eaglescout526

Is it a Jeep forum? The adjustment is this: Key on engine off Check sensor input voltage, Connect negative lead to TB and positive to TC Note here is to not unfasten the sensor nor unplug it from the harness but back probe the connector. Move the throttle plate to wide open, be sure throttle linkage contacts the stop Note the reading for the input voltage for B and C should be 5V wide open Return throttle plate to resting. Check sensor output voltage by taking positive lead from TC and put it in TA. Move and hold the throttle plate wide open like testing the input voltage. Note this entire adjustment is with the throttle plate wide open so it will be a bit tough to do alone but it gets easier the more times it is done. Voltmeter reading should be 4.6-4.7VDC, adjust the output as necessary. Loosen the bottom retaining screw for coarse adjustment and loosen the top screw for fine adjustment until the output has hit between 4.6-4.7VDC and then tighten the screws while holding the sensor still during tightening.

We tried the tests for them and came up with bizarre results. We never got the 5V to the sensors from the ECU so theres something wrong somewhere and it all just might boil down to the 5V circuit.

Not that I can think of. Starter relay/solenoid is good as the engine cranks, ECU pulses the injector, injector is good on the resistance, spark comes from the coil, CPS tests alright, FP runs with good pressure, good bat voltage, fusible link to pin 30 for FP relay is good, ignition switch is good, engine fires with fuel down the TB. The only thing we absolutely don't know about is the MAP and the TPS.

No idea. Just sent him a PM talking about it, he's pretty good about getting back to me. At the moment he isn't sending the parts out yet but I can't make a promise on how quickly he can get the ECU out

Well theres a $100 you don't have to spend. I don't think those injectors ever go bad but they are just GM injectors.

Well, trying to help prevent ya from buying a new ECU. Not sure what the return policy is at parts stores on if the ECU fixes your problem or not. Buuuuuttt if we go the ECU route send @70barracuda a PM about a 2.5L ECU. I am buying his old one off of him and he could probably send the ECU to you for testing purposes.

Try anywhere inside the cab that touches the sheet metal. Also doing the resistance test on the injector should say something. Since you had the injector unplugged for the light test, take one lead and put one on one injector post and the other on the other post and see if it has more or less than 10 ohms resistance. Ok I missed this new page, disregard what I said.

WTF! Its like everything checks out. So I wonder what voltage is getting to T6(if any goes there) at the ECU connector, perhaps a voltage signal is not going to the relay to energize it.

No you can get a stalk without cruise with intermittent wipers. Only the cruise talk has a wire that leads down. But if its got pre H.O. cruise stuff I'm interested in it.

All I needed was something to go off of. Thanks. So with the relay installed do you see pressure on the fuel rail?

Hooooo, shes free of the tarp!

So both are getting power to them? So then it should be energizing the relay for the fuel pump.

Both of ya but mostly you. But lets do see what our voltage looks like where Ohm said.

Ok that eliminates the fusible link being blown. Could pin 86 be tested on the FP relay during crank to see if the ignition switch is sending voltage to energize the relay? Thanks Ohm!

Ok pressure is good, pump is good. That takes care of the fuel system as far as delivering fuel. What is the number for that pressure gauge kit so I can hunt one dow if you don't mind me asking? Your guess is as good as mine for the fusible links. Its all in that electrical diagram I posted in thirds. I would imagine the splices would be soldered pieces of wire in the harness. T16 on the ECU is the 5V supply for TPS and MAP. D1 D2 4 1 3 6 9 12 15 5 2 2 5 8 11 14 6 3 1 4 7 10 13 Which pins are you jumping on the FP relay? 30 to 87? That will rule out the fusible link for that area if you are jumping those two. Were just looking for voltage of some kind, not resistance.

Right right right. My brain is going a mile a minute. But we can confirm that jumping the relay causes the pump to run, so we can test the voltage and see if we are seeing 12V or not. Back up the line to 30 on the relay, it goes to a red fusible link. Then 86 on the relay goes to splice "B" which is a yellow wire all the way to splice "E" then splice "D" to the ignition switch. I wonder what T3 shows at the ECU connector? Splice "B" also shows to go to D1_2. Looks like the MAP and TPS share the same 5V circuit from the ECU. Ill admit, I'm learning right here with you.

This makes sense why you don't see little dealer ships like that anymore. Damn Iacocca. So theres probably dozens of AMC dealers that are hidden in small towns because of the big dealer ship idea.

Youre gonna hit a point where I will be jealous of your MJ and some of the neat factory options like a hidden winch.

Both would indicate open loop but I would test for both just to see what we could be looking at. And let me know on that tool kit and ill see if I can hunt down a semi cheap kit to add a pressure gauge to mine. Also the injector is not supposed to have more than 10 Ohms of resistance.

This one definitely is a unicorn of issues. I'm not sure if they have a kit for all fittings but hopefully they have the right one for our TB's. If they do let me know, id permanently hook one up. Ok looking at the 86 electrical book, from 87 on the FP relay, that wire goes to splice "K" which goes up to C113 that goes to splice "N" then one of the five other orange wires goes to the fuel pump with C100 then to C200 then to the Sending Unit. So theres only two connectors between the splice and tank. Two other orange wires go to the laod swap relay which is probably that silver one in the pic and another one goes to the PS switch. Another orange wire goes to C219 which is not used. Thank goodness for dual monitors.

Relay, solenoid, they do the same thing. Man 86 is an animal that's for sure. On the side of the TB is an allen head bolt snugged away by the fuel lines facing the drivers side fender. If you can manage to find a pressure gauge to fit that port you can see what the fuel pressure looks like. Have you seen any fuel leaks around the TB area?

I wonder where your starter relay is. I looked at my 86-87 parts book and saw a couple like that silver one but I know its not the anti diesel timer so it could be the power steering relay.

Do you have AC or Fog lights? Possibly O2 relay. I meant the other 5 pin connectors, the GM weatherpak ones. Gonna need TNT to blow this stump.

Actually it could rack up miles on the speedo. If the output shaft is spinning, chances are so is the speedometer and the odometer. So even leaving it in neutral is fine but youll rack up miles. I'm sure theres a liability reason and stuff like that that I can not think of.

Sure!! If we weren't in this current situation the world is in, lol. First thing I would look at before absolutely diving into the harness is cleanliness. How clean are the FP relay and the starter relay contacts. Possibly a connector could be loose on that relay. Had that happen once, wouldn't even engage the starter until I found a connector coming unplugged yet it had started the day before that incident. Are there two 5 pin connectors by the passenger side shock tower by the relay center?