M1009 suddenly only crawls, eventually tops out at 35 MPH.

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edpdx

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On my way fishing- never happen when I'm on my way to get a root canal, and the pedal feels off as the engine starts bogging. I can keep the Blazer moving t get off the highway, but only just.

Visual inspection turns up nothing. I limp back into town, find a diesel shop, but they can only guess it's fuel filter related. I limp home- lots of impatient drivers giving me the
evil eye 🤘.

All fluids are fine. No symptoms beforehand. I get the same result in all gears. New transmission, no recent slipping. From a dead stop it just crawls. Around 20MPH I can goose it into passing gear- it revs but only a bit and I can get it to about 35-40 mph tops.

I could use some help here. Any ideas of what it might be?
 

rtk

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I hate to diagnosis something this way , but try this ,Start with the basics , fuel flow , are any of the fuel lines leaking or old and cracked ? IE; loosing prime . The sock in the tank has also been known to give problems . Check to see if you have fuel at the filter , if not lift pump , if yes and your fuel filter is good , time for IP check . From your description of the symptoms it sounds like fuel starvation and if so you need to get with the TM's and they will help you understand the system and how it works . Good luck and post your results
 

Barrman

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Fuel or air.

Fuel wise a clogged fuel pick up sock in the tank, clogged fuel filter on the firewall and then a clogged fuel return check valve on the Injection Pump are the easiest to check.

Air filter and making sure a birds nest isn’t in the intake manifold are about all you can check.
 

cucvrus

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Have you looked at the right side where the fuel pump hose connects to the fuel pump. Are the motor mounts bad and have a small hole or cut worn in the feed line. I seen that on my own vehicle already. No fuel leak just allowing no suction.
 
Last edited:

Miah

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I 2nd that. Since the shop suggested fuel filter, did you immediately change it? Also did you very recently fill up the tank before this occurred? Could you have gotten a batch of contaminated fuel that's mixed with what you already had in-tank & plugged up the works?

Person could try a gas can of fresh fuel run to a new fuel filter & see if that changes things
 
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edpdx

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The filter is a couple of months old. I did fill the tank yesterday at $2/gallon. I wonder if the diesel was bad. Hmmm :unsure:
 

rtk

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Well the filter is a easy R/R . so that would be a good start and you can check your fuel flow at the same time
 

nyoffroad

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The filter is a couple of months old. I did fill the tank yesterday at $2/gallon. I wonder if the diesel was bad. Hmmm :unsure:
Fuel is a long shot unless you got gas instead of D2, accidents do happen. Check the lift pump pressure, from my experience when that goes bad it's hard to start not so much your symptoms.
 

edpdx

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Changed the Fuel filter, and checked all fuel lines for leaks or damage. Nothing changed. Starts at a crawl eventually gets to 35-40. How can I rule out the transmission?

Reinstalled the fuel pressure gauge after the filter- holds fairly steady at 8lbs.
 

edpdx

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This morning I checked the vacuum Pump- I got a median read of 20 Hg with the needle bouncing wildly between 16 and 22. The fuel pressure is pretty steady at 8Lbs. I removed the metering valve from the injector pump- more work than I needed to do in retrospect. It was a little funky- only a year since the rebuild. Cleaned up with solvent and 300 grit scouring pad. It seems fine, but after the initial test drive, the speed still slowly gains and I have not got up to 40 MPH. The VRV needs further adjustment to bring the shift points down. I shooting for 15 (1st gear to 2nd) and 25 to 30 for 3rd gear. I haven't done all my research yet, but I want to rule out the VRV- hopefully I'll find a way to test if its still good- it was installed new a year ago.

I could use more suggestions- any help is appreciated
 

cucvrus

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Have you ever removed the fuel tank from this M1009? If not I would definitely be doing that. Many times this is what you will find. A filthy sock and it is sucked shut. Good Luck.
DSCF6708.JPG
 
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edpdx

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Have you ever removed the fuel tank from this M1009? If not I would definitely be doing that. Many times this is what you will find. A filthy sock and it is sucked shut. Good Luck.
View attachment 799320
Thanks for the visual, cucvrus. I'm sure you are right on this, but like everyone else, I wanted to follow the path of least resistance before dropping the tank. I filled it up the morning the Blazer presented with this problem. I'm about out of remedies to try so it looks like its time to drain the fuel and drop her. Does anyone think a whole new unit should go in, or just replace the sock and clean the tank. I've never cleaned (or dropped) a tank so it'll be a learning experience. Any tips are welcome.
 

cucvrus

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First thing is to get the blasted skid plate off. Do that and move on from there. Make getting the skid plate off the goal for a day. Toss all the bolts and use new ones to reinstall. Use 3/8" x 16 1 1/2" bolts and new SAE flat washers. 6 bolts and they can be a PITA. use never-seize when you reinstall and a thread chaser to clean the captured nuts. Heat may be used to get them loose. The 2 back strap 11/16" hex head nuts are also very tight and temperamental. Get 2 new nuts 7/16 X 14 for reinstallation. Use Never-seize there also. After you have the tank down [part way carefully reach up and cut the fuel lines and carefully unplug the wire on the sending unit. Carefully with a small pliers. DO NOT yank on the wire. The ground is on the under frame flange on the rear of the drivers rear wheel. 1/2" ratchet wrench and patience. You will need about 12" of 3/8" , 5/16" and 1/4" fuel line and get all new clamps. disconnect the fuel filler pipe and the vent hose. Do NOT cut the larger filler hose. Nothing special about the smaller vent hos. that is just 5/8"or 3/4" emissions hose. I do away with the pinch clamps and use new drive clamps all around. Include the clamp that attaches the fuel filler hose to the cargo floor under side. Take pictures and ask questions if any issue arise. But I would clean inspect and recoat as needed. Check out my CUCV repair project thread for fuel tank replacement on M1009.


Good Luck. Report back. Take Care.
 

edpdx

Member
744
10
18
Location
Oregon
First thing is to get the blasted skid plate off. Do that and move on from there. Make getting the skid plate off the goal for a day. Toss all the bolts and use new ones to reinstall. Use 3/8" x 16 1 1/2" bolts and new SAE flat washers. 6 bolts and they can be a PITA. use never-seize when you reinstall and a thread chaser to clean the captured nuts. Heat may be used to get them loose. The 2 back strap 11/16" hex head nuts are also very tight and temperamental. Get 2 new nuts 7/16 X 14 for reinstallation. Use Never-seize there also. After you have the tank down [part way carefully reach up and cut the fuel lines and carefully unplug the wire on the sending unit. Carefully with a small pliers. DO NOT yank on the wire. The ground is on the under frame flange on the rear of the drivers rear wheel. 1/2" ratchet wrench and patience. You will need about 12" of 3/8" , 5/16" and 1/4" fuel line and get all new clamps. disconnect the fuel filler pipe and the vent hose. Do NOT cut the larger filler hose. Nothing special about the smaller vent hos. that is just 5/8"or 3/4" emissions hose. I do away with the pinch clamps and use new drive clamps all around. Include the clamp that attaches the fuel filler hose to the cargo floor under side. Take pictures and ask questions if any issue arise. But I would clean inspect and recoat as needed. Check out my CUCV repair project thread for fuel tank replacement on M1009.


Good Luck. Report back. Take Care.

I forgot to adjust the shift points via the VRV 🙄. So, I think I messed up something because I have rotated the VRV fully towards the rear of the vehicle and I cannot bring my 1st to 2nd gear to shift any sooner than 24MPH. 3rd never comes in until over 35mph. Not sure, but I feel like my biggest problem is not IN the fuel tank.

The face collar, I think is in the wrong orientation, so that first.

Happy Mothers Day!
 

chevymike

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I forgot to adjust the shift points via the VRV 🙄. So, I think I messed up something because I have rotated the VRV fully towards the rear of the vehicle and I cannot bring my 1st to 2nd gear to shift any sooner than 24MPH. 3rd never comes in until over 35mph. Not sure, but I feel like my biggest problem is not IN the fuel tank.

The face collar, I think is in the wrong orientation, so that first.

Happy Mothers Day!
I had a problem like that and it was the vacuum modulator on the trans. Swapped out with a new one, all the shift points were back to normal.
 
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