M1028 Fuel Issues

Bottom line up front, I'm reaching out for ideas. My truck has started acting strange lately. It loses prime when sitting over night (will be replacing all rubber lines and installing spin on fuel filter). It also randomly stalls out. Most of the symptoms point towards injection pump so I've started looking for a new one. I came across a really good deal for a brand new HMMWV injection pump for a N/A 6.2 (less than a rebuild from a local shop). Other than the top cover needing to be swapped from the old one, is there any reason not to go this route? I've had to clean the check valve on the top cover 3 times now. It's getting plugged by the black specks of doom that I've read about on here meaning it's coming apart internally. Thoughts? This is my Norway truck with less than 8,000 original miles.

Just as an option, Badger diesel in Kenosha,WI just did a fantastic job for me. All new guts and no core for 725. It was pricey for sure but they offered to calibrate it any which way I wanted. Lots of questions about what I've done to the truck etc to get the right setup. There are others cheaper but it was the best price I found for all new internals including pump and rotor.

Researching more, member Barrman has done this exact swap on a few of his trucks with no issues. Swap top cover and let it ride. Member Cucvrus did this swap and noticed a little more power on a M1009 so I have that to look forward to hopefully. I hate being a parts swapper but I've got a Parade coming up soon and this is my wife's truck. It really showed it's tail at the Ga Rally this past weekend. New IP is inbound, already have a spin on filter base and will be purchasing new fuel line soon. Lift pump looked like it was pumping well when bleeding the fuel system after a filter change last month but will change that as well if symptoms don't improve.

Unless the fuel shut off is what is bad. My truck ran perfect... push into a snow pile once every like 2 snow storms... truck shuts off... fires right back up.

Driving out like 100 miles... take a turn... truck shuts off... refires no problem...

One day... oh let me go out and put the plow on snow is coming... no start... done... crank no fire...

Swap top cover (with known good) never had a problem again...

I called it "shutting off" but maybe someone else could call it stalling.

Is that likely your issue... no... but I feel it is worth mentioning...

I would never change the FP... I changed mine (was leaking)... was bad within a year... and ended up having me pull apart a good ip because I was getting the same symptoms I just described... turned out the new JUNK was not only not pumping but BLOCKING the fuel... it now has a used am general pump on it.

Mine is back running good for the moment, looks like I got some bad fuel or years of sitting has caused alot of condensation water to plug the fuel filter. I'm still going to switch to a spin on fuel filter with a viewable bowl so that I can check water contamination off the list a little quicker. I'm also going to install a pressure gauge on the other output side of the filter head to be able to do a quick check on lift pump pressure. I've got a HMMWV pump on the way as well with 0.290 plungers used on 6.2's instead of 0.310 plugers used on the 6.5's. I feel like changing it since I'm not sure when General Motors updated the injection pump to get rid of the governor ring which is known to deteriorate and I'm very certain mine is still the original from 1985. I'll get it gone through and shelve it in case I need to go in again down the road.

I confirmed injection pump failure. It runs fine with the check valve eliminated. I installed a known good check valve (housing pressure regulator) and it was clogged after 20 miles of driving and the truck started getting low on power. KeithJ posted a detailed explaination in another thread but I'll try to summarize. Fuel from the high pressure side bleeds into the housing side of the injection pump and exit through the check valve. When the check valve becomes plugged from bits of the elastomer ring, pressure from the high side will equalize in the housing. That will cause the advance mechanism to sit still, cause late timing, stall the injection plungers and stall the truck out. While it's still running, it will cause late timing, excessive smoke, etc. My truck has all of these symptoms. New Injection Pump should cure my issues and it'll be installed soon.

I've pulled the old injection pump. Stanadyne DB2829-4267 which cross references to a 1984 model that was superseded by DB2829-4520 in 1986. I looked over the pump for the triangle shaped tag with an "E" on it indicating an updated Elastomer Insert Drive and no such luck. Now for the good news, I was able to source a DB2831-6277 manufactured in January of 2018. It supercedes DB2831-5149 which was used on 6.5 N/A HMMWV's making 170 HP. I have no clue what was updated but it's rated at the same 170 HP.

Now for a few questions. I plan on swapping the top cover from my current pump to retain the 12 volt shut off solenoid and cold advance. Do I need to turn the main fuel screw down while I have the top cover off? I don't really pull heavy loads or long grades in this truck but I don't want to melt anything either. That's all for now, the new injection pump should be set in place tomorrow, intake should be in place Wednesday or Thursday. I only have 2 hours each evening to work so I think I did okay getting everything apart in 2 hours.

Some progress today. I've got the new injection pump installed and the fuel lines hooked up. I'll install the CUCV top cover and intake tomorrow and finish up the loose ends on Thursday. I did some reading, the cold advance solenoid is in the top cover in case someone searches about this issue in the future. I've got a Veterans Day Parade to participate in on Saturday but I think she'll be ready by then.

A little more progress this evening working between rain showers. Tightened all of the injector lines at the injection pump thanks to my new 5/8" crowsfoot wrench. Got the 33 year old gasket scraped off of all mating surfaces and set the intake in place. Tomorrow's task involves installing CDR Valve, oil fill, ground wires and swap injection pump tops. I also got to rotate the vacuum pump back into position, install the vacuum valve on the passenger side of the injection pump, install the throttle cable bracket and attempt to start.

Just a couple Questions? Have you tried clear fuel line from pump return to pump return hard line in front of engine to check for bubbles?

On my diesels I run a 5 and 1 micron Wix filters with water petcock on bottom of the 5.

You also said that The black particles are in the fuel. I dump fuel out of filters into a glass jar and observe. Rubber fuel line from frame hard line to firewall hard line most times goes bad first. I pull fenderwell and replace. Not a hard job but still takes time.

Rubber lines in bent areas go bad first. I Have minimized any soft line areas. Using fittings to make straight, near straight as possible. I use trans line or a friend that works at Yellow Freight got me this hard flex line like plastic that their mechanics use.

Fuel tanks, well about every ten years I pull off and clean or replace on my civi diesel pickups. Fuel stops have more crap in their fuel ten fold then Military fuel depo's. And better consistency. better fuel, JP.
Good Luck

Sir,
I have not tried clear fuel line to check for bubbles. The black particles were only observed when I removed the housing pressure regulator valve, they were holding the check ball closed. It was only 3 little specks but it doesn't take much to plug the valve. Cleaning the valve caused the truck to run great again, eliminating the check ball made the truck run well also. Going off the peer reviewed comments in this forum concerning symptoms for an injection pump failing is what drew me to the conclusion that the injection pump had failed. In concern of rubber lines, the only non-filtered rubber line leading to the injection pump is the 2 foot section from the fuel filter to the injection pump inlet. The rubber line appeared to be fine but I replaced it when I installed my spin on fuel filter assembly so I don't think that was where the rubber specks were coming from. I'm fairly certain the governor drive ring was coming apart which seems to be a common issue amongst the 1985 and earlier injection pumps.

Joseph

You are right on task. The injection pump is bad. Have it rebuilt or replaced. Don't bother putting a used or a NOS injection pump on. I had a few brand new ones fail a few months after installation. You will be happy with the results of a fresh rebuild injection pump. I would also drop the tank and replace the fuel strainer sock if you have NOT already done so. I replaced this sock 10 years ago. The truck M1009 sat wrecked the past 10 years. But continue on the path you are on and you will get it done. I don't think rubber particles from fuel line would get thru any filter. I always had the particles right before the injection pump went out. Good Luck. Have a Great Day.

When the Pellethane damper ring breaks down, the particles clog the fuel return check valve, causing case pressure to rise which retards timing. Knocking the glass ball out causes timing issues as there is a cold start advance which holds the valve open when the engine is cold, causing case pressure to drop which advances timing. With the engine warm, the timing is still too advanced so the idle clatter is louder.

Removing the check ball is just a stop gap measure, without the Pelletane ring, the governor cage wears on the input hub which can cause further wear from particles. The fuel for the hydraulic head comes from the transfer pump, fuel in the case is all return to tank. But because the fuel return is at the top, all metallic debris concentrates on the bottom where it can cause problems with the main shaft, advance mechanism and the cam ring/rollers.

Replacing a pump before it bricks itself saves you the core charge. It isn't hard, just time consuming. Allocate 8 hours and lots of patience. If you aren't sure, read the TM and ask questions.

Sarge is running again. If you use a newer 6.5 injection pump you will have to find a solution to adapt the throttle shaft to the vacuum modulator for the transmission. My idea so far is to drill a hole for the roll pin to fit in, grind the flat tipped end of the shaft that would fit into a throttle position sensor and let it ride. The mounting boss is the exact same on the newer injection pump. I took it for a short drive and 1,200 rpm shifts occur if the modulator doesn't receive a throttle input to regulate the vacuum. As for my top cover concerns, the CUCV top cover works fine on a HMMWV Injection Pump and the HPCA works as it should as well.

Took if for another drive today. I zip-tied the rotating assembly on the vacuum modulator valve at about 1/2 of it's rotational travel. It's shifting at about 2,300-2,500 rpm judging by ear. This feels like a whole new truck. It accelerates much stronger than before and oddly enough sounds much less stressed going 55 mph. I'm sure that's likely due to advance curve differences between the two models. I do have some light puffs of black smoke if I stand on the throttle but no worse than I've seen out of HMMWV's before so I think this is a worthwhile upgrade over a pump with .290 bore plungers. It also did not lose prime overnight like the other pump was doing. Now to sort out the mounting of the vacuum modulator this weekend but his biggest task today is to go get ice cream for my little buddy. He wasn't too happy about Sarge being down for maintenance.

I used an old picture showing my little buddy getting icecream. Here is today's picture. The truck did fine and will be in the 1st Annual Leesburg Veterans Day Parade along with General Non-Sense (M923) and Welder1's Deuce. I'm glad I got it's issues figured out and back together in time.

Sarge made the Veterans Day Parade today with zero issues. I was driving my 5 ton and everytime we took off from a stop sign my wife would put about a 1/4 mile between us before I could get up to her speed. It's running very well with a 6.5 pump.

Those prices are crazy

https://youtu.be/imPV93Byfww

No those prices are insane. And I know where that place it. Glad I never stopped to ask. I am OK with the $350. rebuilt injection pumps. They haven't failed me yet.