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1994 GMC Pickup Not getting power


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MrJp32
Novice

Nov 22, 2013, 11:51 PM

Post #1 of 5 (1613 views)
1994 GMC Pickup Not getting power Sign In

1994 GMC K1500 5.7L .... Lets start with when I start the truck, it starts up and sounds perfect. As soon as I put it in gear all hell breaks lose. When I give it gas it bogs down, then eventually pick up to "normalish" speed, sometimes on rare occasions back firing. If I slow down to much or pull up to a stop light/sign it will stall on me and die. I have to put it in park to get it to stay running at stop lights. When driving on the highway after about 50mph it just kind of bogs down, I will give it gas but there isn't any power. Every once in a while it will kick into gear and it drives normally and I can hit 60mph. My oil pressure seems to always be low even when there is plenty of oil, I do have a good size oil leak which I added lucas to try to fix the problem. I haven't noticed it over heating, and I always pay attention to my gauges, but just now on my way home from work I noticed the temp going up so I pulled over for some antifreeze coolant. It was bone dry, I added the entire container and noticed a very large leak. It has been raining here tonight so I could not get under the truck to investigate where the leak was coming from. ...not sure if the coolant leak has anything to do with a more major issue which is causing the no power issue. . Also, my Battery Volts have been sticking around the 12ish area and not directly on the 14 where it normally is, could this be an alternator issue?

I have replaced.....Fuel filter, Rotor, Distributor Cap, Plugs, Wires, Coil recently along with MANY other parts.

What I think the problems may be....alternator or fuel pump, or motor is just shot....Help me out I'm running out of money just buying random parts that my friends think is wrong with it.


(This post was edited by MrJp32 on Nov 22, 2013, 11:53 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 23, 2013, 3:32 AM

Post #2 of 5 (1600 views)
Re: 1994 GMC Pickup Not getting power Sign In

Bet you don't fix this problem with vice grips like you did the last one..................



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



nickwarner
Veteran / Moderator
nickwarner profile image

Nov 23, 2013, 4:23 AM

Post #3 of 5 (1596 views)
Re: 1994 GMC Pickup Not getting power Sign In

Ok, please realize your friends suck at giving automotive advice. Since you would be stuck in the rain to even look at this looks like none of them have a garage you can use either. Wish I could get rain here, its snowed the last three days and the air temp is 2 degrees with an 18mph wind bringing windchill into subzero on opening day of the gun deer hunt.

Your truck is 20 years old and not in the best shape. Maybe your gauges are lying, maybe not. You ran this thing with no coolant, which is not good for any engine no matter its age. Maybe you got lucky. What your friends have suggested to you is to throw parts at it in the hopes it would fix it. You personally don't seem to mind cobbling things to patch it temporarily. Neither of those mindsets make for a vehicle that is reliable.

Instead of guessing and throwing parts at it, why don't you start TESTING things? Many special tools you may need for this are available on a loaner program from major parts stores. Just put down a deposit to use it and it is refunded when you bring back the tool. No money spent on a one-time-use tool and you still get the advantages of having one.

For starters, get a compression tester and pull out all 8 spark plugs. Remove the fuel pump relay. This is going to keep the injectors from firing and dumping fuel as there will be none to dump. Thread the tester into a spark plug hole, hold the throttle wide open and crank the engine for 5 seconds. Your battery must be fully charged and remain so while testing, so if you need to hook up a charger or booster pack to it. If you get a lower cranking speed on later cylinders the test results are invalid.

Get a notebook and note the readings of the cylinder you have tested. Then move to the next and repeat the process the exact same way. When you are done with this test (the dry test) we move on to the wet test. It is the same as you did, but you squirt about three squirts out of an old-school oil can (think what tin man from wizard of oz had) of engine oil into each cylinder just before you test that cylinder. You can get that can at your local hardware store. Repeat that test noting the readings on all cylinders. Report back to us with the results on the dry and wet test.

You will also need to check for codes, which you can get with a paper clip by jumping the a and b terminals of the ALDL and turning the key one. Here is a vid of how to do it

http://www.youtube.com/watch?v=UIKdbTFvyUU

Post all codes you get here.

You also need you pressure test your cooling system to find out where your coolant is going. It does no good to get this running if you are going to melt this down from overheating. The coolant temp sensor is in a coolant jacket, and gets its reading from coolant which transfers heat about 6 times better than air. Same reason you die in 40 degree water and not 40 degree air, fluid transfers heat much faster. So If your coolant sensor is in air and not water it can actually read low temps when the engine is dangerously overheating.

So now you have three tests to do. Pressure test for coolant leaks, pull your trouble codes, and do a compression test both wet and dry. Post back with your results and we will go from there.

No more vice grips from this point on unless you like walking in the middle of the night.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 23, 2013, 4:41 AM

Post #4 of 5 (1595 views)
Re: 1994 GMC Pickup Not getting power Sign In

Leaking oil and coolant, low oil pressure and low voltage. Backfires, very low power - did I miss something?

Lucas to fix oil leak! NOT.

If you want to keep this truck spend the next $$ on a complete diagnosis by a pro on that list to decide how much it's going to take. No question several things that could exceed value of this truck at 20 years old. Don't forget to ask for a back pressure test. Right cat/converter for these isn't cheap and probably junk by now too,

T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 23, 2013, 7:10 AM

Post #5 of 5 (1589 views)
Re: 1994 GMC Pickup Not getting power Sign In

I agree with Nick that a compression test is a good place to start as stated in his great post.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 23, 2013, 7:14 AM)






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