It may just be my inability to search but I have not found much on this topic.
The basic issue is the at starting, cold or hot, the car runs too rich to start. Sometimes I can pull out the fuel pump relay, crank it till it stops trying to fire, turn the key off, plug the relay in & give it a go. It runs a bit rich otherwise but not so bad it dies.
History: I picked up a 1999 Sunfire 2.2L OHV with 170000 miles. I was told needed a new motor. The fuel pump was dead & the tank already out. He had also taken off the valve cover. I gave it a new fuel pump, put things back together & got it to start working around the issue above. "Cool. I'll drive it till it dies." Compression was low, 80 PSI, but even across all cylinders.
It was running a rough so I figured between what little bad gas was in the lines & tank plus sitting for ?how long? Id let it run for for 30 minutes or so to flush out the fuel system. That was a bad idea as it finished blowing the head gasket.
Replaced that & cleaned the 1/8 inch of gunk off the head & what I could reach. The owner saved a lot on oil, as in never changed it. The cylinders looked After bolting it all back together It started better & ran OK. Changed the oil & topped off the cooling & took it for a drive. It was low on power & throttle response sucked but drivable. It still has the starting, issue raw gas smell at the exhaust when starting, but less when running.
Plugs are now sooty but not wet. I have unplugged the IAT, TPC, MAP, ECT & IAC in different orders but it never changes anything. There are no codes & the sensors read good on my ScanGauge II. Injector spray pattern looks good & even across all injectors. Ohm on the injectors ins in spec @ 2.1+-. The intake & throttle body look OK. No clogs that I can see other than the oil gunk from the PCV. & Interesting the PCV does not blow out air like I see in most engines.
I tested the spark by taking off the plug wires 1 at a time, inserting a screwdriver, laying it close to ground then cranking the motor. I noticed the 1-4 coil did not have the spark that 2-3 did but seemed OK.
Does anybody have an idea why it would run too rich to start normally but when started seems to run OK?
Oh. I forgot. I can blow threw the fuel return line & I switched out thew FPR with one from a running ecotec. No help.
I had a similar problem with my 99 2.2. My issue was I had a leaking injector. I would also look into fuel pressure regulator.
Leaking or stuck injectors was my 1st thought. I pulled the rail & had my son crank the engine wile I watched the injectors spray into a towel. The injectors had 5 or 6 holes so I assumed the pattern would be round but it was flat on all of them. They all looked dirty at the tip but then spray holes are about 1/4 inch inset & looked clean there. I may test that again one at a time.
As for the FPR I took one that looked the same & fit from a running 2003 Ecotec.
Just as a test I went out & blew in the running Cavs fuel return line. It actually has more resistance.
Will retest the injectors tomorrow & may see about getting a coil to test that. Still seems like a fuel issue.
Did you replace or clean the injector? If cleaned with what?
I yanked the injector rail yesterday. With everything still plugged up I had an assistant turn on the key but not crank the engine a few times to prime the rail. The pump whirred for the 2 seconds like it should each time but there were no signs of a leaking injector. I unplugged all of the injectors & plugged 1 in at a time watching the spray in a glass jar while my assistant cranked the engine. The spray pattern was good & mostly round with no signs of leaking after shutdown.
I did notice the fuel was clear but had a milky color to it. Water in the fuel. I put in a bottle of iso Heat water remover. I cycled the fuel pump a few times to help mix up the gas in the tank & purge what water may be in the lines. When I cranked the engine it started right up. It idled OK but after varying the RPM for about 10 minutes I let off the gas & it died. I could not get it started after that. I did a compression check & all cylinders were down around 60 PSI as opposed to 90+ before I changed the head gasket.
Today I tried to start but it just turns over without even thinking of starting. A cold compression check gave not quite 60 PSI. Squirting oil in the cylinders got it up to 100 PSI. "Think the rings may be bad?" he ask rhetorically. Its still interesting that blow-by & oil burning do not seem to be an issue. But then I doubt Ive had it running for more than 45 minutes.
Last ditch effort is to try some engine "Engine Restorer and Lubricant". If that does not get me a few hundred more mile I guess I'll get a rebuild kit.
