Fuel leak, air in system, squeaky noise related to fuel delivery, need HELP

[stranger75]

So, first I need to apologize for not having thoroughly searched. I am in a bind and humbly ask for assistance with my issue. I am working 12 hr days, do not have a day off ther than thanksgiving for a couple of weeks, and only have access to Internet though my iPhone during business hours.

i have a 1984 M1009 with just over 100,000 miles. It is my DD and currently my only vehicle.

there is a fuel leak coming from the rear of the truck. It has caused air to get into the system, which is causing hard starts. I have been keeping the tuck parked nose down on an incline to help.
I have removed the skid plate (not an easy task), and think that the leak exists at the fuel sending unit. I have purchased the necessary fuel hoses to replace them, but have not yet dropped the tank in order to do so.

what I really need help with is identifying the source of the noise that is occurring. While driving, when I let off of the accelerator, a squirrelly squeaky noise happens. It sounds like it is coming from the rear passenger side of the truck. I thought maybe the mechanical lift pump until I found out that that part is located under the passenger side alternator. I wonder if it is the sending unit? I am unfamiliar with the mechanics of that part and don't know if it would cause the noise.

i plan to drop the tank and change the sending unit fuel lines. While it is down I can pull the unit and inspect it.

have any of you experienced a failure of the mentioned parts? Experienced a noise like the one I described? This will be my first time attempting repairs to the fuel system other than changing the fuel filter.

Any my help or advice you could give me would be appreciated.

 

[firefox]

This is just a guess and may be totally unrelated, but since you having to do a lot of hard starts,
my suggestion would be to check to see if the bolts that hold the starter to the block, are not
starting to loosen up.

 

[Mg84648]

The squeaking could be your lift pump cavitating due to air in the line. It's probably not your sender since there are no moving or rotating parts aside from the float arm. Looks like your on track with the fuel line replacement.

 

[stranger75]

Firefox thanks for the tip. My starter (original) is firmly in place with the bracket attached. I have not experienced any difficulty in that neighborhood. The hard starts I'm having are due to improper air/ fuel mixture. The engine is starved of fuel when attempting to start when the engine is cold.

mg84648, thanks for the reply. As stated above, the noise is coming from the rear. Would the pump up front cause that? Like it's trying to suck fuel through the line but isn't getting it? I'm kind of a noob when it comes to this sort of thing lol

 

[Mg84648]

Understood, I guess the only sure way to see where it's coming from is to have someone manipulate the accelerator while your listening from the outside. The acoustics inside the cab could be misleading. I had a "metal in a blender" noise coming from the fan area when I first got the truck. I swore it was coming from the fan area. It turned out the be the tranny cooler lines rattling right under my seat.
One more thing. Remove your fuel filler cap and see if that changes the sound any.

 

[Drock]

If you look down inbetween the cab and the bed you can see the top of the tank. And if you twist your head right you'll see the short rubber lines spider webbing out from it. If it were me I'd undo and slide the bed back before I'd try dropping that heavy tank.

 

[cucvrus]

Sergeant Drock he is working on an M1009. If you had trouble removing the M1009 skid plate you will be over joyed with the fuel tank removal. That requires a lot of patience. You will need to cut the small rubber fuel feed hoses on top of the fuel tank sending unit to remove the tank. Most of the clamps are shot by this time. Remove the ground wire from the left frame flange back at the fuel tank. I am thinking that you may have a fuel line rusted thru on the right side frame rail. Double check and identify where the fuel leak is before you get deep into it. When you go to reassemble it replace all the nuts and bolts on everything that you are putting back together. It makes things so much easier. Grease every bolt with never seize. Good Luck it is always nice to clean everything and undercoat or paint everything while you have it apart. The noise well that could be anything.

 

[Drock]

If you look down inbetween the cab and the bed you can see the top of the tank. And if you twist your head right you'll see the short rubber lines spider webbing out from it. If it were me I'd undo and slide the bed back before I'd try dropping that heavy tank.

OOPS Sorry, I guess I read what I wanted to read. Thought we were talking about ah 1008.

 

[phil2968]

There is a capped fuel line from the tank behind the right rear wheel outside the frame rail. There is a short fuel line near there that you could tap into it until you find your leak.
No idea on the squeak.

 

[doghead]

I would be prepared to replace the sending unit when you drop the tank. The steel lines are known to rust through.

 

[stranger75]

I plan to get into it tomorrow. Yes, it's Thanksgiving, but without much family here I don't have plans until the evening.

Unfortunately I was unable to find a fuel sending unit today. I called several Napa's, and the O'Reilly's here that has a distribution warehouse, and none of them had it in stock. I'd have to purchase the part online and have it shipped. Awesome. Speaking of this, there are two sending units available on the market, one for a 25 gallon tank and one for a 31. The M1009 has a 27 gal tank, so I assume the available 25 gal sending unit would suffice. Right? I imagine the 31 wouldn't fit (too long/ deep). I guess I could upgrade to a 31 gal tank... but if I start down that road I'll be upgrading the entire fuel system before I know it, and right now, in the short term, all I really need is reliable transportation to and from work.

I will definitely search hard for the source of the leak. It has been forming a drip at the bottom-most area of the fuel tank. That is the leak's exit point from the truck. The actual leak, where the fuel exits the fuel system and then rolls down is what I need to track down. The fact that the drip is forming on the bottom of the tank leads me to believe the leaks begins on or above the tank somewhere. Unfortunately, unlike the M1008 apparently, I can not visually inspect the fuel lines on top of the tank without removing it from the vehicle.

phil2968- I will check out the lines that you mentioned, but do not know off hand which lines you speak of. I can visually find their locations, but what do they do? There is a line from the filler neck into the tank, a line from the tank to the lift pump and then IP, there is a... fuel return line? and I think there is a fourth that comes off the sending unit that is capped that can be used as a drain. That's what I found out by googling and such at least. I'd love to wrap my head around which lines you're talking about and why connecting them would help my problem.

cucvrus- I've never dropped the tank before. Is there not enough slack on the rubber fuel lines? Would I need to cut them before unbolting the fuel tank straps? I read somewhere else (can't remember where) that the fuel hoses provided enough slack to allow one side of the tank to let down.

mg84648- this noise is extremely disconcerting and has worsened over the past few days. I wish I had a list of adjectives to describe it better than "squeaky" and squirrelly". That's pretty vague i know. It happens immediately after letting off the accelerator. You're right, I may be able to get a better idea of it by changing my perspective and listening from outside the cab, but I don't know if the noise will be re-created while the truck is stationary in the driveway.

doghead- It's been a while since I have been active on this site, but I noticed your profile pic doesn't have Elvis in it!! What happened?!?! lol

 

[cucvrus]

cucvrus- I've never dropped the tank before. Is there not enough slack on the rubber fuel lines? Would I need to cut them before unbolting the fuel tank straps? I read somewhere else (can't remember where) that the fuel hoses provided enough slack to allow one side of the tank to let down.
I just cut them so I don't need the hassle with the old clamps. Unplug/unbolt the wires to the sending unit before you cut hoses. I never recall having enough slack in the hoses. I always replace them hoses anyway and then I put a we bit more slack but not much. Same as the fill hose and vent break them OEM clamps and replace them. Do not cut the filler hose and vent hose. You can buy filler vent hose at NAPA. But they are always reusable when I see them. Good Luck. Happy Thanksgiving. I will be here all day watching. And no you don't need to cut them hoses before you remove your fuel tank straps. Just put something under there so the tank don't just fall down and have the hoses supporting the weight of the tank. I hope the fuel tank is almost empty.

 

[doghead]

doghead- It's been a while since I have been active on this site, but I noticed your profile pic doesn't have Elvis in it!! What happened?!?! lol

Fixed that, sorry for the confusion!

Good luck today and Happy Turkey Day.

 

[phil2968]

First pic is the aux fuel pick up for an arctic heater. It can be used to fuel the engine.
The second is the short line on the outside of the frame rail that connects two hard lines. That is a popular place to mount an electric pump. Run a new rubber line from that connection the the capped pick up. See if your air leak disappears.

 

[cucvrus]

It ran for 30 years and the electric pump will fix the problem? I will sit this one out and watch. Good Luck. I was always told the auxiliary pick will only pull fuel until the tank is at 1/4. Then the pick up end is out of the fuel. I even observed that when I had fuel tanks out that that pick up did not go to the bottom of the tank. I am relying on memory. Survey says?

 

[phil2968]

Well since you did not sit this one out, I never said an electric pump would fix his problem. In speech that is called putting words in someone's mouth. I said that is a popular place to mount one.
I recommended the aux pick up to diagnosis is air leak problem. Not a permanent fix. Hence the last sentence.
Why did you choose to post in this thread? Your reply was the same old same you always post. It gets old. We all know how you think. You don't need to remind us in every cucv fuel related thread.

 

[cucvrus]

Hey this isn't Facebook. I am not your friend. I am helping the man out with his fuel issue. Just as you are trying to do so. So remain calm play nice and keep your rude opinion of me to yourself. If you don't agree with me that is fine. I know with out looking that I worked on more of these vehicles then you ever saw. And was only trying my best to get this mans vehicle up and running at the least expense. My way he don't need to buy an electric pump. But feel free to advise him to do so. The fuel issue can be solved with out the purchase of an electric pump. I am sure he is not a fulltime mechanic. And that is fine also. He reached out to the site for help. And that is what I am offering good free reliable advise. Have a happy Thanksgiving and in the future I would stick to drilling holes in wood planks and skiing down hill. Have a nice day.

 

[phil2968]

Wow. Where did I recommend an electric pump again? I must have missed that. Did I call you a friend? Missed that to I guess.
Has far opinions go, I did not post one. Just facts. I'm glad your so talented with cucvs and know everything the is to know about them. I'm glad you know me so well too.

 

[stranger75]

Turns out there IS a pinhole leak on the bottom of the fuel tank. I could not find the source before because it was obscured by fuel being blown around all over the bottom of the tank while driving. I wondered why I couldn't find a wet spot around the edge of the tank leading upwards. It's always been coming from the bottom in the center. I took a video of it with my phone but the file is kinda large and I guess its not really worth uploading to an image hosting site and providing link here. It's obviously a steady drip from a single source. A very tiny little freaking hole.

I value everyone's opinions on here, no matter the school of thought. No need to get upset with each other guys. If someone tries to help me with information not entirely pertinent to the matter, I'll still say thanks and file it away for later when I may have an issue that needs that kind of help.

So, tiny little hole. About an eighth of a tank of fuel in there. My Harbor Freight fluid transfer pump doesn't reach far in enough to pump that out in order to stop the drip and patch the hole. I guess there is some sort of fuel resistant epoxy I could apply to the hole? I don't think I have anything like that at the house. Once again, today is Thanksgiving, all the stores are closed (NO, I am NOT going to Wal-Mart when their black friday sale opens!!!) and my only day off for a few weeks. Heh. Gotta love Murphy's impeccable sense of timing right?

Once again, thanks to you all for helping, and Happy Thanksgiving!

 

[cucvrus]

Ok now that you have made the discovery of the pin hole in the bottom of the fuel tank. That will resolve the fuel leak. But you were concerned with air in the fuel line during the starting process. Am I correct on that? You are saying air in system. I would not see that a small pin hole in the bottom of the fuel tank would put air in your fuel lines. And if you do have a fuel drop problem. Have you looked at the entire fuel delivery system. Do you see any wet areas? Behind the fuel filter is a common leak area. Check the hoses at the fuel filter and trace the metal lines on the right frame rail from front to back. How long must you crank this vehicle till it starts? I am only trying to help you out. I understand it is your daily driver. It could be the smallest leak and create this issue.