Engine Performance problem
2000 GMC Safari 6 cyl Two Wheel Drive Automatic
My troubles started with driveability and hard starting problems. The vehicle now will not start unless I dump a little fuel down the throttle body. The only trouble code I get is P1351. The mitchell manual takes you through the ign. System to deal with this code. I have been going in circles chasing this code for some time now.
However! I found from another source that this code will also set if engine rpms are below 250.
I now suspect that cranking the heck out of the motor is causing the code. The real clue to my problem is the dumping a little fuel down the throttle body.
I'm not getting any gas.
The injector harness will light up a NOID test light for all cyls. I have 60 psi fuel pressure. Fuel just kind of dribbles out of the disconnected fuel return line with the pump running.
I suspect the fuel pressure regulator but the mitchell manual requires a set of fuel shutoff adapters (!$250.00!) To test it.
At this point it seems that if I had the adapters the test would indicate either the regulator or grounded injectors are my problem.
Any ideas on a work around or alternative pressure regulator test?
Try to remove the feed line off the front of the fuel filter, test the amount of fuel being pumped out when you crank the engine over. Let me know how much comes out.
January, 8, 2009 AT 7:56 AM
Ken, The pump delivers about 1 gallon per minute (it was replaced last summer).
Thanks again, Steve
January, 8, 2009 AT 10:36 PM
Hi Steve, lets remove all electrical connectors from the fuel injectors. Perform a Ohms test across the terminals, replace any injector that's reading is greatly different from the others.
January, 10, 2009 AT 1:07 PM
Ken, All 6 injectors test at 11.5 to 11.8 ohms. This doesn't seem like enough variation to warrant replacement.
January, 10, 2009 AT 6:11 PM
Hi, yep, those injector are probably ok. With the key in the on position test the injector connector, one side should have power.
January, 10, 2009 AT 10:11 PM
Yes Ken, as I said initially, I can light a NOID light at all 6 positions on the harness. I believe this indicates battery voltage on one side as well as proper function from the VCM.
To recap, the engine will run as long as I dump fuel down the throttle body, so, I have spark. Your suggestions have shown there is fuel delivery of 60 psi @ 1gpm, the injectors seem good, the VCM is doing its' job. Is there any other possibility besides the pressure regulator?
January, 13, 2009 AT 12:49 PM
The trouble code you mentioned is for the crankshaft position sensor. If that sensor intermitted fails it could cause the condition you are describing. I have replaced many of these sensors. Please check it out and get back to me.
January, 13, 2009 AT 1:58 PM
Hello Ken, The crank sensor is new, as is the coil, ign module, hall sensor in the distributor, and VCM (passlock code relearned). Also since my problem started I went ahead and threw in cap, rotor, wires and plugs since they were about due anyway. (I work for an auto parts company and get a heck of a discount).
It really seems as if the ign system is good as well as the electronic side of the fuel system.
I've been reading a lot about the many problems with the GM CSFI fuel system and the popular conversion to MFI. I'm considering this as a real possibility. Whaddya think?
Thanks for your patience,
January, 13, 2009 AT 8:56 PM
Hi Steve, have we checked for spark at the plug wire? please follow this video