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Truck Turns Off While Running


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Hello everyone,

 

Here I am again with another problem with my 88, 4.0, 5 speed.

 

This is the third day in a row that my truck shuts off on the way to work. I happens while I am accelerating. Not heavy acceleration, just normal stop and go traffic. The first two days I was in third gear when it shut off, tack went to zero. I put in second popped the clutch and away I went. Today I was in fourth when it happened I put it in third popped the clutch only this time it didn't start wright away. It took longer to start and when it did it back fired. Three loud pops and a good amount of dark smoke. Then away it went as if nothing happened. It only happens in the morning  about 2 miles into the drive. Before and after it happens it runs smooth and does not happen on the way home.

 

I appreciate  any help anyone can give me as this my only ride.

Thanks

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Thanks for the response.

I thought that when the CPS goes bad it just won't let the engine run. Or least that what happened when it went out before.

Test your CPS. Post 7 in my Tips. 

 

Keep in mind that te signal for almost all of your critical sensors goes through the C101 connector...Post 2.

 

I would do posts 1 through 5 as a preventative step anyway. 

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Another possibility is the O2 sensor -- how old is it?

 

The Renix system is a decent system, but an old design. It always starts based on the ECU programming. Until the engine gets up to operating temperature, the ECU ignores most sensor inputs and operates on a pre-programmed fuel-air map. This is called open loop mode. When the temperature gets close to normal, it switches into closed loop mode and responds to sensors.

 

Your mention of this happening 2 miles down the road is why I mention this. When I was driving an '88 4.0L as my daily driver, I was able to sense when it switched from open loop to closed loop. There was just a very subtle little hiccup in the engine -- and it was generally about 2 miles down the road. At one point, I was getting backfires at the point of change-over. I guessed that the O2 sensor was going south, replaced it, and all was good.

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I checked the CPS and got a reading of .47 volts AC using a Fluke multimeter. I also had 2 cheap meters that I used and they gave me a reading of .3 volts AC. I used the cheap meters because the Fluke has so many settings that I sometimes wonder if I have it on the correct setting. What do you think is the CPS bad?

 

The O2 sensor is about 2 years old. Is their a way to test the O2 sensor or is it time to change it? I checked Cruiser's tips and could not find a test for it. 

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  • 1 month later...

Hello gentlemen

Sorry that I have not gotten back with you on this issue but I got some rather bad news and everything stopped for me. My wife's cancer came back. So I parked the truck used and started using my son's car.

 

So I finally took the truck to the rehab center with me, so I could start on some of cruiser's upgrades. It ran fine for about 2 days, then it stared to act like it was starving for fuel. After awhile it ran fine. I did most of grounds yesterday, saving the big one when I'm at home. Today got it to start but again very rough. Then it shut off and smoke came out of the breather box. Got it going again and it ran smooth all the way to work.

Also before I parked it, it backfired so bad that it split the muffler open. Not much just enough to make it rumble.

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DId you check the ground by the dip stick to make sure its clean and tight? Ages ago i had a similar problem (backfired so bad it blew the muffler completely apart, ya) long story short that ground was completely lose and covered in oil and grime. Once cleaned and tightened all of my problems ceased.

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Yes. That was the first ground that I cleaned up. Any other thoughts? I still need to do the big connection but I don't dare do it in the parking lot of the rehab center. The wife goes home Saturday, so I'll do it then.

 

Thanks for your input everyone. Much appreciated!

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Check the knock sensor, bottom of block, driver's side. My old original knock sensor fell apart a couple years ago, and caused similar symptoms. Replaced it and cured the problem. The replacement knock sensors are of a different design than the original, but have the same electrical connection (they use the same plug).

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Check the knock sensor, bottom of block, driver's side. My old original knock sensor fell apart a couple years ago, and caused similar symptoms. Replaced it and cured the problem. The replacement knock sensors are of a different design than the original, but have the same electrical connection (they use the same plug).

I would disconnect the knock sensor and drive it first to verify. I'm really having a hard time thinking that's it. 

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Well now, I didn't say that at my age, my recall was all that keen anymore   :hmm:, but I'd be glad to check if you'll give me a week or so to get back up after I get down under her.....

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Well now, I didn't say that at my age, my recall was all that keen anymore   :hmm:, but I'd be glad to check if you'll give me a week or so to get back up after I get down under her.....

I'm waiting. LOL. Do the dizzy unplug while you're at it. 

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Hello everyone,

 

Well I finally got the wife home from the rehab center but then had to keep attending to her as a result of the operation from the cancer. Anyway I finally finished all of cruiser's updates 2 thru 5. Boy what a time I had with the C101 connector. When I did the Ohm test on the TPS, it gave me a reading of 3 Ohms. I don't know if that is considered low or not. But when I wiggled the wires as instructed it never waivered. While there I checked for adjustment. It was off so I adjusted it back to 17 percent.

 

Cruiser in further reading step # 8 is says if I have a resistance of more than 1 Ohm I'll need to do some sensor modifications. As mentioned above I got a reading of 3 Ohms when I went from terminal B to the negative battery post. Can you tell me what sensor modifications I need to do to get it down to 1 Ohm or 3 OK?

 

Another odd thing it started doing before I finished the all the steps was that when I would start it in the morning it either would not start on the first try or it would shut off and I would get white smoke coming out of the air box. But that seems to have gone away.

 

Anyway I'll drive it this week and see what happens. Thanks again everyone for the help so far.

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Well it shut off again on me today. It started fine this morning, went to work about seven miles. About an hour and a half later I had to make a trip about a mile or so. Then it shut off. I got it going again. Then at the next signal it turned off again. Got it going again and was fine the rest of the trip. No problems on the way home.

 

88whitemanche the white smoke has not occurred again since that one time. I don't hear any popping when I start it other than that one time with the smoke. I'll check the plug wires but the truck runs smooth most of the time so I don't think it's the wires.

 

Cruiser I think that I should be able to do that step and is something that I want to do but do you think that is my problem. This is my only ride and I need to be able to accomplish this in 1 day, so I can have access to another vehicle incase I need it.

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Do you think it might be the fuel pump going bad? This past weekend I changed the fuel filter as it has been awhile since I changed it. I also wanted to change the rubber hose that goes from the engine to the metal tubing. But the end that connects to the metal tube down below is crimped to the tube. The NAPA rep said that he didn't carry it but might be able to order it if I had a part number. Does anybody have it?

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