6.2 hard start

[86c20]

ok i am really starting to to hate my truck. finely got it running good looking good and no elec problems. now the dam thing will not start in the morning at all. she starts good in the cold with just the plugs. here is what it takes to get her going after sitting all night. crank it alll dam day till that batts are dead or give it a shot of ether witch i dont like. and now it is getting worse buy the minute. it was fine after it was going for the day now after 2 hours of sitting she will start but takes a good 15 sec of cranking. plugs are working fine i tryed changing the filter and that didnt help at all. when it wont start i am geting fuel at the injectors not alot but dont know what should be there. one thing i am thinking is the mechanical fuel pump is bad so its not holding the prime?. this motor has always started fine even down in the single digets. once she is going seems to run fine. is ther any thing i should check? this is the thierd time this truck has f**ked up before a trip and this trip that i am going on nect wensday is 600 miles to get a nother truck for parts. HELP lol thanks, mike

[csb#356]

Are you using #1 or #2 diesel fuel? How cold is it getting? Maybe you have a leak somewhere that is letting air into the system and you're having to bleed it out each time you try and start it. It sounds like your glow plugs aren't working or maybe that the engine doesn't have the compression it needs to heat the cylinders up and ignite fuel.

[86c20]

i think it is winter blend fuel. it has been alot colder and started fine. plugs are working 12v at then and no open elemnts in them.

[83GMCK2500]

Not to take away from this forum in ANY way, but I know there is a TON of knowledge and experience in regards to the 6.2L/6.5L engines at www.thetruckstop.us I know for a fact that the occasional diesel-site drama that has plagued the larger sites does not exist over there, that is one of the reasons that site was founded... (I've been there since the get-go.)

EDIT: First thoughts: fuel tank sock, fuel pump (like you suspicion), plugged fuel tank cap (not venting). Also, not sure which one you're running now, but consider the gear-reduction starter and do NOT forget to put the brace on the front of it. I know it's a PITA, but it is worth it for starter longevity.

[Cheng]

Does the truck turn over fast enough? Dirty battery cable connections or a weak battery could cause slow cranking speed and lead to lower ignition temperatures. Just that quick shot of ether might be giving it enough additional cranking speed to sustain combustion.

Otherwise I agree that it sounds like you are losing prime on the fuel system.

The most common leakage point for a 6.2L of our vintage has to be the Stanadyne Model 80 Fuel Filter Housing. The air leaks in either through the filter restriction indicator, the heater element or the vent/drain plugs. I rebuilt my Model 80 with all new Viton O-Rings and it reduced my cranking times from 20 seconds to only a few revolutions before ignition.

It could also be the mechanical fuel pump, but if there is no entry point for air the system should quickly re-pressurize once the pump begins to pump.

Adding a fuel pressure gauge after the Filter might be a good troubleshooting tool.

[D13]

NEVER ether a 6.2 with working glows! The resulting bang bends rods and breaks cranks.
WD-40 is better suited as a light oil that works well, hit the glows, then start cranking and give it a light mist of WD40 (without the air cleaner, and while cranking!). FYI, once you have to start using ether, these become 'ether sluts', and then refuse to start without it. dieselplace has a good 6.2 section also.

I found on mine, in order:
1) Replaced glows with self limiting 60G's and a manual switch, and give it another 10-15 seconds after the factory timer quits, really helped (wired in parallel so that the after glow works too).
2) New big batteries, cleaned high quality connections (particularly the double on the RH battery, if it gets dirty the connection will get hot and melt the batttery post. BTDT).
3) make sure the starter spins the motor fast enough, clean connections (very common problem) and replace starter if needed.
4) put a clear hose on the return at the front of the IP, if you get bubbles when it starts you have an air leak problem (which led to new hoses and lines for me, and soon to replace the Model 80 with a spin on setup).
5) below 20 degrees plug it in for an hour.
6) injectors and pump

I spent about $600 and 2 weekdends to get mine set up. I walked out a couple weeks ago, truck has been sitting since Novemeber (tore the rear end up), fired on the 2nd revolution.

[86c20]

ok guys this is what we go so far.
1. new batts
2. new starter
3. she deff cranks fast eniugh.
4. i will try the clear line on the return today.
5 idk but i really dont want to drop 600 bucks on it right now lol

[hatzie]

1. The Lift Pump may be weak. Weak or failed lift pumps make for hard starts.
2. The Stanadyne 80 filter housing is a #1 leak point. They are a light cheap alloy that corrodes pretty easy. If the corrosion isn't real bad on the O-ring seats they can be re-built with new nitrile O-rings and carburetor dip.. I replaced the 80 on my CUCV with an intake mounted 92-98 6.5L top loading fuel manager filter assembly. I used a Medium Duty truck CAT filter head for a few months till I lucked into the FFM on a blown motor.
3. The return line daisy chains are a common Bosch Injector leak and air bleed-back point.
4. Put 5 PSI but no more in the tank and check the steel fuel lines over for pinholes.

[FarmerDale]

X2 on fuel filter housing. Have a Deere skid loader with same filter and housing and similar symptoms. Had to prime to start in mornings. Replaced housing and problem disappeared. I fortunately never had that problem with my 6.5, but PMD issues trumped other problems.
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[cdm10700]

is there a fuel shut off relay or cut off switch on top of motor

[V30 mongo]

I just had the same runaround with a 88V30/6.2. My problem ended up being the fuel filter assembly on the firewall. There is a pressure sensor in the back of the fuel filter unit. The O ring that keeps it from leaking goes bad. Irt will run good all day. If it is shut down over a couple of hours it is hard to start. If you diconnnect the "pink" wire on rhe injector pump and go through bleading procedures it will start, no problem. Eventually I has to remove the sensor from the filter unit and tap the hole for a screw. The filter assembly is not avalable new any more and junk yard units have the same problem. You can also replace the fuel filter assemply with an after market unit such as the type used on tractors. Some oil furnice filter units will work too.

[hatzie]

Originally Posted by cdm10700

is there a fuel shut off relay or cut off switch on top of motor

She starts so the fuel cutoff solenoid works. The fuel pump is mechanical so it only runs when the motor turns.

[86c20]

ok so we got an update. i put in some clear line to see what is going on. out of the ip i have some are vary small bubbles. on shut down get alot of air in the same line but coming form the return side. i did change out the feed line to the ip. that sucked lol. when i had the clear line in after the filter i had not air there witch is way i changed the line thinking the other end maybe bad. how do i test the ip pump and the mechanical pump? thinking the presseurs on cranking are not high enough and there sucking air??? also could it be a bad return line on the injectors??? thanks, mike

[hatzie]

Originally Posted by 86c20

ok so we got an update. i put in some clear line to see what is going on. out of the ip i have some are vary small bubbles. on shut down get alot of air in the same line but coming form the return side. i did change out the feed line to the ip. that sucked lol. when i had the clear line in after the filter i had not air there witch is way i changed the line thinking the other end maybe bad. how do i test the ip pump and the mechanical pump? thinking the presseurs on cranking are not high enough and there sucking air??? also could it be a bad return line on the injectors??? thanks, mike

There's a check valve in the fuel return line fitting on the Injection pump and there's also one on the fuel lift pump. It sounds like one or both may be leaking. The small bubbles from the injector side ar probably the return hoses or the end caps.

"An intermittent no-start condition on some diesel engines could be due to an inoperative check valve in the engine
fuel delivery (lift) pump. This condition could occur after the engine has been running, then stopped for a short time.
Fuel could drain past the inoperative check valve back into the fuel tank. To correct this condition, replace the fuel
delivery (lift) pump."
--Page 366 GM_STG_16015_05_1C_1987_The_6_2_Liter_Diesel_Engine.pdf

[Sterling]

Originally Posted by 86c20

ok so we got an update. i put in some clear line to see what is going on. out of the ip i have some are vary small bubbles. on shut down get alot of air in the same line but coming form the return side. i did change out the feed line to the ip. that sucked lol. when i had the clear line in after the filter i had not air there witch is way i changed the line thinking the other end maybe bad. how do i test the ip pump and the mechanical pump? thinking the presseurs on cranking are not high enough and there sucking air??? also could it be a bad return line on the injectors??? thanks, mike

86 C20, I think I have your answer

When was the last time you replaced your LIFT PUMP? Its on the passenger front side of the engine block, looks like any old Small Block manual pump

The DB2 Injector pump has enough power to effectively act as a fuel pump. HOWEVER, you still need to get fuel to the IP to get it going, then it can take it from there

I found out my 6.2 was running with a blown fuel pump for a while, took a lot of cranking to start. $20 dropped at NAPA later, and I was golden

Another issue with the fuel pump:

There was actually a GM Recall/Service Bulletin on our 6.2's original lift pump. They have a sort of "anti drain back valve" in them, to keep the diesel lines going to IP "primed" when sitting. They updated the lift pump with a new design, eliminating the fuel draining back issue (thats maybe why it takes so long to crank over and start, fuels already back at tank)

Quick way to check your lift pump

Unscrew the pressure output fitting going from pump, you can do this from under the truck. Put bucket underneath. Pull pink wire off of top of IP (kills the ignition, keeps her from starting and sucking air)

Turn over the truck for 5 seconds. Go back to bucket. See if fuel was being pumped, or if it was just trickling out or nothing comes out

No fuel = No bueno. Go drop $20 on a cheap pump at napa, and your truck will start at the FLICK of the key after 10 seconds of glow plugs.


-Sterling

[86c20]

ok so i went back to the drawing bord and started all over. rechecked for air no air ok good then moved on. rechecked the plugs after pulling them and what do i find?? 6 of them are open circs and the 2 that did have cont where 180k ohms and 3600 ohms. yea f!!ked so got 8 new plugs form autozone for 10 bucks each. got the acdelco 60g. put those in today and seems to work will no better in the mornin after she is good and cold

[special-K]

Reading through this I wasn't convinced you had glow plugs. If problem persists,it could be the controller. My '85 needs one right now. Last winter it would crank a while,fire,but not stay running. bout as many times as not,it would barely start the second try. The rest of the time,that was it,the batteries couldn't cut it. Batteries are not the issue,glow plugs all new and functioning. Spring till winter everything fine. Now,same thing this winter. All summer long I knew I needed a controller and never bothered. It's just not giving enough glow time for once it's down to so cold. The batteries just can't take turning a cold high compression motor.

[hatzie]

Glow plugs or air in the fuel.
When you said the plugs worked I assumed you already tested the glow plugs.
Glad you found it.

[Edahall]

Unfortunately, the AC 60G glowplugs are slower to heat up than your previous glow plugs. As a result, your controller probably won't give it sufficient time to ensure easy starts. I ended up using a push button to activate the glow plugs. I've ran the glow plugs for up to 45 seconds without any issues.

[86c20]

yea i thought that i did check them the right way but a few to many drinks will make you look like an ass, lol my plugs are on a toggle switch so i can time they as needed