Bad Injector Pump?

[drbeeper17]

I suspect my M1008 may have a bad injector pump and wanted to see if anyone here can confirm it. The symptoms are as follows:


When I am cruising on the freeway at about 2650 rpm, the truck will suddenly not be able to accelerate or maintain speed. It feels like I have taken my foot off the throttle but I do not move my foot at all. Then as I do decrease throttle, the response is not as it should be. Its a bit hard to describe, but it as though the truck starts having a mind of its own and starts jumping around in rpm range from 2000 rpm to 2500 rpm all on its own. It doesn't matter if I pump the pedal or keep it steady, the truck just revs where it wants. This only happens in the top gear (3rd gear for my TH400). The truck revs fine when in park or neutral and revs up just fine in 1st and 2nd.

The incident happened for the first time back in June on my way home from off-roading. I was climbing some unmaintained fire roads and using engine braking all day on the descents. When I got back on the road I couldn't go more than 2500 rpm. It continued to get worse on the hour drive home. There was one point where white smoke was coming out of the exhaust but it only lasted for about 5 minutes then cleared up. It got to a point where I was going about 40 mph on the freeway and couldn't rev past 1700 rpm. When I came to a stop it dropped down to 400 rpm and stalled out. It does start up fine since then and drives good until I get up to around freeway speed (60-65 mph). I have taken the truck on 2 other long trip before June and power/rev range was fine and as I expected. Now it seems to have developed this problem.


What I have tried so far to correct the problem:

New fuel filter
Bled the fuel lines to remove air
Bled the water in fuel line
Disconnected the return line from the IP and blew into it. After about 10 seconds of consistent pressure, the line finally clears and I can hear the fuel in the tank bubbling.
Removed and cleaned the IP return check valve.

When I cleaned out the IP return check valve, there didn't seem to be anything wrong with it. No noticeable chunks of rubber where in it and the check ball moves freely when I put pressure on it.

The first time when I blew out the return line and cleaned the check valve, the truck ran fine for about 30 miles on the freeway until the symptoms returned. I tried the same process today and the truck made it about 1.5 miles on the freeway when the symptoms returned. Also, as I was exiting the freeway without my foot on the accelerator, the rpms were jumping from 2700 down to 300 and were all over the place. Once I got back onto the side street the rpms stabilized.


So with these symptoms and what others have experienced, what should be the next step I take? Is this indicative of a bad injector pump? If I need a new injector pump, where do I get it? If I buy a civvy one from Autozone will it cause the truck to be less powerful? The engine already struggles for power and I thought what made the military 6.2 more powerful was a tuned injector pump?

Any help on this issue would be greatly appreciated. Thanks!

 

[acesneights1]

sure you are not sucking air somewhere ? I'd sightglass it first. Usually when a DB2 takes a crap it smokes like a sick whore on a piss pot. The advance could be sticking as well Make sure it moves freely. I would not buy a reman from Autozone. Take YOUR ip to a local diesel inj shop and have it rebuilt. If there are no REPUTABLE shops then ship it to Accurate Diesel. Google will find Tim fast. Your IP should be a 2829. Nothing special about it. Just a plain old 6.2 Pump AFAIK.
Might wanna put a fuel pressure gauge on it too. If you are running the mech LP that could be on it's way. They are junk. I usualy convert to electric. One off a 93 6.5TD works perfectly.

 

[drbeeper17]

By sightglass it you mean to put clear lines coming from the mechanical fuel pump to the IP and a clear return fuel line and see if there are any air bubbles?

To play with the advance do I have to tear into the area where it attaches to the injector pump or just push and pull it in and out a few times until it feels non-sticky?

 

[drbeeper17]

UPDATE:

Replaced the mechanical LP fuel pump on the block - same problem
Replaced the fuel return line coming from the injector pump check valve which had cracks - same problem
Looked at my fast idle solenoid and found that it was completely shot. When I take it off and apply power to it, nothing happens. The rod jiggles up and down freely when I shake it, so I just removed it. Thanks goodness I live in SoCal because a new one is $178!!!

Tonight I drove about 4 miles on the freeway at about 60mph (2650 rpm), truck ran fine. Pulled off to check the new fuel pump to ensure not leaking, truck idled fine. Got back on the freeway and within 0.5 miles it started the symptoms I first described. Any suggestions????

Next I will open up the governor assembly on the top of the injector pump and see if the HPCA is working. My guess is that it isn't because when I apply 12V to the lead I do not hear or feel anything. Does anyone know where I can get a new gasket for the governor assembly cover? I'm taking about the top of the injector pump that is held on by 3 screws and houses the return valve. If it is anything like a carburetor, when I take it off the gasket is ruined. Not knowing what the gasket looks like, I'm not sure if I can just use RTV on it in place of a gasket. Also, does anyone know where I can get a new HPCA, which is the cold advance solenoid? Even doing a quick Google seach I find nothing, except a whole new IP that comes with it.

Also I suspect the cold advance is not working because the truck cranks for about 10 seconds after the wait to start light goes off to fire up after it has been sitting for a few days. However it always starts, hot or cold, it always will start. When it is hot it starts right up. Also, there is no noticable smoke either idling or on the freeway when it has the symptoms.

 

[drbeeper17]

So I changed out the cold advance solenoid (HPCA) in the injector pump. Turns out mine was not working at all. I also sightglassed the line going from the fuel filter housing to the injector pump. I drove the truck maybe 2 miles and then at around 35 mph it was sputtering and would not go past 1800 rpm. I pulled over and there were very small bubbles in the sightglass section. When I move it around the bubbles go away. I started driving it again with the same symptoms, but this time when I went to pull over it stalled out. Looking at the sightglass then, there was only about 1/2 full of fuel, the other was all air.

Any suggestions what to try next? When the truck is parked it starts up every time just fine. I can rev it up to 2700 rpm and keep it there all day and nothing strange happens. I do not see any bubbles in the sightglass either. It only seems to bubble when I am driving, but obviously I can't see to what extent until I stop. There only is a problem when I am driving, parked it does everything fine. Also, I have not seen any white smoke during this process of it sputting, stumbling, then stalling out.

Should I change to a spin on filter?
Should I check the injector pump timing, if so, how do I do that?

Any and all help would be greatly appreciated. I just want to go out and play with it.

 

[Southern Off Road]

I am not real sure but it sounds maybe your filter could be clogged, cause i would be able to rev it up while your parked but looses power while in a load, js cheap fix if so.

 

[Stonepicker1]

I had the same problem on one of my M1028's. I had water and junk in the main fuel tank. Cleaned out the tank and solved my problems.

 

[drbeeper17]

I changed the filter once and some green and dark red gunk came out. I haven't check this one since I put it on about 2 months ago.

It's interesting that you mention the tank because I only noticed the problem when I got done trail riding and rock crawling and sloshed the insides of the tank all around. The thing that sucks is that in the spring I put a new sending unit in the tank because my gauge wasn't working. I didn't dump the diesel that was in it out because it was nearly a full tank and I was too cheap to waste diesel. Guess I learned my lesson...maybe. I will let you know what happens. I'm thinking I will do it Sunday.

Thanks for the help/suggestions.

 

[Cleptomaniac]

Had all kinds of fuel delivery problems with my 1009 yesterday! So I got/bypassed the old fuel pump and still wouldn't work. So long story short she has a new spin on fuel filter and pump! Works great but killed the starter trying to figure it all out
So it is getting that rebuilt today!

Good luck keep us posted!

 

[Stonepicker1]

I changed the filter once and some green and dark red gunk came out. I haven't check this one since I put it on about 2 months ago.

It's interesting that you mention the tank because I only noticed the problem when I got done trail riding and rock crawling and sloshed the insides of the tank all around. The thing that sucks is that in the spring I put a new sending unit in the tank because my gauge wasn't working. I didn't dump the diesel that was in it out because it was nearly a full tank and I was too cheap to waste diesel. Guess I learned my lesson...maybe. I will let you know what happens. I'm thinking I will do it Sunday.

Thanks for the help/suggestions.

A lot of junk got into the fuel tank when Soldiers dumped 5 gallon cans of fuel into their trucks. They would remove the screen on the fuel spout that stops the junk from getting in the tank just so the fuel would flow faster.

 

[drbeeper17]

So I ended up removing the tank and there was all sorts of rust in it. I used some laquor thinner, old diesel, and acetone to clean it out. I was able to get most of the rust out but there was still some residue (when I wiped the inside of the tank with with a cloth it came up with mirco-scopic rust particles and the rag was a burnt red color).

Installed the cleaned out tank, put in a new fuel filter, and put fresh diesel in and the problem has yet to return. I bought another fuel filter for backup if it acts up on the trail again. Fixed...for now.

Looking back, I think I should have just put a new tank in for $120, but I was concerned about the quality and durability of the tank as it is probably cheap Chinese steel that will dent the tank into the pickup when I smash a rock on the tank's skid plate.

Thanks everyone for the help. Hope this helps others out in the future too.

 

[chicagodiesel]

DrBeeper,

Could you post info on the part number for cold advance solenoid? Need to get a new one myself and am having difficulty finding the part. Thanks so much.

 

[drbeeper17]

Chicagodiesel,

I was unable to find a part number for the cold advance solenoid, also know as the HPCA. I checked all local stores and no one had it. I finally found it on ebay. Search "6.2 HPCA" and you will see one for sale by accuratediesel. It comes with a new ip cover gasket as well and with shipping it was around $35. I think the reason why you can't buy one at the stores is because it is part of the injector pump and they don't sell the internals seperately. It's the only place I could find one.

 

[Stonepicker1]

So I ended up removing the tank and there was all sorts of rust in it. I used some laquor thinner, old diesel, and acetone to clean it out. I was able to get most of the rust out but there was still some residue (when I wiped the inside of the tank with with a cloth it came up with mirco-scopic rust particles and the rag was a burnt red color).

Installed the cleaned out tank, put in a new fuel filter, and put fresh diesel in and the problem has yet to return. I bought another fuel filter for backup if it acts up on the trail again. Fixed...for now.

Looking back, I think I should have just put a new tank in for $120, but I was concerned about the quality and durability of the tank as it is probably cheap Chinese steel that will dent the tank into the pickup when I smash a rock on the tank's skid plate.

Thanks everyone for the help. Hope this helps others out in the future too.

Thanks for the update.