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1994 Chevy K3500 6.5 diesel 4x4

R

retired09

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rving across U.S.A.
truck runs fine when not hooked to camper. when hooked to camper, loosing power and transmission doesnt wont to shift into high gear. Pull camper in Drive. Steady flow of fuel at tee bleeder valve with motor running so lift pump is running can hear it. Changed PMD 2 weeks ago and remote mounted it with cooler plate. Have several diagnostic codes. 15- engine coolant temp. sensor, 18- pump cam reference pulse error, 35- injection pulse width error ( response time short), 49- service throttle soon lamp circuit fault, 78-turbo wastegate solenoid fault, 85- undefined ratio ( trans. related), 87- high ratio (trans. related). Could someone tell me what parts I need to buy to fix truck other than coolant temp. sensor. Am rving across U.S.A. and need help very bad. Thanks...
 
Did you clear all codes after new new PMD install????? With that many codes I would start with
1 clean all grounds
2 check all heavy cable connections
3 load test batteries
4 test alternator
then keep us posted.................
 
clear the codes and see what comes back. Can clear them with a reader/scanner or the manual way with the pedals.

What size tires are on the truck? pulling in 2WD?
 
buddy said:
clear the codes and see what comes back. Can clear them with a reader/scanner or the manual way with the pedals.

What size tires are on the truck? pulling in 2WD?
Click to expand...

Cleared all codes and drove truck. Checked codes again and same codes pop up. Cleaned all grounds and have new batterys. Alternator charging 14 volts plus. Someone said that oil pressure switch may be bad cause it runs lift pump also. While checking codes could hear lift pump running. Same guy said wastegate solenoid could be bad. Checked vacuum on actuator and has right vacuum pressure. Cant move rod while truck is running but can when engine off. Have Lt225/75R16 tires all around about 7000 miles on them.
 
625fireman said:
Did you clear all codes after new new PMD install????? With that many codes I would start with
1 clean all grounds
2 check all heavy cable connections
3 load test batteries
4 test alternator
then keep us posted.................
Click to expand...

did all of the above. Batterys almost new. Can hear lift pump running after clearing codes and driving truck again. Have almost new tires all LT225/75R16 and pull camper in Drive not overdrive and in 2wheel drive not 4wheel drive. Could oil pressure switch be going bad cause it runs lift pump too and doesnt get enough fuel to truck under heavy pull load and makes injection pump run truck without lift pumps help? Thanks...
 
Did this come on all of a sudden, during your current trip?

Just speculating here......the 18 and 35 code might show up with a bad load of fuel, goofing up the Optic sensor causing a cascade of other faults with tranny shift timing, etc.?

Another thought, it wouldnt be the first time someone installed new PMD, abandoning one on the pump, and didnt fish the resistor out of the old one, and put it in the new one mounted up front. Would that cause fuel delivery issues under load?
 
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Dont think resistor would cause any of this. Without it, ECM should default to "5" and it only looks for it about every 50 or so starts.
Could be bad lift pump. Just cause it is running doesnt mean it is pumping anything. Check pressure asap.
Hook gauge to t-handle with long enough hose you can tie it wiper arm to see inside while driving. Should not drop below 4-5 at any time. If it does replace asap, bad lift pumps will take out the injector pump.
Or like Yachtcare said could be a bad load of fuel........
Or could be a leak in the fuel supply line somewhere too.......
 
Good question, did this just happen, or did you just get the truck like this?

What are you using to check and clear codes? Truck must have been running while checking to hear the lift pump. If you have fuel pressure while its running then the OPS is at least passing voltage.

If you have vacuum to the wastegate, what did you measure it to be? This would say the wastegate solenoid is working, otherwise you wouldnt have vacuum at the actuator.

Is the Coolant Temp Sensor on the T-stat Crossover even plugged in? This would cause you to be full cold advanced all the time. Its probably coding because it never warms up, but IATs are higher and tranny temp is high.

Does the Service Throttle Soon light (top left of instrument panel) come on with just the ignition?

225/75/16 - is that what came with it stock or did you put them on? Seems like a short tire for a 1 ton. Do you notice your spedometer reads high and maybe seems like you get good fuel mileage according to odometer? The tranny codes could be from wrong tire size because it has more RPMs than what it should and speed to the speedo and PCM is not correct. It may not have given you an active SES light for these tranny codes even if it started 7000 miles ago.

The DTC 18 is causing the most of your problems though, this will put you into limp mode, and can be caused either by having a bad Optical Sensor in the Injection Pump, or is could be getting blinded by something, like air in the fuel, or if you try to use Used Motor oil as fuel, or some crazy fuel system cleaner/lubricator.
 
Have never seen service throttle light come on. Only light that comes on and stays on is service engine soon light on right side of instrument panel. It stays on until engine is turned off. No other lights come while driving down road. Tires on truck are what came on truck when bought. Replace with same size when changed all same brand, no mismatched. Could bad fuel filter cause some of these problems? Had truck serviced before left on trip 2 weeks ago. Oil change, greased, brakes checked, all tires properly inflated, all lights checked for proper working order, etc. Changed PMD 1 week ago in rv park. Remote mounted it with new chip installed, didnt use old chip out of old PMD. Put PMD on cooler plate bought separately and 6 foot extension on wiring harness for PMD. Another owner of diesel truck said could be oil pressure switch cause it runs lift pump. Truck runs fine without camper but looses power when pulling camper. Will check lift pump for pressure and see if it will pump on external hot wire instead of plugged into system. Thanks...
 
Where did the extension harness come from? Are all the wires in the extension harness black?
 
When did this problem start? If its in limp mode now and youre saying it runs alright with no camper then it may have been this way for a long time, or is the SES light always on a new thing?

There is a bulb check when you first turn on the ignition, should see a lot of stuff on the dash when you first turn IGN to on for like 10 seconds, and they then go out.

So STS light code may not be of any concern, its just not working.
 
retired09 said:
did all of the above. Batterys almost new. Can hear lift pump running after clearing codes and driving truck again. Have almost new tires all LT225/75R16 and pull camper in Drive not overdrive and in 2wheel drive not 4wheel drive. Could oil pressure switch be going bad cause it runs lift pump too and doesnt get enough fuel to truck under heavy pull load and makes injection pump run truck without lift pumps help? Thanks...
Click to expand...

I clogged sock in the tank could or a pinhole in the fuelline from LP to the tank somewhere if it's sucking air.. Maybe I missed it but is the truck blowing any excessive smoke ? Black ? Grey ? White ?
 
What state are you currrently in ? Maybe a member is close by ? If you plan on keeping your rig for awhile a very good investment would be GMTDScan. It is the ONLY thing that works well with 6.5TD OBD1 besides GM scanner.
www.enghmotors.com
You may want to try sightglassing it. I have found that as a cheap easy way to find problems in the fuel system although I realize your mobile so not sure excactly what you have access to. You can take about 2-3 ft of clear 1/4 tubing(hardware store, tractor supply, plumbing supply home depot etc) and disconnect the fuel line right at the IP and splice the clear in with a union then put the line in a pail or cup and run the LP(this is easy to do on OBD1. Instructions are in the stickies of which pin on the ALDL connector to put power to) then purge the new clear line and connect to the IP. Run the truck high idle 1800+RPMs for about 30 secs and then let it idle and wahtch the fuel in the clear tubing. You can also rev the truck up a little. If you see ANY air bubbles you have a leak on the influent side of the LP(Between the LP and fuel source ie:tank). ANY air in thse trucks will play havoc and drive you nuts. If you have no air and steady FP then we need to look at other things even possibly a failing IP. The WG code is most likley a broken wire or bad soleniod.
 
Was it a new pmd or a used pmd? Did you leave the ground on the pump or did you bring the ground down to the remoted heatsink? Also on the 94 there is a resistor in the harness next to the optic sensor on the pump. Might want to take that resistor out and see how it runs. Where did you get your pmd and harness? Can you rev the engine up to 2000 rpms and hold it there?

I would also do what Acesneights in getting the clear hose and check for air in the system. Does your cruise control work?

Did you say you put in a new fuel filter?
 
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