Stumbling during acceleration and load - Defender Source
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  #1  
Old June 12th, 2006, 09:13 AM
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Greg
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Stumbling during acceleration and load

Hopefully this is simple problem (if there ever was one). I would like to see if I can fix this myself before taking it to the shop to have them tell me "This wire is corroded" and charge me $175.

Anyway, I have a 95 D90, 3.9L, 5 speed with 87k. About a month ago, I replaced the plugs, wires, distributor cap, rotor arm, and injectors. The truck was running perfectly. This past weekend was spent in the woods, doing a little bit of rock climbing on some intermediate trails.

On the way home from the camp site I noticed that when I accelerate or go up a hill (even a small one) the vehicle seems to "stumble". It happens in every gear, and then engine sounds fine when idling or rev'ing. I wouldn't say that it is a surge, more like a "gap" in the power.

Any ideas?

Thanks,

Greg.
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  #2  
Old June 12th, 2006, 09:36 AM
Andrew Vick
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What type of cap and rotor?
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  #3  
Old June 12th, 2006, 10:03 AM
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Greg
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Quote:
Originally Posted by Andrew Vick
What type of cap and rotor?
Lucas cap and rotor from Atlantic British.
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  #4  
Old June 12th, 2006, 10:13 AM
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Bryan Tate
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I had a similar problem it was the Throttle Positioning sensor (used $40) it is on the front side of the area where the throttle attaches to the motor

Your description was a little different than my problem, but it is something to consider before hauling it in for service

To clarify....I found at a certain RPM range it would jump or feel like there was a fuel shortage.
If I changed gears and got to a new throttle position it would be fine.
Its easy to test also, take it off with and hook up a circuit tester.
Turn the lever and the needle should smoothly go up and down.
If broken it skips a spot and the needle jumps around.

The sensor tells the computer what the throttle is doing
Hope this helps.....
Bryan
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  #5  
Old June 12th, 2006, 10:54 AM
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Greg
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Bryan,

This seems to happen at all RPMs as long as the engine is under a load, whether it be acceleration or climbing.

I will check the throttle position sensor tonight though.

Thanks for the help,

Greg.
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  #6  
Old June 13th, 2006, 09:30 AM
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Greg
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Fuel?

OK, so I think it is a problem with the fuel system.

I do recall hearing a rather loud thud as I was riding over some rocks on the trail. I stopped to check out the underside because I could smell fuel. I saw that fuel had made its way out of the vent tube that comes off the fuel filler neck.

I think I smacked the fuel tank on a rock which caused the fuel to get pushed out the vent tube. Could this also have damaged the fuel filter or fuel pump which is causing the "stumbling"?
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  #7  
Old June 13th, 2006, 11:49 AM
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Dave Souza
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Try your fuel filter. Inexpensive item to replace, and if you're never changed it, its probably due. Perhaps you stirred up some crap in the tank that is now trapped in the filter and reducing the flow of fuel.

I've never had thishappen on my 90, but I've had that exact symptom on a previous Honda, and it was the fuel filter. Highway load it'd bog down, but idled and revved fine in neutral.
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Old June 13th, 2006, 08:48 PM
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Greg. Did you physically damage the tank? Or did it hit just the skid plate? If you bonked the truck right, it may have just splashed up the vent line, and not damaged anything. But IIRC they are poly tanks, not steel, so it is possible that if you DID physically hit the tank itself, that it may have cracked something in the pump assembly, but the tank can pop back into shape.

But that is just a worst case thought. Like Dave, i'd more be worried about old sediment getting stirred up and clogging the filter. Or possibly something else getting dislodged externally.

Also. Was the wheeling done at a significantly different altitude than at home? Might also be the engine re-tuning itself for the different air density, and getting confused. Perhaps disconnecting the battery for a couple minutes, letting the computer reset to original, and letting it go through the whole re-learning process may help. If you do that, just remember that it will idle wierd for a few days while it re-learns the truck specifics.

-Hans
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  #9  
Old June 14th, 2006, 08:02 AM
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Greg
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Quote:
Originally Posted by Hans
Did you physically damage the tank?

Was the wheeling done at a significantly different altitude than at home?

-Hans
Hans,

I checked out the skid plate last night and it looks to be fine, no dents. I will be changing the fuel filter this weekend, so hopefully that will "get her done". We were at the same altitude for the off-roading, so I don't think altitude is the culprit.

I did notice that black box located in the rear passenger side wheel well (assuming it is a vapor seperator or something) has a broken connection so I will need to replace that I guess. That seems like a bad spot to put a piece of equipment, IN the wheel well?

Thanks for all the help.

Greg.
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