1995 GMC Sonoma 1995 Sonoma Starts and then dies right away

Tiny
ILOVETHE800
  • MEMBER
  • 1995 GMC SONOMA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
I have a 1995 gmc sonoma that will start and then die almost right away. It will do this over and over eventually it will start. When it does start it barely runs for a few seconds and then runs fine. It runs fine while driving. Also It has a vaccumn leak in the a/c system that I need to fix because the vents have lost control(i don't know if this is part of the problem). Also the ignition module was replaced about 2 weeks ago because I thought this may be the cause of the problem. Once the engine is hot and warmed up it starts right up.
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Friday, March 20th, 2009 AT 9:19 AM

11 Replies

Tiny
RACEFAN966
  • EXPERT
Ok I would first check the fuel pressure on this. Fist off you need to know what V-6 you have. If the 8th digit is a W then the fuel pressure needs to be 60psi to start and runs on 50-55 psi after that it is any less then it is very hard to start if it starts at all.
Now if it is a Z code then it only needs 9-13 psi of pressure to run. So I would check the pressure and make sure that the fuel pump is priming the lines on initial start up. Other question is how old is the fuel filter? GM seems to like to have the filter replaced yearly. Get back to me and we will go from there.
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Friday, March 20th, 2009 AT 10:21 AM
Tiny
ILOVETHE800
  • MEMBER
Yeh sorry I forgot to put all the info. Its a 4.3 with cpi injection vin w. The fuel pressure is fine I checked that its about 57 psi and I replaced the filter sometime later last year so it is fairly new. Also last year I replaced the crank sensor the cam sensor and the catalytic converter is fairly new with about 30,000 miles on it so it probably has nothing to do with them.
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Saturday, March 21st, 2009 AT 7:51 AM
Tiny
RACEFAN966
  • EXPERT
Ok then if all that is good then lets check the coolant temp sensor first. I would like you to unplug it and set you meter to ohms and check the resistance of the sensor (not the wiring harness). Now if you do this when it cold then get back to me with the reistance and the outside air temp at the time of the test.
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Saturday, March 21st, 2009 AT 9:41 AM
Tiny
ILOVETHE800
  • MEMBER
I think I may have solved the problem. GM has a service bulletin out for hard to start and rough idle on start up. The bulletin says that one ore more of the poppet nozzles in the spider injector may be sticking. I have run marvel oil along with lucas oils tune up in a bottle through the truck and it hasnt had the problem. Is it possible that this is the problem? However that may be because it has been warmer here lately, I bought a coolant temperature sensor because it was only 10 bucks so I figure it can't hurt to just replace it. With my luck though I will probably be back
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Sunday, March 22nd, 2009 AT 8:00 AM
Tiny
ILOVETHE800
  • MEMBER
Ok all of that seems to have solved the problem. I have one more problem to ask about. The truck has had a problem with the fuel pump relay for some time. Occasionally the fuel pump will not work. If yo smack the relay a bit it will start working again. The relay has been replaced. At one time the relay would make a buzzing sound. Is this due to a bad ground? If so which contact on the relay block wiuld I need to repair the ground on. The relay block has constant power to it on the bottom right contact point. Ant it has power to the top right when the ignition switch is turned. The center right contact has no power or ground so I assume this is a wire run to the ecu. The two far left contacts have a ground but I believe one of them is faulty which would I need to repair?
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Sunday, March 22nd, 2009 AT 11:16 AM
Tiny
RACEFAN966
  • EXPERT
Wow funny that was going to be the next try as that is true and if that didn't fix it then it was to pull of the upper plenum and look to see if the fuel lines had cracked as this is also a comon problem. As for the ground it is tied in with the harnes and go to the right rear cylinder head. It is the A1 term off the relay if that helps. Let me know where you want to go from here. Glad to hear it is starting better.
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Monday, March 23rd, 2009 AT 3:00 PM
Tiny
ILOVETHE800
  • MEMBER
Thank you for all of your help. I ran Marvel Mystery trough the Fuel system. Tuned it up just changed the fuel filter the plugs and wires changed the air filter and fixed the vaccumn leak and changed the temperature sensor. It has never run or idled better. Haha it seems I have a never ending list of problems when I was scanning for codes it pulled p1864, p1886, p0753 and p0758 I know these are transmission codes and have to do with the shift solenoids. Do you have any tips or suggestions on how to solve the problems?
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Monday, March 23rd, 2009 AT 8:01 PM
Tiny
RACEFAN966
  • EXPERT
Ok first I would clear them and do a trans service if it has been awhile. If you haven't done it a couple of yrs then it is time anyway. So get a filter and gasket kit and fluid (dextron 3) 6 qts. Remove the trans pan and filter and then replace with new and then start with 5 qts of fluid and start it and run throught the gears (no need to drive it) then put in park and with it running check the fluid level and top off as needed. Then see what codes come back and we can check it from there.
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Tuesday, March 24th, 2009 AT 10:32 AM
Tiny
97SONOMA_POS
  • MEMBER
Wait did you find out the problem to your rough idel/ instant dying?

I have a 4cyl sonoma with exact same problem. I replaced so much stuff on it, I was told it sounds like a IAC sensor which may sound about right. But I just got done doing cylinder head. I have no clue what the problem is with this thing, but like you said it will die right away, and once its warm has virtually no problem. I thought origionally O2 sensor but that throws a engine code(which I dont have showing).

Post back on my 97 sonoma. With the solution to your starting problem.

Much appreciated man
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Tuesday, April 14th, 2009 AT 7:56 PM
Tiny
ILOVETHE800
  • MEMBER
What exactly have you replaced? Mine just needed a tune up it was just a whole bunch of little things. Does your 4 cyl have a distributor ignition system. If so you may want to check the timing as it could be slightly off
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Thursday, April 16th, 2009 AT 6:55 PM
Tiny
97SONOMA_POS
  • MEMBER
As for your fuel pump. I replaced my fuel pump (4cyl 2.2l sonoma), and inside the new pump box there was a note to replace one of the connectors to th e fuel pump because GM said " It tends to lose connection and arc back and forth, thus causing the plug to melt itself to the fuel assembly--big problem.) That may be your problem.
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Thursday, April 16th, 2009 AT 6:57 PM

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