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Random no start

2

2po2watch

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I just bought a 1996 2500. It has a random crank, no start. When it happens, it has good fuel pressure. I discovered there is no resistor in the PMD or extension harness. Can this cause the no start? Is there a way to determine the appropriate resistor?
 
Welcome to the forum! yes a missing resistor can cause a no start situation. best thing to do is check for codes. if the PCM is registering a missing resistor the SES light will be on. also a good thing to do is clean all grounds. there should be at least three wires with eyelets bolted to the intake up by the passenger side near the trans dipstick.

as far as determining which resistor is needed, it's usually a guess. is the old PCM still mounted on the side of the IP? if so, chances are the resistor is inside the old PMD. start out with a #5 and see how it goes. there is a kit you can get from the auto parts stores that comes with a #5 and #9 resistor. those two are the most common ones.
 
when you get your resistors in, just a thought. I installed mine in the female connector of the extension harness so that when I have to replace my PMD I don't have to fiddle with getting the resistor out and transferred over to the new one!

lots of guys have a second PMD mounted on the heatsink with a dummy plug in the connector just to keep the dirt out. when the existing one fails and your out on the road. all ya have to do is switch the dummy plug and the harness plug and your off on your merry way and not stuck on the road side having to pull and replace it, or having to get a tow truck!
 
2po2watch said:
Thanks for the reply. There is no PMD on he IP. The one on the heat sink is a black Stanadyne unit. No way to know it’s age. Checked grounds. They are clean and tight. I have ordered a resistor kit. No one has them locally.
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Welcome to the forum 2PO.
If You do not have a spare PMD, best to get one of those coming. Do not leave home without it.
Leroy Diesel and Quadstar tuning has the Flight Systems PMDs and they are warranted for life.
I am currently running one of those but also have the Stanadyne grey PMD for a standby in case the black box fails.
If You go tje route of the grey box Stanadyne, be sure to also get the adaptor wire harness. Your resistor can be made to fit the grey Stanadyne by filing, grinding or snipping off the location tabs on the ends. Just be sure You get it plugged into the PMD in the right direction.
 
dbrannon79 said:
when you get your resistors in, just a thought. I installed mine in the female connector of the extension harness so that when I have to replace my PMD I don't have to fiddle with getting the resistor out and transferred over to the new one!

lots of guys have a second PMD mounted on the heatsink with a dummy plug in the connector just to keep the dirt out. when the existing one fails and your out on the road. all ya have to do is switch the dummy plug and the harness plug and your off on your merry way and not stuck on the road side having to pull and replace it, or having to get a tow truck!
Click to expand...
After an evening that required me to get on the ground in nasty weather and switch the extension harness from one pmd to the other. I ordered another pmd harness. I run both harnesses up to the intake and just swap harnesses there. Much easier and I don't get my butt chewed by the boss for getting dirty on our way out someplace.

Get made in the USA harnesses from the same sources listed above. The Chinesium harnesses are just asking for trouble.
 
Never run a pmd without a heat sink. Factory mounted on the pump used the aluminum alloy housing and fuel inside as the heat sink but problem is when you shut off engine all the engine heat ends up getting pump hot and sending heat into pmd.

get the pmd out the engine compartment, front bumper is a prime location- If you want to see pics of where- ask and someone here could post a pic.

replace the ip (injection pump) return fuel line with clear tubing. It is 1/4” diameter, about 6”’long coming out the front of the ip. You should see clear, clean fuel flowing through when you are cranking it and when running. Getting a tiny air bubble trapped in the line is ok, but you should not see any traveling bubbles. This indicates air intrusion and will keep an engine from running.

you said you have fuel pressure. EXACTLY where are you reading it and what pressure?

What rpm is the engine cranking at?

is there any smoke coming out exhaust and if so what color and what does it smell like?

RANDOM CRANK? Define this please. Does it not crank over sometimes when you turn the key?

dont be afraid to post pics of engine- sometimes we see something that way.
 
The PMD is on a heat sink. I have installed new fuel lines, upgraded lift pump(holds 12psi), Cat primary and secondary filters, new batteries and cables. When it doesn’t start, the engine spins strong. No smoke from the exhaust. Fuel pressure gauge is permanently installed gets its reading between the secondary filter and IP.
 
Ok. After you pop in the resistor, if it still doesn’t start- trying spare pmd then Crack an injector nut, wiggle line to be sure it is free of the seat, and trying starting. It should spit out fuel.

If you buy a new pmd as the spare (like a spare tire- ought to always have one) I would order complete kit from Leroy and mount it next to other one on bumper, now you know the extension cable is good. then use one the new one and verify old one is good afterwards. If pmd is the issue, buy a second new one, if it is good, still run the new one with lifetime warranty, keeping old as spare for when the warranty unit dies and you are waiting a couple days on shipping.
 
jrsavoie said:
I hadba bad pin in the ip harness once. Sometimes it would make when wiggled.
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I think I remember reading about that, or another one of the exact same problem.
I once had a loose pin in a connector. Pull the two halves alart and they all looked good. Shove them back together and the problem would persist. I dont remember what vehicle or problem was, anyhow, finally got the small needle nose pliers, started pushing and pulling on pins within the connectors and there it was, one pin would push back into the plug when th harness was connected then pull back out when the two halves was pulled apart.
 
2po2watch said:
The PMD is on a heat sink. I have installed new fuel lines, upgraded lift pump(holds 12psi), Cat primary and secondary filters, new batteries and cables. When it doesn’t start, the engine spins strong. No smoke from the exhaust. Fuel pressure gauge is permanently installed gets its reading between the secondary filter and IP.
Click to expand...

What is "Cat primary and secondary filters"?
Is the Glow Plug (Wait to Start) light turn on?
 
If it was a glow plug issue he would have a ton of smoke from unburned fuel.
Filter type doesn’t matter, he has fuel pressure.

If the return line out the ip (replaced with clear tubing) has fuel flowing through it while the engine is cranking- checking that fuel is coming out the injection lines is the next step.
 
Batteries are brand new. I think I have found the problem. When it doesn’t start, fiddling with the plug at the PMD extension harness near the IP gets it going. I tightened the pins in the plug and it hasn’t failed since. I have an IP and extension harness ordered.
 
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