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Discussion Starter #1
hi guys. here is my problem. i own a stock 98 12 valve, auto, with 355000 km. today, while making a four hour trip home, it started missing while going 65 mph. just a few days before this, i had driven the truck for about 6 hours, non stop without any probs. after i noticed the missing, i took my foot of the throttle, and the engine died. i waited a minute or so, and she fired right up, but ran rough . at a slow speed, when i took my foot off the throttle, the truck seemed to keep pulling on its own, for a few more feet, before slowing again. i stopped, and changed the fuel filter, and noticed that the old filter looked a little black, so i thought that the filter was the problem. the truck took right off, but after about three, or so miles, started missing again, at highway speed. when i let off the throttle, it did the same as before. i was in the middle of nowhere, so i decided to give it a try, and keep going. after about an hour and a half,(and all of this time, the truck would miss when i needed to accelerate), i noticed a couple of times the truck seemed to run perfect for a short bit. then, of course, as i got closer to home, it started running perfect. by the time i drove up the driveway, she was running like a brand new dime. whats up? this is the second time it has done this. the first time was about eight months ago, and i was just coming home after work. it stalled when i took my foot off the throttle, i restarted it, drove it slowly home (and it ran rough all the way), went out after, restarted it, and it ran perfect till today. i also noticed, today, that when it began running rough, and missing, the motor seemed to be a little more noisy than normal.
after i changed the filter, i left the filter cover loose, and cranked the motor, and there was all kinds of diesel spraying out , so i felt that my lift pump was ok. does this maybe have something to do with my injectors? where should i start? like i said before, now the truck runs perfect. thx
 

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probobly wouldn't help, but advancing the timing might clean that up
 

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Sounds exactly like the problem that many '94&'95 engines have with warping delivery valve cylinders.
First time I've heard of it on other years.
If it progresses like mine did it will happen more and more, often separated by months of no problems.
I found it would never happen with the fuel tank on the full side. Ithink the additional fuel cooled the injection pump more.
What finally cured mine was a rebuilt injection pump.
 

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Discussion Starter #4
well, thats not really what i wanted to hear, but i do want to know what the problem is! i did have a full tank when this happened. that also made me wonder if i had picked up some bad fuel. is there any way to find out if it is the injection pump, before replacing it? thx
 

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You can pull the delivery valves one by one and look for scuffing on the valve or cylinder.
You will need a DV socket.
 

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I know this is an old thread but did you figure out what the problem was. I have a 94 with the same symptoms. I'm thinking maybe warped delivery valves? I just don't want to pull the pump off unless I'm sure that the problem. Thanks.


Sent from AutoGuide.com Free App
 

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I know this is an old thread but did you figure out what the problem was. I have a 94 with the same symptoms. I'm thinking maybe warped delivery valves? I just don't want to pull the pump off unless I'm sure that the problem. Thanks.
During your search did you happen to read about pouring cold water or icing the pump when the engine starts running badly? (If it is missing call the police). If the engine smooths out, the pump is bad.
 
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