Runs great when I can get it started. Just cranks but no fire.

Things I've done:
New fuel pump, filter, closing relay, plugs, wires, distributor, AFM.
Things I've checked:
Relays, fuses, sensors.
Im really stumped here
Please help. Also a newbie to this forum
Thanks

 

Fuel, air, spark.

Use your timing light on each plug to see if they are firing. (Then check the timing while you're at it.) Pull a plug and look at it: is it bone-dry? Wet and smells like gasoline? Jumper FP to B+ and see if you can hear the fuel pump running. Remove the electrical connector from the Cold Start Injector to see if that makes any difference. (Shouldn't; if the CSI is the problem it's more likely that it is not opening.)

[I really don't recommend starting fluid. Ever. But if you insist and it runs for a few seconds, that tells you it is a fuel problem not an ignition problem.]

 

Thanks Scope. I'll try your recommendations and get back to you

 

Also, just replaced plugs last night and some of them were wet with gas

 

I used starting fluid to start it and it runs fine after that. It used to start up cold and then not restart after hot, but now it doesn't start at all

 

Did you recently rebuild it or has it just been sitting? When I rebuilt a few 3vzes I always had to start it on starting fluid and run it off of that for the first minute/ minute and a half. After that it would start up on it's own.

 

It's been sitting ever since this started happening. But before that it was a daily driver.

 

How did you get the starting fluid into the throttle body? If you disconnect the air box to do it, you're also disconnecting the VAF. Which means you may be able to start it but it will quit after a few seconds because the fuel pump shuts off (unless FP is jumpered). So if you ran with the air box disconnected you have a COR problem.

If it starts with fluid cold, and starts on its own hot, I would suspect a stuck-closed CSI. If it starts on its own cold, and won't start hot, you may have a stuck-open CSI flooding the engine (you should get a too-rich code with that).

You could pull the CSI out of the plenum (upper intake manifold), put it into a jar, and crank when the engine is cold. (I'd disconnect the coil to reduce the chance of a stray spark.) If nothing sprays that might be your problem.

 

it could have bad injectors or bad headgasket. when i ended up with bad headgaskets it would take a few tries before it would start and then run rough for a min.

 

Scope
I pulled the hose that goes from the valve cover to the throttle body and put a couple of squirts of starting fluid. The vafm was never disconnected.

I will try the CSI tonight

Thanks

 

Scope
What is a COR problem?

 

circuit open relay

I have NO CLUE what it is, just remembered that's what COR meant.

 

Yep. Already replaced the COR
Thanks

 

The Circuit Opening Relay powers the fuel pump, when either: the key is turned to start, or, when the VAF senses air flow. If you get into a crash and break a fuel line, the lack of air flow into your now-not-running engine will shut off the fuel pump.

If your fuel pump runs whenever the switch is on (which is the only way the engine could run with the VAF out of the intake circuit), you could have FP jumpered, or the COR circuit could be shorted.

Of course, "COR circuit shorted" doesn't necessarily mean the relay is bad, you could have simply damaged the connector shoving in a replacement part (or shorted the wires a million other ways). That's why the phrase "you're throwing parts at it" is a pejorative; if you don't know that a specific part is bad, you don't know that you fixed anything by replacing it.

But in your case, I would worry about the COR circuit way down the list.

 

Scope
Tried the CSI in the jar, nothing sprayed when it was unplugged. Does that mean its bad?

 

The CSI is an injector, so it opens when it gets an electrical signal. So if you disconnected the wiring, nothing should come out.

Which is a good thing; if fuel sprayed without a signal you'd definitely have a bad injector. But I meant to suggest leaving the fuel and electrical both connected, so that with a cold engine the CSI should spray. If it doesn't, you need to check the electrical before damning the injector; injectors are expensive.

 

What voltage does the injector open at?

 

Ok. Tried CSI plugged in and in a jar and it sprayed.

This is aggravating

 

Do a compression test yet? If not... I strongly recommend it! Sometimes motors with compression will start really rough, but once warmed up will run fine.

My bud has a 93 just like mine, he bought it with a hard start symptom, didnt even look at it before he bought it, just had it towed to my house... Well when it showed up, it was tore down for timing adjustment(the p.o. thought the timing was off) and all the related parts were in the back seat

After several months of tinkering with it, timing it, re-timing it, and timing it again, checking all sensors etc... I could get it running if I used another rig to jump it, and crack for a while, and when it would run, it ran great... after warmed up, it would start on the first bump of the key, cold starts were a process tho... I finally ran a compression test, and sure enough I had 1 cyl at 150psi the rest were between 0-30.... thus the hard start ...

I never did figure out why, my bud just bought another motor... but I suspect one of 2 reasons... It had recently had the hg's done, and either a) the higher compression from non leaking hg's sucked the rings out, or b) they didnt plane the heads or block... Could also have been mis-adjusted valves as I would hope they did that while the heads were off...

Either way... run a compression test! At least that way you know the general health of your motor, and may know which direction to head after....

 

After messing and cleaning the CSI it started a little better. But not 100%