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Modified pump; now won't take throttle.

5K views 18 replies 5 participants last post by  ByronRACE 
#1 · (Edited)
Hey guys,

I replaced my side cover and while my IP was out I decided to put a fuel pin in the IP, change the governor spring, and put in a dynamic timing adjuster.

I carefully performed all 3 of those mods on the bench and am sure I did it right, but I'm not having the desired result. Should the truck run with no modification to the idle speed screw or the fuel screw afterward?

After doing all this work, I reassembled and hand-bled the fuel system with the lift pump lever, then cranked it over and it started. I then bled all the injectors a half dozen time to make sure the air is out. The engine starts easily and idles fine; though it idles lower than before..so I turned the idle screw about 1/4 turn to get it up to where it idles.

Ran it for about 10 minutes; everything seems fine...idle seems OK.

BUT. If you apply throttle, the RPMs go up ever so slightly and that's all you get...it sits there at sort of a high idle; even if you floor the throttle. No revs. If you do floor the throttle, then let off it dies. The exhaust is relatively clean during all of this.

I'm not sure what I could have done wrong, so I'm wondering if there's a required fuel screw adjustment or other adjustment necessary post-mod that I don't know about? Any ideas?

I did not break my pump lever; it was moved out of the way of the fuel screw when the pump halves were mated.
 
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#2 ·
Acts like it's starving for fuel.

I'm done for the night, but my last observation for the evening is that it seems like it's starving for fuel to me; like the governor is activating just off idle. Only; it's not the governor because that shouldn't make it stall/stumble. And, if starvation made it stall as I open the throttle, why does it restart and idle so easily/perfectly.

The pump went in exactly how it came out; keyed...mark on timing cover aligned to mark on pump. Shaft was never rotated. I followed the procedure. Everything aligned. They key is there; I took a picture of it during install with my phone to make sure.

Unless someone has a better idea, I'll probably start by inspecting/reversing the modifications one by one; starting with the governor spring because that area seems to be the only area that could explain this. Though; I can't for the life of me see how. I can feel that the spring is there when I turn the throttle shaft with my fingers...and the rpm does move some when I turn the throttle; so I know it's connected to something. Could it be something else in there I moved when I as mating the pump halves together? I was aware of the fuel screw and fulcrum lever contact problem and resolved that by pulling the fulcrum lever away from the fuel pin toward the front of the pump (with a wire) while I mated the pump halves together. Could that do anything? I didn't pull it hard; just enough to clear the fuel screw. What about the other lever in there toward the side of the pump furthest from the head. Could I have gotten that wrong somehow?

Hmmm.
 
#3 ·
Could the fuel pin be in backwards? I could see that situation allowing it to idle but not allow it to rev up any higher. I haven't cracked into my IP, so I'm not sure if that's even possible. But it's something to think about before you tear into it again.
 
#4 ·
I don't think I'm that dumb, but it takes 5 minutes to check...why not.

The fuel pin is the "boost proportional" fuel device, right? There is no boost at present; I'm testing this with the tube off of the intake elbow. Is that a problem? With the stock fuel pin it would run and rev fine with no boost.
 
#5 ·
Sounds like an indexing problem to me. When you installed the new governor spring it would not take much more than one mark off on the indexing to cause the problem you are having. You can re-index the pump on the vehicle. IIRC you move the indexing mark counter clock wise one notch then test.

Bob
 
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#8 · (Edited)
Indexing

So, throttle shaft indexing is what we're talking about here I assume. Or...control lever shaft indexing.

I will try again tomorrow. I really don't see how this could be it. If the control lever was off by even 20%, opening it would still cause the RPM to increase, no?

The control lever shaft goes through the housing and connects to the governor spring. I can feel that the governor spring is connected when I turn the shaft counter-clockwise, so that's still there.

The index of the slot relative to the linkage is in the same spot it was in when I removed it. I marked it. I've also tried both sides of that mark. On one side it idle higher, on the other side it won't start unless you depress the pedal some. Makes sense to me.

When I rotate the control lever shaft counter-clockwise and take the slack out of the gov spring linkage, the slot points right at the 2nd index mark, which is the one I marked as well. That's where I have it set now.
 
#9 ·
Mine also idled at 1000 rpm which was not much of a problem with a manual trans. but would be a problem with an auto trans. The question then becomes does it die when you try to accelerate, if it does not stumble you are on the right track but not done. After working on mine, at 1000 rpm, I was able to drop the idle with the idle adjust screw. I now have an idle at 800 rpms and it has been this way for about 8 years.

Bob
 
#10 ·
Stumble

It does stumble when you try to accelerate. Sometimes it'll sound like it's missing randomly; sometimes it'll stall; sometimes it'll gain rpm smoothly for a very short range (maybe 1200rpm) then sit there. When you let off the throttle, it almost always shuts off. Restarts easily. I'm going to go out there and try indexing the control lever such that the shaft is rotated more counter-clockwise. Maybe it needs it. I did have to turn in the idle screw to make it idle. I don't think this is entirely the problem, but I'm listening to the suggestions.
 
#11 ·
I would not re-index more than 2 index points CC unless you see noticeable difference in performance of the pump. You will have to adjust the idle to get it to idle at a lower rpm once done. I would also suggest removing the air intake hose from the turbo and have someone standing by with a flat piece of plywood in case the pump starts to runaway.

I had a guy ask me to give him a hand as he had the exact same problem as you have and his Gov. spring was put on by a Diesel Mech. I could not for the life of me figure out the problem. I even called a friend in the Diesel performance business who was very familiar with the VE pump and he could not help. This was before this upgrade was widely done.

Bob
 
#12 ·
So check this out...

I found my problem. It became evident something was screwey when I cracked the bleeder valve right after it stumbled/died and witnessed SUCTION at that port...it sucked the residual fuel hanging on the bleeder back into the fitting!

Bad lift pump? No, if you pump the arm a few times it fills up with fuel and spits out of the bleeder. If you crank it; fuel pours out of the bleeder.

Then what? Clogged/blocked filter? Pulled it, pumped the lever...fuel comes out. Blew a little air from bleeder to filter area...it's clear.

But it creates suction...how. Maybe the banjo fitting is blocked after the lift pump. Cracked it...pumped, fuel comes out. Nope.

At this point, I knew something was blocking fuel between the filter and the tank; but the lift pump was good...so I started removing and examining parts one by one. I pulled the banjo fitting so I could check the line and realized there were NO HOLES (so I thought) in it. How in the hell does fuel flow from the lift pump to the filter then? Made no sense. I blew into the end of it and fuel came out a tiny hole in the side. I stared at that tiny hole for about 5 seconds in disbelief, then spotted the copper washers and realized what I had done.

When I took this apart, I put the parts up on top of the engine, and failed to realize that there is a serious difference between the feed side banjo bolt and the return side banjo bolt on the injection pump.

Of course I fix that and it runs perfectly. Live and learn. :doh:

 
#13 ·
Just drove the step van; runs better, doesn't smoke at wot (not sure if it's supposed to, I have not touched the fuel screw), and seems fine. I have what appears to be a small seeping fuel leak at the throttle shaft now. I noticed some vendors supply new throttle shaft o-rings with the gov spring, so I'm assuming I should have changed this and that this is common after having messed with the throttle shaft and pulled the shaft up and down in the bore a dozen times... I'll order some o-rings from Cummins, pull it apart and change it. I bet I can do it in an hour now; I'm getting good at it.
 
#15 ·
Yeah, but now...

After my freeway test drive and declaration that my oil leak was solved, I noticed a few drips in the driveway further back from where the throttle shaft leak was...so I pulled off the doghouse and investigated.

Well, it appears that the source of my oil leak was not entirely side cover and vacuum pump. Something above the side cover is leaking oil; and since I'm not aware of any sources of oil above the side cover except for the head gasket...I'm afraid I may have a blown head gasket . The oil is puddling on the top lip of the new billet side cover and cascading over the side, running down the side of the engine, and collecting on the oil pan rail, running to the rear then dripping.

Anyone know a source of oil leaks above the tappet cover on the driver's side of the the engine? The valve covers are not leaking; all new seals and it's dry up there.
 
#16 ·
Glad to see you resolved your problem and in the process added another piece of info on problem solving to the VE.

Bob
 
#17 ·
Thanks; hope it helps someone.

Yeah, that was a good one huh? :hehe:

Anyway, now I have this "above the tappet cover" oil leak. I'm purposely not using the words that rhyme with bread basket because I'm holding out hope that it could be something else.

OK, it isn't something else. Sucks to be me.

On a scale of 1-10 how likely do you guys think it would be that re-torquing head bolts could slow this leak enough that I could make a 1000mi mountain trip and back; considering I made this trip before with it pouring out 1qt every 100 miles. I don't expect this move to stop the leak, only perhaps slow it down. Or, maybe I shouldn't touch it at all until I have time to pull the head.

October 3rd I'm leaving for a camping trip. I'm either taking this RV, or I'm cancelling it. I work full+ time during the week, and next weekend is not a possibility. This leaves one weekend between now and the camping trip to potentially pull the head off and swap the head gasket. Doable, provided nothing goes wrong...which is not that likely considering the head/exhaust has never been off since 1992. More than likely I'll find something bad along the way that needs to be addressed.

Not sure what I should do.

When I do the head gasket, should I use a cummins gasket or should I go with a MLS gasket (cometic) which is likely a lot stronger. I need to know right away; cometic cuts gaskets to order and it'll take 1.5 weeks to get one.

B
 
#18 ·
Hunting my persistent oil leak.

So the oil seems to come from right around this plug...and I may have more that oil because there appears to be a gelatin-like substance in the residue; perhaps oil and coolant mixed.



What is this plug? I assume it's a coolant port. If it's an oil port; that's probably the leak point. If it's a water port, it may be leaking, but something else is also leaking oil; and it appears to be coming from the area right below this plug.
 
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