Loss of acceleration today?

[Bob H]

I was heading 30 miles to a MV event today, truck running fine (84 M1009)
after a leg of the trip about 12 miles at 60 mph, had to make a turn.
Low acceleration power, initially though that it just didn't downshift. Couple miles to a stop sign, took off pretty doggy long time to pick up speed with the pedal down. once up to speed it was running fine, a few more miles and another stop, this time real dang slow to get going, like I had a 60,000lb load behind me.
yet will just purr at 55 mph.
I was figuring it was the fuel filter, but it has no problems at highway speeds and had been running fine all morning except that it did stall after the 1st startup this morning & took a bit to refire. Has started good the rest of the day.

Ideas?

Left it there, will probably use a trailer to bring it back after the show. Hope she don't mind being saved by the M880.....
Sourcing new fuel filter next

 

[Ilikemtb999]

I think you're on the right tract.


Happen to fill up recently? I've certainly gotten bad diesel before (not in my cucv) and was a similar situation. A refill and some emergency diesel additive fixed it.

 

[cucvrus]

I want to go a bit deeper here. I will put my usual suspect to the side for now. I would look at the fuel delivery lines and mainly in the fuel lift pump area. I have had this happen to me once at Rausch Creek. The fuel lift pump on the right side of the engine is dangerously close to the front cross member. When the motor mounts get worn. And your are worn out if you never changed them. The feed line nipple of the fuel pump will make contact with the cross member and wear/cut a hole in the line. This is a big issue. now it may not fluid leak but it will suck air. It kicked my butt while out wheeling. I had changed my motor mounts the week before going to Rausch creek and they were not the correct ones. I was in the Rausch Creek parking lot the Friday night before we were going wheeling and I started my Crown of Thorns M1009 and it shut off and started hard. I thought what the hay? I drove home it ran fine. The next morning it started right up and ran fine. On the trails as I flexed and drove it kept shutting off and would start but after bleeding the fuel filter. I could see no fuel leaking. It kept getting worse as the day progressed. I finally had enough and was towed out to the lot by a 5 ton and made a run for home. About 30 miles away. Mostly down hill. I would get it up to as fast as it would go and coast when it shut off. In my head I thought injection pump is failing. I would stop along the road it would start and go again. About 5 miles from home all the belts came off. End of the line. i was towed home by a HMMWV and we proceeded to remove the injection pump that night and replace it. Still same issue. I had a brand new HMMWV injection pump and the CUCV would not stay running. It had fuel but was sucking air. Before you jump to conclusions you must know I had this same M1009 for 17 years and over 100K and never done a thing to the injection pump. It was always a slower driving m1009 and i always thought it may be the injection pump was set back or something but it ran and started everyday for all them years. My Son drove it back and forth to Ft Drum every other weekend as many times as he was on leave. I discovered the fuel drop and I mean 1 drop on the front differential. I looked up and the line was just nicked a small bit. When I pushed on it fuel came out. It was tight against the front cross member and had bent the metal nipple up slightly. I replaced the motor mounts with Energy Suspension motor mount inserts and also replaced the fuel pump with a Delphi fuel pump. Fast forward less 8 months the injection pump failed and I replaced it with a rebuilt one from Diesel Care in Memphis and have been living happily ever after. Matter of fact this AM I went out after it has been sitting for 2 weeks glowed it and it started right up and ran perfect o. The HMMWV pump never ran perfect. It always stalled and made a loud advanced timing sound no matter what I done to it. I had it at a pump shop and they said it was internal. Thus that could be why it was discarded by the military. Because I seen a whole box of them in the scrap bin brand new. I was allowed 1 with a replacement for inventory. That was all the cores I had at the time. No waste it was a PITA anyway in the long run. Left me sitting in 40" on snow. No pictures. You get the point. But check that fuel pump pick up line and see what you find. I hope this long story was helpful for a resolution to your problem. If not enjoy the story and it may help someone else. Have a great day. I am going out to work on my Cadillac today. I am almost done with it and it looks alike brand new. I was amazed at the condition under the 9 + years of dirt that were on the car. Glad it was in a dark garage. The entire car is immaculate. It was my buy at a police auction. 1996 Cadillac CUC/V = Civilian Under Cover Vehicle. That was a cool acronym in the sale paper. Out in the heat I go. Have a great cool day.

 

[Bob H]

update:
After the show it started up for a second, stalled, cranked a little bit started idled for a few, drove it onto trailer, 30 mile ride, sat an hour or so, started up, backed off trailer, parked 150' away, sat another hour or so. Checked hoses @ lift pump, all in excellent shape, (notice clamp on a nearby hose is an inch away from where it should be yet hose is snug)
Suspect hose issues up stream. on start & stall / possible air sucking issue.

Test drive:
Started up pulled out into road 1/4 to a stop sign, turn & go , normal acceleration, 1 mile, then stop & turn around, 2 miles stop & turn around, 1/4 to 1/2 mile, slam on brakes turn into a drive, check out CJ2A that is for sale while cucv idles, CJ2A is warm as in just parked, no-one to be found, back out & take off, sluggish acceleration, 1-1/2 miles slow & turn, real bad acceleration, 1/4 mile turn into drive, no acceleration, idle speed 130 feet & stalls, remove filter & shake about while draining, reinstall start-stall-crank alot-drive another 300ft & park, new filters will be here Tuesday.

 

[Tinstar]

Every oil change I also change my fuel filter.

Betrer too early than too late.

 

[Bob H]

Update:
The filter isn't the problem.
Not knowing squat about diesels, I'm guessing injector pump.
Will surf through the troubleshooting section b-4 I spend $ on a pump.

 

[cucvrus]

Lift pump?

 

[Tinstar]

Fuel pickup sock?

 

[Bob H]

Each time filter was full of fuel, so it would seem the issue is upstream of there.

 

[cucvrus]

Each time filter was full of fuel, so it would seem the issue is upstream of there.

Each filter? Did you use a pump and try to draw fuel from the tank? That would be how to check the the in tank fuel strainer/sock for obstructions. Also did you check the lift pump? And if it is lifting fuel and the strainer is clean. I tend to go after injection pumps. They are often the root of much evil and problems within the CUCV fuel system. Very seldom did I ever have to put a 2nd injection pump on after replacing the original one. And my lesson learned was a new NOS injection pump is NOT always the answer to or substitute for a fresh rebuilt one. I had a NOS in the sealed box and put it on my Crown of Thorns M1009 and it lasted less then 6 months. It was an issue from the day I installed it. Keep up the diagnosis and good luck with the repairs.

 

[Bob H]

Guess upstream isn't the right term, when it dies out, the filter on the firewall is full of fuel. So my thinking is if the sock or lift pump were the issue the injection pump would have sucked the fuel from the filter.
Thinking the issue is between firewall filter and the cylinders.

Odd that no one has had and solved this problem.

 

[cucvrus]

But if the injection pump does not deliver an accurate properly pressurized delivery of fuel at the exact precise time the Diesel engine will not run. So even with diesel fuel present and not being properly managed / pressurized at an on time delivery the engine will not run. That injection pump is a very fine tuned and precision piece of equipment. Good Luck.

 

[Bob H]

I believe I may have a injection pump issue. Definitely related to the fuel return. 84 M1009
It has slowly progressed, After an 1/2 hour or so of driving, once you stop it would have no power & take forever to get back up to speed. Let it sit for a while and it would go back to normal. Each time on the road it would happen sooner that the last.
First thought was fuel filter starving it, new filter plenty of flow. In an effort to get it in the parade this morning, last night I decided to pull the top off the pump checked to see if anything was physically sticking, used a little 2 cycle oil to lube things up. put it back together, made it worse. I blew through the return hose to clear it. starts up fine, runs fine for a minute, or will idle for several minutes & then want to die out. Pull the return hose blow it out and she'll run fine again. So I'm guessing that too much fuel is going to the return line. Going to pull the top piece off again for a look see. Would appreciate your thoughts on this.

 

[cucvrus]

Break the glass ball in the return line on top of the injection pump. It will get you by for a short time. But yes it sounds like a rebuilt injection pump is in order. I like the way that rebuilt injection pump fixes a lot of ills and gets the truck down the road in a new way. East fix for less than $400. and about 3 hours time. Good luck. But as mentioned before. I would go over the entire fuel system. From fuel tank to nozzles. Funny thing. I always buy my parts at Autozone and they sell Delphi fuel pumps. Delphi are made in Mexico. I had a friend give me a NAPA pump (Easter find M100 and it was free so I did not refuse it. It was made in Korea. I see that Korean pumps are far more superior then Chinese fuel pumps. NOT. I am going to use it. The pump fits use it. I am wearing shoes that are made in China. Fit fine. Good Luck. Fix it right the first time and it will serve you a long time.

 

[Bob H]

It was a gummed up sticking return line check valve, after cleaning, it literally is clear! and running good so far.
A couple had recommended breaking the glass check valve, but as I said it was like it was getting too much fuel in the return. So I wasn't about to break ****.

 

[scottladdy]

It was a gummed up sticking return line check valve, after cleaning, it literally is clear! and running good so far.
A couple had recommended breaking the glass check valve, but as I said it was like it was getting too much fuel in the return. So I wasn't about to break ****.

Glad to hear she is working again.

However, if this is the original IP, you should seriously consider getting a rebuilt unit. There are a number of known issues that Stanadyne addressed over the years including hardening of internal parts to deal with the lower lubricity low sulfur fuels to the plastic weight retaining rings which were known to fail.

If you want to keep the truck replacing the IP is cheap insurance in my opinion.