So as far as the blazer leaving me on the side of the road only 3km from home, here is the more in-depth version. I was going up the hill to my neighborhood about 60km/h constant speed, rpm, throttle, and all of a sudden it cuts out and I had no power at all, the gas pedal had no change on the engine and I was seemingly just coasting, however, the engine was still running and just idling, it cut back in when I jabbed the gas pedal down a bit more and felt normal for a few seconds until it cut out again, the same thing repeated itself and I knew I had to get off the road so I turned at the closest intersection and onto a side hill. I was going up the side hill looking for a nice place to stop and have a look at things when it died going up the hill and I coasted it to the side of the road, it started up again but I could tell it was running rough, it would idle ok but showed misfires on all cylinders and stumble when I gave it gas. It had no power to move anymore up the hill and I was stuck in place, it was showing 2 new pending codes I did not expect to see, P0172 and P0175 for rich on both banks. After waiting 15 minutes or so I started it up again and it ran seemingly better, good enough to limp home without more problems. Once I was home and unpacked the blazer and gave it a nice clean it was time to look into some things, first thing was fuel pressure and it showed 58 psi and didn't leak down, I checked it while running and was seeing some large fluctuations at idle but other than that would idle 50-52psi when not fluctuating. I then looked into the rich codes a bit, the scanner was indeed showing the engine was running a bit rich on both banks, rich enough to set the code. So I first saw the fuel trims more normal in open loop and go rich once in closed loop, I also saw the fuel trims change from -12.5% LTFT on both banks to lean with just unplugging the MAF. It's also worth noting when I plugged the MAF back in and it was back in closed loop the fuel trims stayed normal.

Now that I have had a look at things and taken it for a few drives without the issue happening again, I'm thinking the fuel pump must be to blame. The reason being is it must be an intermittent issue that can make the engine cut out and stall seemingly out of the blue, either fuel, spark, or air delivery must be effected. Given the fact when the problem was happening the truck would idle but have no power to go up the hill I was on and would stumble even when giving it gas in park, I am convinced the problem lies in either the air or fuel delivery. Now I'm about ready to put a new Delphi pump in as I need to have my truck back in working order to start work here. What do you guys think? What would you guys do if you had checked over what I have and hadn't found anything, and can't seem make the problem present itself again by driving it around more.

 

I used to have a TBI s10 that would do very similar to what you describe, one time every month or two - just die going down the road and refuse to start until I had sat for 15 minutes or somehow moved the wiring harness just right. After a year or so of this I finally replaced the entire engine wiring harness with another from junkyard and it never did it again. It could have been the wiring was bad, or it could have been a bad connection - but it was electrical. Bottom line - at this point you just don't know unless you catch it in the act with the right tools. It could be fuel pump but it still may die going to work the first day after putting it on. I would wait to see if it becomes a problem where it can be diagnosed better.

That said - Great Trip!! I'm sure you will remember it for many years to come!!

 

Thanks Les! It was a spectacular trip, a real dream come true to travel across my country and see everything. Even more, I was able to do it in this blazer which makes it all the more special to me. Seeing it perform day after day rain or shine and putting down about 1000km most days without even breaking a sweat was remarkable, a lot of work to get it to this point. I got the blazer at 242kms, engine blew at 250, and I left for the trip at 272, I'm now sitting at 291. So I've put about 50k on it in almost 5 years of ownership and 19k was in the last month, I find that insane!

Thanks for keeping my mind open with the problem I'm having, I may go take it into town today and run some errands maybe I can get it to act up again. It will definitely be a hard one to diagnose, not a hiccup for 19000kms then out of the blue it just dies! I will also add it was about 44 degrees outside when it happened so the hottest temperatures across the country, that may have played a role in it as well. I forgot to add that while I was diagnosing it the P0172 and 175 codes went away on their own. I will say when it happened it was a distinct cut out, one second all was fine, and the next it just cut out and was idling, then the same thing when it cut back in. I'm not sure how else to describe it. After it had died and I had it idling again but it wouldn't go anywhere it felt like something was choking the engine and very weak. I'll see if I can make it happen again today, but I'm not sure what else could fail like that, it felt like a fuel delivery problem. The fuel pump is also about the only thing that I haven't replaced and tinkered with in the fuel and air delivery systems, I'm thinking it may be worth while to finally make the fuel pump pressure tester and test the max output, especially with the fluctuations I was seeing at idle, just no parts stores near me ever have that Dorman part you need to connect to the fuel filter connector!

 

Amazon sells Dorman stuff IIRC
so what's your first job out of school?

 

Thanks Les, I took the blazer into town twice without issue now and got the adapter made! NAPA had one of those Dorman fittings in a nearby store and I was able to get the 3/8" hose and fittings from my local hose store. BIG THANKS to Christine and the info posted on the "Fuel pressure test results interpretation help needed" about the adapter fittings, couldn't have done it without that, even the guy at the hose store needed the picture of the setup to know what I needed LOL. I have looked at making this adapter for a long time now, Christine's method of using the adapter that comes with the pressure tester makes it so you just need to go from the normal Schrader valve thread to a 3/8" hose, and those fittings are much more common, pics below.


So after letting the thread sealant dry last night I was out ready to test today, I'm very relieved my pump would only pump to 58psi!! It was crazy, like I still had the regulator in the mix because I see the same pressure at the service port lol. I tried over and over I think 5-6 times of priming it once it was at 58psi and it would not go up anymore, I also checked my battery voltage just in case and had a strong 12.8V. Needless to say I'm very relieved I got this adapter together when I did and finally did this test! I have falsly blamed the fuel pump a few times before as its about the only thing that's not brand new and could make the engine not run well, but this time it looks like its really the problem. I guess it's only fitting, I've probably had it gasping for air running at highway speeds pretty much all day everyday for the last month. Now I'll order the new Delphi pump and get on installing that, I think I will also do the fuel filter and get a new lock ring while I'm in there, and maybe also clean out the tank while I have it out. I'm so happy I have found the problem! Once it's fixed I'll be able to take it back up in the trails with confidence. Pics below of pump test first, service port test second.


As for my job, thanks for asking! Going back to the same place I was at the last 2 summers, doing HVAC and plumbing design in Revit for new apartments going up in the area. It's not my first choice but it will pay the bills and counts for EIT time, and close to home. I would like to get into the auto industry some way or another, even if that means relocating to somewhere in the States in the future, I feel like working on designing cars, or off-road vehicles and their parts for a living would be awesome!

 

58psi is pretty odd, but definitive on the fuel pump. Good job diagnosing.

Behind every part there is an engineer!! Good luck with your career and best wishes.

Keep in touch on the Blazer.

 

Thanks Les!! One of the only times I think I have guessed the part that's wrong from the beginning lol. Anyway, I survived the first week back at work, I didn't drive the blazer at all as I had a new pump, lock ring, and filter coming in. I can't help but be so grateful for the blazer right now and the fact it let me enjoy that trip without needing to worry about anything, we passed many many people broken down for various reasons on the side of the highway. I'm thankful that was never me and it got me home all safe, fixing the blazer at home is a walk in the park compared to being in the middle of nowhere!

All the parts came in during the week and I started dropping the tank today. I drained the tank first using the fuel pump and the jump terminal in the fuse box, it took awhile to devise a method but I came up with some 10ga wire and a 15A fuse with a couple of spade connectors did the trick just fine. I drained about 50L out until no more would come out, my mom's car needed a fill-up up so it worked out good! Pictures of the setup below.


I dropped the tank after that and it took a bit to get those lines off, but eventually, they came. Then I decided the tank straps and filler neck could use a new paint job, pictures below.


Once that was done I was back working on the tank for a bit, I vacuumed up all I could from around the pump and gave the whole tank a good wipe down, then I ran out of paper towels and that marked the end of working tonight LOL. Tomorrow I just need to give it a final clean then I should be good to pull the pump out, I'm planning to clean out the tank as well with some water and dish soap so its not the end of the world if some dirt does fall in.

 

I got the old pump removed, then gave the tank a good cleaning with water and dish soap as per delphi recommendations, I'm glad I did as the tank was a bit dirty inside. Then I put the new Delphi pump in and put the tank back in, filled it up with about 35L of gas and I was good to go! I had it running late on Sunday just in time to take to work the next day. It's been running great all week so far.


One thing that's been a lurking problem on my blazer has been the HVAC seeming to have a mind of its own sometimes, I mean it would decide to blow air out the main vents when I had it turned off, etc... Now I first noticed this on my long trip to Bella Coola last year which was the first time I really took it on the highway for an extended period, and it would only happen when I was on the highway. So once I got back of course it didn't happen anymore and I forgot about it, well it came right back on my trip across Canada! It would always seemingly blow air out of the main vents "whenever it wanted" so I did some research and thought first it was the check valve on the vacuum lines, I went out and took the valve out then blew threw both sides and confirmed it was working proper. Then I hooked up my vacuum pump to the vacuum reservoir line and noticed I had a substantial leak, the line was not the correct size on the nipple and leaking. I had replaced this line before as it rotted out and the shop didn't have any of the correct size I remember, so I thought I got one size under of fuel evap hose, but I guess it still didn't fit tight enough. Lucky for me I had some brand new vacuum line laying around from when I replaced the lines that go to the transfer case, and that fit much more snug on the nipple, I tested it with the pump and no more leak! I also noticed if the system is holding vacuum properly you should be able to switch the HVAC controls setting some time after turning the car off and still hear the doors move behind the dash.

 

I had to replace my vacuum hoses several years ago. Then in the last year I noticed the HVAC starting to "have a mind of its own" too. I never thought the hoses could go bad again. I'll have to check this on mine.

Congrats on the gas pump replacement.

 

Thanks Christine! I hope you get your HVAC issue sorted as well. I don't think you will believe this, I'll start from the beginning of this story which goes all the way back to Newfoundland... In particular, it was the day I got stuck. So my steering had been pretty bang on for the whole trip across the country so far, the alignment felt nice and the truck tracked straight. Now pretty well right after getting stuck I noticed it was no longer tracking straight, and this was pretty shortly after I got on to Newfoundland maybe only a half hour down the highway from the ferry. So I tell myself for the whole way across Newfoundland to St. Johns then all the way back it was probably the "crappy" roads and the lack of road crown causing my truck to pull a bit (truck is aligned to go straight on a crowned road), I told myself I would know for sure when I was back on the mainland with better quality roads. I got back to Quebec and had to take a look at things, I could see my passenger tire was rapidly wearing the outside and starting to get cupped a bit as well. So next I had a push and pull of the steering linkage and found both tie rod sleeves were loose and could pretty much rotate freely (thanks alignment shop), so I set them as straight as possible and torqued them down proper even getting the torque spec up on my phone while in the middle of nowhere lol. Only one bolt was loose on each sleeve so it would allow some movement but not a lot, I figured after tightening them again that I was probably all good and the alignment may have been a little off from that but not much. I had looked at getting an alignment from somewhere down in Ontario, but since Ontario has no public crown land it also has no 4x4 shops or anything! I guess 4x4s aren't as big over there. Even with the rapidly wearing tire I made the call to drive about 7000 more km's back home with holding my steering wheel crooked most of the time. I finally had time to jack the blazer up yesterday and checked what was going on, it turns out my one ton idler arm blew and left me with a very sloppy steering. I'm quite shocked I managed to blow the idler arm that comes off a 90's K3500 within a year on my blazer, I got an ACDelco to replace the moog this time so I guess I will see if it holds up any longer.


Aside from replacing the idler arm, I'll have to get a new tire as the outside is almost down to the wear bars with severe cupping now that I have driven so far with the alignment bad. Somewhere along the trip, the lower steering bearing started clunking and making a lot of noise too, I have ordered a replacement for that as well. I will also mention within 5000km's both of my brand new cv axles that at the time I installed about a week prior, had already blown their inner boots, maybe I'll devise some custom boots made for more articulation, and while I'm at it modify the inner cup for more articulation. Lately I have been thinking how happy I am with the blazer's current state, it's reliable, very fun, has all the power I need and more. I have been contemplating holding off on the triangulated 4-link dana 60 front 14 bolt rear and saving the axles for a buggy build from scratch, I will get really tired of replacing cv axles and idler arms the way things are going though!