Low pressure all of a sudden

[OR VietVet]

Pump sounds like the right call with the o-ring and pickup tube thorough cleaning. You can buy MAFS cleaner at the same time as the new MAFS and just trying cleaning before replacement. That way you can take back if you have not installed. Directions on cleaning will be on the cleaner. No telling on the wiring work with the stereo replacement. I still say you should replace that oil pressure sensor. Do you have a Tech 2? If not, get one. You do so much on your rigs you need one if you don't have one. On ebay for great prices. Is the current software updates at I think, without me looking and knowing others will chime in if I am wrong, 33.004?

Chris, I was wondering something like this as well but was uncertain if it pertains at all:

"I'm wondering something: Does any one know if the PCM will make the gauge drop to "0" if the actual pressure drops to a certain threshold to promote a sense of urgency? I know this is or was a Jeep thing. The oil gauge on my XJ would display actual pressure but then drop to "0" once it was down to ~10psi. This would make the dash warning lights and all come on even though it still had oil pressure. I doubt it, but am curious if the GMT800 had the same or similar function."

 

[Tim907356]

I did the sea foam thing on my 220k mi., 2004 Yukon 5.3L recently. I had a weird engine sound come up all of a sudden; sounded just like a loud belt or bearing squeak on one of the pulleys. After removing the belts, determined it was under the valve cover, right side. I had a GM mechanic listen to it, and he'd never heard anything like it. He wanted to 'dig around', which sounded expensive. I talked to another mechanic, and he recommended sea foam, based on a friends success. I dumped the recommended amount in, just after an oil change. Within 25mi., the squeak was completely gone!
But, I think I made a mistake by leaving it in there, as the engine began to run rough, and a noticeable valve tick began, and got louder. I changed the oil again within 200mi., but the noises stayed with it. Even though the oil was new, it was really black, and full of flecks of goo. Maybe some thicker oil (10W-30) would have helped, but I was on the verge of trading, and it was running well otherwise.
Moral of the story; sea foam is effective, just be careful with use.

 

[OR VietVet]

Great "food for thought" story Tim and welcome to the forum from Oregon.

 

[Joseph Garcia]

Welcome from NH, Tim.

GREAT perspective on your actual experience. Thank you for sharing!

 

[mijohnst]

Boy that Seafoam is awesome trouble. Thanks for the story Tim and welcome! You'll love it here.

I couldn't wait until I got off work so I ran home at lunch after stopping at the parts store to grab some MAFS cleaner.

I took it off and cleaned it out really well, let it dry and hit it again. I put it back in, connected the battery and started it up. It ran perfectly with 42psi oil pressure like it did before and I thought, "OMG! That was it!" Then after 20 seconds it immediately (not gradually) went back to running like shit again... I went ahead and cleared the codes and start it again. It ran really rough like it was about to die for about 45 seconds but I didn't get an engine light. My next option is to replace the MAFS tonight. I bought one while at the store so I'll throw that in and we'll try again. I'm not hearing anything knocking in the engine other than it just sounds like it's starving or being flooded with gas.

Could the ignition security system have anything to do this? As I said before, I replaced the factory stereo last weekend and it only worked correctly for about 1 day before I started having issues with it rebooting constantly. I wasn't having engine issues until yesterday. Just a stab in the dark. Thanks again all!

 

[OR VietVet]

You should clean the throttle plate as well. That is also recommended when you do the MAF cleaning and I forgot to tell you. Check out you tube for 2-3 videos to see what to do.

 

[Joseph Garcia]

When you were working on your stereo replacement, did you loosen and then re-tighten any existing ground connections? If yes, please re-check those ground connections (if you have not already done so) to ensure that they are clean and tightly connected.

 

[mijohnst]

When you were working on your stereo replacement, did you loosen and then re-tighten any existing ground connections? If yes, please re-check those ground connections (if you have not already done so) to ensure that they are clean and tightly connected.

I actually only disconnected the radio from the harness and connected back to that with the new stereo. I'm going to pull all that out tonight just to see if there is possibly something in it that's causing me issues.

 

[Jbirdstruck]

oil and filter change asap, like at work in the parking lot. never put that in the oil, gas tank and in a vac line is fine, never the oil.

 

[Jbirdstruck]

oil and filter change asap, like at work in the parking lot. never put that in the oil, gas tank and in a vac line is fine, never the oil.

I use sea foam in the oil all of the time. Was very successful at getting rid of lifter tick in more than one vehicle. It is a recommended use on the can, however you are only supposed to use a few ounces and for just a few hundred miles right before oil change. Read the label and use accordingly.