1993 K2500 6.5 TD:


I had the injector pump rebuilt by a diesel shop and reinstalled. Truck will start when cold (although it might need new glow plugs). Truck will not hot start unless I add ether.


Any ideas? Very frustrated with this, thinking of converting to gas or selling if I can't get this fixed.

Replace all your battery cables. Replacing the cables will eliminate them as a possibility.


Starter could be worn out and not able to turn fast enough.Edited by: quantum mechanic

4911 pump? did they rebuild yours or exchange it? did you have a hard start hot problem before and did you tell the shop that?

1993 K2500 6.5 TD:


I had the injector pump rebuilt by a diesel shop and reinstalled. Truck will start when cold (although it might need new glow plugs). Truck will not hot start unless I add ether.


Any ideas? Very frustrated with this, thinking of converting to gas or selling if I can't get this fixed.


Your say will not start hot, Does it turn over and not fire off or does it not turn over. I believe these had to turn 100 RPM to make the pressure to start. so make sure all battery connections are good and cables and batteries are in good shape too. Draging starters cause alot of hot start problems too. This is just a check list so everyone can chime in with other ideas.

New starter, good batteries, good cables. Truck had hot start problems, then would not start at all. Don't remember the model number, but the pump was rebuilt and put back into service. It is a mechanical pump. I told the rebuilder about hot start problems. If I spray ether into the air intake, it will start after a few spins.

Black label pump should have had the 'green tag, blue label' upgrade, for starters, but was the timing set replaced at the time the pump was 'rebuilt'?


NOTE - ether can ignite and flash-back to the spray-nozzle at the can as the intake valve opens, exposing a path to the red-hot glow plugs.Edited by: gmctd

Black label pump should have had the 'green tag, blue label' upgrade, for starters, but was the timing set replaced at the time the pump was 'rebuilt'?





I have no idea what you mean by green tag, blue label, please elaborate.


Explain timing set. As to the apparent allusion regarding your quotes regarding the pump being "rebuilt", it was sent to a shop that specializes in diesel pump repair and overhaul with instructions to rebuild/overhaul. It was not given a "backyard rebuild".


Regarding the ether, I have not figured a way to simultaneously crank the engine from inside the cab while spraying ether into the air filter. I simply spray then go crank. Probably not the best for the engine, but it does start that way. Otherwise, I am left waiting until everything cools off enough to cycle the glow plugs and start the darn thing.

You say it won't start "hot". Explain "hot". Normal operating temp after being shut down for a few minutes? Does the glow plugs cycle when "hot" ? How long of a cycle on average ? just trying to see if something else besides just the pump. maybe something else over looked. I believe the 93 6.5 was mechanical pumps just like the older 6.2 were, except the glow plug cirucits were wired differently. There may be a chance that a glow plug sensor is bad maybe.Edited by: bowtie

You say it won't start "hot". Explain "hot". Normal operating temp after being shut down for a few minutes? Does the glow plugs cycle when "hot" ? How long of a cycle on average ? just trying to see if something else besides just the pump. maybe something else over looked. I believe the 93 6.5 was mechanical pumps just like the older 6.2 were, except the glow plug cirucits were wired differently. There may be a chance that a glow plug sensor is bad maybe.





Hot = running for a while and achieving normal operating temprature. GPs do not cycle when it is in this condition. It is a mechanical pump, no electronics on it.

there is a temp sensor in the glow plug circuit on pre '94s that keeps the plugs from running when the truck is supposedly "hot enough". this sensor may need replacing or checking.

Early 'black label' 4911 pumps were plagued by 'hot-start' problems, most of which turned out to be mismatched or bad batterys, bad cables\connections, dragging starters, etc.


Number of returns did show excess rotor\head clearances, enough to warrant several production changes.


Production pumps with revised rotor\head assys got blue labels.


Black label rebuilds were to get green tags, then blue labels replaced black, with revised numbers indicating rebuilds to new specs.


Rebuilds with new rotor\head assy is 300 bucks more than 'rebuild' without.


Have no illusions when alluding to allusions - the term was yours.......


Timing set - 1 chain, 1 crank drive sprocket, 1 camshaft driven sprocket


Usually required if engine has 75 - 100k miles, but some shops just advance inj pump timing, which does't help cam timing, exacerbating hard starts.


Edited by: gmctd

Timing set not replaced. Engine has 180k on it, but recieved a short block rebuild at 120 when down for a bad head. I think the timing set was replaced then (done by PO). I will check with the rebuilder to see if the rotor head assy was replaced.


Any other causal analysis? Should the glow plugs cycle when engine is at normal operating temp, shut down and starting attempted after 4-5 minutes? (they dont)

Plugs should go thru glow cycle briefly, even at hot.


Not sure where the gp coolant temp sensor is located on your engine, but it works in conjunction with the timing circuit in the controller to determine duration.


Follow one of the smaller wires - maybe green - off the controller till it hits a two wire sensor in the water jacket in one of the heads, probably passenger-side, or thermostat crossover manifold.

Plugs should go thru glow cycle briefly, even at hot.





Yes mine cycled 5-7 seconds even with a hot motor





Not sure where the gp coolant temp sensor is located on your engine, but it works in conjunction with the timing circuit in the controller to determine duration.





Check towards the back in one of the heads, on top in the valley, big round controller looking item, same location as on 6.2 ?





Follow one of the smaller wires - maybe green - off the controller till it hits a two wire sensor in the water jacket in one of the heads, probably passenger-side, or thermostat crossover manifold.





I believe these newer style of the old 6.2 system used a sensor that goes where the old controller was and looks just like the old controllerEdited by: bowtie

My '89 6.2 had the sensor in the t-stat manifold, just below the heater hose tap - yellow and black wires.


Glow controller was on driver-side head, rear, mounted to the studs for the plate which seals the coolant passage - same location as my '95 6.5TD.


Location could be same on '93, but wiring colors may reflect early PCM requirements for flame-proof wiring.


Should be able to trace one of the wires on the controller to the sensor.

If the truck starts cold, I think we can rule out glowplugs.


How much was your bill for the pump? ~$500 'standard' DB2 rebuild, ~$800 DB2 rebuild with new H&R. Do you have a copy of the workorder with a parts list perhaps? 29123 Heads which were in all the original 4911(turbo) and 5088(n/a) pumps. This head was found to have a problem with internal leakage causing hard start hot complaints. Updated 31506 H&R was the answer, but even if your pump already had the late style head in it, that doesn't mean it wasn't worn.

[QUOTE=Cullins]

1993 K2500 6.5 TD:


I had the injector pump rebuilt by a diesel shop and reinstalled.
Truck will start when cold (although it might need new glow plugs).
Truck will not hot start unless I add ether.

<>Any ideas? Very frustrated with this, thinking of converting to gas or selling if I can't get this fixed



Sounds like every case of a worn head and rotor, those pumps are
notorious forthat problem. They probably didn't put a new one in, you
can tell by how much the rebuild cost most of the time. When it turns
over do you get any smoke out of the tailpipe? If not there is the
problem, adding ether (badbad idea) gets the engine speed up and the
pump will make fuel.

Everyone of those pumps we do get a new H&amp;R just because of this,
it is near imposiible to get the real world heat soak like a truck
experiences while on the test stand in an A/C'd shop.

Brian.



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Is it possible that they reused his H&amp;R to hold cost down. Guess they bill or the total cost might show exactly what was replaced. I'd be interested in figuring this one out for future referrance

Blalley makes a good point, I've seen this occur as well, the technician may have inspected the H&amp;R and determined is was not the cause of the hard start hot condition, and just replaced the delivery valve/spring and on the test bench with a fuel temp of 115-120 it passed specifications. Its been my experience that if you don't get atleast 35ccs instead of 28ccs (I think thats spec for 4911) you are risking a hard start hot complaint, and these pumps you have to be especially careful because they are so notorious.

Blalley makes a good point, I've seen this
occur as well, the technician may have inspected the H&amp;R and
determined is was not the cause of the hard start hot condition,
and just replaced the delivery valve/spring and on the test bench with
a fuel temp of 115-120 it passed specifications. Its been my
experience that if you don't get atleast 35ccs instead of 28ccs (I
think thats spec for 4911) you are risking a hard start hot complaint,
and these pumps you have to be especially careful because they are so
notorious.



Add being down a few cc's on start and a slightly slow cranking spped
and it will definatley cause a problem. I like to check just real quick
battery/cable/starter condition. Unplug pump so truck will not try to
start, then with truck already hot, crank it over. If it will not make
an honest two dozen revolutions before the cranking speed slows down
there is most likely a problem in the starting system also.

Brian.

I agree completely, cranking speed is essential and cranking delivery drops off dramatically if the pump is not rotating fast enough. Transfer pump needs speed to build pressure to fill the pumping plungers and more fuel can leak from the H&amp;R delivery port at lower speeds. Any fuel shop will know this and want to see the vehicle to verify cranking speed and supply system before diagnosing the pump as the fault.