Is it possible to mount an LED light to monitor juice comingback from the PMD?

[jrsavoie]

Is it possible to mount an LED light to monitor juice coming back from the PMD?

I was thinking this would be a good idea to monitor the PMD and save some diagnostic time. Would go hand in hand with a fuel pressure gauge.

I made a test harness to check for juice coming back from the PMD - rather than probe the wire - the last time I had an issue. I was thinking that if that lead that I have T'd off went to a small LED bulb, you could see no juice coming back from the PMD and narrow a person's search a little faster.

Is anybody willing to make something up or specify parts needed?

I am having an intermittent issue with the 94 K3500 dying. It's done it twice shortly after start up - acts like an air in fuel issue possibly. 2 other times it did it going down the road after about one mile of driving.

I am going to swap PMD's and see what happens.

Does anybody sell a fuel pressure gauge kit? Digital read out or other?

A lot of people have mentioned they do not want fuel run into a gauge in the cab.

After the first time - in the driveway - I pulled the IP return line, blew it out. Pumped a quart of Sea Foam/ diesel mix through baCK TO THE TANK WITH A SPARE LIFT PUMP, changed the fuel filter, primed and it started. The next time I ran the lift pump with the toggle switch for a few minutes and it started. On the road, I sat for a minute and it started.

Lift pump is running good while the truck is running.

Acts either PMD related or air in fuel. Any other suggestions for things to check? I have the lift pump running now to see if there is any dampness around the fuel filter when I go back out.

Grounds are good and the truck does not start right back up. It did start right back up after running the lift pump with the toggle. Not sure what is coincidence or if anything I have done so far actually tells me anything.

Need a fuel pressure gauge and to try a different PMD. If the problem goes away with the other PMD, I'm done until I get a fuel pressure gauge.

 

[Will L.]

That's a good idea about the PMD light to monitor. It may not prove everything is good but if you lose power that's on way to show it's not working.

Do you have a clear line returning from the IP to see any bubbles?

Scangauge2 mounted in the truck is a nice monitor system.

For just the fuel pressure, make sure it has a vacuum gauge also. Harbor freight sells a basic one for like $30. My preference is this Mac:


While I'm next to it, here's a cheat sheet I keep with my test gauge incase it helps someone on other stuff besides fuel. Keep in mind the little description and spec is for non boosted gas engines, but kill your turbo and valve tests, and such still work-just not as dramatic changes.

 

[schiker]

I don't know. I think the PMD is a failure at board level with solder joints (or components burning out) so I guess you would have to splice in between the PMD and the solenoid. BUT that signal is so fast I am not sure you could see it. Might be fast enough that it just makes the LED a bit dimmer than a solid 12V signal similar to PWM????

 

[jrsavoie]

I have had to test for power coming back from PMD's a few times. So I thought that having something permanently mounted would be handy. It sounds like it would be relatively easy to do.

On my test harness I added wire coming off to test, instead of probing my good harness. I always have trouble making myself probe a good wire.

An extra wire from the proper pin could be added to an extension harness and you could run from there to the LED light or volt meter.

For the fuel gauge, I want a permanently mounted gauge in the cab. If I get one vehicle done and like it, the rest would be easy.

My current issue appeared to be the PMD. I installed my spare and had 4 trouble free miles. Time will tell. It was an old black Standyne. I have still had my greatest longevity out of the old black Standynes. But some of the others haven't been out as long as some of the old black Standynes lasted for me.