Isuzu 3LB1 / Powertech Gen. Issues

[GZM2024]

Hello everyone.
I am seeking some expert advise on what I may have done wrong. I have a 1998 Isuzu 3LB1 / Powertech 8kw generator. It has been sitting for a few years when I got it from my uncle who bought it new in 98'. The gen. would not start so I pulled the injector pumps and found the #1 pump (towards front end of engine) to be locked up solid. I pulled the pump down, cleaned and reassembled. I re-installed all 3 pumps but in doing so, I had to slide the fuel rail / rack slightly to align the pins into the slots on the rail. On the last pump, I slid the rail all the way towards the front of the engine and it snapped into position and stayed there until I manually pulled the rail back towards the rear of the engine. I continued re-adjusting the pumps sliding pin until it slipped into the rail / rack slot.

After everything was hooked back up, I thought, ok, I have it now. After 3 failed start attempts the engine finally fired up but went to full throttle and puffing huge amounts of black smoke. My overspeed light came on and the master switch would not turn it off. I finally got it to shut off after unplugging the fuel shutoff solenoid. This generator has always ran perfectly so I have not bothered re-adjusting the governor or anything. Whatever reason it is going to full throttle has to be something I did wrong with manually sliding the fuel rail / rack back and forth I'm guessing. It feels as if the governor is stuck wide open.

My question is......Can someone please tell me what I could have done that has caused this thing to rev out of control?

[Mickeyrouse]

Fuel injector pumps are extremely precise devices. Your engine appears to use the same common rail injector system as my Isuzu 4LE2 main propulsion engine. Each injector pump is adjusted- tuned- by shims between the pump body and the mount on the engine block. The number and thickness of each shim should be unique to that particular injection pump in that particular location for its designated cylinder. If you removed them to clean them, there is a fair chance they didn’t go back in the same place with the same shims. Sounds like you will need the help of a diesel injection mechanic familiar with common rail systems, preferably Isuzu. You may have other issues as well with injectors (and/or pumps, lines, governor, , etc) being clogged after a multi-year lay-up.

[GZM2024]

Originally Posted by Mickeyrouse

Fuel injector pumps are extremely precise devices. Your engine appears to use the same common rail injector system as my Isuzu 4LE2 main propulsion engine. Each injector pump is adjusted- tuned- by shims between the pump body and the mount on the engine block. The number and thickness of each shim should be unique to that particular injection pump in that particular location for its designated cylinder. If you removed them to clean them, there is a fair chance they didn’t go back in the same place with the same shims. Sounds like you will need the help of a diesel injection mechanic familiar with common rail systems, preferably Isuzu. You may have other issues as well with injectors (and/or pumps, lines, governor, , etc) being clogged after a multi-year lay-up.

Thanks for your reply. I actually marked each pump as I pulled them to ensure they all went back into there correct hole. I also followed this video step by step as I re-assembled my pump. I them tripled checked everything to ensure I did not miss anything. I am thinking it must be something to do with the governor / rack rail but I am not sure.

https://www.youtube.com/watch?v=trXaLmwqEkk

[skipperpete]

My question is......Can someone please tell me what I could have done that has caused this thing to rev out of control?

Sorry to hear about your incident.
In the first instance, you should have bought a new injector pump on ebay for $200 (or 3 for $500) or taken the 3 pumps to fuel injection tech and had them serviced for probably the same price as the new ones, and for future reference, always be ready for an overspeed if you mess with an injector pump.... particularly on gensets where a high rotor speed can do damage to the stator. Its usual to have clear access to the air intake and a flat piece of wood to choke the air supply. Alternately, if the air intake is too hard to get to quickly.... and I do mean QUICKLY, consider putting a ring spanner on each of the injector pipe nuts in a vertical position if possible but horizontally off the injector pumps is just as good if the sound shield is restrictive. Only ring spanners, they won’t fall off as the engine spools up and you can quickly loosen the 3 nuts before reaching the moment when its wiser to put some space between you and the rapidly accelerating engine.
The simplest way to avoid all this drama is to spin the engine over with all the injector pipes loose until fuel appears at the connections ... THEN activate the stop mechanism and spin er over again...... no interruption to fuel flow means you cant shut it down and an overspeed is possible.... BUT , NO FUEL means no overspeed ....
its still entirely possible that you had a high idle overspeed, not usually destructive, just heart stopping.

[Rider8965]

Hi
Did you manage to sort the problem out? I’m having a very similar problem with my Isuzu 4LE1 after doing injector pumps.
Many thanks