Hard to start and keep running

[gboone]

My car sat idle for a month and tried to start to drive it. It was running perfectly last month and have made no changes whatsoever. It's now hard to start, cranks fine but doesn't fire up easily and when it does, it runs very rough and seems to be missing on a cylinder from the sound and engine shaking. I've pulled a spark plug wire one at time but won't restart in my attempt to isolate a cylinder. I was able to datalog my last brief run time, attached. Any ideas?

2011-06-15_22.04.37.msl

2011-03-20_19.20.10.msq

[trakkies]

If one cylinder is the problem the spark plug should show it.

[gboone]

The spark plugs all look the same, but fuel fouled. I got it to start and run but I changed the plugs anyway. It starts and runs fine for about a minute and starts missing again and dies and won't restart. The timing light indicates way too far advanced for some odd reason. The crank sensor is tight and has not moved. I checked the distributor drive gear orientation. I burned several old msq files that are known to be good. No change. I think the plugs are fouling because of rich misfiring. But I cannot figure out why the ignition timing has gone so far advanced. I'm still stumped. Help appreciated.

[Matt Cramer]

But I cannot figure out why the ignition timing has gone so far advanced.

The log is showing 27 degrees of advance. If that's your real advance, you're getting the timing in your timing table, which is probably too far advanced, and then your cold advance on top of that. It would help if you specified how much advance you're actually seeing.

[gboone]

I made another engine start attempt last Thursday with the intent of checking the ignition timing while trying to start. With making absolutely no changes after it sat for a week, it started up immediately and purred like a kitten. I let it run up to full op temp and reved it up and it had instant throttle response, turned it off. Started it again in 5 minutes, all Ok. Waited 3 hours and it started and ran fine. Started and ran fine again tonight. I just hate the mystery of a month of struggling with the problem and wondering if it's going to happen again.

[gboone]

I finally discovered the problem. There was air trapped in the fuel line. Multiple cranking attempts didn't push the air pocket out. I discovered the problem by partially opening the Schrader valve for my fuel pressure gauge connection and air came out first. Soon after I vented all the air out, the engine started right up. I found some slightly loose hose clamps between the gas tank and fuel pump that likely allowed air to be drawn into the system. Maybe this helps someone with a problem like this. It was difficult to diagnose because the spark plugs were fuel fouled during the whole process.

[siggy_freud]

Awesome followup on your problem. It's soooo helpful when people take the time to return with the solution. Most just drive on and forget they had a problem to begin with.