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Wayne
Wayne, Journeyman
Category: Medium and Heavy Trucks
Satisfied Customers: 8426
Experience:  worked on, Gmc, Macks, Freight liner,Mercedes Benz,,Ford, sterling
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I have a 1999 Freightliner RV with Cummins 5.9. I have had

Customer Question

I have a 1999 Freightliner RV with Cummins 5.9. I have had a problem with algea in the fuel. I had changed fuel filters so I could drive it about 65 miles from where I had stored it about 6 months with 20 gallons of fuel in a 100 gal tank. Condensation occurred and algea grew and stopped up the filter. I have treated the fuel with Bio Klean and added some fresh fuel. I have again, replaced both primary and secondary filters. Presently, when I start it, it will try to idle and the RPM's will drop from 800 to 0 about 10 times at rate of once per second. The throttle is dead, no response. This occurs in the parked mode. I can put it in Drive or Reverse, and the idle will smooth right out, steady, but I still have a dead throttle. I have actually moved it around in D or R at idle with no throttle response. Help, Please
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Curtis B. replied 1 year ago.
Have you checked the fuel suction in the tank? With algae in the tank, the screen can be plugged.
Expert:  Curtis B. replied 1 year ago.
Where is the fule pump, in the tank?
Expert:  Curtis B. replied 1 year ago.
If you have external fule oump, you could try fuel test line from the pump inlet, into a fuel container.
Customer: replied 1 year ago.
The fuel pump is on the side of the engine and I have replaced it with 100 gallons per hour pump. Every time I check the secondary fuel filter it's full of fuel so I don't think I'm having a fuel starve problem. When I put it in drive the engine idles just fine but I still have a dead throttle. If the pick up tube was blocked it wouldn't idle smooth or fill up the second filter.
Expert:  Curtis B. replied 1 year ago.
Let me opt out and see if someone else can help. sorry.
Expert:  Wayne replied 1 year ago.
Hi I'm Wayne
I will help you with this
I see Curtis opt-out
Your issue seems to be the throttle position sensor,(TPS)
it is located on the floor on the pedal
has 3-4 wires to it, unplug it and clean the terminals
they may just be corroded, from storage
If this helped you, Please rate my answer
3 or more stars
If not, please reply for more info
Thank you
Customer: replied 1 year ago.
Well I took it off earlier and was going to test the resistance but could not find info to do it so I reinstalled it There was no corrosion and the connectors are inside. This wouldn't make the idle act different in nuetral and drive would it? Is the computer in limp mode?
Expert:  Wayne replied 1 year ago.
Thank you for that
to check resistance , set your oHM meter to OHMS,
probe each terminal ,move the pedal, this should change if it is good
Limp mode, yes very well can be,
but you would have to hook up a lap top to clear that
with cummins software /insite
Wayne
Customer: replied 1 year ago.
My RV is 70 miles away from Nashville TN and I can't drive it anywhere. That is why I contacted Just Answer.
Expert:  Wayne replied 1 year ago.
Hi Thank you for that
We can only suggest issues,
I am not there , to see problem,Please understand this
you are the eyes and ears for us, again we can not see hear the engine
Like I suggested , you need to hook up to Cummins insite,
did you check the resistance in the TPS
what was it
Wayne
Customer: replied 1 year ago.
No, I am not at home until Firday. There are about 4-5 wires going into it. I couldn't find a pin out on the Internet. Most Cummins 5.9 stuff is on Dodge trucks. Different throttle switch. I thought you folks would recognize the idle behavior in park vs drive.
Expert:  Wayne replied 1 year ago.
Morning
Check the hot wire in the harness, should be 5+ volts
Remove the multimeter probe from the
accelerator pedal/lever position +5 volt
supply test connector wire and connect it
to the accelerator pedal/lever position
signal test connector wire.
When the accelerator pedal is in the
released (idle) position, measure the
resistance. The multimeter must show
between 1500 and 3000 ohms
Customer: replied 1 year ago.
Great, I will do this Friday when I get back home. Thanks
Expert:  Wayne replied 1 year ago.
Ok, Thank you
Customer: replied 1 year ago.
This sensor has 6 wires on it in 2 different plugs. The 1st plug has a red, black, & white wire. Red is the 5 volts, white is ground & the black is variable. Between black and white I get 100 ohms at ide position and 2900 at wide open throttle. The resistance climbs steadily as the TPS is turned. The other plug has orange, blue & green wires. At idle, the blue & orange show continuity and the green and orange do not. When the pedal is depressed, it is opposite: green and orange are connected & blue and orange are not. The measurement on this wires is on or off, no variable resistance... ??? I guess this TPS shows as good?
Expert:  Wayne replied 1 year ago.
Thank you for that
if it is not showing any
variable resistance, It is faulty
Wayne
Customer: replied 1 year ago.
It is showing variable from 100 to 2900 ohms...
Expert:  Wayne replied 1 year ago.
Hi Thank you for that You mentioned that it was not showing at different times, key on, any plug you should see that meter read
Customer: replied 1 year ago.
????
Expert:  Wayne replied 1 year ago.
Hi
I see we are not real see eye to eye
let me send this to you , this is for a 2 plug basic, system
it is same as you have
Expert:  Wayne replied 1 year ago.
If INSITE™ is available, monitor the
accelerator position sensor for proper
operation. If not, follow the
troubleshooting procedures in this
section.
Disconnect the 3-pin connector from the
accelerator position sensor.
Connect the test connector.
Connect the multimeter positive (+) test
lead to the accelerator pedal/lever
position +5 volt supply test connector
wire. Connect the negative (-) multimeter
test probe to the accelerator pedal/lever
position return test connector wire.
Measure the resistance. The multimeter
must show between 2000 and 3000
ohms when the accelerator pedal is
released (idle position) or depressed (full
-fuel position).
If the resistance is not within the
specification, the accelerator position
sensor has failed. Replace the
accelerator position sensor. Refer to the
OEM troubleshooting and repair manual
for the procedures.
Remove the multimeter probe from the
accelerator pedal/lever position +5 volt
supply test connector wire and connect it
to the accelerator pedal/lever position
signal test connector wire.
When the accelerator pedal is in the
released (idle) position, measure the
resistance. The multimeter must show
between 1500 and 3000 ohms
Expert:  Wayne replied 1 year ago.
Depress the accelerator pedal assembly
(full-fuel position) and measure the
resistance. The multimeter must show
between 250 and 1500 ohms. This
resistance value must be at least 1000
ohms lower than the resistance value of
1500 to 3000 ohms measured in the
above check. If the resistance values in
the two previous steps are not within the
specification, the accelerator position
sensor has failed. Replace the
accelerator position sensor according to
the vehicle manufacturer's procedures. If
the resistance values are within the
specifications, the accelerator position
sensor must still be checked for a short
circuit to ground.
Check for Short Circuit to Ground
Connect the multimeter positive (+) probe
to the accelerator pedal/lever position
return test connector wire. Touch the
negative (-) multimeter probe to the
chassis ground and measure the
resistance.
The multimeter must show an open
circuit (100k ohms or more)
Expert:  Wayne replied 1 year ago.
Hi
I hope this helps you ,
I still suggest to replace the TPS
Customer: replied 1 year ago.
Good info, I will process and check as soon as possible. Will be out of town next two days, Thanks.
Expert:  Wayne replied 1 year ago.
Morning
OK, Keep me posted
Wayne

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