Bad Injection Pump? [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: Bad Injection Pump?


rfolea
05-31-2010, 02:59 PM
Hi Guys,

New here, but have found the info here stellar.

Inherited a 1982 Chevy Silverado, 6.2L Stanadyne DB2829 4274 J

Was only used once or twice a year by my father-in-law. I rarely used it, but it always started REAL easy (over several years), never gave me any trouble.

My son had truck out in the fields one day and it simply would not start after sitting for a while. Killed a battery trying to get it to re-start.

He was on a steep hill and low on fuel so I assumed he got air in system.

Followed all the instructions here to get the air out of the system (after cranking until the batteries died didn't work ...):
1. Applied pressure to return line to clear air past first filter.
(Used clear tube out of filter into bottle so I could watch the flow)
2. Replaced 2nd filter (filled it with oil before replacing.

3. Cranked engine until oil out of 2nd filter was clear of air bubbles

4. Reattached hose to IP inlet, detached one injector line at
IP and attached Clear hose so I could see what came out.
Cranked many times for 5-8 seconds each.
>> NOTHING.
5. Pulled a couple glowplugs - no fuel mist out of any.

6. Opened top cover of IP. Full of fuel.

7. Tested fuel cutoff solenoid on work bench (applied 12V)
>> Works Great

8. Test solenoid in system - Works great
(Removed pink wire and reattached with key in "on" position - could hear definite audible click)

9. opened Top cover of IP sucked oil out with a turkey baster.

10. Cranked engine. IP fills with fluid VERY slowly.
Maybe an 1/16 inch per 5 seconds of cranking.
Can see shaft spinning.
In retrospect I didn't move the govenor/fuel shut off ..
but without the solenoid it should be open...

11. I attached a clear hose between the 2nd filter and the IP. Intentionally left a small air bubble in it. Cranked engine. NO FUEL is entering IP. (bubble did not move) Solenoid is getting 12VDC and clicking when I remove/replace pink wire.

12. Removed IP from engine

13. Turned by hand. Fuel shoots OUT of INLET. There is a squirt out, then a small suction in. Repeats every turn. No pressure crreated on ANY of the 8 outlets. Very easy to turn even though it is full of oil.

14. Manually moved govenor forward (away from inlet). Now when
I turn by hand, I can feel the pressure build up, see fluid getting sucked into IP and there are small squirts of fuel out of the outlets. Very small squirts, maybe a few drops, but is definitely trying to squirt.

The above is a paraphrased version of 2 days of dorking with this ...

Q1: Before I tear into this thing, does anyone see anything obvious I have missed?

Q2: The linkage inside the top of the IP: When I rotate the black metal tab towards the inlet, it sticks (the position it would be in if the Solenoid was off). I kinda expected it to spring back when I let go. If I nudge it, it does go back, but it is not real happy about it. Should this linkage spring to the open position?

Q3: Where is the plastic part everyone keeps talking about. I thought that was supposed to be part of this pre 1985 unit (or was it just the 1985 units that had it?)

Q4: Can anyone recommend a source for a rebuild kit (assuming that is necessary)?

Q5: If kit is an option, is this a doable job by a backyard mechanic? This site seems to imply it can be done, many others say don't even try it - too many fine calibrated adjustments.

Q6: If not rebuild - can any one recommend a reputable re-man outfit?

Thanks for your time!

p.s. Pictures are in the attached pdf

whisky runner
05-31-2010, 05:15 PM
are you getting good fuel from the lift pump to the secondary filter..do you have dual tanks and are sure the switch is working..

rfolea
05-31-2010, 06:12 PM
Yeah, Good fuel delivery all the way to the IP.

Does have dual tanks.

4320Diesel
05-31-2010, 06:22 PM
the ip wont shoot fuel out the high presure outlets just while turning it with your hand. i noticed mine wouldnt shoot fuel out yet it worked on the truck.

sls639
06-01-2010, 08:26 AM
sounds like the linkage is sticking. Be sure to replace the cover correctly, place forward about 1/4" then slide back into place.
Might try wiggling the linkage around to loosen.

rfolea
06-01-2010, 10:22 AM
sounds like the linkage is sticking. Be sure to replace the cover correctly, place forward about 1/4" then slide back into place.
Might try wiggling the linkage around to loosen.


Thanks. The linkage is definitely sticking, actually dragging. It's not getting stuck at one small area, it is dragging for the last 1/3 of the throw.

Have been installing the cover correctly, sliding back into place from front rear, so I know that is not the problem.

Sounds like maybe I just need to take it part and clean it real good.

But the linkage SHOULD be free to rotate and spring back - right?

whisky runner
06-01-2010, 12:37 PM
i just checked 2 of my pumps i have off ..and on niether one does the linkage return on its own without the throttle return spring on..

rfolea
06-01-2010, 01:52 PM
i just checked 2 of my pumps i have off ..and on niether one does the linkage return on its own without the throttle return spring on..

Interesting.. That is what I am seeing too - throttle does force it. So that appears to be normal ... Hmmm...

I'm beginning to wonder if maybe I just needed to prime the pump.

I may just stick it back in now that it appears to be pumping and see what happens.

Thanks ..