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Discussion Starter #1
Hello guys.
I've recently run into a rather strange issue on my 96 drivetrain that I swapped into in my 01 1/2 ton in my sig.
I've got fuel pressure gauge on the IP inlet port from the secondary filter, TorkTek OFV, stock lift pump, just changed the spin on fuel filter about a month ago.

The truck has been a little temperamental starting recently, always wants a touch of pedal which doesn't bother me, my 97 is the same, and so are my old diesel Mercedes, the truck idles good once warm, around 7-800rpm I'd guess with AC on in drive. Just about dead on the first line below 1000, sounds good, doesn't ever stall once its warm, will stall if you try to jump in and toss it in gear the first fire it makes (I never do that, I'm working on breaking my wife of the habit too).

I changed the original injectors 5x.09 or whatever the 180 pump got stock out this past winter for a set of 5x.10s that would be the 215 stock size I believe. Cleared up a bunch of whitish grey haze and made the truck idle a TON smoother and run better overall, power seems about the same but I drive like a grandpa anyhow.

About a month ago I changed the fuel filter (spin-on), added the pressure gauge, discovered my in-tank strainer was clogged up and restricting flow when towing, so I've pulled the sending unit, cleaned out the tank, added a goldenrod mesh filter on the frame rail (not paper element, big stainless steel mesh) fuel pressure won't ever drop below 20 even when WOT pulling a gigantic boat up a hill, tends to hover around 27 at idle.

The truck has run beautifully for at least a month after doing that, until just about the past week it has been getting more and more difficult to start. after just a few revolutions I have 20-25psi registering on the gauge, but the truck refuses to even fire. acts just like the FSS is down.

Since the PO had replaced the FSS and entire bracket with a piece of baling wire, I got a cheapie china-express fss kit that had the whole bracket and everything, I couldn't find a bracket any other way, so I was figuring I'd use the bracket and have to replace the FSS with a quality one nearly immediately. But the FSS pulls and holds as expected, and has done so for well over a year.

I'm suspecting I've got a very small air leak that has gradually airlocked my IP and the injectors aren't getting fuel, which means time for some fun chasing fuel lines and trying to figure out where the leak is, and then bleeding my injector lines.

I'm a tad puzzled that it would build pressure so well though. I suppose if air is getting into the IP it may not get back out through the TorkTek though.

Any suggestions or things to check before I just decide to replace all my fuel lines and call it a day?
 

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No, I suspect you have an air leak on the suction side of the lift pump. Any air that gets passed into the IP is gone in a flash. Have you read Joe Gs writeup? Joe G's fuel system writeup
 
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Discussion Starter #3
Interesting! I have read through JoeGs writeup, brilliant info, I did notice I missed the grommet thing on the lift pump supply line, I'll check that, I went through this mess when I was sure I had removed the fuel heater last year.

If someone put a fuel heater back on there I swear...

I figured if the lift pump was getting air into it the fuel pressure wouldn't come up to 20psi at the IP inlet while cranking, but air intrusion always seems to be my problem one way or another.
I'll pop that line off as soon as I get a chance and check how that grommet looks, probably just replace it to be safe.
 

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Discussion Starter #4
Ok, after waiting for parts, I've gone through the entire fuel lines and everything.
Here is where I'm at:
I get solid fuel at the top of the filter and the overflow valve, no bubbles, no nothing.
The lift pump is working properly, producing 25psi measured after the spin on filter at the IP inlet while cranking.
I changed the filters for good measure, fuel pressure was a few psi lower with the old filters, fuel looked and smelled like diesel, no water or anything, primed the entire system.
I did have an "event" about a year ago where I suspect someone had put some sawdust in several of my vehicles fuel tanks, but I'd say that is long gone now, sucked out tanks, changed filters on everything, haven't had any issues with any equipment since.
The FSS operates normally, pulls when turned to start, continues to hold when released to run.
The FSS lever and shaft that enters the pump are moving (I had the keyway fall out once and it didn't actuate)
I charged both batteries with a trickle charger overnight, it cranks good and fast.
I get no smoke out the exhaust when cranking.
If I crack the injector lines at the pump or at the injectors and crank, I get no fuel, not even wetness regardless of throttle position.
Nothing happened to the truck that would make me think something catastrophically failed, it was getting harder to start,but once started it would run smooth and pull good, minimal smoke, no issues.
I drove the truck to pick up a customers jetski, drove home with no issues, unhooked the jetski, parked the truck, shut it off, and it hasn't started since.

Is is possible for the rack to stick, or delivery valves to jam or something? Could that sawdust in the fuel tank make it that far past all the filters, and how would it take a year to cause issues?
Is there even a way to check that?

I probably should be checking the nut on the front of the pump, I've never touched it, and the PO was an old guy who used the truck to haul hay on his farm, I'd expect timing to be untouched, and even if it had slipped I'd still get fuel out of the lines, just at the wrong time right?

I'm stumped, if I pull the AFC can I see anything useful?
 

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I would closely study that woodruff key/ keyway. I would take it part to positively verify the shaft is turning with the fss.
 

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Discussion Starter #6
I would closely study that woodruff key/ keyway. I would take it part to positively verify the shaft is turning with the fss.
I removed the FSS, loosened the arm, removed it, keyway looked good, I moved the shaft back and forth with my fingers, I can hear it actuate something inside the IP.
After inspecting that, I reinstalled the keyway, arm, fss, plugged it back in, and the truck started right up...

I don't know what to say. I didn't change a thing. I'm contemplating getting a box of keyways so if it refuses to start again I can pop the hood and toss a handful in.

Maybe the keyway had shifted a little to where it wouldn't quite allow fuel? or me wrenching the shaft back and forth freed up whatever was stuck?
I'm gonna let it sit and try it again tomorrow, I'm beyond baffled.
 

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Ah, yes, the old "I took it apart, saw nothing wrong, put it back together and now it works" fix. I have a love/hate relationship with those. Just go with it.
 

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"...added a goldenrod mesh filter on the frame rail (not paper element, big stainless steel mesh) fuel pressure won't ever drop below 20 even when WOT pulling a gigantic boat up a hill, tends to hover around 27 at idle."
Good to see you fixed the problem.
Side note- I was wondering if anyone else was using a Goldenrod Tank style filter. Now I know I'm not the only one.
I'm using a sump, to a Goldenrod with the water absorbing element, directly to the lift pump and the factory fuel filter after that, of course. I eliminated the fuel heater/pre-filter unit. 20 PSI at idle through the paper element.
 

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Discussion Starter #9
I was wondering if anyone else was using a Goldenrod Tank style filter. Now I know I'm not the only one.
I debated on the paper element being too restrictive for the suction side of the lift pump, so I used the stainless steel 470-15 mesh as a strainer to catch big stuff, I find smaller junk tends to settle out because it is such a big bowl as well. I removed the in-tank screen as well as the heater and little prefilter screen from the truck I was having issues with here, the prefilter screen at the heater/lift pump thing was torn anyhow, so I put the goldenrod on to catch gunk before it got to the lift pump.

I've got that exact setup on both of my trucks and one of my diesel Mercedes. I had an issue with the Mercedes getting bad fuel at a station I'd never used before, and kept plugging filters, so I put it on there and all the gunk settled out and other than having to clean out the bowl a couple times it caught probably close to a quart of gunk that would have plugged the tiny prefilter that came stock (similar volume as the little filter under the fuel heater on our trucks)

Well worth the time to install it.
 

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When I rebuilt my 12v, i eliminated the whole pre-heater/filter assembly, and i changed my fuel filter & water seperator to a larger one that doesnt have a WIF sensor, just a drain valve built in to the filter can itself. I have a goldenrod with fine mesh screen that i plan to install before the lift pump, when i swap the motor into my ford.
 
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