91 Regal Won't Start 3.1


Metro Mighty Mouse
09-30-2011, 05:06 PM
Hi,

I could use some help troubleshooting a likely cause for a no start issue. The engine has spark, There is fuel pressure as pressing the valve gets a pretty vigorous squirt and I can hear the pump run when the key is turned (I am going to buy a pressure checker in the next few days and will confirm proper pressure), the engine just cranks without even attempting to start. I hit it with some starting fluid in the intake hose and it started right up and sounded good. It has stored 2 codes, 33 and 44. 33 is MAP sensor and since I had the money I went ahead and replaced it to no effect. 44 is O2 sensor and I didn't think that would create a no start issue. So it appears there is insufficient fuel pressure (I don't think so) or the injectors are not firing and the reason hasn't set a code. Any ideas where to look for the cause?

Thanks in advance!!
MMM

Tech II
09-30-2011, 06:42 PM
Does the car continue to run after you stop spraying the starter fluid(use carb cleaner, less dangerous)?

44 is a lean condition, this could be due to low fuel pressure, or even a plugged fuel filter.........could also mean you have a vac leak, which could also be the cause of you MAP problem.....could even be an exhaust leak, which would cause the vehicle to run rich and foul your plugs....

Check the vac line to the MAP...it tees off and goes to the f/p regulator....also check the electrical contacts in the MAP sensor, and the harness....

Metro Mighty Mouse
10-02-2011, 01:11 AM
Answer to 1st question, no it doesn't keep running.
Checked fuel pressure, 40 and above when cranking, and when running (started by chance)
As for vac leak, while it was pleasantly idling I sprayed brake cleaner, (and after that starting fluid just to be sure) in all areas with vacuum lines and such to no effect.
It continued to run and rev normally for a couple of minutes so I decided to drive around the block. Of course it stalled just a little bit down the block, just absolutely shut off and would not restart. Hit it with starting fluid and it would kick over but not run. It seems that something electrical is shutting it down or the computer is not running the injectors.

I didn't find anything useful when I searched the the forum originally but on a related post the forum brought up It talked about a bad injector shutting the car down. beginning to wonder if that might be the problem.

Thanks again!!
MMM

Tech II
10-02-2011, 11:56 AM
Well, when it WON'T START, spray carb cleaner into the intake.....if it starts and runs as long as you spray, then it's a fuel delivery problem......you say fuel pressure is ok, so you may have an injector problem....I believe a '91 is multiport, that means 3 injectors fire at the same time....if one injector or circuit goes bad(like a short), the injector driver will shut down, and you lose 3 injectors.......possible problems are ECM(rare), injector(s), or wiring.....have seen a lot of cars where rodents get under that warm plenum and eat the insulation off the injector wiring, causing shorts.....

Metro Mighty Mouse
10-02-2011, 02:37 PM
That is an interesting tidbit and almost definitely going to be the problem. I just wish it wasn't so difficult to get to most of the dang injectors!! I have also purchased my last Chiltons manual, what a load of useless crap.

Thanks again, really appreciate the knowledge!!!

MMM

Metro Mighty Mouse
10-03-2011, 11:01 AM
found injector #6 is dead so hopefully that will resolve the problem.

Thanks,
MMM

Metro Mighty Mouse
10-06-2011, 10:56 AM
injector for #6 had 2 ohms resistance. Apparently that shuts down the whole injector system Replaced it, started right up, ran with no new problems.

Thanks for the help!!
Jon

Tech II
10-06-2011, 08:36 PM
Actually, it would shut down 3 of the injectors.....

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