Pump or pressure regulator

 

Agreed, if you replaced the pressure regulator a year ago it's not likely that, and your filter was just replaced before testing. only major thing left in the system is your pump.

 

Thanks for the feedback. That’s what I am thinking. I hate intermittent problems but am going to go ahead and replace pump. Looks like a fun project to drop the tank ...☹

 

I need to replace mine as well, saw a good vid the other day, A1 Auto, they made it look easy

 

I drove mine until it started starving for fuel to make the tank lighter. Still took me two evenings after work with all the rust from the previous owner. but I love the 1A Auto vids on YouTube, they're always helpful.

 

I will search for the 1A vid. Below is a good one also.... This guy bought some new mounting bolts which is not a bad idea.. also they make a retaining lock ring tool for about $15-20 bucks but not sure if I will buy one... going to see if autozone has a free rental.

 

Update: It died again today. But after a few minutes it cranked and she was able to get home. She won’t let me drive it because she hates driving my Silverado. It has half tank still so I want her to drive it..

Once she got home I checked pressures again. Interestingly the Key On /Engine Off was only 40 psi which is more support it’s the fuel pump... after cranking it the running pressure normalized to 43 psi.

I removed FP relay and jumped across battery pins and relay churned and pressure jumped to 48. I had also previously swapped the relay with another one on board to confirm a relay was not going bad.

so far all the little things add up to be the pump going out. My new pump from Rock Auto arrives Wednesday. RAuto Adelphi pump is $60less than same model at Azone... planning to do it this weekend..

 

10 years ago, I had a slow failing fuel pump on my '93 burb, which presented identical symptoms to what you describe. After taking it to three different shops to not be diagnosed properly, I found this forum, bought a service manual, and began trying to figure it out myself. My first official repair job was dropping my tank to replace pump. I remember writing up an article for this forum afterwards. It's really not a terribly difficult job. And it hooked me on learning to home-wrench on all my vehicles.

Wish there was 1A Auto videos back then. They are really helpful!

Good luck!

 

Thanks for sharing. That’s about my story also. YouTube has taught me a lot about many subjects. Having fun doing lots of my own work ..

 

glennst, when or if you drop that tank, be sure to inspect it inside carefully for rust etc. Use an inspection mirro to see the corners and the top surface inside. Good luck.

 

I never thought about that... if I see rust what do I clean it with?

 

Sounds like crank sensor, went through same thing.

 

My '04 Express 6.0l did the same thing. Turns out the crank sensor wasn't reading the reluctor because the thrust bearing had worn beyond specs allowing the crank to move forward. It turns out it's a common thing in older LS engines. The thrust bearing is the #3 main instead of the rear (#5) like most engines. Check your crankshaft end play if you can......

 

They have shim kits for the sensors also

 

Good luck getting the O ring in the kit to work, if it gives you too much trouble just reuse the original. I fought for an hour trying to get the lock ring back on.
05 Suburban

 

Mitch did you have any DTC codes for the bad sensor / reluctor issue? If it’s not the FP (changing Saturday) I will tackle the CPS next. A few people have indicated it sounds like the CPS. But how do I know if a shin kit is needed and would the shim cause a bad signal if it’s not the gap distance?

Thinking - since the stalling is so rare (maybe only every few days) that I wonder if it’s the reluctor wheel distance unless the RW rarely moves forward.

 

To tell you the truth it was a quite a few years ago on my Yukon that i had the problem so I can't remember the logistics of it all's I know I replace the sensor and had the same problem so I had to get a shim kit I think I actually tried shimming it out with cut up soda can shims first or something I can't remember but I know the dealership sells shim kit for that sensor to compensate for whatevers worn that makes the sensor off so doesn't read correctly. There is a spec on the distance from the reluctor wheel , i can't remember what it is though. Yeah i would try that first before you go diggin into crazy stuff. its easy to get to. I would get the shim kit and specs for gap and try it before actually purchasing a new sensor though. But it definitely sounds like the same problem i had .

 

The CPS sounds more logical to me but before you do all of that check your battery grounds and integrity of the cable and clean and tighten all grounding points.
Had this symptom in my 02 LS, talked to a friend who is a long time Suburban owner and he had same issue.
I found the neg cable ground on mine just a tad loose, Have not had thr problem since Easy things first

 

Mitch / Redbird/Tester or anyone who is suggesting the CPS. For those who shimmed was this on a sensor located in the front of engine? For those GM actually had a bulletin to shim the sensor. My 04 Tahoe has the CPS in rear of engine near the starter. Has anyone had to shim the CPS on the rear side?

 

Update 12/15/19 - This weekend I changed the fuel pump. All went well with no issues. It cranked right up. I notice when checking fuel pressure when turning key on /engine off the meter screamed to 52 psi. A lot faster and stronger than old pump.. The engine run pressure was a solid 43, only up 1-2 psi compared to old pump. I also notice it idled better at 600 rpm with with old pump it was around 450-500 rpm.

I drove it about 60 miles through various conditions with no issues. During my I ran my Torque Pro app and a pleasant surprise was that I never had 1 misfire in C1-7, with C8 taking a couple misfires on a few occasions for no more than 8 total...

So far this is much better. Time will tell if it solved the stalling no start situation.. If it happens again I will look into CPS gap spacing..

 

Update 12/20 - arrrrggggg. It Friday but my wife called me on Tuesday (was traveling) and informed me it happened again. At least I have a good FP and learned how to change it.

Next I am tackling the CPS. I need some help / info. I am not getting any DTC codes for CPS. So should I shim existing CPS before buying a new CPS?

Shimming? I can’t quite grasp this in my mind. If I shim it I am in essence moving the sensor further away from the reluctor wheel right? So how is this helping? I would think it would need to be closer?

 

As I understand it, the shiming compensates for bearing wear.
As the bearing wears the reluctor gets closer to the sensor, the shiming restores the correct spacing.
But, to my mind, you would need a lot of wear before that became an issue.

 

Thanks Ray. I replaced the CPS today with a brand new ACDelco... I added a 0.02”” shim I bought from Auto-zone. It cranks and runs good, but I did not do a CKP variation relearn because I do t have a scanner to initiate the test. In morning driving to local garage and ask them to do the relearn..

I hope this fixed my stall no crank issue. Update later..

 

UPDATE!!!

For those interested this is summary.. Symptoms were stalling, would crank over but not start. If vehicle sat from 3-10 minutes it would crank and run on for a while. This occurred 2-3 times a week.
Feedback was it was either the Fuel Pump or Crank Shaft Position sensor (CPS).

I changed fuel pump last weekend (9 days ago) and pressure quality improved (slams to 50 psi when turning on ignition), however running idle psi only went up from 42 to 43 psi which is spec. 2 days later wife had another stall.

Yesterday I changed the CPS with new ACDelco sensor. I did add the 0.030” spacer washer/shim. Engine cranked up and idled great. No codes were present. I did not have scanner tool to initiate a CKP crankshaft variation relearn.

Today I drove to local garage to have a relearn performed and on the way my EL came on and flashed on occasion. It threw a P0300 misfire code with misfires occurring on several cylinders. All codes were cleared before relearn. After the relearn was performed all codes Remained clear and I drove 15 miles home with no EL indicators or codes.

So now I am back to letting wife drive it again and see if the stall no crank occurs. Fingers crossed hoping this is resolved. I will not post another update unless problem returns..

 

Thanks the update and congrats on fixing the problem! Merry Christmas.