6.2l quits after initial start

[Alaska9076.2L]

Having an inconsistant problem with starting in the morning after sitting overnight. Truck will start fine initially then stall after about 3-5 seconds. When attempting to restart it will take up 30 seconds of cranking. Cranking speed is great, there is fuel smoke present, then about 10 seconds of cranking later she will fire off. Any experience will help!!!
- Cold advance is working
- Glow Plugs are working and New
- Batterys are good
- Great cranking speed
- Ambient temp is around 45f
- Only when engine has sat overnight
- Small fuel stain at bottome of fuel filter (looking into that now)

Dave

[Robyn]

What you are experiencing is "Fuel drain back"

This condition can be caused by leaking injection pump seals and or a small air leak in the suction side of the supply line.

What normally happens is that the throttle shaft seals, advance piston seals, cover gasket and possibly other places will allow a small amount of air to be drawn in after sitting and the fuel drains back to the tank over night.

The IP has enough fuel in it to start but soon encounters air being pushed into the system which causes the stall and hard restart.

Once the air is purged, the problem goes away.

The issue can also be a leaking filter, a fuel pump (lift)

What year rig ?? electric or mechanical lift pump ??

Its going to take a thorough going over the fuel supply system, to make sure there are no leaking hoses on the suction side.

If this turns up nothing, then the IP is suspect.

How many miles on the rig ??

More info please

Missy

[Alaska9076.2L]

Thank you for the response,
1985 1/2 ton Silverado, Mechanical lift pump, completely stock. 178,000 Miles on truck engine unknown.

I did locate a fuel leak around the fuel filter. Most of the fuel leaks out within the firs hour or two after every shutdown leaving a 3-4 inch stain on ground. Build-up of fuel occurs on the bottom of filter, and from some other souce it finds its way to the water drain line then to the ground. Issue has not occurred for the past 2 days. Fuel stain on the ground has remained the same. Have been reading up on the Stanadyne 80 Housing, seems there have been plenty of issues with it in the past. I have no doubt the fuel is coming from filter/housing. Question: Why the white fuel smoke during crank after stall, is fuel getting to the cylinders but with poor atomization. I would think an air lock would allow for no fuel to get through ip pump?

Thank you very much,
Dave

[DmaxMaverick]

To explain the white smoke, the DB2 with a mechanical lift pump is self priming. Meaning, it will eventually send fuel from the tank to the injectors while cranking. The injection pump will still pump fuel, even full of air. Once the air is pumped into the injector lines, it will continue to push fuel to the injectors. Most of the air is released into the return, but once it's able to reach injector pop pressure, fuel will begin entering the cylinders. With the air in the pump and injector lines, the air cushion causes a delayed injection event, which greatly retards timing, resulting in the white smoke. The fuel atomizes the same, it's just really late. The system will eventually purge itself and clear out.

If you have an external fuel leak you can see, you have a huge air leak after shutdown. This is compounded by fuel/air contraction in the fuel tank as it cools, like overnight. If you haven't already, replace the fuel tank filler cap, as the vent does fail at some point, and can cause increased fuel tank vacuum. To minimize the "vacuum" condition, loosen the fuel cap for overnight sits. You will still get the drainback issue until the leak is fixed, but it will minimize the vacuum pulling fuel from the injection system.

In the meanwhile, shop around for a fuel filter assy. You are not required to continue using the OEM filter. There are many aftermarket options available. Any fuel filter with the features you want/need that will fit in the space will work. Racor is a good brand to consider. They are relatively inexpensive, and filter elements can be had just about anywhere.

[Alaska9076.2L]

Thanks for all the help,

I now know where to start! Sounds like getting rid of that oem filter housing is the way to go. On another note, i may have an oportunity to get a factory 6.2L that was for a 1983 K10 still in the crate for very cheap. My only concern is if the seals will still be in serviceable condition. All thoughts on this are very much welcomed.

Thank you again to everyone,

Dave

[DmaxMaverick]

On the "new" engine, much depends on how it was stored. There should be no worries about internal seals, but some long term exposure can damage seals exposed to the outside. The only other concern would be the rear main seal. If it's an original "rope" seal, and it's been stored dry for a very long time, it may take a long time to seal, or it may never. If it has the rope, I suggest replacing it with a rubber rear main seal. This can be done by removing the oil pan and rear main cap. At most, the crank may have to be loosened (loosen all the mains) to R/R. Properly resealing the pan (and the valve covers) would go a long way to prevent future leaks. Sealer only on these, no gaskets. A piece of cake on the engine stand. A real PITA in the truck.

[Alaska9076.2L]

DmaxMaverick,

Thank you for the insight on the engine, will be getting a better look at it soon. My current engine is leaking like a son of a gun out the front and rear mains. My concern is going to a different model of engine and comprimising my fuel economy, amazingly I am able to achieve 21 mpg on the high and 15.5 in town. Is there a easy way to tell the model of engine I have, and what is so nice about this "J" model intake. I have just ordered your 6.2 reference manuals vol. 1&2 so i hope to learn a little more. In reference to early post, I have located a RACOR 660R1210 filter @ &175.00. Is this unit the one you had in mind, it has a 200 watt heater in it. Anyhow thank you again, next is 700R4 Rebuild :(, slipping when starting from stop, and leaking every were. She is my daily driver, just want to take care of her. Maybe throw some reasons out there as to why over the last 5 years I have had to turn the idle up incrimentally to maintain a suitable idle speed:confused:

Thank you,
Dave

[DmaxMaverick]

I'm not personally familiar with that Racor filter assy, but it should be fine. There are a lot to chose from, and none bad that I can tell. Robyn may have an opinion on that. Value it.

Actually, the early(ier) 6.2L's got the best mileage, regardless of the rating (C-J). 83-86 were the best. 82's were good, but had a bit less power. Still, you'll get all the economy your foot-feed will allow.

The TH700R4 tranny doesn't normally "slip" on takeoff when they fail. That's usually a used up torque converter. If it works well once rolling, fix the leaks and replace the TC. If you do rebuild, consider a Trans-Go HD shift kit, and a TCC mod (locks the TC early, and keeps it locked). Not only will it help to improve your power and mileage, it may keep it around a lot longer. My 85, with these mods, has over 1/2 million miles on it, and I rarely treat it "nice". If it's possible for you, find a "K" case 700 for your rebuild. You can usually find them at wrecking yards for cheap if they are not working. The "K" case is stronger than previous models. You can identify them by a large (top of case to bottom) "K" on the right side. 4L60 cases also bare this mark, and can be used to build a stout 700 with very little modification (by a good shop). With that in mind, you could also find a good 4L60 and get the controller for the cost of an average good 700R4 rebuild (I just happen to have one, like new, for sale). In any case, Robyn has some good advice on building them right.

[Robyn]

Maverick has pretty well touched on all the high points of Blue smoke issue and such and the 700R stuff.

I have used the Racore 230R2 filter assembly.

I am going to assume that your truck has the factory square cartridge type filter assembly.

Just remove the old filter and install the Racor in its place on the firewall.'

You may need to fashion an adapter of sorts to allow the Racor to bolt onto the firewall, but thats no biggy.

The Racor I use (230R2) has a spin on filter with a removable see though bowl on the bottom.

You can plumb this in easily.

The leak at the filter is most likely the entire cause of your starting issues.

The rundown that Maverick went through on the seals and such is right on the mark.

If your truck is a 4x4, doing the rear main seal and pan and such in the truck is not all that tough. At most you will need to jack the truck frame up a tad to get a little more room between the pan and the font axle.

With everything clean and spiffy, use the High temp RTV on the entire pan rail to reseal it.

The rear main can be a ROPE, A felt or a rubber type lip seal.

One of the most common reasons for major oil leaks in these engines is excess blow by.

With the engine running, remove the oil filler cap, if there is a LARGE amount of vapor HUFFING out the fill opening then it is considered excessive.

Some vapor/smoke is normal but with a slight raise in RPM above idle (1000/1200) the vapor should go away as the CDR system sucks it out.

The crankcase is supposed to run at a very slight negative pressure, which reduces the incidence of oil leaks.

The front seal is a typical steel cased rubber type drive in seal in the timing cover.

As far as the 83 engine you spoke of, GRAB IT. I would not worry about the seals,

What casues most issues with these engines seals is the Heat/cold duty cycle and not the age.

A crate engine IMHO should be a drop in and go thing.

The silicone sealer used on the VC and Pan is good for almost ever, only oil and heat will do much to it.

The rope rear main seal is mainly a little oil dam as the rear main area is well channeled to keep the oil drained away.

The felt seal used on some 6.2 engines was just a soft felt ring.


Now the 700R4 is a major undertaking to do a proper rebuild.

I did a complete writeup on buildng a 700R and it should be located on the chassis and gear box forum.

The "K" case is definately the best box to build.

To sum it up, IMHO, grab that crate engine and replace the old one.
Get the Racor filter on the beast and life should be good again.

To do a 700R the right way is about $2000 if its done in a shop.

The last one I did cost me about $1000 and I did everything.

The transgo "DASH 2/3" shift kit is the real deal.

Read my writeup on the 700R. http://www.thedieselpageforums.com/tdpforum/showthread.php?t=24728

Good luck and let us know if you have any more questions.

Missy

[Alaska9076.2L]

Robyn,

Does that Racor 230R2 have a fuel heater in it, and can you recomend a good vendor to purchase from. With regards to the main seals, my truck is a 85 4x4 with a 3" lift, sounds like the replacement of those should be easy enough?

Thanks very much for all the help from both of you, a wealth of knowledge.

Dave

[DmaxMaverick]

The main seals are easy to do. The problem is access. The front seal is pressed into the timing cover, like nearly all traditional design V-8's. It can be R/R'd without removing the cover, but unless the leak is significant, it can wait until a water pump or timing set job. Replacing the rear main seal requires dropping the pan. IMO, a real PITA, no matter how it's done in the vehicle. 4x4 just makes it (slightly) less of a PITA.

A fuel heater is a "nice to have", in most cases. Usually only "required" in moderate climate areas, where unexpected cold snaps are possible. If you are in an area where the fuel is always treated, seasonally, it isn't really necessary. The filter won't thaw the entire fuel volume, tank to cylinders, no matter how good the heater is.

The WIF sensor is generally a waste, too. By the time the light comes on, too late. It will just tell you why you can't go anywhere. Restriction sensors are good, though.

[Alaska9076.2L]

Thank you again !!!

I think i am good on my own, i will update though:)
I am looking forward to the 6.2L books that i ordered.

Thanks,
Dave

[Robyn]

The 230R2 can be fitted with a heater unit.

The water in fuel system can also be fitted to this filter.

The wif system goes into the Bowl and will alert the operator before any water gets into the the IP.

The probe will sense water after the water gets to about half way up the height of the bowl.

I dont use either, the water sensor or the heater in mine, just keep an eye on the filter when I check the oil in the engine when Im fueling up.

The factory WIF sensors are of little use, as the light goes off about the time that your IP is chewing along on dirty water. :eek:

A good dose of water can be a death sentence to the injection system if its allowed to sit in there very long.

The water will etch the fine surface finish of the injectors inner parts as well as the pumping plungers and other goodies in the IP.

Really bad Ju JU to run any water through these.



Missy

[Alaska9076.2L]

Very nice!!!

I have the filter assy on the way now, because of living in alaska i opted for the 230R with the heater the only concern i have is the unit comes with a 30 micron filter. Will this be too fine of a filter over the 2 micron, and be an issue down the road. I am assuming i can purchase the 2 micron filter alone.

Thanks,
Dave