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Discussion Starter #1
Hey Guys...going to head out today and the ole gal won't start. I've had a p0401 for a couple of days buts I don't think that would keep it from starting.

I hate to say it but I'm leaning toward the PMD. The truck still has the orginal and it's in the stock location. Do they just fail and never come back? I've had no starting problems until today.

The lift pump was replaced about 3k miles ago. How would I test for a fuel problem? I've checked the battery connections to....It turns over fast enough it just won't start.

thanks!
 

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Begin with the end in mind... in the end, you should get fuel flowing to the cylinders. So let's check fuel flow.

Open the 'T' valve while somebody cranks the truck... you should get fuel coming out of the drain line that comes off that valve. If you don't, the issue is Lift pump.

What if this is OK... fuel comes out? Then we go to the other side of the IP.

Grab a wrench, crack open (just loosen) one of your injector lines (cylinder #1 is easy to reach), and have somebody crank over the truck while you watch ... does fuel leak out of the fitting while cranking? It should.

That'll tell you if your IP is sending fuel to the cylinders.

If you have fuel before the IP, but no fuel after the IP, I would suspect the PMD. Check grounds and connections. It's sorta strange for them to just stop like it did. Usually, they give you lots of warning they're going bad... stalling, cruise control dropping off-line, hard starts when warm, etc.
 

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Discussion Starter #3
Thanks for the tips jifaire.

Lift pump test passed.

When I opened the injector line I did not get any fuel. I had the fitting loose enough that I could turn it w/ fingers....is that good enough?

and the saga continues.....
 

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The p0401 is related to your EGR. Exhaust Gas Recirculation (EGR) Flow Insufficient

Lot of info in the FAQ thread about EGR troubleshooting.

Once you get it running you might check that one out.
 

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Can you get your hands on a 'known good' PMD to check that out? If so, unplug the PMD on the pump, plug in the 'known good' one and give it a try.

If it starts, that's your issue. Shut it off - you can't run a PMD very long when it isn't protected from frying.

If the PMD is dead, I suggest replacing it with a Heath Unit - costs a little more, but 7 yrs warranty is a good thing.

If the PMD test fails, then you're looking at an IP problem ... ugh.
 

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Discussion Starter #6
With the injector line loose, should the fuel spray everywhere or just weep out? The reason I ask is when the truck was being turned over I got nothing out of the line. But I just went back outside to tighten the injector and there had been some fuel weeping <I hope that's a word> .
 

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The fuel is under (should be under) a lot of pressure, but the volume is low. It should come out of there fairly good, but there won't be a lot of it.

ie: if your pump puts out 100 mm^3 per stroke (it won't, but I needed a number), it will put out 1 cm^3 (1 ml) every 10 rpm. That's about 20 drops.

Not a lot of fuel, but if the fitting is loose, you should see it when cranking. Like I said, it's at pretty high pressure.
 

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Discussion Starter #8
where is the fuel pump solenoid located?
 

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Just a little FYI about the P0401. I've been having problems with that code for a couple of months now. It has never prevented my truck from starting or caused it to stall and it seems to be running completely normal.

I haven't spent too much time trying to source what is causing the code because I have a re-flashed ECM on the way that will eliminiate the EGR system.

Dave
 

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You talking about the FSD (Fuel Solenoid Driver) also known as PMD (pump Mounted Driver), Oilhammer?

It's the black box screwed to the side of the injection pump. It's damn-near impossible to get off. Don't ask how I know that.

When one dies, usually we replace it with a remote mounted unit (on a heat-sink, out of the engine compartment), use an extension harness to get the wires run out to it, and just leave the old one right where it sits.

As a warning to other bad ideas.
 

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Discussion Starter #11
ok......I was thinking there was another solenoid somewhere in addition to the PMD.

I think my next test is to pull the fuel outlet hose off of the front of the pump and put a piece of clear hose on it and see if fuel come out when the engine is turned over. If I get fuel out then that means the PMD is ok right? If there is no fuel present then I need to get a new remote mounted PMD...

thanks,
Paul
 

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OilHammer;1587245; said:
ok......I was thinking there was another solenoid somewhere in addition to the PMD.

I think my next test is to pull the fuel outlet hose off of the front of the pump and put a piece of clear hose on it and see if fuel come out when the engine is turned over. If I get fuel out then that means the PMD is ok right? If there is no fuel present then I need to get a new remote mounted PMD...

thanks,
Paul
Fuel Outlet Hose? We have one of those? I'll Bdamned.

As far as I know, you have a fuel INLET hose and 8 High-Pressure injection lines ... some funky electronics, a PMD, and a Fuel shut-off solenoid (looks like a roll of quarters mounted vertically on top of the IP).

Got a picture of what you're referring to? I'm not too swift, and pictures help me a lot. Small, one-syllable words are good, too.
 

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He's talking about the return line.

I'm not too sure about that as a positive proof of PMD being bad either.

Seems it just proves that the pumps not pumping.



Fuel solenoid your talking about is another part of the IP. I have no idea how you could test it.
 

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Ahhh. THAT line. I'm also not sure if that will prove anything about the PMD, but hey, give it a shot. You might be getting fuel back outta there even when the IP isn't running, for all I know.

I never tested mine when my PMD gave up ... I had all of the other symptoms to go by.
 

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There has been a post in recent days / weeks about testing a PMD. This may work in this case. A complete and total failure is not what most of them do. They usually stall and stumble along for a while.


I can't find the thread now.

It's about testing for a totally failed PMD prior to putting it on a test bench.
 

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I think my next test is to pull the fuel outlet hose off of the front of the pump and put a piece of clear hose on it and see if fuel come out when the engine is turned over. If I get fuel out then that means the PMD is ok right? If there is no fuel present then I need to get a new remote mounted PMD...
My experience with a similar problem (no start condition) has been if no fuel is coming out of the injector lines, no fuel will come out of the IP.

Let us know if you see otherwise.

Peter
 

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Depending on the version of PMD. It can just fail, like a light bulb burning out.
New versions will work intermittently, with plenty of stalling in my case and so far always starts.
 

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Discussion Starter #19
Hopefully when I get home today, I'll be able to pull the lines and see if I'm getting any fuel. I think I need to brake one of the injector lines loose again and see if I get fuel, I'm not sure that I did it right yesterday.

If I'm getting good fuel flow out of the pump and out of the injectors what's going to be my next step?
 

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Let us know.

I think if you get to that point it's going to crank if it's diesel coming out. Unless it's not turning over fast enough, or the glow plugs are not working.
 
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