6.2 won't stay running

[tommythefarmer]

I have a 83 blazer with a 6.2 Diesel engine it fires but won't keep running as if the fuel gets shut off. I've changed the fuel pump to no avail. I have an electric lift pump on the fuel tank to help prime I just wondering if I'm missing something easy any help would be appreciated

 

[CrpMag122]

Maybe a stupid question but did you check the fuel filter? And by the fuel pump do you mean on the injection pump?

 

[blazinzuk]

Or check for leaks in the fuel system

 

[tommythefarmer]

Has two filters they are fine. I changed the mechanical pump on the engine. It'll fire up for a second and quit like someone hit a switch. I'm assuming there's trouble in the injection pump.

 

[diesel4me]

Might be the fuel shutoff solenoid is not getting enough voltage to open fully,or maybe it just died...you could use a jumper wire from the pink wire on the injector pump that plugs onto the solenoid to the battery positive and see if it'll fire up and stay running..
If the return line from the injector pump plugs up,that can kill the flow of fuel and shut it off too...

I had to take off the top cover of the injector pump on my '85 Suburban's 6.2,it sat long enough to let the lever inside that shut off solenoid moves to get gummed up...the solenoid was "sticky" and I sprayed it with carb cleaner and moved the linkage inside by hand until it freed up,then I was finally able to start it..its rather scary knowing an electrical solenoid is swimming in a pool of fuel inside the injector pump housing...if one ever shorted out and got hot enough---...

 

[tommythefarmer]

This trouble started all at once losing power ect I limped it home and I've been messing with it on and off for weeks. Diesel is not my strong suit. If this persists I'm selling or re powering with a small block chevy

 

[diesel4me]

I understand your situation,I was there once myself..don't be too hasty,it may not be anything major or costly..


I knew squat about diesels when I got my first 6.2 in 2003..
I knew gas engine inside and out,had done swaps,rebuilt a few,but diesels,all I knew about them was they ran on diesel fuel and high compression instead of spark plugs...not much else!..

I was ready to do the same thing,swap in a 350 I had,if I failed to get the 6.2 to start...mine was dead when I got it,someone installed a "good" used engine from a salvage yard,then couldn't get it to start,got pissed,and sold the truck to me cheap--they knew nothing about diesels either I guess!..
Some members here like tRustyK5 and some others guided me along and I learned how to rig up a push button for the glow plugs..and some other tips on getting it "primed" to start..

I finally got it to run after I chopped off all the hack "plumbing" someone did to to dual tank setup,and put the main fuel line and return line in a plastic jug with diesel, and finally got it bled out,and to start, using starting fluid as a last resort...then I just ran a new hose to one tank ,and deleted all the switches and hoses the previous owner had jerry rigged...one tank leaked and was junk anyway,and I never go far enough or could afford to fill two tanks..

Even if you think the filters are fine,they can plug up fast--all it takes is one tank of dirty fuel,or water in the fuel...I neglected to change the filter on my pickup until I got stranded 15 miles from home about a year ago--cost me $100 tow,plus $20 for a new filter...the Wix one was still on it that was there when I got it......

I cut it open and it was FULL of sooty crap and the inside of the canister was flaking off in big chunks..I had driven over a very rough road just before it died,I assume all the crud got shaken up and lodged in the filter paper element..

I would take off the return line hose at the injection pump and blow compressed air into it,if its plugging up it can cause what your experiencing,so can the fuel shut off solenoid,or any air getting into the fuel lines between the tank and injector pump..sometimes a rubber hose will have its lining get soft collapse inside too,diesel has that effect on some hoses..

 

[tommythefarmer]

Thanks for all the input I'll give it another go keep you informed

 

[campfire]

Any update?

If it fires but won't run, it's probably not getting fuel. If you're 100% sure that it's not either of the filters, I'd be looking at that fuel shutoff solenoid or the injection pump.

If you're sucking air the engine will surge and die as air bubbles displace fuel. Run the electric priming pump and open the petcock on the top of the larger primary filter on the firewall. See what comes out. If this is flowing well, pull off the return line from the IP and see what flow you are getting there. If you see air bubbles or low flow rates, you will have found your problem. If not, post back up and we'll talk you through more diagnostics steps.

 

[campfire]

Note...the primary spin-on filter is upstream of the mechanical lift pump. So if you crank the engine with that petcock open it will fill the line running to the IP with air. The electric pump is your friend.

 

[paratrooper307]

Might be the fuel shutoff solenoid is not getting enough voltage to open fully,or maybe it just died...you could use a jumper wire from the pink wire on the injector pump that plugs onto the solenoid to the battery positive and see if it'll fire up and stay running..
If the return line from the injector pump plugs up,that can kill the flow of fuel and shut it off too...

I had to take off the top cover of the injector pump on my '85 Suburban's 6.2,it sat long enough to let the lever inside that shut off solenoid moves to get gummed up...the solenoid was "sticky" and I sprayed it with carb cleaner and moved the linkage inside by hand until it freed up,then I was finally able to start it..its rather scary knowing an electrical solenoid is swimming in a pool of fuel inside the injector pump housing...if one ever shorted out and got hot enough---...

Solenoid problems were very common on 6.2 and 6.5 HMMWVs in Iraq. The heat would cause fuel vaporization issues, which would ultimately kill the solenoid. When the solenoid went, you knew the injection pump probably wasn't far behind, because at that point it had been starved for lubrication (JP8 fuel doesn't lubricate as well as diesel to begin with) and the vaporization issues just added to that problem.