Ignition only with starting fluid

[onedollarbob]

'83 stock CFI. Quick question before I troubleshoot in the wrong direction. Cranks but no ignition. If the car will start and run for about 2-5 seconds with starting fluid, is it strictly a fuel-related problem? Does this rule out distributor/ignition/timing stuff? I replaced the gas. Fuel pump primes with key on (haven't verified pressure yet). Known driveable car until last night.

[jaywish]

Most probably fuel. Pursue the fuel issue first as it is certainly the likely culprit.

[DerekTheGreat]

Hrmm.. Like Jay said check the fuel pressure. Then if that checks out (Not sure what pressures they run but if they're anything like GM TBI you should have >13psi) have someone crank it while you watch the fuel infectors as they do it. No squirty means no runny. Then have them give it gas while they crank it over. I say that because my '85 (Slightly different set-up with it being EEC-IV and all) wouldn't fire unless you gave it gas or would have it on the fast idle cam of that stupid choke-pull off mechanism. Since you say it runs with starting fluid I'll assume you've got spark.. I couldn't find nothing about that in my owner's manual so I assume that wasn't normal. If I still had it I was going to look at the crank position sensor and then the throttle position sensor, which was most likely the culprit.

[onedollarbob]

Okay, thanks guys. I figured. Will verify fuel pressure and delivery at the injectors first.

[gadget73]

yep, no fuel. If you have pressure, make sure the connector at the front of the CFI unit is plugged in all the way and clean. If the pump or the relay were dinked, I wouldn't expect to hear it prime.

[DerekTheGreat]

How scuzzy is your fuel filter? Just a thought..

[gadget73]

and a good one

[onedollarbob]

Thanks for the replies. Problem: no squirty at the fuel injectors. I found some bad wiring at the harness by the throttle and it's all good to go now. 10-4 on changing the fuel filter--always a good idea regardless.

SIDE QUESTION: the last few hundred miles the car has started misfiring at 1/4 throttle, *only after* a good 20-30 minutes of warm up. I hoped it was the above issue that I resolved, but, nope, I took it out for a good long drive today and it's back. Past threads seem to identify this behavior with the TFI, but of course that's on the later cars. My '83 still uses the old style ignition box--I'm used to those just plain dying in the middle of the road if they go bad.

Is the ignition box something to consider for the light-throttle misfire after warm up? The distro cap looked trashed inside, so I replaced that and the rotor but no difference. No vacuum leaks detected around the throttle body or gaskets.

[gadget73]

I'd be looking at all of the vacuum lines very closely. Change them all if there is any doubt.

Would be worth checking or changing the oxygen sensor too.

[onedollarbob]

Would be worth checking or changing the oxygen sensor too.

It's been three years since the last one. Why not? I don't mind Whack-a-Mole if it's cheap.

[knucklehead0202]

Is that a duraspark ignition? Only problem I ever had with that is they get funny when they get wet, lol. Anyhow, have you looked at the rest of the ignition system? If the coil is old, change it. Ditto for plugs and wires. Cheap insurance and will at the very least narrow things down. My experience with vacuum woes was worse when cold rather than warm, but I guess every car is a different kind of asshole. Hey, we're practically neighbors! Glad to see another poor bastard here stuck in California.

[DerekTheGreat]

Misfiring? You sure it's not like a stumble or falter? I ask because I have a similar problem with our TBI 454 GMC. Seemed to only do it when cold though, you'd go to accelerate and it would stumble around and then pick back up and continue to do it until it revved up to a certain point or you either hammered it or let off the gas. I've been driving it the past three days as my DD to save the Townie from salt but it hasn't done that garbage since the first day. Whereas in the past the thing only got driven to do junkyard runs or to fill in when one of our cars was out. So despite me taking the TB apart, hand cleaning the injectors and rebuilding the TB the injectors are still bad.

[gadget73]

If the oxy sensor is not original, its probably fine. I'm just used to hearing about problems with 30 year old cars and damn near all of the parts are original.

[onedollarbob]

Misfiring? You sure it's not like a stumble or falter?

Yeah, I should rightly call it an extended stumble, not true misfiring. It "feels" like how misfiring feels, though. For me it was after full warm up but completely fine when cold.

So, I resolved the issue. Not sure how, though. I noticed the rear air hose to the valve cover was not connected to the air cleaner housing anymore. I hooked it back up (there's a sponge filter behind it inside the cleaner housing) and the issue immediately went away. Car drove perfectly fine the last few times I took it out, and I made sure to get it good and hot. I can't see how that hose would have any effect on my specific symptoms. The PVC system just sucks air into the valve cover back there, so it shouldn't matter if it's air from the cleaner housing or not. Or maybe it does? Is this actually a closed system on *both* sides?

Knucklehead, yeah, owning a box Panther in LA is fun with the smog inspections!

[knucklehead0202]

If you're toying with converting to SEFI at some point i'll give you all my old shit if you want it. Within the year i'll be dumping my stock intake, injectors, fuel rails, etc, and may just yank the whole motor out more or less complete. It runs fine but the other one will be better, especially if I go 347, which is looking pretty strong at this point.