New to me 1984 M1010 Engine Question #1

I got my 1984 M1010 running. The fuel tank was emptied and fresh fuel put in with a bit of Marvel Mystery Oil. It also has a new fuel filter in place. For the record I did start it before changing the fuel or filter .....maybe not a good idea. It starts up pretty good when cold after three 4 second hits on the glow plugs...no ether. It idles a little high but seems to run OK. If I rev it up at all when it is cold it tries to stall. After a ten minute warm up it is still trying to stall. If I drive it and let off the pedal quickly it will stall. It starts right back up. When it gets to full operating temps it seems to do better but still hesitates a bit like it wants to stall. When pressing on the pedal it sometimes wants to rev up real fast but not always. What do I do first.

When was your injection pump last rebuilt? If you have good clean fuel coming to the IP and the return line is clear, the plastic parts inside your IP are wearing out.

The most common failure for the DB2 injection pump is the throttle shaft seal. In this case the engine will start and idle. Once you put load on it, put it in drive and step on the pedal, it will die. It will take 30-60 seconds of cranking and start again and be fine for the rest of the day. After 12 hours the problem will reset.

NDT said:

When was your injection pump last rebuilt? If you have good clean fuel coming to the IP and the return line is clear, the plastic parts inside your IP are wearing out.

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The truck has 18000K on it so I suspect it has never been rebuilt. It has been sitting for 7-10 years (I think) but was used in parades and the like before that. It seems to run fine when I have pressure on the throttle but when I back off quickly it dies. Fuel looks clean coming out of the bleeder vent on the filter. How do I tell if it is getting back to the tank in the return line? The filter didn't look great when I pulled it. Trying to send a picture of the filter cut in half but having trouble converting from HEIC format to JPG format. I hate computers. This didnt happen last week.

87cr250r said:

The most common failure for the DB2 injection pump is the throttle shaft seal. In this case the engine will start and idle. Once you put load on it, put it in drive and step on the pedal, it will die. It will take 30-60 seconds of cranking and start again and be fine for the rest of the day. After 12 hours the problem will reset.

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IT's not really doing that. IT starts right back up after it dies....like 1/3 revolution of engine and it is running.

Can I drive it like this if the pump is going or is it going to quit on the road pretty quick. I want to drive it home.....50 miles vs driving 100 miles to work on it a few days a week.

Add towing to your auto policy ….

It ran great till I tried to drive it home.....50 miles. I got about 5 miles into the trip and it died....no fuel. Started right back up and drove another mile and it died again...no fuel. It did this several times and got harder and harder to get started again. I got it turned around headed back to my starting location and it died again and this time I could not get fuel out of the bleed port on the filter. I swapped filters thinking it was either that or the lift pump. I could not get it to spit fuel out the bleed port at all after the filter change. I got very, very lucky and had a diesel mechanic show up and stop to help. He got the system bled and started again. Lift pump seems to be OK and I drove it back for more troubleshooting. I can't find any hose leaks but did see a puddle of fuel in the engine valley and apparently it is leaking out of the weep hole in the bottom of the front of the pump. I ordered a replacement yesterday. Tracking says it will be in tomorrow evening. Time will tell. I do have towing on it but don't want to start with a tow bill on a new policy! : ) I also plan on replacing the lift pump "just because" it is 40 years old. Seems prudent.

Marv

ballencd said:

I got my 1984 M1010 running. The fuel tank was emptied and fresh fuel put in with a bit of Marvel Mystery Oil. It also has a new fuel filter in place. For the record I did start it before changing the fuel or filter .....maybe not a good idea. It starts up pretty good when cold after three 4 second hits on the glow plugs...no ether. It idles a little high but seems to run OK. If I rev it up at all when it is cold it tries to stall. After a ten minute warm up it is still trying to stall. If I drive it and let off the pedal quickly it will stall. It starts right back up. When it gets to full operating temps it seems to do better but still hesitates a bit like it wants to stall. When pressing on the pedal it sometimes wants to rev up real fast but not always. What do I do first.

Click to expand...

Marvel mystery oil is basically two parts low flash point solvent and one part atf. Just look up the
MSDS and there it is. I have never been a fan of putting solvent in my engines.

Thanks for the input but I did not ask what you thought of Marvel Mystery Oil. Turns out the weep hole in the injection pump was leaking fuel so I ordered a pump. IT is in today but not yet started. Time will tell if that was my whole issue.

So, update is in order. I swapped in the new injection pump and got it started again after a long ordeal with the water drain on the filter housing leaking and letting fuel out and air into the system so much so that I could not get it primed. I got the leak fixed and the pump primed and it started without using the glow plugs at all. All seemed good. No more smoke and it idled good even when pedal pressed and released fast when cold. Today I buttoned up the few remaining things that needed done and wired up the two 12 V alternators after verifying the wiring several times. It started, had about 25+ volts on the batteries and everything checked out OK, so I started home....50 mile trip. About 2-3 miles into the trip, the truck died again....pretty much like last time....I was going about 35 mph and it just lost power and the engine stopped. It started again after I verified that I had a prime and I turned around back to the shop. It quit 2X more on the way back but started again easily. My only thought now is that the lift pump may not be supplying enough fuel when I get up to speed. I had tested the pressure at about 3.5 PSI which is low but my gauge is not known to be good....also tried the 15 second turnover pumping into a empty canister and I got about 1 liter of fuel in 15 seconds. I assumed the pump was good but then it stops on the road. My next plan is to swap out the lift pump with a new one and try again. I will test the fuel pressure with a better gauge before I start for baseline.

Anyone have any other ideas on where to go from here?

Thanks

ballencd

Suggest you verify 12 volt supply to the solenoid on the injection pump is not dropping out.

That is something that I will look into first. I suppose I could wire up a light in the cab using power from that wire and see if it was flashing or out when the engine dies. A friend suggested to just hot wire that solenoid from the battery and see if it quits....same test different way of going about it. While sitting still with no incline it seems to run fine and does not stop but when traveling it acts up. thanks for the idea.

I ran the PM tests on the lift pump....I got 6 psi and almost a liter of fuel in a 13-15 second turn of the engine so I am thinking the lift pump is good. I have fuel. I hot wired the fuel cutoff solenoid to the battery and tried again. It died again in a few minutes on the road. It still starts back up in a few minutes but seems to get worse and worse. I am going to pull the tank and make sure it is clean, sock (if there is one) is clean, blow out the lines, fix the fuel gauge sender if that is the issue with my fuel gauge and verify/replace any rubber lines from the tank to the Injector pump and try again. It seems to idle all day without issues so at this time I'm thinking its got some kind of blockage in the supply section.

My later model Chevy with 6.5 is giving me fuel fits as well, I am about to plumb in this fuel pressure gauge between the filter and injection pump so I am not flying blind anymore.

That's a good idea for sure. I pulled the tank today and found a lot of junk coating the tank and sending unit. Looked like a combination of rust and old, old fuel. The new fuel I had put in there doesn't look new anymore and is a little red colored. Most likely part rust and part Marvel Mystery Oil. I will be sure to filter it well before using it. The sending unit was not working and the gauge dropped to zero when grounded so looks like the tank needed to come out anyway in the long run. I am going to order a tank and sending unit tonight. Anyone know of a good place. I'm looking at LMC already but maybe there are better suppliers...???

I would say you have this figured out.

One can hope. Tank and sender are ordered. Time will tell! Have a good weekend!

I got my tank and sender from rock auto but I’m sure LMC is fine too