I'm looking for some help with my 1991 Chevy K2500 w/ the 6.2 L, vin J with about 130,000 miles on it. If I run the truck and shut it off for about 2 hours on a hot summer day she won't fire up easily or at all. Sometimes it takes 3 - 4 long cranks and in some cases won't start until the engine cools down completely. I can not figure what is going on here. About 1 1/2 years ago I went through the fuel system (i.e. installed rebuilt injector pump, injectors, fuel pump, fuel pump relay, and oil pressure switch). The pump is lined up with the timing mark too. Recently I swapped out the shut down solenoid with a spare one and that did not help. I changed out the original starter, as I read on the forum that as they get older they draw more power thereby starving the shut down solenoid of the 10+ volts to turn it on. This did not help. The batteries were load tested too so the batteries are fine.


I am assuming the rebuilt injector pump was "bumped" up to flow more fuel through and don't know if it would cause it to run too rich (i.e. chokes)? Is that possible?


On cooler days (i.e. under 60 to 70 degrees) the truck starts easily and runs strong.


I appreciate in advance any help, thoughts, or comments.


Thanks,


Glen

Glen,


I have a 82 chevy with the same problem. It has to be a really warm day but mine will do it too sometimes. I'm not really sure what the problem is I was told by one mechanic that glow plugs on these 6.2 s is really important. There is a bi-metalic strip like that on a thermostat in your house. Sometimes it doesn't work right and it won't trigger the glow plugs. I don't know though, anybody with any info would be greatly appreciated.


thanks Justin

usually that is the sign of a tired pump, as they heat soak the clearances inside the pump open up enough to not create enough fuel pressure at cranking speeds.

If your truck starts fine when its cold but won't start when its hot it has nothing to do with the glow plugs. Grape is on the right track, its the pump.

Read through the posts under:

6.2L wont start (for some reason this is in the 6.5L list of forums)

oh and something else, lots of times when shops rebuild pumps they don't do the head, this is where the no-start problems are, so just because your pump has been rebuild doesn't mean its not the problem.

one way to check if its heat soak causing the orifices in the pump head to become oversized is to make sure the engine is already up to operating temperature . turn the engine off and let it set till the the problem occurs, take a pitcher of ice water and slowly pour it over the pump head (where the injector lines connect to the pump) very slowly, mabe two or three to cool off the pump head. then try to crank it. if it starts your pump head is worn out. if not youve got other problems. possibly a glow plug controller, air in the return system ect. try this , if not we'll go else where with it.

I think grape, jjw565, and fixitman have nailed it down in regards to the pump head being worn even after the rebuild. It makes sense as prior to installing the replacement injection pump I never had a problem with "heat soak", but rather it no longer had the power it use to. I'll try the trick of pouring ice water on the head of the pump to see if it fires when this condition arises. If this test does work the only bright side is I kept my original worn pump and I'll know better what to look for in a rebuilding shop. I'll keep everyone posted and very much appreciate the input.

A gallon of tap water will do it. Just let it sit a coupla minutes before you start it. The head in the pump can seize if you try it to soon. Water on it while running hot will seize it to.

I'd like to add that if it still has this problem after you pour water on it that it could be what's called vapor lock , your fuel lines dont have the cover anymore at the tank switch , the fuel lines could be 2 close to the exhaust system , fine when its cold ----forever but shut it off ---vapor lock's -----then cools down and starts again , I have seen the pump gone lots of times but also seen this problem .

hope it help's
ps you can also vapor lock your brake lines as well , but i wouldnt reccomend

Doug Gritner
Doug's Repair
Alexis Creek
British Columbia
250-394-4578

Do the glo plugs cycle on?


My '84 has the same problem. The glo plugs do not come on at all on a hot day if I've been driving it in the last two hours. Makes running errands a hassle.


I take a screwdriver and manually short the GP solenoid for 5 seconds and it starts like a champ.


Time for manual pushbutton on the dash http://www.dieselplace.com/forum/smileys/Wink.gif

The glow plugs are not required when your engine is warm. The thermostate controller on the right rear head prevents the glow plug solenoid from being activated. If your engine will not start when it is hot then your injection pump is probably worn out.

A tired pump cannot be the only reason. My pump was rebuilt and controller replaced 15,000km ago and has needed glow for warm starts the whole time I've owned it. http://www.dieselplace.com/forum/smileys/Ermm.gif

Good topic. I'm listening http://www.dieselplace.com/forum/smileys/Thumbs Up.gif

u2slow: I don't understand why you are having a starting problem on a warm engine unless your pump is defective or maybe your fuel injectors. You can have a bad rebuilt pump. If the injection pump piston is putting out 1,500 PSI then the diesel fuel will be atomized and ignition will happen automatically in a warm engine without any benefit of a glow plug. That it is the way it has worked in every diesel engine that I have owned. I don't doubt what you are saying.


It may be that your fuel injectors are leaking when they are warm (or cold for that matter) so that the fuel pressure never builds up to the point where the fuel is atomized. Maybve your fuel is just squirting out. The fuel injector tips are spring loaded to release at about 1,400 to 1,500 PSI as I remember and if the pre-chamber is hot then combustion is automatic. If you think your injection pump is good then I would pull the injectors and have them checked or probably overhauled since it wouldn't be that much more. I have about 215K miles on my injectors and a some injectors don't get much more than 100K so I am running on borrowed time. I have overhauled Mercedes diesel fuel injectors, but I have never taken a Stanadyne injector apart so I don't know how the parts wear, but I know the principal of operation.


Good luck on solving your problem and I would like to know how you resolve it.