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Old 09-27-2021, 02:05 PM   #1
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Replace fuel injection pump? Cummins 5.9 turbo pusher

Looks like a major task ahead, replacing a Bosch P7 inline injector pump. Has anyone any experience? Looking online indicated is near impossible!

Symptoms: heavy black smoke at heavy load accompanied by synchronized whine. Starts/idles/low speed fine.

Cummins 6bt5.9 intercooled turbo.

Problem started after intense cranking with air in injector pump. Fuel pressure good, turbo winding up fine. Adjusting pump ACV settings, removing air filter, Seafoam injector treatment we're all negative. Only two possibilities now: bad injector (s), bad injector pump (causing whine?)
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Old 09-27-2021, 10:59 PM   #2
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The P-7100 injector pump is a massive chunk of engineering , with a very specific removal process to insure the replacement pump ( or re-installed ) original is properly timed . In 14 years of Dodge/Cummins repairs I only did one P-7100; moved the pump to a rebuild engine after a killer dowel pin, lunched the original motor .

Of the four injector systems Cummins used in the years I was repairing them the P-7100 was the most trouble free.

The whine you mention has me thinking I'll see if there is mention of the noise and check on the injector testing .
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Old 09-29-2021, 04:17 AM   #3
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Thanks for your reply! Since the engine starts now and runs fine at idle and has full rpm range at neutral I think the injector pump must be fine overall. Your comment helps.
I've never had an injector fail on numerous diesels owned over the years and didn't realize they could whine. Thanks for that insight too. So much black smoke comes out when climbing hills I thought it must be something more.
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Old 09-29-2021, 08:08 AM   #4
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Black smoke , from the exhaust can have any one of a number of causes , and reducing the smoke, was the reason for the changes in the diesel fuel injection systems .
I have a link to the possible causes, of black smoke in the exhaust , somewhere in my note book ; I'll flip through and re-post .

Have you checked/changed the air filter ?
Done any tests on boost pressure?
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Old 09-29-2021, 09:43 AM   #5
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Here is a link to diesel smoke diagnose by color . One of the best I've come across.

http://www.capitalremanexchange.com/...moke-by-color/
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Old 09-29-2021, 07:04 PM   #6
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Skip noted boost pressure, I wonder if the whine you hear could be a boost leak, at a CAC hose, clamp or even a hole in CAC ...

You didn't say how engine performance was, low power? Only that turbo was "winding up fine"

I've heard boost leaks that didn't sound like boost leaks.

The pumps on those engine are tough, take more than a little air or running out of fuel to take it off line.
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Old 09-30-2021, 03:48 AM   #7
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Here is a link to diesel smoke diagnose by color . One of the best I've come across.

http://www.capitalremanexchange.com/...moke-by-color/
Skip
Thanks for the link, I did check it out. More detailed than others I have read.
I have felt the exhaust turbo fan for looseness and spin. Ok. RPM responsive (distinctive high pitch whine). Checked connections, CAC and all is good.
The injection pump is unlikely and I did do some adjusting of ACV settings.
Engine in neutral runs fine, has full RPM range and responsive (but puts out a brief puff of black smoke on sudden flooring the pedal).
Air cleaner was removed for prior testing (new one now installed).
So I think it must be an injector issue. I did have the fuel line off one while trying to start originally when it wouldn't start. Perhaps some spec of dirt fell in.
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Old 09-30-2021, 03:56 AM   #8
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Skip noted boost pressure, I wonder if the whine you hear could be a boost leak, at a CAC hose, clamp or even a hole in CAC ...

You didn't say how engine performance was, low power? Only that turbo was "winding up fine"

I've heard boost leaks that didn't sound like boost leaks.

The pumps on those engine are tough, take more than a little air or running out of fuel to take it off line.
Mackwrench
Thanks. More confirmation the fuel injection pump isn't at fault. About the only component I can't replace, forcing me into a distress sale!

The engine has much less power uphill while billowing black smoke and reduced RPM with the accelerator floored. No smoke downhill. No smoke on level highway except when accelerating.
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Old 09-30-2021, 05:00 PM   #9
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I doubt you have a pump or injector issue. The 5.9 runs without a turbo but has a hard time getting out of its own way. I'd check all the boots and the intercooler. Pressure check with 2-3lbs of air and soap.
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Old 10-01-2021, 09:01 AM   #10
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Heavy black smoke at full load without any smoking at idle and light load surely sounds like a boost issue. The P7100 pump as previously stated are pretty much bullet proof. I have no idea what you adjusted on it and would be curious as to what it was. They are relatively easy to remove. There is a timing pin in the engine on the back of the front cover that you use to time the engine. In the side of the injection pump there is a cap with a pin in it that flips over and pins the pump. A nut behind the oil filler gets removed and you use a tool to pop the pump out of the gear. After that itís just lines and bolts mounting it to the timing cover. Say that I would be highly surprised that your issue is anything to do with the injection pump. Going through my not so reliable memory banks I believe they should be a boost reference line going from the intake manifold to the injection pump. May want to check that out.
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Old 10-02-2021, 06:39 AM   #11
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I doubt you have a pump or injector issue. The 5.9 runs without a turbo but has a hard time getting out of its own way. I'd check all the boots and the intercooler. Pressure check with 2-3lbs of air and soap.
Thanks, I'll be digging into boost once I get a new injector installed. One is fizzing, possible sticking open I think. Carbonized tip.
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Old 10-02-2021, 06:45 AM   #12
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Heavy black smoke at full load without any smoking at idle and light load surely sounds like a boost issue. The P7100 pump as previously stated are pretty much bullet proof. I have no idea what you adjusted on it and would be curious as to what it was. They are relatively easy to remove. There is a timing pin in the engine on the back of the front cover that you use to time the engine. In the side of the injection pump there is a cap with a pin in it that flips over and pins the pump. A nut behind the oil filler gets removed and you use a tool to pop the pump out of the gear. After that itís just lines and bolts mounting it to the timing cover. Say that I would be highly surprised that your issue is anything to do with the injection pump. Going through my not so reliable memory banks I believe they should be a boost reference line going from the intake manifold to the injection pump. May want to check that out.
Thanks for the info. From your comments and others I am looking at a bad injector - one that I uncapped for checking fuel 2 weeks ago now when trouble began. Fizzing when I crack it now when idling so I think the nozzle pin is sticking. Carbon around spray nozzles when I removed injector. Will try to disassemble today, new injector comes Monday.
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Old 10-05-2021, 01:39 PM   #13
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Update:
Removed what I thought might be a stuck injector. Some carbon on tip but plunger was clean and free. Nozzle spray pattern ok (tested with a straw on a can of brake cleaner spray). Reassembled an put back in service. This is the first injector I've dismantled and have no qualms about doing it again. 6 injectors = ~$1,000.

Thanks to all the comments here I concentrated on the turbo boost system. Found I'd not replaced a hose clamp on a pipe near the intake manifold. Didn't think anything of it before when problems first began, thinking the somewhat loose fit wouldn't harm anything - neglecting the effects of turbo pressure!

But mostly I finally located the turbo exhaust gate valve and linkage. Very difficult to find it, buried under the turbo unit. Managed to blindly feel the gate linkage by reaching up from underneath. Quite firmly stuck in position, partly open! Managed to get a crowbar tip up to the linkage joint and whack it to the closed position. Attached pressure gauge at the now non-functional waste gate valve hose on APC and now measure peak 21 psi up hill, whereas it was 11 psi (and smoking) before closing the waste gate.
Whine disappeared, power and RPM are back with moderate smoking which I should be able to tune out.
Since the wastegate control can't be removed without removing the turbo I'll just leave it closed. I don't think it was doing much over-boost limiting anyway.

Thanks so much for everyone's assistance! Crash course in turbo diesel mechanics lasting 18 days! Had I taken to a shop I am sure I'd be in for several thousand dollars and being an older RV it would've instead be sold as a hunting camp. We've seen many of these old RV's rusting away in back yards, not many on the road! I am 74.
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Old 10-05-2021, 02:10 PM   #14
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I've had my turbo off ( I am 72 ), and other than soaking all related fasteners; overnight in advance ; removing the turbo to free up a sticky wastegate isn't a huge undertaking .
On an engine with electronic controls ( ECM ) a closed wastegate isn't a huge issue : BUT : the mechanical engine , can't reduce power ( over boost ) by cutting fuel to reduce boost , I'd hate to see your next project be a head gasket .

Remember the wastegate got to it's, stuck partially open position, somehow.
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