Hey guys,
'73 2.0 FI blew a spark plug out...fixed it and it ran so-so...then it didn't run at all...then it ran perfect for 20 minutes...then next day ran for a minute and died. Plugs have weak spark but couldn't get a pop out of any cylinders for two hours....still dead....have checked a lot of wires and logically it should at least fire a bit but absolutely nothing. Maybe spark too weak to fire under compression? Or some component dead I can't figure out? Even with starting fluid not a single pop. Your thoughts? Thank you.
gg

Needs fuel, air, and spark.

Sounds like the spark is weak. Not great. Possibly try disconnecting all the extra stuff from the coil (tach signal wire, any extra crap that got plugged in) and see if that improves it.

Check for fuel. You can put the injectors into jars and look while the starter is cranking. You can also look at the spray pattern to make sure it is vaguely cone-shaped.

Check for air--or rather, compression. All four cylinders.

If you have those, the only variables are when the sparks happen (timing), and how much fuel is going in (mixture).

--DD

Thank you DD...I did pull injectors and they squirt....it is a real puzzle unless there is no spark in the cylinder....is that possible? Driving me nuts....car ran beautiful but quit in driveway....something changed....but what??
gg

Do you smell gas when trying to start? If you pull a plug after attempting to start is it soaked with gas? As for weak spark, assume this is based on pulling a plug and cranking with the plug grounded against the engine case or other good ground?

If she is flooding, I'd take a look at your CHT sensor. A bad sensor or broken lead/harness wire on the CHT can cause flooding and no start, even to the point of showing no willingness to kick/pop.

Wow Somd914....you are describing it exactly as it is. I am judging the spark with a spark plug pushed against a part of the engine....very weak spark....lots of gas smell....while repairing the blown out spark plug I nudged and pulled on all the wires in the area. I will get back in there and double check all of the wires. How do you test the CHT? Thank you.
gg

Did you nudge them to the left, or right? How's the barn coming? Did you sell off the other cars?

Have you checked out the Fiat x19 forums? They are great fodder. Seriously, you could win there.


-oi812

It's been a while since I messed with D-Jet, went carbs several years ago.

I'm looking for the resistance specs and D-Jet harness pin out, but you'll need a multimeter to read the resistance of the sensor. Its resistance changes with temperature to change fuel enrichment. With high resistance or an open such as a broken lead wire, the mixture goes very rich and the engine won't run.

First step is to disconnect the CHT from the D-Jet harness and test the resistance at the CHT connector. If out of tolerance, then replace the sensor. If it's good, reconnect the CHT connector to the harness, then you will need to pull the harness cable at the engine control unit and test resistance from the control unit connector.

In my case, I had a broken wire in the harness a few inches from the CHT connector. It made intermittent contact, so it would run occasionally then die, or it would crank with no signs of firing off, just flooding.

Sorry, I'll see if I can track down resistance specs and control unit connector pin outs, or perhaps someone else will chime in...

Check your distributor cap center (coil contact) pin. It's spring loaded and should push in at least 1/4". If it's worn to the end limit it will make a poor "on again, off again" contact.

Broken MPS diaphram will flood the engine like it is WOT.

If this post is for real...

Check the braided ground wire between the advance plates in the distributor. It's not uncommon for one end to come loose. If that connection is bad, it causes weak spark. Sort of a needle in a hay stack, so good to know.

Yes this post is for real. I have a new distributor cap on there and will be checking the braided ground wire as suggested. Will be tracing the CHT sensor lead wire as well. Mikey said he has new CHT sensors but I wonder if the 012 vs.017 part number discrepancy will be an issue? Thank you for the PM Mark and all other responders.
gg

Trying after all the OU812, you understand.

Greg has been here awhile.

Sigh. Sorry Greg. Kent's word is good enough for me. It's just that ou812 left a bad taste in our mouths, changed his screen name to something like second wind... The remains of a polluter. I just don't have tolerance for trolls, but letting it go.

Seriously, check the ground wire between the dizzy plates. Happened to me in a parking lot. Cranked, backfired, wouldn't run. Checked spark, it was weak yellow. Found the wire broke loose on one of the plates. Still had *some* spark but it was weak. Swapped in a spare dizzy and it fired right up. YMMV but just something on the table.

Oh...Ok....I get it...you're treating me like Emmett Till but just now realize I'm some other guy....I will let it go if you can solve the puzzle.....
Regards,
gg

Yeah Rand.....thanks for the help. Just to get it out of my system, I suspect the only bad taste in your mouth is from Kent's dick. Fuck you both!!
Sincerely,
gg

Wow, sounds like someone needs a time out...

--DD

MPS passed pressure holding test....thank you.
gg

Your a EDIT. I was standing up for you. Are you the guy with the light blue 914 that was at the last WCR?

Wow....I know you stood up for me...thank you....no anger aimed at you...those two other guys were accusing me of being some other guy...how did I offend you? I whole heartedly apologize for upsetting you...
gg

I spent some time the other day with 2ndwind and his '73 2.0L.
I had set up the mps and adjusted it with my AFR meter, it ran pretty good.

I found the #4 spark plug had loosened it's time cert and was no longer holding compression.
The main problem seems to be the engine is flooded, plugs 1, 2, 3 were all wet, plug 4 was bone dry. One of 2W's problems could stem from a bad connection on injector #4 (dry plug).
The battery has been run pretty low and needs a good day of charging.

I checked everything that has been suggested here, (pertronix doesn't need the ground strap in the dizzy, but it is there).

One of the items that seemed odd was the fuel pump would run for 30 seconds or more?

He relocated the pump a while ago, and I must say the plumbing job is top notch.
After checking the hoses for kinks, with the pan off, the pump acted normally, about a second on and then off. Repeatable.

I did check the orientation of the relays, we replaced one that had it's cover come off.

The last time it fired up gg said he had left the key on for 5 hours, that's what prompted the Pertronix question. FYI they are WAY sensetive to reverse polarity, DO NOT MIX UP + AND - ....


I really have to say the 2ndwind is just like me, he freaks out when his car is not running right!

I think a new set of plugs, let the battery charge and dry out the cylinders, FIX the time cirt correctly, and he like me would be happy as a clam, rushing down the road to the next 914 issue to set the emotional rollercoaster in motion.

Stuck valve? Put your hand over the throttle body and crank the engine. Vacuum should suck your hand tight.