ugh. problems getting the truck to run after putting my old engine back in -Timing? Valve lash??

[scouthead]

ported vacuum is not what you want to see. only manifold vacuum.

put a ac delco icm in it, before loosing all hair trying to chase the code 42. Check the the dist 4 wire loom is as far away from spark plug cables as can be.

hmmm in my looking around 2 nights ago- I saw in several places that dual plane intakes get erratic readings from manifold vacuum (the port I used the other night would be 1/2 way down one of the planes that feeds something like #7, and #6??), and are not necessarily a good indicator of valve guide health. I assume because the available ports in the rear of the intake are more isolated to specific cylinders?? I would think using the PCV port on the front of the throttle body would be a more ideal place to measure vacuum that's farther away from each individual valve... -edit- either the 3/8 PCV port on the front of the TB, or possibly connecting to the brake booster port would be best manifold vacuum sources for a dual plane TBI intake????

I will definitely check the proximity of the pug wires to the loom - i saw them the other night, and the 2-3 of the plug wires are laying on the loom around the back corner of the driver side head. The plug wires would not be making contact with any individual wires, but are touching the plastic split loom cover in that place.

 

[Wes Harden]

well there are ports on carburetors that have manifold vacuum, i am sure there is one on tbi unit but don't remember which. I don't normally use the intake for vacuum readings. but at least 4 cylinders are connected to that port.
Maybe the brake booster, I don't like the PVC option because you need to account for that metered leak while diagnosing and tuning. Many will say the air filter assembly needs to in place as well.
Yes the secondary magnetic field might be inducing voltage into the EST loom giving the computer bogus info.

 

[scouthead]

coolant temp sensor was reading about 100-150 ohms higher at various temps than the table of values I found... had another one that spec'd almost perfect. swapped it in.

MAP is easy to change... in the event that the one in the truck had been damaged by the backfiring - I swapped my spare in....

-cap and rotor both looked great and were brass (or brass plated)... getting a meter on it to measure resisitance uncovered problems- high and inconsistent resistance all the way around. trash. one of my spare ac/delco caps had perfect spark plug terminals, but high resistance on the coil terminal - went in the trash with the brass stuff. The last spare ac Delco cap had a couple hundred ohms on the coil post, and after a quick scrubbing of the contacts - zero resistance. that cap and coil went on the truck.


the spark plug wires going to the odd bank were laying on the wiring loom and on the back of the head... although they were not in direct contact with any of the individual wires going into the ICM, they were within an inch... the factory spark plug wire organizer thing on the back of the head just kinda routed the plug wires in that direction... I pulled it off its tab, and zip tied it up to the brake booster vacuum tube...

-have not replaced the ICM, but i disconnected the pick up coil, and measured it. passed the test with flying colors- less resistance than my spares, and the instructions said to bend the leads gently and see if the resistance increases? My spares both saw an increase of 1-2 ohms. not sure if that is enough to worry about? But the one currently in my truck was rock steady - no change in resistance at all while moving the leads.




upon starting the engine- it burned off all the crap and unburnt fuel from the previous run... and has since stopped ALL vapor from the exhaust. It was excessive before, and i was starting to worry about it possibly being more that just running rich. after a few runs and letting it cool down over night, this problem is fixed.

the engine idles like a freaking swiss watch. I mean - like perfect, like I cannot remember a time it ran that smooth- seems to rev up and idle back down correctly. ran well in open loop - idle speed dropped when into closed loop, but still ran smoothly, and quietly... no misfires or vibrations...

Had my fuel pressure gauge attached while it was sitting there for testing. 12 PSI . that's where I left the regulator last time I monkeyed with it. revving the motor or holding the RPMs around 3000 for 10-15 seconds makes no difference to the fuel pressure -12psi aalllll day long.

had to take the gauge back off before diving as the air cleaner hits it.

 

[scouthead]

was really happy with all the improvements, but, upon last night's first test drive -I still have an issue.

idled for 20-30 min with no problems.
-drove around the block taking it easy on the new piston rings... no prob
-got about5 miles down the road, and in 3rd, about 40 MPH... rolling the throttle open slowy - engine just barely loaded and pulling... split second power loss again. Whiplash and cursing again from the driver seat.

no check engine light. enging did not "stall" as it was still running when I got the clutch pushed in and revved the engine a little (just like last time). I continued driving for another 8 miles until I got where i was headed. I could feel a VERY slight surging when I was accelerating gently in 2nd gear. I feel like If I were to lean into the skinny pedal while it was doing that, I would get another momentary loss of power. seems load sensitive. not really noticeable in 1st gear. It is noticeable in 2nd, and all the times I've had power cut out, was in 3rd, somewhere between 25 and 45 MPH. I drove it to work this morning, and it did not seem to have that slight surging while in open loop.

 

[scouthead]

update... lots of things tested, and a bunch of stuff replaced "just because"... including the ICM with AC Delco replacement. Pick up coil had tested perfectly, so it was left alone.

I had it running pretty damn well. Almost like a brand new truck. biggest contibutors:
- swapped on a cap and rotor that were not FUBAR
-replaced all fittings and hoses connecting to throttle body -several were too old and loose or had minor cracks/leaks
-replaced egr valve that may have been ok, but was juuust leaking a lil bit instead of fully seating when closed
-pulled off my bored out throttle body that had quite a worn and vacuum leaky shaft, and replaced with a standard bore unit that was "like new" condition
-cleaned the injectors myself (will probably post a thread)


ditching the bored throttle body and replacing with the stock one had quite the detriment to overall power available, but drivability was good, with less immediate punch off idle, and a little more controllability of the throttle pedal.

it just falls on its face now over 3000 rpm, unlike the constant pulling power up to around 5500 that i was accustomed to

 

[scouthead]

I drove the truck to work for a few days- ran great. drove it a couple hundred miles to the desert, up a couple thousand feet, and up some long grades and hills to my cabin. big power difference trying to pull those hills with the stock throttle body. 10.5mpg going uphill with a fully loaded truck (with no overdrive, on 35 inch tires)... I can live with that out of a repaired engine. once at cabin:
changed the oil.
-checked trans oil -level was great. oil looked brand new.
-checked 241 -oil level low, smelled like it had gear oil in it, and PLENTY of fine metal particulate suspended in it... uh oh. insert clean oil and drive.
-tinkered with the winch wiring and cleaned some stuff up.

then took the truck on a 4 hour drive to death valley and surrounding areas where I thoroughly abused it for 5 straight days. probably 8-12 hours of hard wheeling every day.

halfway through the trip we moved about 80 miles to a new camp site. This was on a paved highway, and while driving up and over a pass, i started having problems with bucking and momentary power loss again- pretty bad in 3rd gear. was a fairly steep road, but the bucking was concerning. I had to drop to 2nd gear and try to keep the engine in its comfort zone. After cresting the top in second gear at around 40mph, I had no more issues. Got to camp, and then had several more days of hard wheeling, long trails, rock crawling, and driving trails over a mountain range from sea level to over 7 thousand feet, and back down again, through a mix af various terrains.



THEN on Sunday,
I stayed to wheel all morning. No issues with a half day of 20 to 30 miles of rough slow 4wheeling. Went back to camp, hung out, aired up tires and packed, and then got on my way home again with a 4 hour drive to look forward to. IMMEDIATE issues with coughing/bucking/power loss. not just in 3rd gear, but in 2nd gear as well. I had a hard time making it up over the pass to get out of the valley, and with zero phone reception in that region I was not going to be able to call for a tow.

Made it over the hill to Trona... and it was very load sensitive. I could not notice the issues as much when pointed downhill, or on flat ground cruising, but ANY kind of incline and extra load on the engine resulted in bucking and coughing... surging and momentary losses of power. thankfully most of the major hills to climb were behind me. I nursed the thing along trying to accelerate like a grandma, and keeping the engine in the RPM ranges where it was most efficient. It DID make it home, but now runs like poop. I drove it to work yesterday, and its having probs in 2nd and 3rd gear with anything other than the lightest, most gradual attempts to accelerate.

 

[scouthead]

I guess with the amount of abuse the poor thing was put through over a week's time, I should count my blessings that i dont have a huge tow bill, or am not still stuck at the back of a rocky canyon in a pile of oil and engine fragments?

still, I had fingers crossed, and had hoped for a little more than 1500 miles out of this engine getting dropped back in.
it will be a while until I have time to look at it in depth. Any pointers or places to start looking would be appreciated.

 

[K5Jimmy]

Take the engine out
Swap it for a billygoat
Shoot the goat
Install LS engine like you probably should have in the first place.

The advice is free
I'm not a mechanic
I've been rwong before

 

[BoondocK5]

Take the engine out
Swap it for a billygoat
Shoot the goat
Install LS engine like you probably should have in the first place.

The advice is free
I'm not a mechanic
I've been rwong before

Finally! You figured it out

 

[scouthead]

Take the engine out
Swap it for a billygoat
Shoot the goat
Install LS engine like you probably should have in the first place.

The advice is free
I'm not a mechanic
I've been rwong before

im terrified of having to deal with the CA state bar, C.A.R.B., or the local smog ref... ive had some eye opening experiences in the past. I wont rant for 3 pages, but if you want to go over to IH8MUD.COM and look for my blue/white FJ55... there are details... and capital F word to ALL of those agencies i just listed -seriously, burn in hell.

-edit- otherwise, I probably would have built my Landcruiser with an LS, and NV4500, and I would have walked right by this blazer with factory fuel injection and factory manual trans. I will build and repair another LO5 if necessary, but getting further raped by this out of control state is not something i am willing to do any time soon, so the blazer will have to stay fairly close to "stock" (even though the only factory part left on this thing is probably the trans itself, and 2 of the 3 seats lol)

 

[max 02]

I’m totally guessing.

Getting lots of fuel? Pickup in the tank may have bounced loose wheeling. Fuel pump bad? Fuel filter?

Bad ground?

Sorry your having so many problems with it.

 

[scouthead]

I’m totally guessing.

Getting lots of fuel? Pickup in the tank may have bounced loose wheeling. Fuel pump bad? Fuel filter?

Bad ground?

Sorry your having so many problems with it.

I will have to check fuel again, but 2 weeks ago, pump was healthy and regulated to 12 psi... injectors were spattering, but im fairly proud of the low buck injector cleaner that i made... pulled and cleaned the injectors and replaced the fuel filter. spray pattern 10 days ago was

 

[TJ1978]

I like your method better . You get it running, then proceed to beat the shizz out of it. Me, I get my blazer sounding/running nice then leave it alone in the drive way. Then I drive it again, something goes wrong fix, better then parked again.

 

[scouthead]

I like your method better . You get it running, then proceed to beat the shizz out of it. Me, I get my blazer sounding/running nice then leave it alone in the drive way. Then I drive it again, something goes wrong fix, better then parked again.

ha!

 

[BoondocK5]

Time to buy an older than 73 square...

 

[scouthead]

Time to buy an older than 73 square...

possibly! anything '75 and older would work here in Ca...

for a while I was thinking of offing the K5 in favor of a diesel suburban... but those don't grow on trees anymore. and as cool as that would be for longer trips and camping... i dont think i could follow a jeep through the trails i drove last week in anything longer or wider than my k5 already is... many many times i wasnt sure if i could fit.

 

[dyeager535]

I got home after a year, changed oil in the Blazer, drove it around a bit, topped off with fresh fuel, hooked up the trailer, and headed out on a 400 mile trip towing my lightly loaded utility trailer. Nice flat ground for pretty much the entire first half. Noticed a couple of what sounded like very light exhaust backfires, so I started getting the feeling something was wrong. By the time I got half way, anything more than part throttle and I'd start to feel a loss of power, significant backfiring, obviously decreased MPG, and a rough idle. I had no choice but to keep going, so bought fuel injector cleaner as a wild guess (injectors are what, 20 years old and have seen maybe 50,000 miles at this point?), and kept going. No improvement for the next ~200 miles. Not a lot of fun when you can maintain 55MPH at best due to the hills on a route that had about 17K of elevation gain.

Limped it to camp, next morning popped the hood and started to look for problems. Right off the bat, noticed #4 plug wire had backed off the plug somehow. Didn't fall off the plug, just came or had been knocked loose and the boot had kept it on the plug, but not close enough to continue firing the cylinder.

Nearly the same symptoms as the truck had when the in-tank fuel line split on me about ten years earlier.

 

[scouthead]

I got home after a year, changed oil in the Blazer, drove it around a bit, topped off with fresh fuel, hooked up the trailer, and headed out on a 400 mile trip towing my lightly loaded utility trailer. Nice flat ground for pretty much the entire distance. Noticed a couple of what sounded like very light exhaust backfires, so I started getting the feeling something was wrong. By the time I got half way, anything more than part throttle and I'd start to feel a loss of power, significant backfiring, obviously decreased MPG, and a rough idle. I had no choice but to keep going, so bought fuel injector cleaner as a wild guess (injectors are what, 20 years old and have seen maybe 50,000 miles at this point?), and kept going. No improvement for the next ~200 miles. Not a lot of fun when you can maintain 55MPH at best due to the hills on a route that had about 17K of elevation gain.

Limped it to camp, next morning popped the hood and started to look for problems. Right off the bat, noticed #4 plug wire had backed off the plug somehow. Didn't fall off the plug, just came or had been knocked loose and the boot had kept it on the plug, but not close enough to continue firing the cylinder.

Nearly the same symptoms as the truck had when the in-tank fuel line split on me about ten years earlier.

the plug wires are one of the first things i will check then! thanks!

I have a brand new set in the box here, but before I left last week, all the wires on the motor seemed good, and I was getting a hot spark through my new HEI ignition check thingy on all 8 corners... so in theory everything upstream from there was doing its job.

but, that was 10-12 days ago, and a lot of hard wheeling ago

 

[Wes Harden]

I am in the fuel delivery corner. Symptoms described are exactly what I had.
Poor fuel delivery at cruise under light accel.
Possibly a leak in tank? Or maybe fuel filter did it's job and collected crud from tank.
Senario, bounce down a drop, pump slips down, but not off hose, now fuel can sleep out from the nipple, instead of being forced into fuel line.

 

[scouthead]

I am in the fuel delivery corner. Symptoms described are exactly what I had.
Poor fuel delivery at cruise under light accel.
Possibly a leak in tank? Or maybe fuel filter did it's job and collected crud from tank.
Senario, bounce down a drop, pump slips down, but not off hose, now fuel can sleep out from the nipple, instead of being forced into fuel line.

also something i will double check- was a rock solid 12 psi at ALL rpm ranges about 2 weeks ago... but, that was before the big trip
I have a Schrader valve on order to replace the plug where i usually attach the fuel pressure gauge... will be much better being able to attach a typical fuel pressure gauge than having to remove the plug, install the gauge, run without air cleaner, then remove gauge and reinstall plug to get the air cleaner back on.