2.3L ('83-'97) 1990 2.3 crank no start, but tries to start, and will if you pop start it.

[Jnic]

I am having this happen on occasion and now almost every day. It seem to be happening when it's been sitting for a few hours or overnight. If it was just running I can usually still start it but it takes quite a bit of cranking. Just hooked a fuel pressure gauge up last night. Running it's at 30 psi, if I unplugged the regulator vacuum hose, it jumps up to about 40 so that is working. If I go to prime the fuel before starting it will barley go up, and I have to cycle the key a few times for it to get up to around 40. So if I cycle the key a few times then go to start it, it still wouldn't start. Here is a video I took of that:

https://youtube.com/shorts/yRgs5hls6dg?feature=share

Here is a video of just what it did before I had a gauge hooked up after it had been sitting overnight .Sometimes it does like this and tries to fire, other times nothing. But like I said if I go pop start it, it starts. Now it doesn't actually "catch" right away. Once I let the clutch out it kinda sputters a but before it stays running.

Another thing to mention is after priming the fuel, it will slowly start dropping. Maybe 5 psi in about 5 minutes. I'll have to check again in a bit, but it definitely wasn't holding pressure entirely.

So all and all with what I've tested so far I'm thinking it had 2 issues. I'm thinking possibly a bad fuel filter causing it to take several key cycles to build enough pressure. Then I'm thinking something with the injectors causing it not to fire even with adequate fuel pressure.

 

[RonD]

Welcome to TRS

Cranking speed with fresh battery is maximum 200rpm
Bump start in 1st or 2nd is 600-800rpm
So I wouldn't read a whole lot into that, the only real difference outside the higher RPM is higher voltage for the spark system when bump starting, because a start motor causes 12volt battery voltage to drop to 9.5 to 10volts

Watch the CEL(check engine light)
It should come on with key on, that means computer is powered up
When starter motor is activated CEL should go OFF, that means computer is getting a timing pulse from ICM so it will start opening injectors

ICM(ignition control module) is the spark system, it gets the timing pulse from the crank sensor, then passes it on to computer for injector timing
ICM was a common failure point when older, poor grounding and brittle wires
They also became heat sensitive, slow warm re-start, but not in your case

I would do the 50/50 test, that will tell you instantly if its a spark or fuel issue
Get a spray bottle of gasoline, or can of Quick Start(ether) or even Carb cleaner

Take off the Air intake hose at the throttle body/intake
Spray fuel into the intake, you can leave the hose off
Try to start engine
If it starts up quickly but struggles and dies then Spark is good, and fuel delivery is indeed the issue
If it doesn't start up quickly then its a Spark issue(or compression)
50/50 instant results

If engine runs strong at highway speeds then not a compression issue, or fuel filter, or fuel pump
Or clogged exhaust
These are things that show up as low power when demand is higher, i.e. highway speeds

 

[Jnic]

Welcome to TRS

Cranking speed with fresh battery is maximum 200rpm
Bump start in 1st or 2nd is 600-800rpm
So I wouldn't read a whole lot into that, the only real difference outside the higher RPM is higher voltage for the spark system when bump starting, because a start motor causes 12volt battery voltage to drop to 9.5 to 10volts

Watch the CEL(check engine light)
It should come on with key on, that means computer is powered up
When starter motor is activated CEL should go OFF, that means computer is getting a timing pulse from ICM so it will start opening injectors

ICM(ignition control module) is the spark system, it gets the timing pulse from the crank sensor, then passes it on to computer for injector timing
ICM was a common failure point when older, poor grounding and brittle wires
They also became heat sensitive, slow warm re-start, but not in your case

I would do the 50/50 test, that will tell you instantly if its a spark or fuel issue
Get a spray bottle of gasoline, or can of Quick Start(ether) or even Carb cleaner

Take off the Air intake hose at the throttle body/intake
Spray fuel into the intake, you can leave the hose off
Try to start engine
If it starts up quickly but struggles and dies then Spark is good, and fuel delivery is indeed the issue
If it doesn't start up quickly then its a Spark issue(or compression)
50/50 instant results

If engine runs strong at highway speeds then not a compression issue, or fuel filter, or fuel pump
Or clogged exhaust
These are things that show up as low power when demand is higher, i.e. highway speeds

Welp sure enough, it didn't have spark. Just put new plugs in and bam now it fired right up.
It does still seem to not be holding pressure completely when it's off. It went from 37 psi to 22 after 30 minutes. Also yes it ran fine at highway speeds. I wasn't really expecting it to be a spark issue or I would have checked sooner. I just did wires and coils because of a missfire issue I was having a few weeks ago.

 

[RonD]

On 1997 and earlier the fuel pressure when off should hold above 15psi for a few MONTHS
But not that big of a deal if it drops to 0psi

Turning on the key will get 0psi to 10psi which is enough to start engine, in 1998 and up it won't be enough
So not a big deal on your 1990

The fuel pressure can leak in two places where you will not smell leaking gasoline, lol
The fuel pressure regulator(FPR), and the fuel pump itself

FPR has the Fuel Return hose attached, if its internal spring is not holding the valve closed then fuel(pressure) will go back to the gas tank
You can hook up a pressure gauge, cycle key on and off to get pressure up to 30-40psi, and then CAREFULLY squeeze the Return hose to close it off
If pressure holds then FPR was leaking
If pressure still drops then its the fuel pump

You can also just remove the Return line from the FPR, put a towel down and cycle key on and off just TWO times, for 20psi, and see if fuel is slowing leaking out of FPR