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Not fuel or pmd but no start now

B

Bobburns

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I have a 1997 6.5 that started this morning and and stumbled and died. Now it is a no start. Fuel pressure is good - there is a liquid filled mechanical gauge at the IP inlet and it to 16 psi and holds. I swapped the pmd with a new one yesterday.

This started with fish biting and stumbling two days ago and longer cranking than usual. It got worse but threw no codes

I have an Ultragauge plugged in but it doesn't seem to light any longer.

So now it is crank and no start.

I can change the Pmd extension cable with a new one I will try later today

Do ECMs just die??

Any ideas what to check?? I will check the hot lead to the PMD in start and run also
 
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JMJNet said:
Load test (NOT voltage test) the batteries one at a time?

There is always a chance that the new PMD is bad.
Click to expand...
The new pmd drove and started this morning

The batteries are new not one year old. They are flooded agm and have 1300 CCA each

It cranks fast enough to meet the 200 rpm required to cause the DS4 to inject unless crankshaft position sensor is bad a d did not throw a code
 
Just FYI, in the process of troubleshooting, you need to test everything no matter how new or old the parts are.
Just to eliminate possibilities of simple things.

Some member posted that they replaced the IP and a lot of difficult parts only to find out that the battery is bad (just one of them).
He spent thousands of dollar.

It is up to you, you can start throwing part at it.
 
Also check voltage to the fuel shutoff solenoid and verify it's clicking when cycling the key on and off. if the solenoid failed electrically or the plunger is stuck inside, it can cause a no start. this will not set a code. connecting the clear fuel line to the IP return and seeing no fuel flowing will also indicate to the solenoid.
 
JMJNet said:
Just FYI, in the process of troubleshooting, you need to test everything no matter how new or old the parts are.
Just to eliminate possibilities of simple things.

Some member posted that they replaced the IP and a lot of difficult parts only to find out that the battery is bad (just one of them).
He spent thousands of dollar.

It is up to you, you can start throwing part at it.
Click to expand...
Yes I know and agree. I have a foxwell bt-100 battery tester and they are still putting that out. I also have four more internal batteries for the tool inverter which full charged adds 3900 CCA for 6500 CCA together. I also carry a small 1000 watt generator and 200 Amp starter / charger in case something happens and I run the batteries low

I found the problems it appears. The lift pump was sucking air from loose inlet fitting. Because there is a pressure plate type regulator in the line without steady fuel pressure, it shuts off the fuel intermittently. And when I swapped the pmd I must have damaged the pmd plug because now the hot lead only let's through. 02 to.. 15 volt which means I need to swap that cable with one of my two new spares and if that let's 12 volts to the PMD fingers crossed it should start

If not the CPS may be bad and that's a job I don't want to do
 
dbrannon79 said:
Also check voltage to the fuel shutoff solenoid and verify it's clicking when cycling the key on and off. if the solenoid failed electrically or the plunger is stuck inside, it can cause a no start. this will not set a code. connecting the clear fuel line to the IP return and seeing no fuel flowing will also indicate to the solenoid.
Click to expand...
It is van and it is hard to access the top of the ip

See my post at https://www.thetruckstop.us/forum/posts/635495/bookmark

I may have found the issues

Fixed one - taking a break and I will do the cable, put a top off charge on the batteries and give her a crank - fingers crossed
 
Honestly just reading through the threads here and other places I don't really hear very many CPS's going bad. air in the fuel system can cause havoc for anyone on a diesel. make sure you have swapped over your resistor from the old PMD too. I installed mine in the extension harness up by the IP so I would hopeful never have to worry about it. :)
 
dbrannon79 said:
Honestly just reading through the threads here and other places I don't really hear very many CPS's going bad. air in the fuel system can cause havoc for anyone on a diesel. make sure you have swapped over your resistor from the old PMD too. I installed mine in the extension harness up by the IP so I would hopeful never have to worry about it. :)
Click to expand...
Yes I was going to put the resistor in the cable too but just too lazy. I have seen these in pmd resistors burn through or burn up the foil trace. I put in a new #9
 
EPITATH

Was measuring wrong pin on pmd cable - nothing wrong there

Closed hood and cranked.

The I remembered sometimes when the engine shutdown, I have to pull the ecm and cig lighter fuses and put them back in before it will crank and inject to start

Stumble starts rely rough and I keep the rpms high enough to eject the air

Hungry and thirsty I head two miles to get a sandwich a d large drink.. Idle has not dropped below 750 and I am worried because the new PMD won't last long like that - and at the drive up WI dow it gives the fried pmd shut down. Restarts a few times and dies - a couple off guys try to push. It is a slight incli e so I am stu k then I think pop the original pmd back on and it starts right away at the right idle

The new pmd is now junk burning hot

It was sucking air through the lift pump inlet causing the pressure plate style regulator to close off fuel intermittently. I tightened the inlet again that internal o ring and it is running normal again
 
MrMarty51 said:
Thats a lot of different problems all happening about the same time.
You did very good in getting alla that figured out. 👍
Click to expand...
It was easy to find because I did it to myself when I changed the lift pump after six years of no problems.

As a part of my troubleshooting I loosened the fuel cap incase there was a suction no flow issue. No evidence the cap vent was plugged plus I had already done the fuel cap drilled hole mod. See https://www.dieselplace.com/threads/fuel-cap.648770/

BUT... I was wrong - as the cap was and is partly plugged.

In the six hours working and cranking, I began to get the sweet smell of R99, and there it was - just a few drops of R99 on the ground.

It took six hours, THE LOOSENED Cap and cranking to get a free siphon going to just below what was a full tank of fuel.

It wasn't so much a drip as it was wet area of the connection. Then as I was under it a drop formed and hung.

If I had not loosened the cap the suction in the tank not would let it leak.

The adapter uses the stock line with an over sized o-ring and it is not necessary to make it mechanically tight to the bottom for it to seal. That way the o-ring does not deform requiring replacement when the pump is swapped next.

I said "F" it and cranked it tight. Dried the wet fitting and it is still dry 24 hours later

I am back to leaving the cap slightly loose again for a vent

For some reason the IP did not like that #9 resistor as the PMD in there for five years has a #5. As I said it is back to normal 640 rpm cold start and 600 rpm hot idle. Very little pedal pressure to go and boost immediately around town
 
JMJNet said:
Sounds like the PMD is not on a heatsink if it is burning hot.
I am not sure ?????

I thought OP said he found the problem with LP.
Then, he started fiddling with PMD that gets hot which obviously is bad now.
Click to expand...
The PMD of course is on a heat sink - placed in air flow right at the hood opening and was swapped once with a new one before the issue was found that fixed it

A couple of things here:

1. Idle would not go below 750 even after it warmed up
2. It had a new #9 resistor when the previous was a #5
3. It was a 100 degree day
4 .I was stuck in slow drive thru at fast food place

I am a fan of don't fix it if it ain't broke.

The previous PMD which is now back on it barely got warm to the touch idling. It has been used for 6 years

The vehicle has a high idle switch for the 1070 rpm and when it is switched on, the PMD gets hotter fast. See https://www.flashoffroad.com/Diesel/fastidle/

The IP uses for a throttle a solenoid at the rear which the PMD drives like in PWM to open the throttle in drive by wire.

Driving down the road the IP speed and fuel pressure pretty much neutralizes any heavy work the PMD would have to do.

Hence low lift pump pressure or non regulated lift pump pressure works the entire systno and can blow a PMD really fast. The PMD design is one that uses power transistors - the round things you can see on the bottom - as switches to cause the PWM effect and load the solenoid draws causes them to overheat holding a throttle open.

Stuck in that drive thru I knew they needed to give me my food fast so could go. Then the first few misfires and I literally tried to drive off but it died

A PMD could literally be sitting on a block of ice and it won't matter because internal electrical fatigue will still kill it.

Usually it can take upto 50 key starts to read the new resistor but in my case I had powered off power to the ecm which made it read the new resistor, and before I could do a KOKO procedure the pmd was fried.

The only thing wrong with it was the loose inlet fitting to the lift pump allowing it to suck air in with fuel.

The PMD can be fixed as a spare by replacing those power transistors
 
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Not sure where you are pulling the PMD overheat explanation from, but, it's not from driving style, drive through lines, etc. I live in extreme heat of 115-121F and have A/C systems literally "explode" from extended times at idle, extended times at fast idle, and any other abuse I could throw at it. PMD's on a heatsink in the front bumper were NOT a problem.

Extreme Cold was a problem for one PMD design under test that I know of so the "Block of ice" has it's own unintended and unrelated problems. Thermal fatigue from extreme cold to operating temperature I suspect. Bluntly, a PMD simply has to not be overheating.

You may have a problem that's taking higher than normal current say in the IP or the PMD. The PMD that's getting hot, assumed on a similar size heatsink, may have a problem. This problem includes intermittent or high resistance connections by wires or internally.

Maybe you are bumping something like the "sense" wire on the alternator plug and the system voltage gets really high.

New Parts do not mean Good Parts.

You have weird symptoms of a 750 RPM high idle, but, I reject your "heating up the PMD" explanation ... you got something else wrong causing BOTH of these "Symptoms". Stated again a hot PMD is a symptom of something else including, but, not limited to: a bad PMD.

I hate throwing parts at things, but, PMD's and it's wiring are one part you do throw at these due to the intermittent failure mode and ease they are damaged.
 
You say your PMD is mounted near the hood opening... post a pic of where it's located.

if near the radiator that can allow it to overheat in a high idle situation where there is little to no air flowing to cool it, only heat is getting radiated into the heat sink making things worse for it. is your extension harness to it made by a reputable source or something from china? smaller wires over a length of feet (6ft extension) can cause a resistance issue that most would never see, but only precise or sensitive electronics would have an issue with. along with GM's famous connectors that tend to melt due to high resistance issues.
 
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