How do you know when the IP is bad

[clubsmoker]

How do you know when the IP is bad? Replaced PMD fixed it for 2 days.Chev. Gave me another PMD. Ran great for a week died one morning would not restart the next day it started. Will start and run now, run all day but afraid to drive it because I know it will make you walk.

[Cowracer]

How do you know when the IP is bad? Replaced PMD fixed it for 2 days.Chev. Gave me another PMD. Ran great for a week died one morning would not restart the next day it started. Will start and run now, run all day but afraid to drive it because I know it will make you walk.

Generally, the only real failure mode that implicates the IP itself is long or short solenoid closure times. Usually, you start with 'surging' at a steady speed, and then it gets worse. Your throttle starts moving more to an "all-or-nothing" proposition and eventually it wont even idle without wanting to do it at 3200 rpm.

A simple dying situation as you state above is almost always a PMD. Its possible that the original replament PMD had issues, and the new replacement one fixed it. I would start driving it around town for a week or so just to get the confindince back.

Tim

[dgrund61]

so do I understand that this symptom of surging and dropping back down will get worse till it fails? Mine is doing the same thing, above 2300 rpm it runs great and @ 1700 & below great too. Sometimes it's better sometimes worse; thought it was injectors but new ones didn't help. A clogged sock wouldn't cause this would it?

[More Power]

Stanadyne insists that the PCM can, in some instances, be the cause of repeat DS failures, though I haven't read a convincing explanation for this process.

The symptoms Cowracer mentioned are due to a sticking or incorrectly operating fuel solenoid (the mechanical/electrical component driven by the FSD/PMD). It can stick in its bore or even become galled. Some feel this is due to fuel quality issues (sediment, water or lack of lubricity).

Try running some B5 or better yet B20 bio-diesel, or begin using a fuel additive that includes injector cleaner and added lubricity - to see if it helps.

Jim

[dgrund61]

I have only put one tankful with fuel additive in it. It's somewhat better than when I first got it. How likely is it that using no additive with a pump that has about 55,000 on it would cause this condition? Is It better to change the pump or just the solenoid? Will this surging, hesitation,cause engine damage?