Part 2. GM no start no fuel troubleshooting "Oil pressure switch"
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- Опубликовано: 17 май 2012
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Part 2. In this video i give an example of one way i go about trouble shooting a no start issue when i have limited resources. on a 95 Chevy Tahoe
We will be looking at the oil pressure switch side of the circuit This isn't how I usually go about it however I wanted to give an example of what you can do with just the basic tools and schematics to trouble shoot a no start issue hope you enjoy
I realize this video was made over 10 years ago but I just wanted you to know that is still helping people today, so Thank you, Will. I have an 89 GMC Sierra SLE 5.7 TBI and have been struggling with a crank no start issue for a long time and no matter how many mechanics I have asked, unless you find one of the old school Shadetree mechanics that doesn't need to hook a vehicle to your computer do you know how to fix it, not one of them knew the answer because of the age of the truck. Your 2 videos on this topic, even though the truck is a newer year model, was the first that help me realized it could be the Fuel Pressure Oil Pressure Switch, which I have since learned differs from year models of GM trucks. ♦Please note for anyone dealing with the same problem please pay attention that it does matter what year model your truck is as to how many pins are in the fuel pressure oil pressure switch, 1988 - 90 will have only 2 pins in the switch, 92-95 may have 2 or 3 and 95 - 99 will have 3 Pins.♦Also, pay close attention that in other videos it may be referred to as a Fuel Pressure Sender which may be accurate in newer 3-Pin models, however in 1988 to 90 Fuel Sender is a separate component/part, in a different location, it is located on the Driver side lower engine block on year models 1988 to 90 and differs from year models 91 to 95 and 95 to 99 where the switch and sender maybe integrated. Video part two was extremely helpful in showing how to bench test a part to show how it works. 🔶Other than discovering this switch could be the issue for I no start, I have also discovered that is very important on your models 88 to 90 as well as 91 to 95 to inspect the braided body ground straps to the engine block. As well as the ground wires to the ECM and fuel pump relay which are black, black/white stripe together and a 2nd set that is a black wire & a tan with white stripe are ground wires that on 1988 to 92 models are typically grounded to the engine block on or near the thermostat housing(bolt)and can become loose over the years from vibration or corroded causing a faulty ground, which I stumble upon by learning from videos regarding testing for proper ground and voltage with a Non-Led test light. As it turns out when I tested where those grounds are mounted it showed a very weak or dim test light, so I jumped it to another ground on the engine block which had a very solid bright light, went to start the engine and was very shocked that it fired right up, all it was was a weak ground connection at the bolt where the ground wires were mounted to the thermostat housing. So if you're having this issue and have this year model of truck, hopefully I can save you a lot of time by checking this and all of your body ground wires to make sure they have clean, tight & proper connection.🔶 When you own one of these year models of trucks it can be very discouraging and frustrating to find out that many younger generation mechanics do not know how to work on them or even care to learn how, even though they are very plain and simple and more basic to work on the newer computerized versions where you just plug it into a computer and it tells you where to start putting parts in it to try to fix it, but don't give up keep searching & trying and you will find the answer.❗🙏I have much appreciation and gratitude to mechanics like Will and others who are old school or enthusiastic enough to learn in order to teach and post instructional videos on RUclips to help us out with our old classic GM trucks. Thank You All‼
I watched both videos and it was my first encounter with your channel. What a great day today is, finding YOU!! Man I just read and liked about 10 comments below & couldn't agree more with EVERY one!!! You SIR ARE an AWESOME mechanic!!! Thank you! I'm troubleshooting a 1987 Camaro 2.8 & feel confident with the info, I learned from you!
Man oh man, this dude is the bomb instructor!! All kidding aside, I really like how he fully explains each detail and even reviews and bench tested the old and new components in detail. This is the first time in my life I ever thought enough about anyone on here to consider giving a positive comment but Robinson you are deserving and the best instructor I have seen on youtube hands down!!! Thanks Bro and I will be telling everyone about "robinsonsauto"...
I don't mind even watching the ads because I actually want this guy to make money 😊
you are the honest face that everyone wants to see in a car mechanic....your video is a lot of help ...thanks a lot
I swear if this is what’s happening to my Caprice classic 96 Chevy I’m gonna burn a chicken in ya honor !!!! I have checked everything fuel pump relay, fuel pump every thing.... tested power at all points....power going into pump kicks up the. Drops....no pressure at the fuel rail...I’m gonna try your method
Would a bad oil pressure switch cause engine misfires? I pulled my relay and the engine shuts off. 1997 Chevy Tahoe 5.7. I've been chasing a p0300 and specific cylinder misfire like p0308 but it's weird every time I take the upper plenum off and recheck everything when I put it back together the cylinder that misfires changes to a different cylinder. The most oddest thing I ever experienced. I replaced everything you can think of and cleaned up all the grounds wires. I notice the fuel pump relay doesn't energize sometimes when I test by turning the key on and off. I keep my hand on the relay and I turn the key on and I don't feel it click. Sometimes like 4 times in a row. I bought a new relay same thing. So would the oil pressure switch be causing this?
The intention of this wiring configuration is for fire protection, for when the vehicle has rolled over and is up side down. In that event it is important to stop the fuel delivery. The way it works is that the oil pump will not have any oil in the sump to pump, thus no pressure. And those contacts, in the oil pressure switch, will open to cut off the fuel pump. Rather than putting full fuel pump motor current though the light duty contacts in the oil pressure switch, a relay is used. Otherwise, a much larger, more heavy duty oil pressure switch would be required. And this is all bypassed , during "start", before oil pressure has been developed. The same as old cars with ballast resistors and points worked.. Been wrenching on cars for 50 years. At first there was no fire protection because fuel pumps were mechanical and cars had carburetors with float bowls that shut off the car if rolled. Then electric fuel pumps got popular and fuel injection and fires occurred after crashes that required to be dealt with. That is when and why wire oil pressure switches came in to play. Today, inertia switches are used instead of oil pressure switches. It is not for in case of relay failure or any other convenience.
I think maybe I stumbled onto my problem
Wonder if that's my problem, thought it was the fuel pump relay, worked for a week, this week same thing, no start...
This 11 year old video helped me fix my truck after replacing the fuel pump and having intermittent issues. Thanks
Probably the best video explaining the fuel pump relay no start related issue. Thanks for posting.
Your video helped me repair my 1999 Yukon ,oil switch ,tapped it vehicle started ,pulled relay shut off .Sir you saved me from dropping gas tank and replacing fuel pump ,thank you
After watching the two videos in this no-start series, you can work on my vehicle any time. Excellent explanation and logic.
If you ever think of retiring, you could be THE BEST automotive Teacher High School, College, Major Automotive company Senior Instructor,........ You absolutely know your stuff, are humble about it and you have that magic that allows you to make it so that others can understand and learn from you. Not using your shop tools and using what a typical home garage guy would have is beyond helpful!
Had the very same problem, '96 Chevy C1500, instructions on both videos were spot on and understandable. Thank you very much.
Your 2 part video was great help for me to troubleshoot this problem. since I had already replaced fuel filter to no avail. due to circumstances similar to ones in your videos I'm almost positive this will fix my problems on my 2000 Tahoe. Thank you immensely...
I just wanted to share a special thank you for this two part video. I've had an ongoing issue with my 98 Silverado similar to the one in this video. My truck would fail to start on humid/rainy days. Following your videos, I found a cracked oil pressure switch, which was shutting off my fuel pump immediately after starting. The humidity was shorting the sensor. Thank you, thank you, thank you!
YOU ARE THE MAN!!!! please never stop making your video's you are helping so many people. THANK YOU!
The two videos about the GM no fuel trouble shooting were spot on and very easy to understand.