tvguy
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- Duluth, GA
First I’ll say I’m no diesel mechanic but I’ve done a LOT of searching both in the forum and the TM’s. After many months of trying I need a little help . . .
SYMPTOMS
About 7 or 8 months ago my truck (an ’86 M1031) became hard to start. I’d have to crank it for 30 – 45 seconds before it would finally “hit”. It would idle up really high then die and plume white smoke. After two or three of these cycles it would finally start, but only if I held the accelerator pedal to keep the idle up. When driving if I suddenly let off of the pedal it would die. Once heated up though it would easily restart. I verified that my glow plugs were working by checking voltage at the plug and I can hear the relay clicking on and off.
Attempt #1, fuel filter
So after a great deal of searching it seemed the fuel filter base was the most likely culprit. I switched to a Racor spin-on filter and bled the system using the pump on the filter and by removing the pink wire on the injection pump and cracking.
RESULT = no change
Attempt #2, fuel / lift pump and rubber lines
At idle, the truck surges. I read that this was indicative of air being sucked into the fuel lines so I changed all the rubber lines in the engine compartment along with the fuel pump. I finished this yesterday (4/27/15) and decided to re-bleed the system to see if this had fixed it before doing the rear lines as the bed will have to be lifted or removed.
Result = no change, although now I notice a hesitation in the throttle sometimes.
I sprayed starting fluid around the rear, rubber lines while it was running to see if any fluid would get sucked in and raise the idle. It did not but I still plan to replace all the rubber lines from the tank. In the meantime I noticed the fast idle solenoid wasn’t working which, in my mind at least, accounted for me having to stay on the accelerator pedal.
Attempt #3, coolant sensors
Since I knew the fast idle solenoid wasn’t working I decided to try and get it operational before moving on to the more difficult job of replacing the fuel tank rubber lines. With a multimeter I checked and had no voltage at the solenoid, nor did I have voltage, even when cranking, at the temperature sensor on the passenger side front head. Just for kicks and went ahead and replaced both of the temp sensors.
Result = no change
QUESTIONS?
Does anyone know what feeds the temp sensor / fast idle circuit? In other words, if I’m not getting voltage at the temp sensor where would be the next point in the chain to check for voltage.
So, it seems I have a couple of issues going on simultaneously. I know the fast idle solenoid isn’t necessary for the engine to run but I want to get it fixed regardless. Meanwhile it’s still hard to start and the idle is rough (surging). Any suggestions on a next step would be greatly appreciated! I'm thinking the next step might be to replace the injection pump but wanted to exhaust any other options before trying that.
SYMPTOMS
About 7 or 8 months ago my truck (an ’86 M1031) became hard to start. I’d have to crank it for 30 – 45 seconds before it would finally “hit”. It would idle up really high then die and plume white smoke. After two or three of these cycles it would finally start, but only if I held the accelerator pedal to keep the idle up. When driving if I suddenly let off of the pedal it would die. Once heated up though it would easily restart. I verified that my glow plugs were working by checking voltage at the plug and I can hear the relay clicking on and off.
Attempt #1, fuel filter
So after a great deal of searching it seemed the fuel filter base was the most likely culprit. I switched to a Racor spin-on filter and bled the system using the pump on the filter and by removing the pink wire on the injection pump and cracking.
RESULT = no change
Attempt #2, fuel / lift pump and rubber lines
At idle, the truck surges. I read that this was indicative of air being sucked into the fuel lines so I changed all the rubber lines in the engine compartment along with the fuel pump. I finished this yesterday (4/27/15) and decided to re-bleed the system to see if this had fixed it before doing the rear lines as the bed will have to be lifted or removed.
Result = no change, although now I notice a hesitation in the throttle sometimes.
I sprayed starting fluid around the rear, rubber lines while it was running to see if any fluid would get sucked in and raise the idle. It did not but I still plan to replace all the rubber lines from the tank. In the meantime I noticed the fast idle solenoid wasn’t working which, in my mind at least, accounted for me having to stay on the accelerator pedal.
Attempt #3, coolant sensors
Since I knew the fast idle solenoid wasn’t working I decided to try and get it operational before moving on to the more difficult job of replacing the fuel tank rubber lines. With a multimeter I checked and had no voltage at the solenoid, nor did I have voltage, even when cranking, at the temperature sensor on the passenger side front head. Just for kicks and went ahead and replaced both of the temp sensors.
Result = no change
QUESTIONS?
Does anyone know what feeds the temp sensor / fast idle circuit? In other words, if I’m not getting voltage at the temp sensor where would be the next point in the chain to check for voltage.
So, it seems I have a couple of issues going on simultaneously. I know the fast idle solenoid isn’t necessary for the engine to run but I want to get it fixed regardless. Meanwhile it’s still hard to start and the idle is rough (surging). Any suggestions on a next step would be greatly appreciated! I'm thinking the next step might be to replace the injection pump but wanted to exhaust any other options before trying that.
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