Gm 6.2v8 diesel starting problem

[Squirrel111]

Hi

Can anyone help me?? I have a GM 6.2 v8 diesel engine, the engine spins over fine, but will not fire.
Thanks

 

[Nauti Fox]

Hi, welcome to the forum, I think you'll need to give some more info on what's been going on, whether this has suddenly happened or not and some history as to the installation and what you've already tried.

 

[Squirrel111]

Hi

It is a brand new engine what I am fitting to my boat, converting it from pertrol to diesel. We have put the engine in and tried to start it, it is just turning over and not firing at all. As if there is no compression.

I have a Chevy pick up with the same GM 6.2v8 diesel engine, I had the immobiliser disconneted on it and since then that has done the same and will not fire at all.

Any help would be appriciated

 

[rafiki_]

I would be amazed if there were an immobiliser fitted, but it does sound like a fuelling issue.

 

[PCUK]

Are the glow plugs working? It will never start without preheat (or Easy Start fluid). You must have a strong flow of fuel from the return on the pump and also a good cranking speed. You have obviously bled the injectors!

 

[simon barefoot]

Ditto. Cant imagine its got an immobiliser, but if it has it may run via the fuel pump, which shuts the pump down as soon as the engine turns. Had the same problem with my truck recently, but it can be bypassed...

 

[PCUK]

Does he mean the run connector on the pump that must have power to it but also there is a cold start connector that also needs power.

 

[Nauti Fox]

Hi

It is a brand new engine what I am fitting to my boat, converting it from pertrol to diesel. We have put the engine in and tried to start it, it is just turning over and not firing at all. As if there is no compression.

You say it's new, is it actually new or new to you?
If it is a used engine was it running ok before you fitted it.
What have you actually tried doing to get it running?
Have you routed the fuel lines-filters correctly?
Are all the electrical connections fitted properly and working?
Are you familiar with diesels, if not it may be worth getting a professional to have a look, there are some really good guys on here.

 

[volvopaul]

As its an automotive diesel you may have to supply 12 volts to the stop solenoid to allow fuel into the area of the pump, which in marine use is wrong because if you get a flat battery your engine stops running, some yanmar units do this, i presume its not a pull lever to stop the engine?.

When you have bled the fuel system and crank with injector pipes slack at the injectors, does fuel pump out in a pulse pattern? it needs to do this if not then there is no fuel at the injectors, in which case it wont run.

 

[Mr Googler]

Check glow plugs, make sure you have 12v to the top of the stanadyne fuel pump, crack the fuel lines at the injectors and turn over in short bursts as volvopaul said. Lift pump is mechanical I think so can take a short while to get the fuel through.
I stripped the top down on one and it took a bit of time to bleed before it would fire up.

Let us know how you get on

 

[Squirrel111]

It does sound like the fuel pump is the problem, I will try those few things that people have susgested, thank you all for your replies

 

[Latestarter1]

Hi

It is a brand new engine what I am fitting to my boat, converting it from pertrol to diesel. We have put the engine in and tried to start it, it is just turning over and not firing at all. As if there is no compression.

I have a Chevy pick up with the same GM 6.2v8 diesel engine, I had the immobiliser disconneted on it and since then that has done the same and will not fire at all.

Any help would be appriciated

Brand new??

GM production of the 6.2 lasted until early 90's when replaced with the 6.5 certainly no later than 1993. Do we assume that this engine has bee in storage for the thick end of twenty years?

Another goofy part of your post is the concept of actually FITTING a near twenty year old engine in a boat without acually TESTING it first!

Please tell us more...............

 

[Nauti Fox]

I've heard that using a clear section of hose on the fuel return lets you see air bubbles etc.

 

[Assassin]

I am with Latestarter on this one, the GM 6.2 never had any factory immobiliser fitted, later model 6.5's did so it would not be the pump as they are manual pumps and not electrically/electronically controlled.

Assuming this engine is 6.2 and not 6.5 and it is a remanufactured unit i would begin with the following:

Check the fuel shut off solonoid as these are prone on these engines, if it is not opening replace it with a Bosch unit as they do a replacement.

Check the timing has not slipped.

Check the fuel feed, many had in tank pumps fitted in automotive applications to feed the injection pump.

 

[Latestarter1]

Squirrel appears to have gone into hibernation on this one....................

There are a mountain of issues regarding what he is trying to do, and sadly, very likely fail. Will a mere 130 Hp bring OP's vessel alive??

A Stanadyne DB9 fuel pump standing around for near twenty years may respond to some technical attention.

If you are 100% sure fuel is up to the pump, select heavy plastic faced hammer and give the pump body a good hard thump whist cranking. Pumping element may be stuck.

 

[Assassin]

Must agree on the hibernation, must also admit its well over a decade since i touched one of these engines.

Their inherent trait was their tuneability, we have had as much as 320 BHP out of them reliably, but that was for automotive use and not industrially rated. With good tuning they produced phenominal torque outputs on a very flat curve, just tailing off at the last 600 RPM which was very good for an oil burner of the day.

 

[Latestarter1]

Pulling any more than 130Hp out of a marine application WITHOUT a lube cooler raises oil temperature to way over 135C, lube takes on consistancy of cats wee and beats the bottom end straight out.

6.5 is the slightly more capable motor using mechanical DB9 Stanadyne off a 6.2, lube temp is always a watch out, US Hummvee favorite engine failure is cracked main bearing saddle.

Is there a plus side? It sounds real nice!

Think the problem with motor is that it just wants to stay in hibernation. Or perhaps OP was nuts to embark on this project.

 

[PCUK]

There's no problem with fitting an oil cooler to the 6.2 so I suppose it is simply that people didn't know in the past. I'm going to see how mine goes in standard trim but expect to be adding a turbo at some point. (I may be in touch for some tips Assassin!). If it blows there are loads of cheap 6.5s about so not too much of a worry.

 

[Latestarter1]

There's no problem with fitting an oil cooler to the 6.2 so I suppose it is simply that people didn't know in the past. I'm going to see how mine goes in standard trim but expect to be adding a turbo at some point. (I may be in touch for some tips Assassin!). If it blows there are loads of cheap 6.5s about so not too much of a worry.

Point was exactly that, if squirrell is struggling to understand the basics to get engine started, how would he be aware that marine applications REQUIRE a lube cooler as you already do.

Tuning a 6.2 is pretty pointless as there are no low compression pistons available therefore simply adding a turbo would be living life on the edge. Plenty of low compression piston options for 6.5, however as engine is IDI not as easy to juce it up like a DI engine. Assume that Assassin can source trick high flow injectors which would reduce rotor head pressure.

I have a bit of a blind side about the engine, guy spent over a grand with me dyno testing a 6.5 marine, he wanted 250 Hp. Fitted heap of trick componets but motor always struggled to pull any more than 200. New pistons and increased fueling. Ran again, white smoke was crazy, once warmed through, I left at 30% load for an hour to bed engine in, however blow-by would not stabilise. I was not willing to pull a power curve, however owner asked me load engine up regardless, he said high blow-by was normal.........Went bang!

Never did get paid for the final dyno run!

 

[PCUK]

Thanks Latestarter, Maybe I'll leave it alone and unstressed!