1994 problems
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1994 problems
So I'm new to the diesels but own numerous other Ford gassers. The current trouble maker is a 1994 f350 zf5 with 170k on it. The problem started driving back home when I got the truck. I'm going to give as much detail as possible.
When I'm driving sometimes the rpms drop and if I press the clutch the truck dies. If I don't press the clutch the rpms go back up to normal sometimes.
Other times it might just die at a red light, die turning a corner, die coming to a stop. All those times it's when the clutch is pressed in.
Now when it dies it might start up right away other times it has to sit for 10-20 mins then it starts again.
It always restarts just depends on how long I have to sit.
It doesn't matter how long I drive it ranges from 5-30 mins.
I really hope someone has had a problem like this and can help because it's been 3 months now and I am lost on where to look on a diesel.
Thanks Adam
When I'm driving sometimes the rpms drop and if I press the clutch the truck dies. If I don't press the clutch the rpms go back up to normal sometimes.
Other times it might just die at a red light, die turning a corner, die coming to a stop. All those times it's when the clutch is pressed in.
Now when it dies it might start up right away other times it has to sit for 10-20 mins then it starts again.
It always restarts just depends on how long I have to sit.
It doesn't matter how long I drive it ranges from 5-30 mins.
I really hope someone has had a problem like this and can help because it's been 3 months now and I am lost on where to look on a diesel.
Thanks Adam
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
No surprise about it returning to normal if you keep the clutch engaged. That's just the movement of the truck restarting the engine.
Are you sure the truck is a PSD? There were three diesel engines offered in '94. If it's a PSD, the most likely suspect is the CPS - cam position sensor. It provides the pulse to the PCM to tell it when to send the signal to the IDM to fire the injectors. It also provides the signal to the tach. So if the tach drops to zero even while the truck's movement is turning the engine, that fingers the CPS.
Oh, one other thing to check - when it restarts on its own by leaving the clutch engaged, does the WTS light come on? If so, then it sounds more like an interruption in the PCM power, as if you turned the key off and back on briefly.
Are you sure the truck is a PSD? There were three diesel engines offered in '94. If it's a PSD, the most likely suspect is the CPS - cam position sensor. It provides the pulse to the PCM to tell it when to send the signal to the IDM to fire the injectors. It also provides the signal to the tach. So if the tach drops to zero even while the truck's movement is turning the engine, that fingers the CPS.
Oh, one other thing to check - when it restarts on its own by leaving the clutch engaged, does the WTS light come on? If so, then it sounds more like an interruption in the PCM power, as if you turned the key off and back on briefly.
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Joined: Oct 2013
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No surprise about it returning to normal if you keep the clutch engaged. That's just the movement of the truck restarting the engine.
Are you sure the truck is a PSD? There were three diesel engines offered in '94. If it's a PSD, the most likely suspect is the CPS - cam position sensor. It provides the pulse to the PCM to tell it when to send the signal to the IDM to fire the injectors. It also provides the signal to the tach. So if the tach drops to zero even while the truck's movement is turning the engine, that fingers the CPS.
Oh, one other thing to check - when it restarts on its own by leaving the clutch engaged, does the WTS light come on? If so, then it sounds more like an interruption in the PCM power, as if you turned the key off and back on briefly.
Are you sure the truck is a PSD? There were three diesel engines offered in '94. If it's a PSD, the most likely suspect is the CPS - cam position sensor. It provides the pulse to the PCM to tell it when to send the signal to the IDM to fire the injectors. It also provides the signal to the tach. So if the tach drops to zero even while the truck's movement is turning the engine, that fingers the CPS.
Oh, one other thing to check - when it restarts on its own by leaving the clutch engaged, does the WTS light come on? If so, then it sounds more like an interruption in the PCM power, as if you turned the key off and back on briefly.
No lights ever come on to indicate any problem.
The rpms dont goto 0 when I'm rolling in gear.
Hotshot
Joined: Oct 2003
Posts: 17,791
Likes: 99
From: Ashland City, TN
The truck needs a minimum of 30psi of fuel pressure to run, 45 to run okay. 65ish makes it run good.
If you're low on oil, it will also give you some of these issues.
The problem is most likely the CPS though.
When it stalls out and you crank, does the tach move?
If it doesn't move, then that is definitely your issue.
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New User
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Your either low on oil, fuel pressure or you're having issues with the CPS.
The truck needs a minimum of 30psi of fuel pressure to run, 45 to run okay. 65ish makes it run good.
If you're low on oil, it will also give you some of these issues.
The problem is most likely the CPS though.
When it stalls out and you crank, does the tach move?
If it doesn't move, then that is definitely your issue.
The tach moves.
I also should have said the previous owner of 3 years barely drove the truck.
If the tach keeps working then more than likely it's the fuel pump?
Senior User
Joined: Oct 2009
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Maybe something is wrong with your clutch safety switch if it only happens when you depress the clutch. Do you have cruise control?
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Lead Driver
Joined: Oct 2003
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From: Madison, WI
Clutch safety switch is for the STARTER. The only reason the engine stalls with the clutch is that the truck's movement is no longer turning the engine through the transmission. It's the way manual transmissions have worked for, oh, 90 years?
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Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
That's a separate switch (all built into one part). It wouldn't have anything to do with the engine failing when the OP doesn't press the clutch.
If the tach doesn't drop to zero, that doesn't rule out the CPS, but it's less of a suspect. Could indeed be something related to injection pressure. You'd just about have to hook up a laptop with AE and run it in log mode while driving down the street and log what happens with ICP, IPR cycle %, RPM, etc. when it happens.
If the tach doesn't drop to zero, that doesn't rule out the CPS, but it's less of a suspect. Could indeed be something related to injection pressure. You'd just about have to hook up a laptop with AE and run it in log mode while driving down the street and log what happens with ICP, IPR cycle %, RPM, etc. when it happens.
Hotshot
Joined: Feb 2009
Posts: 10,408
Likes: 75
From: Plankinton, SD
I'd do a couple cheap things first. I'd try a new ford or IH cam sensor, they are only 25 bucks, and you need a spare to put in the glove box anyway. Then if no success, I'd pull the ipr and check the orings on it.
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The one I have in the cart is motorcraft. They have other brands one is even more than the motorcraft. Check them out they smash the part stores on price. An example wagner front pads for that truck same part number 89 from advanced 29 from rockauto.