Need help in diagnosing why my engine is cutting out

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rashenup

Active member
Apr 20, 2004
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I have a '95 Disco (ie 3.9) and ran into some serious issues with the engine cutting out this past weekend. The first couple times happened when I was crusing along (not accelerating) on the highway at ~60mph. With no warning the engine stumbled and died. My first reaction was to pump the accelerator to see if the engine was still running, but there was no reaction at all to this. After ~5secs the egine came back to life as I was starting to pull off onto the shoulder. This happened once more before I got to the next exit. Then the same beahvior happened again when I was crusing along on a side street at ~35mph and again after ~5secs the engine came back to life and it was fine for the remainder of my drive back home (all on surface streets).
I had noticed the last couple times out that the engine would stumble once or twice but never had completely died before.

From searching the archives I came across a few instances that seemed to be similar but not exactly the same and without a resolution so I'm not compeltely sure I'm seeing the same problem. From what I can surmise the likely culprits are the VSS, TPS, or MAF. Do the symptoms I'm seeing line up with any of these parts that could be failing?
 
MontrealRR90

MontrealRR90

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May 21, 2004
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rashenup said:
I have a '95 Disco (ie 3.9) and ran into some serious issues with the engine cutting out this past weekend. The first couple times happened when I was crusing along (not accelerating) on the highway at ~60mph. With no warning the engine stumbled and died. My first reaction was to pump the accelerator to see if the engine was still running, but there was no reaction at all to this. After ~5secs the egine came back to life as I was starting to pull off onto the shoulder. This happened once more before I got to the next exit. Then the same beahvior happened again when I was crusing along on a side street at ~35mph and again after ~5secs the engine came back to life and it was fine for the remainder of my drive back home (all on surface streets).
I had noticed the last couple times out that the engine would stumble once or twice but never had completely died before.

From searching the archives I came across a few instances that seemed to be similar but not exactly the same and without a resolution so I'm not compeltely sure I'm seeing the same problem. From what I can surmise the likely culprits are the VSS, TPS, or MAF. Do the symptoms I'm seeing line up with any of these parts that could be failing?
Click to expand...

crank sensor ?
 
Robbie

Robbie

Well-known member
Apr 20, 2004
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x2 on fuel pump. mine had a bad connection at the pump where it would slightly lose contact while driving and do the same thing. before i discovered this, it would go days with no symptoms and then other days it wouldn't let me even get out of my neighborhood. stranded me on my way to MAR a few years ago. after diagnosing and going through a bunch of tests that all checked out, noticed the loose connection, zip tied it in place and hasn't happened again in 2+ years.
 
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lrcb40

Guest
PT - I had similar symptoms on my 95 RRC when the amplifier pack for the dizzy was on the way out. It finally cut out (on my teenage son) in the middle lane on eastbound I94 between a bunch of 18 wheelers - I'm still trying to get the stain out of the seat leather......simple job to fix too.
 
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rashenup

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Apr 20, 2004
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One of my first thoughts was the fuel pump as well, but it was replaced ~3 years ago, so while I'm not completely ruling it out as the cuplrit, it's not the first place I'm going to look.

And PT you're correct, this doesn't seem to be heating related at all. When it cut out on the highway the truck had been running <5 mins and it was only ~50 degrees out. Not enought time to get up to full temp. Also when I had to make a quick run out to the grocery store for dinner tonight it cut out on me again almost right away (in the first 2 mins). It did start right back up after this without any drama.

I put the order in for the VSS today so I should have that to swap out soon enough and know.
 
ptschram

ptschram

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Sep 27, 2004
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rashenup said:
One of my first thoughts was the fuel pump as well, but it was replaced ~3 years ago, so while I'm not completely ruling it out as the cuplrit, it's not the first place I'm going to look.

And PT you're correct, this doesn't seem to be heating related at all. When it cut out on the highway the truck had been running <5 mins and it was only ~50 degrees out. Not enought time to get up to full temp. Also when I had to make a quick run out to the grocery store for dinner tonight it cut out on me again almost right away (in the first 2 mins). It did start right back up after this without any drama.

I put the order in for the VSS today so I should have that to swap out soon enough and know.
Click to expand...


OK, now you've added some more info that leads me in another direction. It could well be the ignition amplifier given what you just described.

To try to clear it up further, has it ever quit when the vehicle was stationary, or has it always been when the vehicle was under way?

I'll apologize now for jumping to the VSS, but given the initial info, it sure looked as though that was the culprit.
 
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lrcb40

Guest
ptschram said:
OK, now you've added some more info that leads me in another direction. It could well be the ignition amplifier given what you just described.

To try to clear it up further, has it ever quit when the vehicle was stationary, or has it always been when the vehicle was under way?

I'll apologize now for jumping to the VSS, but given the initial info, it sure looked as though that was the culprit.
Click to expand...

Woohoo! I bested PT! Check in the mail, PT?:rofl:
 
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rashenup

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Apr 20, 2004
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ptschram said:
To try to clear it up further, has it ever quit when the vehicle was stationary, or has it always been when the vehicle was under way?
Click to expand...

It's never quit on me when stopped, but this has only started happening in the last week and I've had the truck out once since the initial trouble. So not a lot of samples to go on.

How would I go about checking the ignition amp to see if that's the culprit?

No worries about jumping on the VSS idea PT. It's not that expensive of a part and easy enough to change out. From what I've been able to pickup it certainly looked like a good culprit (and who knows it may still be the issue). Even if it's not the cause of the issue here with how often they do fail it certainly won't hurt to replace it as preventative work :)
 
MontrealRR90

MontrealRR90

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May 21, 2004
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Montreal,Canada
Robbie said:
x2 on fuel pump. mine had a bad connection at the pump where it would slightly lose contact while driving and do the same thing. before i discovered this, it would go days with no symptoms and then other days it wouldn't let me even get out of my neighborhood. stranded me on my way to MAR a few years ago. after diagnosing and going through a bunch of tests that all checked out, noticed the loose connection, zip tied it in place and hasn't happened again in 2+ years.
Click to expand...

i have the same problem has we speak.Its only when i try to give a little more gas than usual. It cuts out when i accelerate hard. Checked the connection to the fuel pump and it was just a little llose and was not getting the full voltage when accelrating hard.Its good now after fixing the connection. I imagine that if i let the problem go it would eventually just stall.
 
Gig'em Ags

Gig'em Ags

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Jun 20, 2008
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DeLand, FL
I had a similar, but not identical issue, with my 97 DI and after replacing the plugs and wires, it was fixed. Of course, I also had a few codes showing misfires too, but I'm sure you would have mentioned that.
 
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rashenup

Active member
Apr 20, 2004
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Thanks for all the suggestions guys! I'll have to play around with the truck this weekend when I have some time when it's still light out.
Yup, no codes are being thrown when this happens so no clues from that. I also replaced the wires, cap, and rotor earlier this spring so I'll certianly check that they're all still seated properly but the parts themselves should be just fine.
The fuel pump was replaced ~3 years ago, so while this could be an issue it wouldn't be my first place to look.
 
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