Discussion in '1982-Present GM Diesel' started by René, Mar 27, 2002.
Is there a difference between the injection pump of a C -, J - , or Hummer engine?
What little I know: There are a variety of DS-2 injections pumps, physically identical but calibrated slightly different depending upon application. The Diesel Page listed quite a few. I checked my TMs and CUCVs and HMMWVs had even more different part numbers. Because of the way diesels operate, my guess is the heavier duty applications are more likely to be DErated in output (keeps the foolhardy from burning the motor up).
In addition, there are two pumps that physically differ from the rest. The DS-2(?) used on the 6.5 before they went electronic with the DS-4 pump and the DS-2 models that were built for ARTIC use with hardened (expensive) internals for use with thin diesel/kerosene.
The mechanical pumps are the DB-2 pumps. The electronic pumps are DS-4.
There are quite a few different pumps for the different years, in both heavy duty and light duty versions. Very slight differences though.
The main difference in the military pumps is the 24 volt fuel shut-off solenoid.
Actually only the HMMWV uses the 24V fuel solenoid and HPCA, the CUCV is still 12V. I've swapped a few pumps back and forth (between CUCVs & HMMWVs) by changing the solenoid and HPCA, never noticed any performance difference. Initial injection timing has a much greater effect on performance.
Check my profile, I no speak crap!
Which says Dan is correct. Only the pump of the HMMWV has fuel solenoid with 24V. I installed recently such a pump into a M1009 and used 3 hours for finding the error. The engine didn’t want to start...
My question was, because I can’t determine different performances in practice. Only models with internal EGR are clearly slower.
With my own engine I’ve large problems. It starts very badly with cold weather. I must one minute glow, then by hand far glowing and start. After 15-20 seconds the engine begins to run, but very hard and my neighbourhood is located in bright smoke.
I checked the fuel pipes for leakage, found no bubbles in the return, and controled the low pressure pump (sucks more than 12 in Hg and push 8 psi). With the injection pump (DB2) I’ve my problems:
Can I measure the system pressure of the pump, and where? How highly does the pressure
has to be?
Is there an increase of the fuel amount for cold startings?
How much is degree before ATDC the beginning of injection?
I ve seen that te marks on the pump flange and the front cover was in a line, so the pumpe should be on ATDC. Now I placed the timing a little earlier (0.15 in to the right) and the engine runs many more softly. But the start problem only changed. Now the engine starts faster but idles not on all zylinders for one minute.
I hope you have still ideas.
Rene, check your high idle solenoid / HPCA for power when it's cold. If the thermo switch goes bad it won't energize. Likewise if the HPCA (small solenoid under the cover of pump) isn't working it starts real hard on cool mornings.
high idle solenoid is clear, but what is HPCA ? Is it contacted by a green wire?
When I shut off this wire, I can hear a “click” and the engine runs clearly more roughly. That is also like that, if the engine is warm. That the high idle sol. is broken might do anything. I must give a littlebit gas only the first minute.
How far are the markings apart at the pump and the cover (timing) with your
Thanks very much
The High Pressure Cold Advance is also on that green wire. This advances the timing during warm. From what you say, it sounds like it's functioning.
I'll have to look at my truck for the timing marks. We use an actual timing meter to dial it in. I don't think the eyeball measurement is very accurate.
Ok that will be it. I have a green wire that’.s hot in start and run. This goes over a sender (I think water temperature) and HPCA to the high idle solenoid. If the engine is cold, the wire has 12V, if it’s warmly still 8V. Is this right?
How highly does the housing pressure have to be? 11 psi?
Unfortunately I have not a timing meter that fits the DB2, but normally 2° more or less constitutes not so much. I ve tested this at a Volkswagen Rabbit this day.
I fear already that the pump is installed incorrect. [censored]!
Thanks a lot, but I’m completely helpless…
Perhaps you should buy yourself a real good truck like my CUCV.By the way, i have one to sell......
And don´t forget, your Suburban is a California model, perhaps it doesn´t like cold wheather????
Greetings from chevyuser
Separate names with a comma.