1986 TBI no start/crank
03-14-2017, 03:08 PM
#1
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Model: Cherokee
1986 TBI no start/crank
Hey Y'all,
This is my second post, but I am still stumped. I have been trying to get my 1986 4cyl TBI 2.5 started for the past three months!!
Here's what happened:
I was driving down the road and the car died. I have had it die while idling before, but never while giving it gas. So I tried to start it and nothing happened. Towed it home. Decided to check spark and found my #1 Cyl plug was bent at the end, as if the piston or something had hit it. They are champion coppers and were the correct length. After replacing spark plugs and wires I verified I had a strong, blue spark, fuel, and compression. I verified spark by removing the plug, reattaching it to the wire, and holding it against a ground while a buddy cranked it. I verified fuel by not only watching the injector spray fuel into the throttle body while it was being cranked (TBI!!) but also spraying starter fluid into the throttle body while it was being cranked. The latter did 'rev' it up a bit more and made it 'closer' to catching, but it still wouldnt start.
Verifying both fuel and spark, I checked the cap and rotor. (I had a problem with the distributor and timing before, but that was solved.) They are both good and functional.
Deciding it was a sensor, I replaced the Stepper Motor (Equivalent to an AIC valve). When that didn't work I took off the throttle body, scrubbed it hard, replaced the TPS, and put that back on. Nothing. I replaced the CTS but realized later that the one I replaced was for the gauge inside the cab and not the ECU. I am willing to replace the CTS for the ECU but I can't seem to find it. Online and in Haynes it says on the drivers side of the block, but I don't see anything down there. (BTW the reason I replaced these sensors is I was told by a mechanic friend that these were the most likely culprits, in the order I replaced them.)
I posted here and someone suggested the CPS, despite the fact that I had both fuel and spark. Replaced that, still no start.
So, to summarize, I have replaced:
CPS
TPS
Stepper Motor
plugs
wires
fuel filter
fuel regulator
Coolant temp sensor (For gauge, accidentally.)
This is my second post, but I am still stumped. I have been trying to get my 1986 4cyl TBI 2.5 started for the past three months!!
Here's what happened:
I was driving down the road and the car died. I have had it die while idling before, but never while giving it gas. So I tried to start it and nothing happened. Towed it home. Decided to check spark and found my #1 Cyl plug was bent at the end, as if the piston or something had hit it. They are champion coppers and were the correct length. After replacing spark plugs and wires I verified I had a strong, blue spark, fuel, and compression. I verified spark by removing the plug, reattaching it to the wire, and holding it against a ground while a buddy cranked it. I verified fuel by not only watching the injector spray fuel into the throttle body while it was being cranked (TBI!!) but also spraying starter fluid into the throttle body while it was being cranked. The latter did 'rev' it up a bit more and made it 'closer' to catching, but it still wouldnt start.
Verifying both fuel and spark, I checked the cap and rotor. (I had a problem with the distributor and timing before, but that was solved.) They are both good and functional.
Deciding it was a sensor, I replaced the Stepper Motor (Equivalent to an AIC valve). When that didn't work I took off the throttle body, scrubbed it hard, replaced the TPS, and put that back on. Nothing. I replaced the CTS but realized later that the one I replaced was for the gauge inside the cab and not the ECU. I am willing to replace the CTS for the ECU but I can't seem to find it. Online and in Haynes it says on the drivers side of the block, but I don't see anything down there. (BTW the reason I replaced these sensors is I was told by a mechanic friend that these were the most likely culprits, in the order I replaced them.)
I posted here and someone suggested the CPS, despite the fact that I had both fuel and spark. Replaced that, still no start.
So, to summarize, I have replaced:
CPS
TPS
Stepper Motor
plugs
wires
fuel filter
fuel regulator
Coolant temp sensor (For gauge, accidentally.)
Last edited by stardust22; 03-14-2017 at 03:15 PM.
03-16-2017, 10:52 AM
#4
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Join Date: May 2012
Location: Lost in the wilds of Virginia
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Yep. That's the #1 suspect. Stop firing the parts cannon, start testing.
https://duckduckgo.com/?q=test+to+se...ffnt&ia=videos
Last edited by BlueRidgeMark; 03-16-2017 at 10:55 AM.