1995 ram 3.9L hesitation

While looking for the cause of my 1995 dodge ram van 3.9liter vans
hesitation I checked the throttle position sensor.The voltage is supposed to
vary between about 1/2 to 5 volts depending on throttle position but at wide
open throttle I'm getting 0.2 volts DC.Supply voltage is at 5 volts and I
replaced the part with a new one that also reads 0.2 volts max(wide open
throttle) Symptoms are slugging, hesitation, bucking,mild back-firing
similar to a vehicle running out of gas.Seems worse when in closed loop
warmed up operation.Stumbles up inclines, seems ok first few minutes of
operation.The fuel pump assembly has been replaced,the computer has been
replaced also,along with the usual plugs,wires,hall-effect sensor,a
substitute coil also.No codes are showing up with a diagnostic matco
tester.Anyone hazard a guess?

scott and barb wrote:

>While looking for the cause of my 1995 dodge ram van 3.9liter vans
>hesitation I checked the throttle position sensor.The voltage is supposed to
>vary between about 1/2 to 5 volts depending on throttle position but at wide
>open throttle I'm getting 0.2 volts DC.Supply voltage is at 5 volts and I
>replaced the part with a new one that also reads 0.2 volts max(wide open
>throttle) Symptoms are slugging, hesitation, bucking,mild back-firing
>similar to a vehicle running out of gas.Seems worse when in closed loop
>warmed up operation.Stumbles up inclines, seems ok first few minutes of
>operation.The fuel pump assembly has been replaced,the computer has been
>replaced also,along with the usual plugs,wires,hall-effect sensor,a
>substitute coil also.No codes are showing up with a diagnostic matco
>tester.Anyone hazard a guess?
>
>
>
>
These engines have two common problems--the first problem is a faulty
timing chain. The second problem deals with the oil pump (and
distributor) drive bushing. This bushing is located under the drive
gear in the block. It has a tendancy to wear out and cause drivability
problems much as the ones you describe. With the van it is very simple
to remove the distributor to check to see if the drive gear has too much
'play'. Of course mark the dist well before removal. These dist.
should be re-synched upon installation.

If it is the bushing there are a couple of tools available from SPX
Miller designed to remove the old bushing and to install and burnish the
new bushing without further dissassembly. Note also that this
distributor MUST be installed correctly. The 3.9 is an odd fire engine,
therefore the old trick of moving spark plug wires around the cap of an
incorrectly indexed distributor will also lead to drivability issues.

I currently have a van in the shop that behaved much as you are
describing. I did find excessive runout on the drive, and the dist. was
installed incorrectly. I had to replace the oil pump drive gear as well
because the misalignment from the worn bushing created some very sharp
and very thin teeth on the gear. The cam gear appeared fine however.

After replacement of the bushing and gear, then correctly indexing the
dist. lead to a van that runs quite nice (It's still in the shop waiting
for a new left exhaust manifold. Talk about a pricey hunk of cast iron).

Hope this helps:

Loren

I replaced the timing chain already.The distributor shaft seems tight, doubt
it (distributor)was ever out of the engine.Are the bushings down in the
block then, and how difficult is it to replace them? Another question, is it
normal to have a max of .2 volts on the center pin of the TPS?
"Loren McPherson" > wrote in message
...
>
>
> scott and barb wrote:
>
> >While looking for the cause of my 1995 dodge ram van 3.9liter vans
> >hesitation I checked the throttle position sensor.The voltage is supposed
to
> >vary between about 1/2 to 5 volts depending on throttle position but at
wide
> >open throttle I'm getting 0.2 volts DC.Supply voltage is at 5 volts and I
> >replaced the part with a new one that also reads 0.2 volts max(wide open
> >throttle) Symptoms are slugging, hesitation, bucking,mild back-firing
> >similar to a vehicle running out of gas.Seems worse when in closed loop
> >warmed up operation.Stumbles up inclines, seems ok first few minutes of
> >operation.The fuel pump assembly has been replaced,the computer has been
> >replaced also,along with the usual plugs,wires,hall-effect sensor,a
> >substitute coil also.No codes are showing up with a diagnostic matco
> >tester.Anyone hazard a guess?
> >
> >
> >
> >
> These engines have two common problems--the first problem is a faulty
> timing chain. The second problem deals with the oil pump (and
> distributor) drive bushing. This bushing is located under the drive
> gear in the block. It has a tendancy to wear out and cause drivability
> problems much as the ones you describe. With the van it is very simple
> to remove the distributor to check to see if the drive gear has too much
> 'play'. Of course mark the dist well before removal. These dist.
> should be re-synched upon installation.
>
> If it is the bushing there are a couple of tools available from SPX
> Miller designed to remove the old bushing and to install and burnish the
> new bushing without further dissassembly. Note also that this
> distributor MUST be installed correctly. The 3.9 is an odd fire engine,
> therefore the old trick of moving spark plug wires around the cap of an
> incorrectly indexed distributor will also lead to drivability issues.
>
> I currently have a van in the shop that behaved much as you are
> describing. I did find excessive runout on the drive, and the dist. was
> installed incorrectly. I had to replace the oil pump drive gear as well
> because the misalignment from the worn bushing created some very sharp
> and very thin teeth on the gear. The cam gear appeared fine however.
>
> After replacement of the bushing and gear, then correctly indexing the
> dist. lead to a van that runs quite nice (It's still in the shop waiting
> for a new left exhaust manifold. Talk about a pricey hunk of cast iron).
>
> Hope this helps:
>
> Loren
>