like a loss of crank position timing, it just rotates, not even trying to fire.

The current owner did drive this car, it never ran well, but it was drivable last year. During one of it's no-start episodes we observed a nice bright spark when we pulled the plug, so I'm fairly confident in the base ignition. Without knowing these yellow injector specifics I'm not even sure how to get a new tune for it.

I just want to get it running again, let him deal with the tune. It did run, that's the really troubling part.

 

Check the ground contacts. I remove my OE ground bolts. tap/ install stainless bolts day 1
The RH frame area can get rusty creating a bad ground.

 

Agreed common grounds. If the injectors are Bosch IIIs, you might be able to rotate them and see the part number on them. Yellow ones do spec out to be the replacement ones for 86-91 but I did change "injector offset vs Battery +vdc" upon discovering them under hood based on values with a internet search but had to extrapolate a few cells.
Bosch III

 

Will check frame grounds this week.

I really like the idea of this being a ground problem, something I was starting to question. Sounds like I need a wiring diagram of the 90. I was unaware these sensors grounded back directly to the ECM, that gives me a new direction, THANK YOU.

Will see if I can determine if Bosch replacements without tearing it down again. Would be nice if they were spec'd for the car and not adding to the misery.

 

Quick update.

Discussing with the current owner that there is likely an issue with grounds. He replied that was not possible since he just redid two of the grounds this spring AND used anti-seize compound on the ground connections. Winner Winner Chicken Dinner, WHY was that not disclosed weeks ago?!?! So, once the current project vehicle comes off the hoist I'll put the 90 back up and redo the grounds like GM did, minus the lovely anti-seize. This could be contributing to the problem if not THE problem, and I'll reply back to this thread once I get under the car. <sigh>

 

Love your way of thinking, thank you, will do one day soon and report back.