6.5 cutting out at idle

Its actually a 94. it quits surging when you unplug the cranksensor and on a cold start takes a long time cranking to get started but after the first start it hits instantly on hot restarts
 
Replaced crank sensor, i would call it more of a miss than a surge, but it still does it and it sputters if u snap the throttle in nuetrual and its a 94
 
pmd failure in have a 2000 with similure problem but wount crank back. until you un hook the battires
 
Replaced pmd,same thing still, have also redone a bunch of grounds too and still no change. Could it have anything to do with oil pressure set up? Cause it does it under 1k rpms and when the pressure has dropped to like 20psi on the oil
 
Oil pressure has nothing to do with the fuel systems on this truck.

There is quite a bit more to those POS pumps other than the PMD. You may also have a faulty speed sensor inside the pump. There is no science to these trucks. Check the following:

Fuel pressure, filter
If you still have a problem, check the injectors, I am sure they have a bit of mileage and could have excessive return.
Finally, pull the pump and get it rebuilt or tested; it can be an expensive test.

Those Stanadyne pumps are garbage. More than 40-50k out of one and consider yourself lucky.
 
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raychem said:
Oil pressure has nothing to do with the fuel systems on this truck.

There is quite a bit more to those POS pumps other than the PMD. You may also have a faulty speed sensor inside the pump. There is no science to these trucks. Check the following:

Fuel pressure, filter
If you still have a problem, check the injectors, I am sure they have a bit of mileage and could have excessive return.
Finally, pull the pump and get it rebuilt or tested; it can be an expensive test.

Those Stanadyne pumps are garbage. More than 40-50k out of one and consider yourself lucky.
Click to expand...

JBrassfield715 said:
The oil pressure sender controls fuel cut off on these trucks
Click to expand...


What he said. 94-95 6.5's use a POS oil pressure sensor that actually powers teh fuel pump when teh engine is running. 96+ use teh ECM to trigger teh relay. the OPS is a COMMON failure point on OBD1 6.5's. Quick check is to open the water drain while it is idling hot and see if fuel comes out or not. If it stalls then the lift pump is not working and most likely the OPS has failed. Use ONLY an AC DELCO OPS, and I HIGHLY reccomend a relay installed inline to carry the load instead of the OPS.
 
JBrassfield715 said:
The oil pressure sender controls fuel cut off on these trucks
Click to expand...

THEFERMANATOR said:
What he said. 94-95 6.5's use a POS oil pressure sensor that actually powers teh fuel pump when teh engine is running. 96+ use teh ECM to trigger teh relay. the OPS is a COMMON failure point on OBD1 6.5's. Quick check is to open the water drain while it is idling hot and see if fuel comes out or not. If it stalls then the lift pump is not working and most likely the OPS has failed. Use ONLY an AC DELCO OPS, and I HIGHLY reccomend a relay installed inline to carry the load instead of the OPS.
Click to expand...

I stand corrected. I looked it up and you guys are right! It has been ages since I work on one. I had a 96 for a few years, hence my comment on the oil pressure. I also mentioned to manually check the fuel pressure. Put a gauge in it. Like you said, if the oil sensor is giving you a problem, zero fuel pressure would be an indication, that or the fuel pump is giving you problems.

Keep us informed.
 
check lift pump is running and has pressure. should be 4-10 psi.
Wire in a relay to take the load off the contacts in the sender for primary power to the pump. Also verify you have power. Most only recommend an AC delco sending unit because some Aftermarket unit omit the contacts for the pump.


check for any fuel leaks. specifically at the filter housing and lines under intake or hardlines running down the back of the block and chassis
.
Change Fuel filter if you have not done so.

Check the air filter.

Check flow of fuel from tank to LP. the socks are known to clog

I installed Napa filter housing and 2 micron filter after the OEM Filter to insure clean fuel to the engine.

Are you dosing the fuel with 2 stroke or other additive to make up for the lack of sulfur for the INJ Pump? If not then do so heavily for a couple takes 2 oz per gallon. after such time use ~0.5-1 oz per gallon of fuel.

Is the PMD located on a cooler in a wind prone area? Do you have a spare to test? If not make sure to get the preferred gray color latest revision.

Rich
 
Sorry forgot to mention... The issue of hard cold starting:

check the glow plugs individually <1 ohm from plug to block; anymore and they are bad. Most suggest Bosch GPs. Be carefull removing any stock AC plugs. The OEMs are known to swell in the bore. I used vice grips and a small hammer to "gently" remove the 2 which have swelled on me in 3 trucks.

Check the GP relay attachments and wires to each plug. How old is the relay? It's cheap insurance to replace it for ~$30.

How long does the GP light stay on? stock mine was 8-10 seconds on cold days.

Lastly swap PMD to a known good unit.

You might also consider an aftermarket eprom since one of the options is to increase GP time for easier starting.

Rich
 
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