95 gmc jimmy shuts off while driving!!!!!

Ok I have had this car for two years. It has over 260000 miles on it and I have done quite a bit to it, but I am stuck now. Within the two years I have had it, I have replaced the starter, water pump, belts, a freeze plug (wierd), battery, alternater, fuel filter, spark plugs, plug wires, distributor cap, rotor, coil pack, and now I am wondering if it is worth replacing anything else. It runs rough and shuts off especially if I come to a red light and stop, but if I throw it in nuetral it is not as bad and doesnt shut off. Just the other day I was sitting at a red light with the car in nuetral and when light turned green I put it in drive hit the gas and it just shut off... I tried to start it and it sounded like it was trying to start but wouldnt then sounded like the battery was dying from trying to start it so we tried jumping it with two different vehicles and did not work. Bought a new battery and that got me half way home and shut off again. Charged the battery put it back in car and got me rest of the way home. When it shut off i was pressing the gas and the rpms dropped all the way down then all my gages lit up. and before this maybe a few days before, i was sittin in a drive through and i had it in nuetral and it reved up by itself i didnt press the gas. This car really scares the sh*t out of me and I want to fix it but dont know what else to fix... Please help

Which engine?

Have you ever replaced fuel filter?

Does check engine light come on?

Have you checked for any codes?

Have you checked volatage at battery while running to see if alternator is charging with a voltmeter? Since you had to charge new battery to get home I would start with this to make sure alternator is working. You should have 13.5 to 14.5 volts while running.

Clean throttle body and MAF sensor.

Condition of air filter.

Check fuel pressure with fuel pressure gauge?

What kind of gas mileage are you getting? Has it changed of late?

v6 vortec 4.3l i replaced fuel filter, check engine light only comes on after car shuts off, i cant take it anywhere to get the codes read yet im thinking about purchasing code reader but not sure which one i need, battery operates at 14, dont know pressure of fuel, i have a pretty bad oil leak on the engine oil lines that might have gunked something up from splashing around, i dont know if that could make it shut off or not, throttle body is clean, gas mileage has been about the same as when i first got it.

Check your fuel pressure, best if you could leave the fuel pressure tester hooked up and drive 20-30 minutes observing fuel pressure. Sounds to me like the fuel pump is heating up and loosing it pressure when warm. Do a search using fuel pressure test and you should find a procedure by MT-2500 that is a excellent procedure to follow. Post readings.

Some 95's have the OBDII system but if you have the OBDI system here is a link for the diagnostic terminal picture:

http://i644.photobucket.com/albums/uu164/tempfixit/95Codeterminals.jpg

http://i644.photobucket.com/albums/uu164/tempfixit/95Codeterminals.jpg

Jump terminal A & B with ignition switch off, once jumpered turn ignition switch to run without starting engine. Check engine light should flash, pause flash flash meaning code 12. Each code present will flash 3 times then move on to next code. Post codes.

Hope this helps

fuel pressure is fine im thinking the oil pressure swith or something to do with the oil pressure is messed up because everything i read says low oil pressure causes system to shut down. My oil cooling lines have had a worsening leak for a while and im thinking all the fluctuation from low and high pressure could have screwed something up. What do u think? I couldnt get any codes either i got it to auto zone and they couldnt get anything out of it

Do you know if it is a OBDI or OBDII system? Not being able to get any codes makes me believe it is a ECM or PCM problem.

When you changed the battery with a new one did it start right away?

Explain the oil pressure flucuating more>

How much oil loss is there? How many miles to quart of oil.

To my knowledge there are not any exterior oil cooling lines for the engine. There are oil cooling lines for the transmission going from tranny to radiator transmisssion cooler.

I am going to look at a schematic for the oil pressure sensor and see if I can fiqure out anything.

Possible Idle Air Control sensor is faulty, Throttle position sensor another possiblity. When it does run and you are driving (Not at idle) how do this engine run?

ANother thing to try is removing the upstream oxygen sensor (the one before the catalytic converter and see if that makes a difference in operation, if it does you have a clogged catalytic converter.

Not being able to retrieve any codes is puzzling..

Try posting your problem under the Blazer forum also, possibly somerone there will have some input.

Have you done a compression test?

I just wanted to add, some 95's have OBD1 with an OBD II connector under the dash. If yours is one of these types autozone cannot read it. There is a way to get the codes posted here somewhere.
You never posted back about the alt readings. Have you verified the alt is good?
Have you checked the EGR valve yet? They are known to carbon up on these engines. If you remove it to check it out it is worth the extra cash to put a screened gasket in it.
The oil cooler lines shouldn't have affected anything. If you replace them get the Dorman lines, they are of better quality and will last longer then stock. I got mine on Ebay for $7.00 shipped.

i do not know if it is obdI or obdII. the ecm fuses were all good when we took them out there was 12 v in fuse and put them back in and everything worked. when it runs it runs great! i love this car i got dual exhaust and tinted windows for my bday. i only paid 700 dollars for it and it has lasted me two years. the alternator is fine. it did start right up when we put a new battery in it, but i dont think we needed either battery or alternator i think it just had to sit for a while to start because i start it and it runs for a little while them shuts off and wont start again for another couple hours sometimes sooner. when i tried to show someone what it was doing, i took it for a drive and it shut off, but this time it started right back up then on way home it shut off and wouldnt start back up. the oil pressure is really what im thinking is the problem because it has had a bad leak for a while and when i would come to a stop sign or red light it would shut off in drive when oil pressure would go down and check gages would come on so i was putting it in nuetral and tapping the gas to keep oil pressure up. I was driving it like this for almost a year and it finally shut off and wouldnt start back up. i wanted to just replace the pressure switch and see what that did but i cant find it!!! I dont know what egr valve is..... sorry. i lose about 1qt if i drive say 25-35 miles, but it wont last that long now..... i went to autozone.com and they have the lines as engine oil lines and there is pictures one is upper and one is the lower it looks to me like they both are leaking and oil is just about covering everything in my under carrage.. what is a compression test? i havent messed with sensor for catalac converter but i will the next time im with my car its sittin at my moms and i wanted to go there today, but i have no car and i lost my phone so i cant call anyone to take me over there, but i will keep replying when i do what everyone tells me to.... thank you everyone!!! and i had the old battery and alternator tested when i took them out the guy at autozone said they passed BUT they could still be bad. wtf is that!!!! I hope i gave enough info. i dont want another car, i want this one to work! thanks again!!

just wanted to add that my chech engine light only comes on after car has shut off while driving

Go to autozone.com, they have a online service manual for your vehicle. Go to Repair Info, then compotent locations and it will give you a description of the EGR and oil switch locations which will help you. Also go to the parts section and look up EGR and oil pressure switch to see what they look like.

Next time it quites running take a rubber mallet hammer or a 2x4 and hit the gas tank to see if that jars the fuel pump ao it will run again, if it does then you need to replace fuel pump, if so use Delphi or AC Delco pump only and also change the electrical pigtail for the pump. Fuel pumps will get hot and lock up and sometimes once cooled off will operate again. Fuel pumps are expensive so you want to make sure it is faulty before replacing and they are in the gas tank.

Get yourself a Haynes Repair Manual for your vehicle about $20.00 at a autoparts store, it will help you.

Compression test is testing of all the cylinder for compression which if there is none or low compression engine will not start or run poorly. You need a compression tester gauge for this also. You need to remove fuel pump fuse and all spark plugs when doing this.

I believe your problem is fuel related. You need to get a fuel pressure test with a gauge to determine if fuel pump is operating at correct psi. If not you will have no start, poor engine performance problems.

If you are loosing that much oil you could very well be right that the oil pressure has something to do with the problem. I am thinking that when at idle the oil pressure drops because of the leaks causing the system to shut down. Replace the hoses then hook up a mechanical oil pressure gauge to see what your actual oil pressure is. Also your oil pressure switch could be faulty and shutting sown system.

I am throwing a lot of things at you but if you need better descriptions let us know and we will help you.

ok i am going to get the oil lines today before i go to school, so i will check on the gages i need to test compression and pressure. i did buy a haynes book and it helped, thats where i read about oil pressure switch but it did not have a picture or location so i went on autozone and they had pictures and explained the location, but im a little confused, do you know if there is two switches or just one oil pressure switch?? the picture i got, is what i see under hood, but it is not where it is supposed to be, it looks like there is one on both sides of block....... could that be?? i didnt read anything about having two switches.... and i believe the fuel pump is ok i hear it come on and took fuel filter off and let fuel run through other side to make sure filter wasnt clogged and it pumped gas, but it will not run long enough to get up to temperature so im thinking its those lines and or switches..... im going to replace those lines only 22.99 and in stock (no waiting) so i should be letting you know what happens in a few days, but if you know anything about that or those oil pressure switches that would take away a lot of confusion!!! thanks again

Once you have oil lines on check oil pressre.

Just because you hear the fuel pump does not mean it is operating to specs. You should have 9-13 psi.

Next I would check the EGR Valve like duke350 suggested because could affect the idling problem which is what seems to happen at stop lights, it idles to low affecting oil pressure and all other functions.

ok i will. i picked oil lines up yesterday along with the oil pressure switch. i found where it is on my car and man that was a pain. finally got it on and it was dark so im doing oil lines today...... hopefully everything goes smoothly. ill let you know what happens....

Taken from the Service manual.

Fuel Pump Oil Pressure Switch (Back-Up Circuit)
To test fuel pump oil pressure back-up circuit, start engine. With engine running, disconnect fuel pump relay. If engine stalls, fuel pump oil pressure switch is faulty. If vehicle continues to run, switch is okay.

Also, fuel pressure is different depending on what engine you have. I may have missed it, but I did not see if you said you had a "Z" or a "W" engine. On a 95 fuel pressure is posted as 55-61 psi for a W engine and 9-13 psi for a Z engine. Buy, rent or borrow a gauge and check it out. Leave it hooked up while driving and see what it does when the car acts up.

oil lines were not that bad to put on and extremely easy to take off. but while trying to replace pressure switch, the distributor cap turned..... now i need a timing light or i might just tow it to a friend and have him do it because that is a very precise fix. so once i fix that i will check everything and post what i get out of it thank you again!!

Here is a link with pics on the distributor which should help you set the distributor without the timing lite:
http://www.automotiveforums.com/vbulletin/showthread.php?t=881442

Did you loosen the distributor or was it loose???????

You will still need a timing light. The link is to help you with the engine or dist disturbed (find TDC). The manual states that your year has adjustable timing.

If the procedure in tuitorial is used the timing should be close enough to start, am I wrong duke350?
Looking thru the posts I do not see if this is a Z or W engine. WHich is it? The vin # should tell.

The link used a 97 as an example, his is a 95. The 97 is not adjustable, the 95 is user adjustable. Just to clarify, on the 97 the dist housing is notched so the hold down bracket will only fit one way. On the 95 it will just spin and spin. It would work to get it close, but in my opinion would be more time and work then is necessary. He said the dist was turned, not removed. Get it close enough to run, just by spinning, then set it with a light, or even by vacuum for now until you can get it to a light. If the timing is slightly off it doesn't matter much other then a bit of mileage and power, but if it is off to much it can cause mechanical damage if left to long.

Its fixed!!!!!!! yaaaaayyyyyy!!!! it was the control module that gives it the spark. only 40 bucks!!!!!! thanks everyone!!!!!!!!:smokin::smokin::smokin::smokin::s mokin:

Congrats on the fix. Just make sure you used dielectric grease on the new one, or it will fail prematurely. It uses the dist. as a heatsink.

Congrats on the fix. Just make sure you used dielectric grease on the new one, or it will fail prematurely. It uses the dist. as a heatsink.
the old one had bearly any on it so i covered this one very good!!! Thanx again!!!:smile:

My Jimmy cuts off randomnly while driving at any speed not too often it smokes like it is flooded then after some kinda long turning over it will crank back up and run fine the fuel pump is brand new and it was doing this even before the pump was changed i think it is a computer problem but its so random it only happens every now and then with long periods of fine driving in between what do you think.

my jimmy randomnly cuts off while driving at any speed it smokes like its being flooded then after some turning over it cranks up and runs like normal it has a new fuel pump and this happens with long periods of fine driving in between is it the computer

I had the same problem on my 95 Jimmy and it turned out to be a bad wiring harness connector to the fuel injectors. I pigtailed in a good one from the junk yard and it fixed the problem.

I had tried everything from new ignition module, new distributor, new wires, plugs, and coil. Even installed a new fuel pump, filter, and fuel injector spider. Still had the problem. Finally took jimmy to the dealer and they told me I had a bad connector to the fuel injector, said it was a common problem. I could have saved thousands if I had taken it there first.

GG~