Hard starting + missing

[dwh4784]

My Lebaron has been running great all through last year and this winter until recently it has been getting hard to start when warm. I would have to babysit the throttle and keep it from dying and it would just run really rough for 10 seconds or so. That problem has been getting progressively worse to where it is hard to start at all now, cold or warm. It smells like raw fuel when it does finally start and idles low and choppy. Also it has developed a miss under slight load. Under boost it makes great power, good AFR around 11.5 at WOT.

Put in new NGK BR9ES plugs this weekend. I was running Autolite 64's but I'm not sure if 64 is actually one heat range below the stock 65 so I wanted to change them anyway. I also gapped them at .28 instead of .35 thinking the coil might be getting weak. If anything it runs worse with the new plugs.

I had a code 21(O2) and 45(overboost), put in a new O2 sensor and coolant temp sensor last night. No codes popped up driving it around last night or after coming to work this morning. The overboosting was due to the w/g arm being too tight I fixed that awhile ago so it was just stored.

It did start a bit easier this morning but the miss was still present. Jay and I tested the fuel pressure and it is fine, I was thinking a bad FPR possibly but it looks good.

What else might be causing hard starts and missing like this? The car doesn't have AIS, I'm used to having to nurse the throttle a bit when it is cold but this is nothing like that. It just doesn't want to run at all.

[dwh4784]

Replaced cap, rotor, and spark plug wires tonight for no reason. Still a fail. Finally bit the bullet and did a compression check. 120-115-103-135. Looks like this engine is toast, #3 at least but all around tired. Up until this recent dilemma it always ran fine wideband jumped around 14.7 like it should. Now it's sitting around 13.5 idling no matter hot or cold, smoking on startup, reeking like gas. It bounces around stoich if I idle it up but misses like crazy. Time to part out or rebuild it seems...

[Tbird232ci]

How did you go about checking your fuel pressure regulator? I had one fail to where the diaphragm split, and it was dumping fuel out of the vacuum line directly into the intake manifold. It ran pig rich, and dumped enough fuel to leave a carbon trail up the street.

[dwh4784]

The vac line doesn't smell like gas and we tested the fuel pressure and it seems to be fine. Primes when you turn the key on, holds pressure when it's off, acts normal when it's running. I'm thinking maybe something between #2 and #3 causing them to both be lower than the rest. Although the numbers seem awfully low to me all around. The last TM I had that I checked was more like 150ish.

[85boostbox]

Did you tape the guage to the windshield and drive it. My bet is a dying fuel pump.

[dwh4784]

Walbro 255 put in last summer, I hope not. Besides that it's running overly rich and smelling like gas, if anything an overfueling issue.

[bgbmxer]

I'd bet its a regulator issue. What for pressure are you running as base pressure. And how quick does your fuel pressure drop once off. Also did you use the correct fuel line when you replaced the pump in the tank

[Tbird232ci]

How do the plugs look for number 3 and 4 cylinders? They will tell you a pretty good story.

With the starting issues being temp related, how old is the ECT sensor in the car? I dont remember how, but I know the info on testing it is on the forum somewhere. Could probably find it on a search.

Have a vacuum gauge on the car? What is it reading at warm idle?

[dwh4784]

All 4 plugs look decent enough. Nothing stands out to say "yeah that's it!" anyway. Although I changed the old ones as soon as it got to where it would barely start, and only used the new ones for two days.

ECT sensor? I'm not familiar with that.

I think I found the issue. I pulled the head and had it pressure checked and it failed miserably, there are cracks in the combustion chambers, water jackets as well as the usual ones between the valves. Looks like I'm shopping for a new head. Edit: Looks like I'm going to try and find a decent core and the guy who pressure tested it (friend of a friend who works at a reputable local shop his dad owns) will rebuild it for $180. That seems like my best bet.

[dwh4784]

Here are a couple of crappy cell phone pics of two of the worst cracks. #1 and #2 both have nearly identical cracks in the front side of the combustion chamber at the intake valve. #3 has one on the back side of the intake valve and another in the water jacket right next to it. #4 doesn't look like it has any.