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confirmed there visual confirmation of the blend door operating... the cable moves with the movement of the lever on dash and it is connected. Today... Drained coolant Changed Thermostat (192°) I did drill a small vent in the flat surface of the thermostat and oriented it 'UP' on placement. I used a Motorrad kit with an New housing, etc, but for a later model year to get the threaded fitting so I could install a mechanical temperature gauge. There was an issue, needed a 3/8 npt male to 1/2 npt female bushing as without the bushing the probe on the gauge would not seat or seal, (Heck the retaining nut would not even start in the furnished adapter) With coolant drained, I put some 'light' air pressure in the hose that is connected to the thermostat housing, (it feeds the control valve and then to the bottom fitting on the heater core. I could hear gurgling of coolant leaving the heater core back to the block.... So... 'assumed' the core was clear. Filled with 50/50 concentration ( from full strength jug) and took my time to hopefully not air lock. (the fitting on the thermostat housing actually looks higher than the temp sender at the back of the head), so I filled until a trickle of coolant exposed itself. Fired er up and waited for it to warm up. did so and then also vented again at the housing fitting, got just a little burp. Still NO heat, and I manually moved the lever on the coolant valve and that hose just did not heat. Day or two ago, I unplugged the vacuum line from that valve and moved the lever and put my finger over the port, it did hold vacuum. I also believe this valve is OPEN with NO vacuum. so at some point "someone" is gonna put a heater core in this thing... and I doubt it will be me. in regards to the mechanical temp gauge, I think it will be 'off' just a bit because of its location, I'll be monitoring it closely. It did show 180, but i expected it to hit 190+.... shut it down, next step will be check system cold for coolant level.

do you see the connector? Is it unplugged? I cannot recall if the sender grounds out when zero pressure, illuminating the light... but that may be the case.

just south of greensboro, almost center of the state.

i just do not see the correlation between the NSS and the vehicle running. The circuits on the wiring diagram just do not seem to go to the ECU..controlling the spark and the fuel. but it does control the starting circuit, the reverse lights, and the transmission controls. If you unplug the NSS at the connector under the hood, the starter would not engage, but I'd think if you unplugged with the engine running, it would continue to do so, but the transmission would only shift with the manual lever. temp 'could' have an effect on connections, as well as the CPS response and its output, and "maybe" circuits in the ignition module, etc cold here in the piedmont too.....

thanks. will be part of process when i change out thermostat and 'new' housing. did a motorad 'kit' and coming from evay seller (seller offer 50% off and free ship)

not sure i'll help much, but... have you tested fuel pressure on the rail during this no start condition? other basic tests... Instructions on site CPS output Spark? think the red herring here is the 'rolling' and then firing... IMHO, probably not NSS Stalling... Idle air controller, cleaning Throttle body and the IAC port the MAP sensor and vacuum line connections Possible leaking injector and 'flooding"? Have you tried crank on Wide Open Throttle to initiate the 'flood' start in ECU?? Yeah these no cranks can be PITA, my recent experience paralled could hear fuel pump run, but NO pressure at rail. its going now though.

thank you both, is it possible to visually see the blend door actuator in the vehicle, what needs to be removed to see it? when is vacuum applied to underhood water valve, on A/C selection, and this closes the water valve?? Once I get it inside on heated part of garage, I'll take my mity vac and apply some vacuum to water valve. Seems the defrost door works and panel door works, as air changes direction on position of the selector. am though leaning towards a core obstruction...

1989 Comanche with A/C 4.0 some help with possible diagnosis of heat in regards to any 'blend door' actuation i do believe i have very low flow through core after testing with heat gun... unsure if thermostat is stuck open (temp seems a bit low to me) will be replacing thermostat and housing with the later version for possible access point for ether a mechanical or electric temp gage, in some research, the control valve ( still closed system) is normally Open, allowing flow until AC is set, then closes off flow. assume this is with vacuum on the valve, and it has none in normal state. images or whatever of the blend door area location and maybe vacuum diagram of the control circuit thanks in advance.

anyone know what retains the collar inside of the column near the shifter?

watching my 89 is still connected, but the collar on the steering column is not connected to the housing for the lever, been that way a long time....

years go I bought a set of o-rings from local dealer, there's 12 in a set, don't have p/n presently IIRC 6 were different color from other 6 and i think slightly different in size. The flat OD is from being compressed inside the fuel rail or the head. I remember lubricating with fuel for insertion. If it was me, I'd probably just replace all the injectors and o-rings (which i think are with new injectors) ya gotta pull all of them anyway to remove rail for just one....

not a bit of help but WoW.... serious money i think on Bring a Trailer 'auction' assuming 4.0

^^^ xlnt advice , one could also access the starter relay and test fuel pump by unplugging connector for fuel pump and applying 12v to that wire, this bypasses the relay and the ballast resistor, pump would run continuously on my 89, the terminal was beside of the large stud at the top of the relay shown on the top left in the image below. this terminal has power applied during the start cycle and drops out after you release the key,

in my case sylvania LED for the 1156 bulb had fitment issues in the stock socket. would insert, but would not twist to secure. tried multiple positions, just would not twist and I ruined one making an attempt..... have no some sylvania 'star' 1156 and will be trying them instead. OP's Amazon link .. on sale seem like a decent deal....

thank you for the additional responses. am aware of techniques with removal, as well as using jumper for pump. sending back to folks i hired out to replace pump recently... did not DYI as I just did not want to lie on gravel to man-handle this thing. I DID years ago replace the tank myself after a rust hole was developed from contact with skid plate insulators, a new tank.... and years ago replaced pump myself... but just not this time. should be able to update next week.

flat ground drips on concrete accumulated drip on bottom of tank but bottom of tank is solid, not rusted out... and it did not leak before first fill-up / nor while driving after pump replacement.

agree, and it did not leak before filling, such are my suspicions of the vent on top that is more difficult to access... ( murphy's law)

long bed, the rear one.... now unsure IF from that vent or fuel sender.... recent fuel pump replacement hired out... believe it is going back to them. was not full of fuel on return, drove it around a bit to see how it worked and get a known position on fuel gauge before filling only rounded off to next tenth gallon or so, did not pack the tank. discovered leak.

Question Can the fuel tank vent hose connections be accessed without completely dropping the tank? Have one hose that mysteriously became disconnected, no problem until I filled the tank, and then... leako...

was going to try some LED, got some fairly expensive sylvania from O.Rei, 1156. two pack they would not fit into the socket (would insert, but could not turn and lock in place) actually messed up one of them trying to twist the original 1156 would simply twist into place. somehow got the second one in the package to 'barely' secure, will see how long before it vibrates loose, then will go back to regular 1156 bulbs...

i posted in the DYI section on an OLD post, a member suggested I link to it here for any 'new' input and responses, as the images in that old post are dead.

was there not a thread about the 'correct' and 'best' O2 sensors available 'now'?

hate dragging this up from the dead, but... as the images are no longer available, is this the front (nearest radiator) port on the valve cover? and feeding to the air box? seems like a potential solution for the non-fitting J hose on the dorman harnesses....

i attempted to insert the used hard hose into the nipple on the air box, it will not insert.... what did you do to make it work? best i can tell the OD of the hard hose on the harness is 'about' 9/16" (probably metric), but the OD of the fitting on the air box is 5/8" went in a rabbit hole searching for bulkhead fittings.... not so fun seems dorman or someone would mold up a hose like the original with larger end at the end of the J to FIT the airbox.... it is not like there are NO vehicles out there in need of these components.. they made a snit ton of harnesses, why not make em 'right'??

Any other input on this ... either J hose or fitment stated above about a small section of old harness to fit up the smaller dorman hose? Maybe a bulkhead connector sized for the dorman j hose relocated to a new hole ??