QuestionI own a 1987 GMC Sierra Classic 6.2L Diesel. My question is how do you go about removing the entire fuel Injector pump. My old pump had a leak and I purchased a rebuilt one and need to remove the old one and replace the rebuilt one. Can you give me step by step directions on how I can do this? Or if you have pictures on this it would also help. I was told by my wife that if I have no direction do not do thejob. So could you please help out? You can email me the information at the above email address.
Thanks for your help and time.
Bruno
AnswerBruno,
If you added an e-mail address, it did not make it through with your question.
The steps are as follows:
First, keep everything as clean as possible. Contamination below 30 microns, which cannot be seen by humans, can destory a diesel fuel injection system. Clean everything off anything having to do with connections on the fuel system and cover any connections left open.
Begin by removing the intake manifold. This will remove the clips holding the injection lines passing underneath and around the intake runners. After removing the manifold, cover the openings in the cylinder head (I use wadded-up paper towels).
Next, remove the clips at the brackets on the injection lines closer to the injectors.
Loosen all of the injection connections at the injectors. Do not remove the lines.
You can remove the water crossover tube if it is in your way, but drain about a 1/2 gallon of coolant before your remove the crossover.
Remove the oil fill tube from the timing cover. Turn the engine clockwise, using a 15/16" socket and ratchet (or breaker bar) on the center bolt of the crankshaft. As you turn the engine over, a bolt will show up at the opening where the oil fill tube was removed. Remover the bolt and keep turning the engine over until you have removed all three bolts. Do NOT use the starter to turn the engine over and, after removing the third bolt, do NOT turn the crankshaft any more.
On top of the timing cover, behind the rounded top, is the place where the injection pump is bolted to the cover from the back side. Clean the top of the timing cover where it meets the injection pump and look for a thin line scribed into the cover and one on the injection pump. Note the position of the two lines (they are usually aligned) for reassembly.
Remove the throttle cable assembly from the injection pump. Remove all the wires from the pump and note which connection the big pink wire goes to. The other wires will be green. Remove the return hose at the top of the injection pump.
There are three nuts holding the injection pump to the timing cover and you will need a 15mm socket and/or wrench to remove them. When you do, the injection pump and injection lines can be removed as a unit. Note the position of the driveshaft of the injection pump to set the new one the same way. If you are not going to put things back together right away, cut up a plastic garbage bag and make covers for the injectors. Secure the covers with rubber bands or nylon cable ties to keep dirt out of the injectors.
Carefully transfer the injection lines to the new pump. It is possible to cross them up so pay close attention while moving the lines. Transfer the fuel inlet pipe to the new pump and whatever device is mounted on the passenger side of the old injection pump to the new pump.
Get a new injection pump to timing cover gasket and install it over the timing cover studs. Install the new injection pump after setting the driveshaft to match the holes in the gear inside the timing cover. The pump can only be installed one way since it is indexed to the gear. Reinstall the nuts on the studs and set the timing marks to the same position they were when you removed the old injection pump (the lines on top of the timing cover and the flange of the injection pump). Tighten the mounting nuts. Make sure that all the injection lines line up at their injectors, but do not tighten the connections at the injectors yet.
Put the first bolt back into the gear through the oil fill tube hole. Hand tighten it and then turn the crankshaft clockwise as before to install the remaining two bolts. Then, tighten all the bolts securely and resinstall the oil fill tube. Reinstall the throttle connections on the injection pump.
Install a new piece of 1/4" fuel line from the fuel filter to the injection pump (the old one is usuall brittle since it never gets changed). Remove the covers over the opening in the cylinders heads and reinstall the intake manifold using new gaskets.
Reinstall all the injection line clips that were removed and the coolant crossover tube (if you removed it and don't forget to add coolant to the radiator). Reconnect all the wiring on the injection pump, except for the big pink wire. Install a piece of clear tubing on the top of the injection pump and connect it to the return tee in front of it (where you removed the rubber hose from the old injection pump).
Now comes the fun part: Disconnect the glow plug relay connector (two small wires in a connector) from the middle of the relay. The relay is usually on the driver's fender and close to the battery.
Crank the engine, in short bursts, until you see fuel in the clear tubing on top of the injection pump. When you do, reconnect the big pink wire on the injection pump. Continue to crank the engine in short bursts (allowing the starter to rest between cranking cycles) until you see fuel dripping out of the injection lines at the injectors. When you do, tighten the connections where fuel is dripping. When all lines have been tightened, reconnect the glow plug relay connector. Remove the clear tubing on top of the injection pump and reinstall the fuel line that was removed from that location.
Then, try starting the engine normally. If it will not start, try some WD-40 down the intake. You can use ether, but you MUST disable the glow plugs be removing the connector at the relay.
The engine may run rough or stall at first but it should smooth out after all the remaining air comes out of the system.
Torque values are as follows:
Intake manifold: 25-37 ft-lbs
Gear bolts: 13-20 ft-lbs
Injection pump mounting nuts: 25-37 ft-lbs
Injection lines: 15-24 ft-lbs ("wrench tight" is fine)
Injection pump fuel inlet fitting: 15-20 ft-lbs
