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977 20A D318 fuel injection pump/rack

977 20A D318 fuel injection pump/rack

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haywood
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Ok so my naturally aspirated 20A seems to be weak on power.

I cracked injector lines while machine running and discovered number 3 wasn't doing very much.

Also did a compression test (got 350 on number 3 and tested #2 got 350 as well)

Smoke coming from machine seems to be fairly clear to me it seems like the thing isn't dumping much fuel to it, I have a tough time getting a bucket full of dirt or climing a hill in 2nd gear with some dirt in bucket.

I ran the injector threw an ultrasonic cleaner and switched it #2 and #3 out and didn't see an improvement on the number 3.

Also tried attempted to observe the spray pattern coming from injectors by hooking it up to pump with injector removed didn't have much luck on either one.

I'm a little in the dark with the injection pumps, my fuel pressure gauge reads good, haven't changed any fuel filters in the machine yet, but the baskets in the injectors were clean.

I'm suspecting a stuck plunger on the number 3 but am trying to get more educated on the whole system and common problems and issues.

Any suggestions or tests to try? Things to look for? I'm guessing the access cover comes off next unless a pump rebuild is suggested, but my fuel pressure is OK according to gauge, needs adjustments?
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Sun, Sep 8, 2019 9:01 PM
d9gdon
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Just take the access cover off and see if any of the plungers are stuck. You can start it up and watch them pump. Spray some penetrating oil on the plunger and work it up and down to loosen.

The fuel pressure gauge is only measuring the pressure from the transfer pump, not the injector pump.
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Sun, Sep 8, 2019 10:38 PM
Old Magnet
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Reply to d9gdon:
Just take the access cover off and see if any of the plungers are stuck. You can start it up and watch them pump. Spray some penetrating oil on the plunger and work it up and down to loosen.

The fuel pressure gauge is only measuring the pressure from the transfer pump, not the injector pump.
@350 psi compression that is way to low and would be difficult starting,
At cranking speed you should see 530 -560 psi compression pressure
About 500 - 635 psi at low idle running speed.
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Sun, Sep 8, 2019 11:40 PM
haywood
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Reply to Old Magnet:
@350 psi compression that is way to low and would be difficult starting,
At cranking speed you should see 530 -560 psi compression pressure
About 500 - 635 psi at low idle running speed.
[quote="Old Magnet"]@350 psi compression that is way to low and would be difficult starting,
At cranking speed you should see 530 -560 psi compression pressure
About 500 - 635 psi at low idle running speed.[/quote]

crap

thought 350 was purdy good was thrilled when I saw it maybe machine is more tired than I thought
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Mon, Sep 9, 2019 8:10 AM
haywood
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Reply to haywood:
[quote="Old Magnet"]@350 psi compression that is way to low and would be difficult starting,
At cranking speed you should see 530 -560 psi compression pressure
About 500 - 635 psi at low idle running speed.[/quote]

crap

thought 350 was purdy good was thrilled when I saw it maybe machine is more tired than I thought
Are you sure those numbers are supposed to be that high? This is a naturally aspirated engine not turbo charged...…..wondering if the spec you gave was for a turbo charged engine
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Tue, Sep 10, 2019 8:07 PM
Old Magnet
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Reply to haywood:
Are you sure those numbers are supposed to be that high? This is a naturally aspirated engine not turbo charged...…..wondering if the spec you gave was for a turbo charged engine
Those number are specifically for the N/A D318 with approximately 17:1 compressions ratio which is low for a Diesel.
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Tue, Sep 10, 2019 10:06 PM
haywood
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Reply to Old Magnet:
Those number are specifically for the N/A D318 with approximately 17:1 compressions ratio which is low for a Diesel.
would a cylinder head that had glow plugs in it change much of anything?
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Wed, Sep 11, 2019 2:05 AM
Old Magnet
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Reply to haywood:
would a cylinder head that had glow plugs in it change much of anything?
no difference.
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Wed, Sep 11, 2019 2:09 AM
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