I have a 6.2L diesel in my Blazer that surges rapidly whether it's cold or warmed up. If you run it up just a little past idle ( I don't know how much, no tach) it smooths out. Anyone have any idea what's going on? Thanks.

Ever replaced your fuel filter?

Both fuel filers & air filter.

check your timing advance and you might want to run a bottle of marvel mystery oil through the tank when you fill up next.

I'll look into that. Is ckecking the timing something that I'm going to need a service manual for? I've never dealt with a diesel before & the truck Chilton manual I have for that era don't mention that engine. I've been told I should run some Seafoam through it also. The trouble with running anything through it right now is that it's not on the road & only runs periodically.

Do you know exactly what engine is in your truck, as in who made the engine and what model? Sounds like it may be an injector issue to me, maybe even a fuel pump. Most diesels have 2 fuel pumps, One is an injection pump which is a high pressure pump that sends fuel to the injectors, the other is a lift pump that gives fuel to the injection pump.

All I know about it is it's a stock 6.2L. I wasn't aware that there are 2 pumps on it but someone had suggested to me that it may be the pump. Another guy told me I should just raise the idle to stop the surging. I thought I'd better ask around a little more.

All I know about it is it's a stock 6.2L. I wasn't aware that there are 2 pumps on it but someone had suggested to me that it may be the pump. Another guy told me I should just raise the idle to stop the surging. I thought I'd better ask around a little more.


You might try posting over at
www.gm-diesel.com (http://www.gm-diesel.com/) they would be able to give a lot more info than you would get here as the specialize in diesel engines.