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6.2 starting...? Bill? Bueller?
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I'm on my 11th 6.2 (not including Army trucks) and I have noticed a common theme in the way they start.
Glow plugs on, foot to the floor, glow plugs go off, then crank. When the engine fires, if you take your foot off the throttle too soon the engine dies and you have to repeat and repeat. Lots of cranking. Where as if you keep your foot mashed against the firewall, for just a second longer, while the engine revs up, it'll keep running after you take your foot off.
They all seem to do this. The Fords with the Stanadyne pump don't do this as much.
What up wit dat cuz?

I have always thought that the injector pump was losing its prime. What doesn't jive with that theory is that I always install an electric lift pump over the fuel tank and it pushes fuel through the mechanical lift pump and pressurizes the bleeders on the fuel filters. So where is the disconnect between pressurized fuel lines and a fuel starved injector pump?
DF


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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DF:

First of all, I have never even touched the throttle when starting any of my 6.2s except in the cold of winter I will sometimes give it a 1/4. The govenor preload spring will keep the rack wide open till the govenor picks up enough RPM to haul the rack back.

It could be that by mashing the go pedal to the floor, you are keeping the govenor from returning and when you lift your foot off, the rack goes to far the other way (momentum???).

Starting is not usually a problem with me as long as the glows are working and the fuel system is tight. The only system that does what you are talking about is the 4911 pumps used on the mechanical turbo charged units. They have an adjustable govenor pre-load spring and if you don't have enough tension on it the engine bogs as soon as it starts.

Try a few starts with no throttle and see.

Get back to us.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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Well I'll be damned. The suburban started on the second try, cold, and stayed running with my foot off the pedal.
I'll have to revisit that theory...Thanks Bill!
Dualfuel


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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Glad I could help.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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Alrighty Bill,
We are back to having to keep the pedal at the mat to get it to start on the first crank. If you don't hold it to the floor it will not start. Its not just one truck but all of them. AND the 6.9 Ford too.
DF


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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As it turns out, I'm having a similar problem with the two that are in the driveway now. No need for the flat on the floor treatment but at least 1/4 throttle. Suspect both have worn pumps and the cold weather of late may have something to do with it. One thing you should check is if your lift pumps are working as well as they should. It also seems that since they switched over to ULSD, the older mechanical engines aren't starting as well unless you hit them with either BD or diesel additive.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post



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I better review,
The suburban, we've had for 5 years now, has its electric lift pump over the fuel tank. Okay anything but full throttle, gets you this...it starts and runs for about a second or two then stalls. After that it takes some recranking (even though the lift pump is pumping away) to get it fired up again.
Its running out of fuel. Thats whats happening. Dunno why.
Is there any way the IP can run out of fuel, even with fuel pressue from the lift pump. Is there a restriction or screen like in the 350s? I don't remember a screen. I suppose I could go look in my junk IP pile....
Is there any way to make the fuel circulate through or around inside the IP and back to the tank with the electric lift driving it? I could then heat the tank that way and use it to heat the IP. That would eliminate the flooring....
DF


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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Does this happen cold and hot? The HPCA circuit also energises a high idle pot on the side of the pump. Over 130 F this circuit is off. If cold, and HPCA isn't working, the timing remains retarded thus no cold advance and no high idle. Flooring the throttle would allow the engine to spool up and give it enough advance to stay running.

1. Have seen lots of electric fuel pumps that are running but not producing fuel.
2. In-tank sock is designed to wick fuel up, even if you are low in fuel, and to close off completely when you do run out of fuel to prevent air getting in. If this sock is clogged up, then its possible it is being sucked up into the fuel intake and restricting the flow. This is a 70 micron filter and with the various blends of fuel, might have clogged up over time (why do these things never happen in the summer when its easy to get under the vehicle and drop the tank???).
3. There is a 50 micron screen in the fuel intake cone going into the IP.
4. The primary filter is made of paper thus if old, can stiffen up and stop flowing, even if it is clean. The older box filter were notorious for this. The fibers just dissolve and fuse together. I change mine every 6 months, just on spec.

Except for the HPCA, I can't think of any of the above that would be affected in any way by throttle position. As much as I hate to say it, it sounds like the IP has hit it's time life. Rarely do these pumps just quit working. They just get harder to start and produce less power till one day they don't have enough in them to do anything. Had one go quickly though, over a 250 mile trip. Started out running strong at 70 MPH and by the time I got home, the car couldn't make it over 35 MPH. Got home, but just barely.

Sorry can't be of more help. Diagnoses by internet has it limits.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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Dear Bill,
I suppose I should say this yet again....I have to do this for ALL my 6.2s and the 6.9. Its not isolated to one old IP, BUT, maybe they all are getting old, after all, I don't own anything newer then 1986.
Some trucks don't have socks in them anymore...
Some trucks have a electric lift pump.
Some have heated tanks.
All have working HCPA.
All have to be floored when cold.
I buy filters by the case and change them biannually as well.
I suppose it should be considered a fatal abuse to start them this way, but after this many years all I replace is the starters once a year or so, and the fuel filters. Once in a while I have a glow plug go down...

That was a good tip about the slow death of a pump. I have a suburban I plow with that is just getting miserable to start. I thought I had checked the glow plugs and starter, but still its got to have little WD40 or it won't go. No power on the hills either. Must be the trouble. I'll change the pump. Its a good plow and worth doing.
Thanks DF


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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DF:

Sorry, should have read the first posting more carefully.

Hate to state the obvious, but if all of them are doing it, the problem has to be common to them all, like the fuel. Assuming they all are bing filled from the same source, could it have been a bad batch of bio, a bad batch at your local filling station, a dead animal in your storage tanks?

If you are using pump diesel, the Stanadynes hate the new ULSD. Try hitting one of the engines with a double dose of the Stanadyne additive. Not one of the competitors...Stanadyne. Don't know what they put in this stuff but it has cured all sorts of pump and injector related problems for me in the past. If it cures the problem, then the issue is fuel related.

Have you also considered "cross platform contagion" Big Grin? If your place is anything like mine, all it takes is for one of my vehicles to get sick and they all get the same thing. This year it was fuel sending units and rear axles. Last year it was electrics and front brakes.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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Bill,
Where do you reccomend I look for a new injector pump?
All I see is rebuilt ones...wish I had packed a few home from Iraq.
I have that cross contagion thing going on here with leaky water pumps right now.

I think you are right about a common theme, I bought some fuel, I used some heating oil, I used waste engine oil, I use biodiesel. It might be the fuel but I don't think so. I am going with 25 year old injector pumps that are wearing out.
DF


"I don't work with collectives. I don't consult, I don't co-operate, I don't collaborate."
Howard Roark
 
Location: Calumet, Michigan, Great White North | Registered: January 20, 2002Reply With QuoteReport This Post
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DF:

Have never bought a new one but have run the gamit of the re-builders. Most of them are crooks. Buying off Fleebay is a real crap shoot. Up here in Canuck land, I have used Valley Diesel out in BC. A bit pricey but every pump I have gotten back has outperformed the original and lasted (took the one off the 89 with over 300K on it and it is now being used by a friend with no indication of going bad). They own BD Dieseland can be found at:

http://www.dieselperformance.c...p/product/index/164P

The people I have been working with in Georgia for years now have both tested used (most of their diesels come to them with less than 100K on the clock) or rebuilt by a local shop that has been doing their pumps for 20 years now. Not much they haven't seen. Usually much cheaper and you can spec your pump the way you want it. Problem is Jamie and the bunch at The Diesel Depot tend to work on "Southern Time" and it tends to be a challange getting anyone on the phone. Great product but it takes patience. Try their website at:

http://www.dieseldepot.com/contact.html

Jamie usually does respond to the email.

Nope this helps.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post



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this thread is kind of mind blowing as the military manual i have for the 6.2L clearly states that at or near freezing you need the pedal floored.

i have noticed mine needing this nearly all the time , at least nearly all cold starts when its cold out and on veggie oil.
The only thought I have is that my last IP didn't require this except when really cold(per the manual)
I think I have the IP timing wrong.

Forget what these other guys are trying to tell you - if the cold advance works, I would just check your IP timing (with a light and glow plug luminance adaptor).
if that is pretty dang close , who cares... get on with life


6.2L GM 1979 K5 blazer -Single tank w/electric preheaters.
Blend =66%WVO, 33% #2 diesel .
4 100watt IP line heaters
custom 160degree 300watt racor 1000 filter heater
polyeurethane 1/2" pickup
other fuel lines flouroelastimers
plastic fuel cell , Mallory 140gph gerotor fuel pump.

OC-50 dieselcraft centrifuge run by SBC gear pump -
 
Location: texas | Registered: February 28, 2008Reply With QuoteReport This Post
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