A.I.R system?? -have loss of power… code 43 for knock, and 44 for lean condition????

[scouthead]

If the fuel pressure is low, it will have been adding fuel from the stock table. Disconnecting the battery will put it back. I think the lean condition code indicates that it can't trim any further. A misfire typically reads as rich.

You could try taking the A.I.R. tubes off the manifolds and plugging those holes as a test. IIRC, it's a weird pipe thread and not a standard bolt thread.

Air tubes are attached but the inlet from the pump is capped off at this time - exhaust SMELLS better but truck is running worse than ever currently

 

[scouthead]

You can unscrew the check valves and use an iron pipe cap to seal off.
1st pull the hoses off check valve and see if any exhuast is coming out off the check valve it is not supposed to.

Take a hammer handle and give the egr top a light rap, sometimes helps the pintle seal if carbon is holding it open.

Didn't say if IAC passages was clean ? Did check the TBI base gasket ?

Yeah I’m going to try tapping on EGR. I’ve tried disconnecting and capping vacuum line- doesn’t run any different
EGR appears to open with a vacuum pump and hold vacuum

As for as I can tell the gaskets on the throttle body are good- nothing inside or outside sticking out and no smoke from the smoke machine leaked out there

 

[scouthead]

Soooo out of desperation to get home for the weekend and bring back axle parts of my daily driver to fix…

The blazer was driven 170 miles in its current state.

Started out not horrible- got worse.

Initially taking off from a stop was underpowered but manageable- carefully feed the skinny pedal and slip the clutch.
Once cruising at Hwy speeds it was ok, but Check engine lights on and off throughout the freeway ride. Steady on the gas pedal, but could feel a percentage of the power disappear and then Come back and then disappear again- not always in time with the check engine light going on and off. I think this may have been the knock sensor retarding timing

Someone cut me off in traffic and the engine stalled when I came off the gas and stabbed the clutch.
Once stopped, lots of cranking to get it running again.

Made it home- it stalled as soon as I pulled up to my garage behind my apartment.

Let it cool off and had to run to catch a date- it runs absolutely horrible now.
Bucking- barely idling- chuffing sound coming from exhaust, no power, not sure how many cylinders are firing, shaking, almost impossible to get it started from a stop. Lots of use of my non synchro low gear - lots of grinding trying to force it in gear to avoid stalling.

I felt like a stressed out octopus trying to parallel park while it coughed and sputtered and stalled

Only code that stuck in the memory this time is 44 - that’s knock sensor right??

 

[Wes Harden]

if you have an hei distributor, drop that in and see if it improves. The TBI dist are crap

 

[scouthead]

if you have an hei distributor, drop that in and see if it improves. The TBI dist are crap

You mean “cap in coil” type? I thought the TBI ignitions WERE considered HEI?? I have a special spark plug looking tool with An aligator clip on it… it’s for HEI ignition systems-has some kind of resistance built in, and a cage around the electrode.
-take plug wire off spark plug
-plug this thing in
-ground the aligator clip
-start motor
- if a spark jumps the gap between electrode and outer cage (1/2inch)

Supposedly that means the coil/cap/rotor,plug wire are all functioning correctly.

This thing was marketed as the HEI version, and I’ve always used it with the TBI stuff.

-quickly eliminates all the upstream components, and helped me find a faulty plug wire one time -was out of spec but still occasionally allowing spark plug to fire

 

[scouthead]

All of my fuel injection parts and pieces and tools are MIA… but I was able to cobble up a pressure gauge from hardware store parts

That don’t look right

 

[scouthead]

Couple thousand miles ago that was 14psi

This is a different gauge than what I used last, but according to this one, I’m not building ANY fuel pressure with the key on before starting, and then while the engine tries to idle it’s between 5-6 psi

Going to see if any of my spare throttle bodies have usable fuel pressure regs on them… (I have a handful of new ones but the box is missing!!)

if so I’m taking the fuel pod out of the blazer to see if it’s shot.

 

[Wes Harden]

yeah I am not thinking spark quality, and thinking timing. These distributors have a high failure rate, shaft bushing, pick up coil. etc.

That is very low FP, where are you tapping into the fuel system ? I use to plumb my gauge in place of the fuel filter.

 

[scouthead]

yeah I am not thinking spark quality, and thinking timing. These distributors have a high failure rate, shaft bushing, pick up coil. etc.

That is very low FP, where are you tapping into the fuel system ? I use to plumb my gauge in place of the fuel filter.

Let’s see… there’s a one inch throttle body spacer… wether or not it does anything for torque is a fantasy argument, but it creates room for a extension between the throttle body and fuel supply line- that extension piece is tapped 1/8npt and I used to have a permanent fuel pressure gauge mounted there- recently was plugged. Pulled the plug and stuck a shrader valve in there yesterday- pain in ass getting a hose in there because the coil, throttle cable are in the way, but it’s possible!

Remnants from trying to pull more power out of a TBI, but I used to have that one inch spacer, an injector pod spacer, adjustable fuel pressure regulator on the injector pod, bored out throttle body with the air horns milled off, removed the sheet metal collar/spacer from between the air cleaner and throttle body -air cleaner sits directly on top now… and a tall air filter lid from an older truck so I can use the 5 inch tall filter elements. It all clears the hood barely

 

[Blue85]

Not saying there's nothing else going on, but you need to prove that gauge is bad or fix the fuel pressure issue. It should be 2x that, so no wonder it's logging a lean code. Possibly all of the lean misfire is tickling the knock sensors.

Do these have a soft return line you can pinch?

 

[scouthead]

Ok- yesterday I pulled the throttle body- removed the adjustable fuel pressure regulator- replaced with one that “looks ok” from a low miles throttle body… no change in fuel pressure afterward.

5-6psi and engine struggling to run

Replaced fuel filter with k&n that absolutely refused to seal on both ends- thought the orings on the lines looked ok, but some slight mismatch in threads… tighten, leak, repeat… no eventual change in fuel pressure.

Engine off/key on… 12.4 volts supplied at the pump.

Open up tank and pull sending unit :

 

[scouthead]

And if you can’t see it in photos from above

The hose connecting the pump to sending unit split in 10 places- not all of them clear through the hose… but enough of them!!

 

[scouthead]

It’s a Delphi pump that I installed about 10 years/ 15,000 miles ago. Gambled on pump being ok for another go… replaced hose. Reinstalled.

Even without the adjustable fuel pressure reg- it builds 11.5 psi turning the key on. It’s holding just over 12psi running.

Idles as well as it ever has since this engine was patched up and reinstalled… and Picked up about 220hp replacing that 2 inch hose!

I’m now wondering if that hose had been weeping for quite a while, because there used to be a little lack of power as you let the clutch out and eased into the gas? Not on this mornings test drive- would have been almost impossible to stall.

 

[scouthead]

I still have an issue with the AIR system, and am fairly confident the bypass valve has shit the bed and is constantly supplying the exhaust with fresh air. Connecting all the hoses makes a rich smell out of the tailpipe in short order. Disconnecting them immediately changes back to normal smelling exhaust. Will work on correcting that situation next

 

[Fastereddie]

I would definitly check the the fuel system pressure and volume.

Do I win a cookie?