Author Topic: Trying to start a 1988 V20 6.2L for the first time since 2010  (Read 3433 times)

Offline MuddiGGEr25

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Trying to start a 1988 V20 6.2L for the first time since 2010
« on: October 17, 2016, 06:14:47 AM »
Hey guys I know I'm usually posting about my gasser suburban Cliffy.  But today I am in need of new help. I'm trying to buy this 1988 V20 suburban it's been parked since late 2010, she's a bit dirty but once cleaned up should be very nice. Only surface rust as it was a California truck before I got to it and it's never seen a salty winter yet.

It's got around 120K on it and towed a 30ft camper with ease up from cali when they moved here in 2009.

The lift pump went out (I'm assuming due to the ULSD ) however the PO was running howes in the fuel and I run howes and/or lucas when I'm using a diesel.

Yesterday I installed a electric pump rated for 7 psi at 35gpm, this same pump sustained a 450HP 7.4L towing at 55-mph if I kept the rpms down, so I know it's able to run the 6.2l.

I have 2 group 75 batteries I installed ( they are used but capable of starting the 7.4l) I was high idling my suburban  with a 150A 10si alternator. But I removed the battery from cliffy and put it in the new burb and was running him with no battery, just jumper cables.

I verified that the fuel it getting up to and through the filter.

The glow plug light comes on and cycles periodically, but the key is stuck on. Like it won't go to the lock position i did nit force it r anything but now its stuck in the run position.

I havevheard i can use wd40 as a starting fluid .

I did have enough juice a couple times to crank it over pretty fast but never saw any smoke out the back or anything

. The diesel was treated when parked and I also post treated it with diesel kleen. The tank was just filled before parked so it's 95% full. But I have watched people fire up old trucks and tractors that have sat 5-15 years and they run the old fuel just fine.

I spent 3 hours hassling with this thing yesterday, my jumper cables are roughly 6awg but the clamps aren't shiny anymore so I'm going to wire brush them, and I'm trying to either pick up a used batery charger with the boost function or I will buy another group 75 they are on sale for 64.99 right now and have 680CCA.which exceeds OEM.

 The temps are between 30-60 here, the block heater core doesn't have a plug.

I hear many relays kick on and off and I have already checked fuses. Is there a simple way to test the injection pump via multimeter?  I have to have this thing runnin by sundown tonight or else I have to leave it and return to harvest
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline hatzie

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #1 on: October 17, 2016, 12:57:45 PM »
The fuel should be just fine.  I've revived more than one diesel after longer hibernation. I would pour in a bottle of algaecide after you get her running.

Make sure the fuel shutoff solenoid (FSS) is tripping on and off.
Pull the green wire off the top of the injection pump cover, with the ignition on, you'll hear the FSS click open and closed.  HPCA (housing pressure cold advance) is on the side of the cover at much less than 50F it should be energized too.
Make sure the glow plugs are getting juice when the relay is engaged.  The glows should engage right after the ignition is switched on.  You should be getting 12v at each tang.

The Stanadyne 80 box filter may be leaking after that long a hibernation.  They are not noted for being leak free.  Look it over carefully.  I usually replace em with 1998-2001 6.5L Fuel Filter Managers in the intake valley.
The mechanical fuel lift pump may not be working.

Air will enter the fuel system through leaks.
The fuel lines may have leaks both in the SAEJ30R9 hose and the hard line.
The sender pickup tubes may be corroded through from condensation floating on the fuel.


If the freeze plug heater is installed I believe you can find a cord on the HELP rack at the parts store.
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Offline 1967KaiserM715

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #2 on: October 17, 2016, 04:17:18 PM »


Make sure the fuel shutoff solenoid (FSS) is tripping on and off.
Pull the green wire off the top of the injection pump cover, with the ignition on, you'll hear the FSS click open and closed.  HPCA (housing pressure cold advance) is on the side of the cover at much less than 50F it should be energized too.
Make sure the glow plugs are getting juice when the relay is engaged.  The glows should engage right after the ignition is switched on.  You should be getting 12v at each tang.

The Stanadyne 80 box filter may be leaking after that long a hibernation.

Air will enter the fuel system through leaks.
The fuel lines may have leaks both in the SAEJ30R9 hose and the hard line.
The sender pickup tubes may be corroded through from condensation floating on the fuel.



you should be able to get it started with air-leaks, but it will be harder, much harder I should say.

so in addition to the above, you may need to make sure you are getting fuel to the injectors and/or the combustion chamber.

first, (after verifying the fuel solenoid is clicking), you can pull the line at the fuel filter that goes to the injection pump- is there fuel? if not, it may be a good chance the filter is plugged up.

next, remove 1 or 2 glow plugs from EACH side of the motor, spin the motor over, you should eventually see a mist of fuel within a couple minutes(say less then 5). if not, you need to start cracking the hard lines at each injector, to verify there is fuel before the injector, it is very possible with too much air, it cant "pop" the injector.

if you still can't get it started there has to be something else wrong; which we can try to determine later.
Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline MuddiGGEr25

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #3 on: October 17, 2016, 04:21:27 PM »
Once I had enough juice to the staeternal she fired right up. But I have to deal with a leak at the new hose connection on the old pump. I might just bypass the mech pump if I can find where the other end of the hard line goes to
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline MuddiGGEr25

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #4 on: October 19, 2016, 05:44:55 AM »
Drove her 16 miles back to town. And the only thing I noticed was the th400 seemed to be shifting late compared to the th400 in the RV
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline roundhouse

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #5 on: October 24, 2016, 08:18:05 AM »
If the new lift pump isn't rated for diesel it won't last long


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Offline Irish_Alley

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #6 on: October 24, 2016, 03:35:49 PM »
round would this be the same deal for fuel pumps? the reason i ask is i have some time on my tbi fuel pumps pumping diesel to my cummins. not doubting your word just wondering if its something that i might have a issue with a year or two down the road
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Offline MuddiGGEr25

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #7 on: October 24, 2016, 03:49:32 PM »
If the new lift pump isn't rated for diesel it won't last long


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Well thr electric lift pump is a 12D diesel pump not gasoline so no issues there.  But turns out it was the starter causing the issues... it failed on me at the fuel pump station at a flying J and it's been sitting since Saturday. 75 for a used pump with a 60 day warranty. Going to install it and a 8D tractor battery tomorrow afternoon.
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline hatzie

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #8 on: October 25, 2016, 09:32:13 AM »
The group 75 batteries will work just fine for either the 28MT gear reduction or 27MT direct drive starter.  They are around 1300-1400 CCA for the pair and they fit the battery trays. 
Keep your old starter on a shelf even if you get a new one.  A good rebuilder will be able to bring the old one back to life and it will last at least a decade.  New Asian replacements are not worth the floor sweepings they are made from.  You'll be replacing them every year.

If you're getting extended crank times you probably have air leaking back into the system through the return lines...  (or at least that's where I'd start).  Replace the injector return loops with new NBR braided jacket hose and replace the caps at the ends.  The good German braided hose doesn't need clamps.  You can buy bulk hose and two termination caps at any VW or Mercedes dealer.  Tell em you have a 1978 240D or an 81-85 1.6L diesel VW Jetta or Rabbit.  The good hose will have GERMANY >NBR< emblazoned on the jacket.
 
The other place that commonly leaks is the return hose on the injection pump.  Get a few feet of the correct Inside Diameter SAE J30R9 fuel hose and use German fuel injection clamps or spring loaded band clamps on it...  IDEAL worm clamps shortly cut into the hose and loosen up while making a mess of the hose.

Be sure the starter to block brace is installed.  The torque from starting the 6.xL engines can and will break or crack the starter mounting pad off the block... or if you're lucky just snap off the bolts.  If it's missing you can fab one or buy one.
  • GM#14028931 *BRACE FOR 27MT DIRECT DRIVE STARTER
  • GM#23502557 90-92 6.2L Diesels, 92-02 6.5L Diesels *BRACE FOR 28MT GEAR REDUCTION STARTER
Be sure all four battery cables are clean and tightly installed.  Be sure the cables are not expanding at the ends from conductor corrosion.  If the battery cable jacket looks lumpy and larger diameter than the rest instead of smooth, or green dust is coming out of the jacket at the end, that cable is shot.  The problem usually starts at the ends. 
When you're sure they are clean, in good shape, and tightly installed use some spray battery cable protectant on the connections.  I usually do the same for the ring terminal connections to the glow plug contactor.

Electric fuel pumps are real nice for bleeding air out of the fuel system but the stock mechanical lift pump works quite well too.  Fuel is fuel.  Diesel should not hurt Walbro in-tank TBI pumps but they can run way more pressure than you need for the DB2 injection pump and may not provide enough GPH flow.  If you intend to run an electric pump long term get one of the stock GM 6.5L frame mount pumps for the 95-02 T400 chassis trucks... they have enough flow at the low pressures the injection pump will like.
« Last Edit: October 25, 2016, 09:56:21 AM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline MuddiGGEr25

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #9 on: October 25, 2016, 11:58:09 AM »
Ok git a new issue... I picked up a used starter (with 60 day replacement warranty ) it's off a 1989 k1500 6.2l 4x4 AT but it appears to be a gear reduction oem... even when I look up the donor vehicle it's a c code 6.2l and the starter is correct for 1989... so is there that big of a difference between 1988 j code and a 1989 c code that would cause the breaking issue? I won't know if my bracket is compatible with the donor but it was the only start available within 200 miles for under 190 so I had no choice... I just need to start it once to get it home so it doesn't get towed
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline 1967KaiserM715

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Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #10 on: October 25, 2016, 06:22:01 PM »
The starter mount breakage occurs on all diesels without the brace, regardless of wether it is a direct drive starter or a gear reduction starter.

You can make one out of a small piece of angle iron, as anything will be better then nothing.

Edit: you should be able to start it once, but if you don't find that front brace don't risk it.

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« Last Edit: October 25, 2016, 06:25:07 PM by 1967KaiserM715 »
Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline MuddiGGEr25

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #11 on: October 25, 2016, 06:50:55 PM »
well i got it started... took about 8 cranking attempts bc i had to get all the air out of the lines with the replacement fuel filter... and it was raining... and my batteries were low, (my inverter must have drawn them down while i was gone 2 days, or just never got them full before the other guy left me there) in anycase i will order the brace using the part number given once i get some money flowing, but i have no choice but to try and start it again tomorrow because i have to get to our attorney which is 50ish miles away and if we miss the meeting we lose any hope of housing assistance (kind of a need at the moment since i had knee surgery in january, broke my foot in june, lost the roof on the house in july, and they are looking at surgery on my other knee and surgery on my L5 too) i intend to just start the truck around 2pm tomorrow and just let it idle until we get home around 6-7pm, by which point it will be out of fuel anyway

I understand i am taking the risk of turning the block into a paperweight without the brace, but on the other hand i do have a built 454 i could slap in here from the RV if i really Fu** it up


they cut the brace in half when they removed the starter from the donor (many choice words here) and i actually thought it was going to be a direct drive, but it was either make it work or lose the $1100 i just invested last week + over $500 in tools i had with me, because until i get back to work there is no way i could pay tow bill +impound fees in that city.


However i only got around 11-12mpg driving home @50-60mph with a 25-35mph headwind, i see people claiming anything under 18 means something is wrong, and i got nearly 20mpg on the way to the city the day the starter gave up.


thanks for all the tips and info, you guys always got the answers i need
1988 V10 Suburban 5.7L TBI/TH350 39K on rebuild 4.10AR GM14FF/GM10SF 235/85R16 & 18.4-16.1

1988 V20 Suburban 6.2L-J/TH400 CA truck, 125K G80 14FF/ GM10 4.10AR GVWR 8,600

1977 Ford Granada ~450HP 302 2bbl/C4 27K original 2.47 215/70R14

Offline hatzie

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #12 on: October 25, 2016, 08:51:02 PM »
Starter brace for the 28MT gear reduction starter. 
Just under $17 with Amazon Prime free 2 day shipping...  https://www.amazon.com/Genuine-GM-23502557-Starter-Bracket/dp/B00GV77H2U

If you have the wind against you it will adversely affect the fuel mileage.  My T400 gets 21 HWY but if I'm bucking a headwind it'll drop like a stone.  I've seen as bad as 14 in those conditions and I have 0.73:1 Overdrive.
« Last Edit: October 25, 2016, 08:58:02 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline Captkaos

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Re: Trying to start a 1988 V20 6.2L for the first time since 2010
« Reply #13 on: November 22, 2016, 02:04:47 PM »
I got my last brace from the dealership.

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