6.2L Diesel Help

[J DeMaio]

Hi guys:



My 1984 Chevy Blazer with a 6. 2 diesel quit running on me the other day. It shifted from second to third, then just shut down. I have a full tank of good fuel, I changed fuel filter and fuel transfer pump and it still isn't working. I blew compressed air from the inlet on the lift pump back through the line to the tank, and it was clear of obstructions. I'm trying to get fuel to the system(bleed filter) but can't get any fuel.



It is similar to the scenario I had with my 92 dodge when the timing bolts came loose and snapped the cam.



Any help is appreciated.



John

 

[Philip]

Hi JD



I am not 100% sure on this. But I think the 6. 2's ran a timing chain with a plastic upper gear on them. You might want to check the timing to see if the gear might have went out and let the timing slip.

 

[Gene Arnold]

My 6. 2 quit about 100 miles from town and had to be hauled in (grateful for AAA). Turned out to be a broken shaft in the injector pump. Mechanic said it was the only one he'd ever seen.

 

[J DeMaio]

Thanks for the replies folks. But, doesn't the supply pump on these engines run off of the crank (that is what my manual said)? I know it's not the main pump because I can't get fuel from the lift pump up to the filter, I don't know whether the crank/cam is rolling or not. I outta just drop a 502 crate motor in her or take it to the crusher



John

 

[PKleine]

Are you sure you aren't getting any fuel to the injectors?



To verify this, loosen one injector fitting and then crank the engine with full throttle for about 10 to 30 seconds. You should see some fuel weeping out past the loosened fitting. Retorque the fitting to 20 ft-lbs.



If there is no fuel, be aware there is a fuel shutoff solenoid in the injection pump that is energized when the ignition switch is ON. Make sure the pink wire is attached to its connector. You might be able to hear the solenoid click as you cycle the ignition key on/off. With the ignition on, remove the pink wire and replace it a couple of times, you should hear it click when you do this.



Hope this helps...

 

[Philip]

I outta just drop a 502 crate motor

YEEEE HHAAAAAA let the good times roll. Make it a 575 HP to.



I was thinking the lift pump was run off the cam on those engine. I'll have to make a phone call and find out.

 

[lil red cummins]

if you have removed the supply line that runs between the lift pump and the injector pump and you have no fuel when you crank, you may need a new lift pump. aren't the lift pumps mounted pretty much in the same place as on a gasser small block? if so, as has already been said, if you loose the cam gear it won't pump. i think you can take the oil filler elbow off the front to see if the injector pump gear is turning.



i am going mostly on memory here since i havent worked on a 6. 2 for a few years. i may not be on the money with some of these recollections.

jim

 

[DHawthorne]

Before you do anything else, remove the check valve from the pump. The fuel return line hooks to it. 9/16" wrench. Look up thru the check valve at a strong light. If see debree in it, chances are thats your problem. The retainer ring in the pump is shedding some parts and is being trapped in the spring loaded glass eye in the check valve. If you restrict the fuel return on a 6. 2 the engine will shut down. Squeeze the fuel return line and you will see it shut down. If this is your problem,



Clean the eye or buy another. Install a inline filter between the pump and the check valve. Jame the check valve in the hose end and then install the fuel return line. Or, you can drill the eye out with a 1/4 drill and drive it for ever. If you drill it the truck will have more pickup and power. Negitives about this is you cruise control will hunt when engaged. The pump needs to have back pressure on it for the engine to run properly. So, I would install the filter.



If you just clean the check valve, it will just jam again if the pump is comming apart.



I use to keep a spare drilled out check valve in my truck for me or for another guy on the side of the road. I would trade him and drill it out and put it back in the truck for the next guy.



Hope this helps.



Dave

 

[bmoeller]

Silly question, when the new lift pump was installed, did the lever on the pump hit the camshaft on the correct side? I know it is a possibility on the Ford 6. 9L IDI engines also.

 

[keimmmo]

I have seen the problem of not getting fuel through the lift pump to fill the filter. It is actually a pretty common problem with the 6. 2. Problem is the lift pump is run off the cam and it takes way too much cranking to get it to take a prime and start pumping!



Loosen a fitting between the filter and injection pump. Apply LIGHT air pressure to the fuel tank. The possitive pressure should get the fuel flowing well enough to fill the system. From there the factory lift pump will usually take over and work fine.



If that fails, hook an electric fuel pump into the system near the rear of the vehicle to prime everything. After you get it started, you can shut it down and remove the electric pump.



Hope this helps.



Steve

 

[J DeMaio]

Guys I installed a new filter and lift pump. It said in my manual to remove the pink wire on the injection pump so It would not try to start while priming the system. That is what I've done thus far. I know there is a full tank of good fuel, the line from the tank to the lift pump is clear, but fuel isn't in the line, the lift pump is not sucking and putting fuel past itself and into the fuel filter. So, I'm thinking that the engine isn't turning. The pump was aligned and the arm was tight against the crank. Thanks for the replies,keep them coming.



John

 

[J DeMaio]

Guys:



Someone told me that there is a pushrod in this engine that runs the lift pump just like on the small and big block gassers. Is this the case?



John

 

[Khood]

Don't know if it will help,but sometimes it can be something simple

like a loose or corroded ground wire. I drove an '85 6. 2 for years.

Once checked the air filter and unknowingly loosened the fuel shut off valve on top of the pump. Shut down instantly! Just saying it could be electrical. Besides the way these shake ,alot more could be loose.

 

[DWest]

Kennedy Diesel

John: Look up Kennedy Diesel on the web, he knows GM diesels inside out and he's a big advertiser on the GM Diesel site. DW

 

[24VChev]

Yes the lift pump has a rod that runs from a lob on the camshaft, just like a gasser. The oil pump is also driven off of the camshaft at the rear, like a gasser. If you can build some oil pressure while cranking you know that the cam is still turning.





That large wire you pulled off the top of the pump should have 12V with the key in the run position. Make sure that you have power there.



Malcolm

 

[AWM]

I've had more headaches from 62-65 mech lift pumps, air leaks etc. than I'd care to remember, went to electric pusher pump ,(from early '90s 6. 5), no problems since. Bob

 

[britannic]

A quick way to check the lift pump, is to open the air drain (with a clear tube connected to it and directed toward a suitable container) on the filter and crank the engine, you should see fuel spurting out in short order. A restricted return line will shut the engine down quite quickly, in an emergency runaway 6. 2/6. 5L you would just bend a kink in the return line on top of the inj. pump to stop it.



Make sure all of the air is bled out of the system first (open the air drain on the filter and disconnect the pink wire, so the inj. pump won't pump air) and that there aren't any air leaks coming into the fuel supply line from the tank to the lift pump. It's not unknown for new lift pump to be DOA and when installing the pump, it's a good idea to use thick grease on the push rod to stop it falling down and getting behind the pump's actuating lever.



The DB2 inj. pump has a vent wire in the return circuit to purge air, so it's relatively hard to air lock unless the inj. lines have been off.

 

[DHawthorne]

"J" Like I said above and other people have stated, any restriction in the fuel return line will shut the engine down.

The issue with the push rod and the mechanical fuel pump has also been stated correctly. With my 85, I changed the fuel pump and still only had 3 psi fuel pressure. I checked the rod lenght and it was still OK. I figured the driving lobe was worn. I put an electric fuel pump in with a filter between it and the tank mounted inside on the right side frame rail. Pumps ran about 80k before needing replacement. There is also a filter in the tank on the pickup tub. You might also check the tank for junk.