Air leakage, no rhyme or reason to it...

[Kris Schneider]

Hi guys, new to this forum...I'll introduce myself and my problem...

My name is Kris Schneider, I'm a resident of Delano, Minnesota attending school at ISU. I'm a big fan of vintage GM trucks having owned several so far:
1969 CST/20 4x4
1967 C/30 duallie
1972 C/10 w/extensive engine modifications (I did my own fuel injection using a 454 TBI)
1958 Apache 3800
1987 C/20

My latest truck, however, I'm proud to say, is my first diesel. 1983 K5 Blazer, convertible top, 6.2 Diesel/700r4/NP208. Some modifications by the previous owner include severely dented doors and front fenders, some dents in the bedsides, 33x12.5" BFGoodrich swampers, 4" suspension lift, Rancho shocks and steering stabilizer. Truck has about 128k on it.

Since I've had it I've installed new fuel filters, an electric fuel pump and a new MP3/Stereo deck (woohoo!)

However, since purchasing the truck hard starting has plagued me. I purchased the truck at a price of $300 with a bad tranny and rear end, installed a new tranny and rebuilt the rear end with a new carrier the PO gave me (it had broken the spiders on the trails and ran front wheel drive for a while). The truck had been sitting for 3 years after the PO killed the tranny. While doing the tranny/diff fixes I also installed new fuel filters. This improved starting somewhat but not completely. The truck still took 2 cycling of the glow plugs (PO installed manual switch) 5 sec on 5 sec off 5 sec on and about 8 second cranking time to start. After getting it down here to iowa state, I decided faster starting would be a necessity if I'm going to be able to use it at all during the winter so I purchased and installed an electric fuel pump and tied it to a wire hot when the ignition is on, which makes for slightly faster start times, but this currently isn't the entirety of the problem.

The other problem I've been having is the truck will, sometimes at random bog or die regardless of temperature, speed, revs, or amount of fuel in the tank but it is slightly less likely to do so after the installation of the electric pump. So far I've ran about 3 tanks of diesel through the truck driving it around and have let out some water in the primary filter/separator, but not much.

The reason I've determined it keeps doing this is air getting into the system somewhere between the electric pump and the fuel tank, because I can hear a definite difference between the pump running dry and the pump pumping diesel,the and previously when the mechanical fuel pump was in place I would have to crack the air bleed on primary filter and crank till it pulled diesel through again. The electric pump will ease some of the strain on the batteries and starter simply because I don't have to crank the engine to get fuel moving to bleed air out. I've kept the mechanical pump on the engine with a line running between in/out to prevent dirt getting in there in the event the electric pump dies unexpectedly.

Sometimes, not always, the electric pump will keep pumping (dry) until it gets fluid moving again which will keep the truck running but with air in the lines it surges and generally runs crappy. Running dry is also really hard on electric fuel pumps as I understand it so getting this figured out would definitely be a plus. Any particular spots I should be checking before I get home this weekend and have a full set of tools and a garage available to me? While stationed here at ISU I am forced to work on the truck in the parking lot which is irritating and runs between the dorm and parking lot to grab tools aren't a whole lot of fun either.

[catmandoo]

does the elec pump have a check valve to prevent bleeding back to the tank.also some of those aftermarket el pumps have to be mounted below the tank to work properly,otherwise check that all glows are working,and if your in ames you are gonna need to plug it in this winter,i'm over in storm lake and once it hits about 15 i start plugging in for at least a couple hours.

[jcomp]

Where is your electric pump mounted? There are a couple of rubber hoses connecting the fuel lines on the frame (roughly next to the transfer case), have you checked them? Have you seen any spots of diesel fuel on the ground?

As a side note, I suggest you pull your glow plugs and make sure they are AC Delco 60Gs (or better). If they are, try a longer glow time before you crank.

Once your truck is running correctly, I wouldn't worry too much about winter. Mine has started the last couple of winters without being plugged in and overnight temps way below zero F.

[Kris Schneider]

Originally posted by jcomp:
Where is your electric pump mounted? There are a couple of rubber hoses connecting the fuel lines on the frame (roughly next to the transfer case), have you checked them? Have you seen any spots of diesel fuel on the ground?

As a side note, I suggest you pull your glow plugs and make sure they are AC Delco 60Gs (or better). If they are, try a longer glow time before you crank.

Once your truck is running correctly, I wouldn't worry too much about winter. Mine has started the last couple of winters without being plugged in and overnight temps way below zero F. Only spots of diesel on the ground have been because of a bad plug on the last injector return line, which has since been replaced. Going to check the lines on the frame once I get back in minnesota and am able to actually work on the garage floor instead of a parking lot.

Truck currently has all 11G glow plugs, and the cycle I described (5 on 5 off 5 on) starts the truck every time if there is actually fuel going to the IP. Sometimes it takes more cranking if its purging air out.


Originally posted by catmandoo:
does the elec pump have a check valve to prevent bleeding back to the tank.also some of those aftermarket el pumps have to be mounted below the tank to work properly,otherwise check that all glows are working,and if your in ames you are gonna need to plug it in this winter,i'm over in storm lake and once it hits about 15 i start plugging in for at least a couple hours. Replaced 6 of 7 bad glows. Couldn't get the one under the hydrastop out (going to try again when I have some real tools this weekend) hopefully it isn't mushroomed...that would be bad. And redid some wiring, all of them are getting power. I'm also planning on adding an intake charge heater from a dodge cummins turbo-diesel to aid in winter starting. Hopefully that will allow me to avoid plugging the truck in over the winter, because it isn't going to happen as it currently sits in the stadium lot. That might change if I can get a work permit to park next to a housing building, but it isn't a certainty.

Electric pump doesn't have a check valve (to the best of my knowledge), but that shouldn't be the problem - air is getting in the supply before the pump, even when the truck is idling or driving down the highway.

Pump is currently mounted halfway up the inner fender, packaging doesn't say anything about mounting it below the gas tank, right now its about even with tank level anyways. The problem isn't the pumps ability to suck, however, as it had this same problem with the mechanical pump. The electric pump just helps starting faster and easing battery/starter strain.

[slagona]

First step, obviously, is to determine where the air is entering the system.

Try replacing rubber sections of hose with clear to narrow down the area of the air leaks. You'll see a stream of bubbles in the clear hose that are in place after the leak - or it may be one of the hoses, connections, or clamp on a rubber hose.

Start at the engine and work your way back one hose at a time. Otherwise, a clear section may replace a bad section and you would never find what the problem really was....

Also, you might want to consider moving the electric pump at close to the tank as possible. In this configuration, it will be pushing fuel (thus easier to identify leaks in the system) instead of sucking fuel and air.....

However, I did the same thing when I converted one of my old trucks to electric fuel pump - mounted the pump in the engine bay after fixing my air leaks.....

[TimK]

Kris,

All the advise you are getting on the air leak is good stuff and I can't add any more to it. However, there are other things worth looking at that can have a big impact on how well the engine starts. Getting heat into the cylinders is critical for the 6.2L to start. My old 83 Sub and 85 Sub before the new engine would not start when warm without using glow plugs. I have a new engine in my 85 Sub and it will now start cold (65 degrees and sitting overnight) without glow plugs. (It spins over very fast on start-up.)

Things to check are: glow plugs, compression, a healthy starter, healthy batteries and real good batter cables. I am assuming with all the cranking you are doing that your batteries are healthy. Now check the cables. They should not feel warm after all that cranking. The battery cable terminals get corroded and tarnished over time. This will happen at the batteries, at the starter and at the ground connections on the block. Just a 1 volt drop in voltage across the battery cable can have a big impact on how fast your starter will spin the engine. The faster the starter spins will be more heat in each cylinder. I swapped out my positive battery cable connecting the two batteries and the battery to the starter to 1/0 awg cable. The Ground cables from the battery to the engine were 2 AWG cables. I found this to help my old engine starting a lot.

Also, while your underneath looking at your starter, make sure the back support bracket is there. When the un-educated replaces the starter they often do not replace this. The 6.2L starter is heavy and long and without this bracket the starter can break the mounting bolts and rip out of the bell housing. The brackets are inexpensive and can be purchased at the dealership or someone on this webpage might have and extra one.

If you have some spare cash. Check out this remote engine heater. It does not require you to plug into an electric outlet. It can work on a timer and runs off of engine fuel to heat the engine. http://www.webasto.us/press/en/am_auto_heaters_734.html

TimK

[Kris Schneider]

How much is that engine heater? I couldn't find pricing info on their website and don't want to waste my long distance minutes calling one of their distributors...

[TimK]

I can't remember what the price is. I thought it was around $1,500. Here's a link to an article that discusses the prices and here is a toll free number for an installer in the Portland Oregon area.
http://www.findarticles.com/p/articles/mi_m0FJN/is_10_37/ai_108902415

Tom Corton from Webasto sent me the following information:

Dear Mr. Kuhlman:

Thank you for your inquiry about our unique vehicle heaters. We have numerous vehicle-specific applications along with "universal" kits that may work in more general applications. I recommend you contact Mr. Gary Parsons at Instrument Sales & Service in Portland at 16427 NE Airport Way, (800) 442-0863, our authorized distributor there. We have heater kits for the vehicles you have listed, but ISS can best accommodate your needs and requests regarding price and installation. "Blue Heat" must be installed by authorized distributors. If we can provide any additional information, please let me know.

Thank you for your interest in Webasto products.

Tom Corton
Sales Manager - Dealer Direct Channel

Webasto Product North America, Inc.
15083 North Road
Fenton, MI 48430
(800) HEATER-1
(810) 441-3113 - Mobile
tom.corton@webasto-us.com
www.webasto.us (http://www.webasto.us)

TimK

[john8662]

whoa! 1500 for a heater, a new set of quick heat glows is the ticket!

[Kris Schneider]

Yeah when you spend $300 on a truck you usually don't spend $1500 on an intake heater...especially when you are a poor college student like me.

Especially not when I can score a dodge cummins turbo intake heater off of ebay for $100, and wire it in myself.