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1986 TBI 2.5 no start/crank

stardust2280 said:
Okay, I haven't been able to get around to testing the things I need too due to midterms, but I can answer some of your guys' questions.

The fuel pump is inside the gas tank.

I'm not sure if my jeep has an IAT or not.

Idle Stepper Motor (Or Idle Speed Actuator) is explained here: http://www.4wdmechanix.com/Tuning-and-Troubleshooting-the-2.5L-Jeep-TBI-Four?r=1 I Think it serves the same purpose as the IAC.

Jeep Driver, I never set the fuel pressure after I removed the TB, didn't realize I had to. My WOT switch looks like it does in the previous link, it is mounted of the throttle bracket, I haven't messed with it.

Yeah, pretty much everything you need to know about my particular Jeep is on that link, including the stuff about the different FPR. It has a picture of it but doesn't mention it; if you ctrl-f 'oe-' the picture above is it.

Not sure what specific Renix parts they used, but I am 100% sure i have a TPS, as I have changed it out.
Click to expand...



You're on the right track, you have a Renix AMC engine.

Yes you have a stepper motor, yes you have a TPS.

You need to check timing before anything else.
 
stardust2280 said:
Okay, I haven't been able to get around to testing the things I need too due to midterms, but I can answer some of your guys' questions.

The fuel pump is inside the gas tank.

I'm not sure if my jeep has an IAT or not. Yes you have one, it is also called an MAT, see the link, info and picture for the MAT.

Idle Stepper Motor (Or Idle Speed Actuator) is explained here: http://www.4wdmechanix.com/Tuning-and-Troubleshooting-the-2.5L-Jeep-TBI-Four?r=1 I Think it serves the same purpose as the IAC.

That is correct! No IAC, but an earlier version of it, a Idle Stepper Motor (Or Idle Speed Actuator. )

Jeep Driver, I never set the fuel pressure after I removed the TB, didn't realize I had to. My WOT switch looks like it does in the previous link, it is mounted of the throttle bracket, I haven't messed with it.

Yeah, pretty much everything you need to know about my particular Jeep is on that link, including the stuff about the different FPR. It has a picture of it but doesn't mention it; if you ctrl-f 'oe-' the picture above is it.

From the linked site: If there is a pressure regulator problem, the pressure regulator fits within the bowl beneath the fuel inlet. When servicing the pressure regulator, you check pressure at the test port. A running TBI engine will have 14-15 psi.
Note—Excessively high pressure readings indicate a possible pinched fuel return line. Pressure regulator adjustments are usually minute and only to correct minor changes in the regulator and system over time. When there is not enough pressure, even after attempts to increase pressure at the regulator’s adjuster, there is either a restricted fuel supply system (pinched line, plugged filter) or a low output electric fuel pump in the fuel tank.

So the fuel pump and FPR are different.
​


Not sure what specific Renix parts they used, but I am 100% sure i have a TPS, as I have changed it out.
Click to expand...
 
go1lum said:
86 2.5 tbi is renix. First year.
Click to expand...

I had an 84 2.5 L, AMC TBI, 4x4 that was not Renix. Very Interesting to find that there was an earlier than 1987, 6 banger Renix on the 1986, 4 bangers. The 4.0 six banger came out in 1987.
 
I don't think the 2.8 ran the renix,

I believe the 2.8 was always running that crap carburetor with the one variation for computer control for the California emissions.

I know the 1986 federal emissions was the same as 84-85, with the addition of a little black box, some kind of service reminder timer.


Sent from my iPhone using Tapatalk
 
EcoMike,

I can't seem to figure out how to test the regulator. I see a little port on the side, do I need some sort of tool to stick in there and test it?
 
stardust2280 said:
EcoMike,

I can't seem to figure out how to test the regulator. I see a little port on the side, do I need some sort of tool to stick in there and test it?
Click to expand...

Yes, you need a fuel pressure test gauge and hose assy. The swivel connector threads onto the test port on my vehicles. I have no idea how to adjust that one. The 87 Renix is not adjustable, I think I read that yours is.

You may be able to rent one free at the parts houses.

Here is one to consider for buying

https://www.walmart.com/ip/Auto-Fue...4406&wl11=online&wl12=949950671&wl13=&veh=sem
 
stardust2280 said:
Yeah, I think it's adjusted by taking it out and using a flat tip to 'tighten' the seal or 'loosen'' it.
Click to expand...

LOL, only an engineer that has never used a tool would dream that crap up.

Disclaimer, I was fixing things, just about anything and everything BEFORE I became an engineer LOL.
 
So, here is the info on the ohms of the sensors, and a video showcasing the sensors I didn’t know what they were but tested anyway. Watch the video first – I found a sensor that a connection broke out! https://youtu.be/qnPesBBGeiI

MAT - .9
WOT - .1
MAP – 0
CPS – 0
Sensor with broken connection - .9
Sensor that goes into the exhaust manifold and is good – 0
TPS- .1
 
Jeep Driver said:
The one with the broken wire is the temp sensor to the ECM, TX28 is the part number.
Click to expand...

Coolant or air intake temp?

The exhaust pipe sensor in the video is the O2 sensor.
 
stardust2280 said:
http://www.4wdmechanix.com/Tuning-and-Troubleshooting-the-2.5L-Jeep-TBI-Four?r=1 seems to agree with JeepDriver - that the broken one is the CTS and the one on of the intake manifold is the MAT.
Click to expand...

The one in the air intake manifold IS THE MAT sensor (also called an IAT and something else in the part houses).

The one in the block coolant passage or in the coolant flow stream.... is the CTS, So replace the CTS since you say it is broken (I can not verity which is broken). Keep in mind it will drain the most of coolant or try to if there is a place for air to get in. It is threaded into a coolant passage.
 
stardust2280 said:
So, here is the info on the ohms of the sensors, and a video showcasing the sensors I didn’t know what they were but tested anyway. Watch the video first – I found a sensor that a connection broke out! https://youtu.be/qnPesBBGeiI

MAT - .9
WOT - .1
MAP – 0
CPS – 0
Sensor with broken connection - .9
Sensor that goes into the exhaust manifold and is good – 0
TPS- .1
Click to expand...

how long has that wire been broken?
 
There is no way to know, it could have been broken for years or it could have come off because of a rock or something and it is causing my no start.
 
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