Alfa cranks but just backfires...loudly.

[kf4lvc]

HELP!
I have a 1974 GTV2000 that was running just fine a couple of weeks ago. I parked it and tried to start it once, which it was 18 degrees out and it wouldn't crank. The rear fuel filter and hoses needed replacing, too. I replaced those today, and the Alfa will not run. I get proper voltage to the pump and the plugs, wires, and rotor cap are new. When I try to start the car, the starter engages well and the engine turns just fine. However, all I get is either a LOUD bacfire through the tailpipe or a horrible misfire that blows flames out of the air filter canister (if I have it open). The exhaust is less than a year old, including the catalytic converter. I was afraid that somehow I miswired the spark plugs to the rotor cap when I replaced it, but it ran like a top for months. I have the alfa bible, but it shows NOTHING about spark-plug/rotor cap diagrams/photos, so if anyone has the proper sequence, I would appreciate a diagram or drawing, just to be sure.
If anyone can help, thanks! I think this is a really simple fix, but so far it's got me stumped!

[papajam]

Yep. Sounds like the firing order is off. Quite easy to fix too. Remove #1 sparkplug. With the trans in 4th or 5th gear, push the car until the #1 piston is all the way up AND the valves are closed. Remove the distributor cap and note the direction that the rotor is facing. That's cyl #1. Reinstall the cap and put the #1 sparkplug wire in the tower that lines up with rotor. Then, in a clockwise direction, install plug wire #3 in the cap, then #4 and finally #2. Should fire right up.

[JoeCab]

kf4lvc,

Why do you have a catalytic converter on a '74 GTV? They didn't have them from the factory - do you need the cat to pass smog?

Joe

[kf4lvc]

Thanks for the info, guys! The catalytic converter came with the car...the state of NC has pretty high emission standards. As for the plugs/rotor position, it seems like a firing sequence mismatch. I've has some 40 odd cars in my life and do most routine (and some not routine) maintainence myself and I've run into one or two firing sequence problems. Only thing is, I can only guess at the cylnder numbers and the rotor positions. Again, the Alfa bible doesn't cover these very basic items for some reason. Luckily, I just purchased a Haynes manual over ebay.
I'm guessing that the cylinders run from #1 to #4, from front of engine(front of car) to rear, in-line. The rotor positions are, clockwise from the 1 o'clock to 11 o'clock, #1-#2-#3-#4. I think this is the right sequence. Got that by looking at photos of other GTV engines!

Vince

[alfajim]

It is possible to get the distributor in 180 out from where it should index. Then at the most inopportune time it will jump into the proper slot and you are instantly 180 out on the plug wiring.

[papajam]

Yes, the cylinders are numbered 1 thru 4 front to rear but the firing order is 1, 3, 4, 2 turning clockwise. If the sparkplug wires are installed 1, 2, 3, 4, then that's the problem.

[kf4lvc]

That may be the problem. Too late tonigt to check in the dark, but first thing in the morning, we'll have another look at it. I think the cap is labled 1,2,3,4, actually. It was a little tough tracking one down in this area. I've been told by a guy in the local alfa-world that there may only be 2 GTV owner's within 100 miles. Unfortunately, my job has kept me very busy for the last few months and I haven't been treating the Alfa the way it should be treated. I also do not have a garage, so no night-time mechanic work for me. Thanks again. I'll let you know what happens.

Vince

[Roadtrip]

Pay absolutely no mind to any number embossed on the distr cap. Unless you put it there yourself. Recommend that after you get the firing order correct, that you do label you cap.

[kf4lvc]

Well, I put the firing sequence right, but still not start. I do get a soft doubl-backfire now. I haven't tackled making sure that cylinder 1 matches rotor position 1, by putting the car in gear and taking out the plug. I'm wondering if my distributor did jump 180 degrees. The other thing I need to look at is the fuel and oil filters in the SPICA injection unit. I'm just baffled by this.
I was driving the car daily, about 60 miles round trip, mostly highway speeds of 70mph. Never experienced any indication that anything might be amiss. Like I said before, I parked it for a few days, and then... nothing!
Now I'm wondering if my spark coil is weak or if something is shorting to ground. The engine turns over very well, but still no vroom-vroom!

Vince

[Roadtrip]

Vince - I think your firing order is still messed up. It'll take you about 10 minutes to get it right, but you have to do all the steps.

1. Take out the number one spark plug.
2. Rotate the engine until the piston is at the top of the stroke and both valves are closed.
3. The crankshaft pulley pointer should be pointing to "P" (trans. PUNTO or Italian for Top Dead Center) on the pulley.
4. See which terminal the rotor is pointing to. Connect you #1 spark plug lead to that distributor cap terminal. Then clockwise, connnect #3, then #4, then #2. Firing order 1,3,4,2

If you haven't moved the distributor timing, that should get it back in firing order.

[kf4lvc]

Well, I tried the procedure and made sure that the firing sequence matched the pistons, everything checks out, but the engine still won't fire up. I pulled all of the plugs and cleaned them, as they were a little blackened from the backfires. Maybe my fuel pump is just not pumping the way it should. It engages and gets the proper voltage, but could it be damaged internally? It's not making any ugly noises, just the usual high-pitched hum it always made.

Vince

[Roadtrip]

Vince -

Let's back up a moment. Did the problem occur "out-of-the-blue" or did it happen after you changed something . . . like the spark plug wires/distributor cap, etc?

Also, btw, 74s don't have catalytic converters. The front muffler looking thing is a resonator, not a CC.

See the picture below, note the distributor rotor rotates clockwise. This is real easy to get crossed-up in your brain.

From here on out, I'm assuming that timing and firing order are correct.

The next thing to check would be a stuck Cold Start Solenoid on the Injection pump. That is a common failure mode, although, the engine will usually initially start, then stumble/die from a grossly overrich mixture. If you've been cranking the engine a lot with an overrich mixture, that might explain the tailpipe backfiring from so much raw fuel pooling in the exhaust system.

Quick check of the fuel system:

1. Does the fuel low pressure warning light come on momentarily when you turn the key to "ON", then extinguish almost immediately as the fuel pump builds up pressure? Did the light used to stay off while the engine was running?

2. Remove the SPICA air box, then disconnect the wire to the rearmost "can" on the top of the injection pump. Tape the wire up so it doesn't short out on anything. That wire is "hot" anytime the starter motor is engaged.

3. Next, take a small hammer or some other object and give the rear right corner of the injection pump a few light taps. This may free up a stuck plunger inside the pump. Try starting the car again. Make sure the spark plugs aren't fouled from previous start attempts. Some "Starting Fluid" you buy in the spray cans may help the initial start. I'd recommend that you keep some on hand, especially when it's really cold outside.

NOTE: When starting a SPICA injected car (or any fuel injected car for that matter) DON'T go pumping the accelerator while cranking the engine in an attempt to get it to fire. The injection system is already enriching the mixture. In cold weather, it may help to slightly push down on the accelerator pedal while cranking. If you're pushing way down on the pedal on a SPICA car, you're making matters worse not better.

Let me know how you make out. It's probably something really stupid simple, but you have to be a genius to figure out which stupid thing it is.

[Roadtrip]

Wire to disconnect. (Cold Start Solenoid).

[papajam]

Quote:

Originally posted by Roadtrip ...It's probably something really stupid simple, but you have to be a genius to figure out which stupid thing it is.

[Alex Csank]

I have had a couple of occasions where an Alfa Distributor would loosen from its mounting and actually turn within the block. This could be the problem. Check and see if the distributor is tight in its housing.

Another possible problem may be the upper timing chain. Not a common occurence, but it might be worth checking.

It sounds like you are getting fuel. I assume that you have checked to make sure that your air cleaner is OK, so you should be getting air. The only other thing is spark...and it sounds like you are getting some, but not at the right time. If it isn't the ditributor, it's probably some other ignition component.

Just my WAG! Jim, what are your thoughts on that?

Cheers,