idles fine - no power under load

[choppa]

here we go again....

took the M37 out for a drive this weekend... started fine, took awhile to get warm as it was only in the upper 20's or something. went for a ride.

trip starts with taking me down my steep driveway, from the house, to a flat road, the flat portion a good 1/2 mile long. then up a slight grade upward, for about 1/2 mile, then onto flat road again. flat about another 1/2 mile.

driving down the driveway, the steepest part, she ran fine..like she always does. On the first flat area, again she ran fine. plenty of power I thought...nearing the top of the long grade, I got a sputter or two, like she was running out of gas. I continued after making this grade along the flat section (1/2 mile) and she ran good.

as my gas gauge does not work, and thinking I was running out of fuel, I quickly turned it around and headed for home.
down the long grade. no problem.. the long straight flat area, again no problem. but then again, there isnt much need for power as its all down hill, but still, she kept up the pace, as per normal, to power it along.

as soon as I attempted to climb the steep driveway, she just wanted to stall. no power. let off the gas, she returned to a nice idle.. several attempts to give it gas, under load resulted in it nearly wanting to die out. hitting the acelerator in NO GEAR, under NO POWER, she reved right up.

now it wasnt apearing to be lack of gas, or running out of gas here.

Had to drag it up the driveway with my little Cletrac Crawler.. (Yay for having that in the barn!)

wel, not having any time to look at it, and it getting colder, I left it until I return in a few weeks. So I need to arm myself wit hte right parts, if any.. Its at a remote location and I am limited to time and access for parts...

does this sounds like an electrical issue or fuel?

My memory wants to point to a few things:

Fuel related: clogged fuel filter...or could this be a bad fuel pump? .or a accelerator pump? or even a bad float?

Electrical: a bad condensor? broken insulation on wiring causign shorts? bad Points?

My truck is a 1963 model M37B1... honestly, I dont own a service manual... I know, I know I need to get one.

can anyone tell me if this thing has a gas tank fuel filter by chance? and if so, is it IN the gas tank or outside?
the original firewall mounted fuel filter is not present. past owner put on a plastic, in line type. no crud there last I looked and I check it out all the time to be sure the gas tank isnt giving off fine rust..

any ideas where to start looking? thanks!

[Master Yota]

I'm going to suggest a fuel issue. A working engine requires more fuel over one that's hardly working or just coasting along.

My thought would be a weak fuel pump, or a plugged filter restricting the flow. As I'm no 230 expert, I'll leave the direct diagnosis to someone who knows better. I would at least start with checking all fuel filters, and connections for debris...

IMS, there is no filter inside the tank. But that doesn't mean one hasn't been added over the decades....

[w30bob]

Hi Guys,

I thought only the early M37s did not have a fuel filter in the tank.....they only have an "S" shaped tube. According to the "Production Changes" page on here it says the fuel filter was moved from the firewall to inside the fuel tank. That change was made in 1952 starting with SN 80042293. So if Choppa's M is a B1 I'd assume it does have a filter in the tank. John at Midwest has reproduced them I believe, as any NOS filter would probably be junk over all these years. I think you have to drop the tank to change it......but others on here can confirm or deny that.

It sounds like you have either a lack of fuel or an electrical issue. I'd check the electrical first, easier and less messy than checking the fuel system. A couple ideas.........simple ones first. I'd bring with me a voltmeter, good distributor cap, new points and condenser, a good coil, a set of new plugs and a dime. First up make sure you have 24 volts going to the distributor when you turn the ignition on. No sense diving into the distributor if the problem is upstream. Assuming you got 24 volts, pull the distributor cap and check for cracks or any signs of arcing. Next check the points. Even if they look good run a dime thru them just to make sure they're good and clean. Then check the condenser and the coil with your voltmeter. Also, make sure there's no moisture anywhere inside the distributor. If all that checks out ok I'd check the spark plugs and make sure all the plug wires are well connected. If all checks out I'd move onto the fuel system. If you did find something not quite right, then after you've fixed it I'd hook up your M to your mighty Cletrac and see how she responds under load trying to pull it.

Assuming all is good electrically it's on to the fuel system. Not nearly as much fun as the electrical stuff.....but probably your problem if the electrical checks out ok. You didn't mention if you'd be doing all this alone......or if you'd have a helper along. Helper is better, as you'll get tired of talking to yourself and cussing with no one to hear it.

regards,
bob

[jim lee]

Sounds like how mine died. Lost power but would idle. Then after a bit it wouldn't do that. Turned out to be fine rust in carb and this was through two new filters. Pull a plug and use the start lever to roll the engine over to see if there's spark for a sanity check. (I didn't know there was a manual lever on the starter when I started this on mine.) From there you can choose what road to take.

Hope this helps.

-jim lee

[choppa]

hummm. well that makes sense IF the later model M's had in tank filters. I didnt know that!

well, I got plenty of spark, as she does and has been running just fine up until now.. now I can start it and it does idel. In fact, after the mighty Cletrac hauled her up the hill, I let it sit overnight as it was getting dark and had other issues to address.. one of the probelms of owning remote property: when your there, there is SO many things to take care of!

Anyway, after it sat all night, I was leaving in the AM and didnt look forward to pushing it into the garage. I started it, it fired right up, and powered into the garage on its own. again, thats flat ground, so???

anyway, it is perhaps a fuel sediment issue I am thinking?

I know that I do NOT have a firewall mounted military style of fuel filter.

your right of course, all of you. I need to diagnose this from the basics forward.
I just needed some info.

I had NO IDEA about the in tank fuel filter. I guess Ill start there. It could be totaly clogged. who knows...

Anyone else know if I have to drop the gas tank to access this fuel filter or not? I cant remember but isnt there an access plate in the bed sheetmetal to get to this?

again, guys, have had LITTLE time to work on this truck. I wish it was in my primary house garage where I could walk outside and do this check. it is not but at its remote location.!

dang!! thanks for all of your pateince wit htis M "neewbie" and my calenges due to its distance away from my home

[Elwood]

Yes, you can access the in-tank fuel filter through the access cover in the cargo box bed, assuming that your truck has the stock fuel tank. No need to drop the tank from the frame.



The instructions start on page 207 of TM 9-8030 (May 1955 edition).

I've replaced the in-tank filter on my '54 with the new style stainless version, but I also have one of these to install on the cowl voltage regulator bracket (where the early style fuel filter was mounted):



Racor 120R-RAC-02 Marine Gasoline Filter/Water Separator 30 GPH

[Chris P]

Do a compression check on the cylinders. My truck was doing the exact same thing; it would idle fine and run at 45 mph on flat ground, but on a hill it would 'buck' as though it was being choked of fuel for brief instants, and I would get a dramatic loss of power. It turned out to be a blown head gasket.

Incidentally, mine is a '54, but I had the in-tank fuel filter. I replaced it and I replaced the mechanical fuel pump with an electric one with a pressure regulator. This was before my truck had this latest problem, so I knew it wasn't a fuel issue. Everything electrical was also new (plugs, wires, wiring harness, coil, points, etc., etc., etc.).

By the way, nice Cletrac!!

[choppa]

thanks for the pix, Elwood.. that will help me a lot. I think in anticipation/preparation for the next trip Ill just order another in tank stainless filter as you all have. mine might very well be a mess.

besides.. always wanted to look in the tank and see what the condition is like

thanks for the advise, Chris on the head gasket/low compression. I sure hope its not that! all the while I have had the truck, its had ample power to climb the driveway in second gear.. sometimes I gotta downshift, but I always asssumed it might just be needing a good tune up.

I bought all the plugs and other tune up parts for it, just never got around to tackling the job. seems like so much more to do around the place in my limited time.

ill get to it!

thanks for the Cletrac compliment. its a civilian 1952 model HG-42 that I went thru a few years ago. replaced all the seals, rebuilt or bought the bottom rollers, etc. motor was rebuilt in the fiftoes sometime (data rebuild tag) and runs like a champ...I added a model-T 4speed tranny installed between the clutch and the transaxle giving me ultra low range.. I made this a sort of sudu-military tracked machined based on ww2 photographs of the pilot experimental models they made for hauling mortars and such... its a lot different of course, as I left the stock pull bar in lieu of the pintle hook the experimental military machines had as well as the over sized ugly butt fenders they had for a flat top fender I custom made.
I now have a pull push/grill gaurd in place and I am adding headlights with headlight gaurds as soon as I get time (right!!)

all in all its a fun little toy I use to drag large logs out of the hilly terrain around my property to cut up for firewood. hopefully it wont be used so much to drag M-37 trucks around

[sturmtyger380]

I also have one of these to install on the cowl voltage regulator bracket (where the early style fuel filter was mounted):



Racor 120R-RAC-02 Marine Gasoline Filter/Water Separator 30 GPH

Nice! I like that. Paint it OD and it almost looks like the original. Alan

[Elwood]

I also have one of these to install on the cowl voltage regulator bracket (where the early style fuel filter was mounted):

Racor 120R-RAC-02 Marine Gasoline Filter/Water Separator 30 GPH

Nice! I like that. Paint it OD and it almost looks like the original. Alan

I had the same thought.

Like the original filter, this Racor has a four port head (die cast aluminum) with two in and two out, so for those of us running the engine primer, it's the same plumbing as the original. The filter is a replaceable cartridge element, which eliminates 99% of water (useful with all of the ethanol in today's "gasoline"), and filters to 10 microns. There's also an optional brass valve that can be installed on the bottom to simplify draining out any accumulated water. Here's the Parker-Hannifin pdf for the specs if you're interested: http://parker.com/literature/Racor/1022 ... Series.pdf

[w30bob]

Choppa,

You may need to bring some "special" tools with you. The screws that hold the plate on the tank that attaches to the fuel filter might just be a bitch to get off. They're Phillips head I believe. On a few of the tanks I have here they've never been touched and when I tried to get a few out it was a mess. So however you deal with stripped Phillip head screws.....be prepared to do so. That being said........I sure hope they come right out for ya!!

regards,
bob

[Elwood]

Choppa,

You may need to bring some "special" tools with you. The screws that hold the plate on the tank that attaches to the fuel filter might just be a bitch to get off. They're Phillips head I believe. On a few of the tanks I have here they've never been touched and when I tried to get a few out it was a mess. So however you deal with stripped Phillip head screws.....be prepared to do so. That being said........I sure hope they come right out for ya!!

regards,
bob

Good point, Bob. I've never had all of the screws come out easily.

A new (ethanol compatible) gasket for the tank outlet cover (aka the plate) would be wise, and some new sealing washers for the cover screws.

[RMS]

sounds a lot like moisture in the dizzy. as the truck heats up any droplets that have formed in the bottom of the dizzy rise to the top and fog out the cap. then under load arks around under the cap making the hesitation. if it was a fuel delivery problem you would run the fuel bowl dry weather or not the truck was under load.

hitting the acelerator in NO GEAR, under NO POWER, she reved right up.

an old O'ring on the dizzy (even cranked down with all 6 screws) can allow water to enter the cap when washing the truck specially if you don't have fender welts. below 50f/10c it can take a good five+ hours for the moisture to boil off and vent to the air cleaner elbow via the tiny breather lines.

[m-37Bruce]

I'm thinking fuel, but I want a CleTrac real bad now .... I also like the RAC -02 filter. I have some issues, very similar, most being that my truck needs to run EVERY DAY, or she no start? Right now we are on day 21 no run, this is mostly my fault, I knew this for a while, I am swapping the points/condensers for the electronic version asap, no points, no problems!

[topellis]

I agree with the electronic stuff.... I got the kit from Charles and have never looked back. In my opinion it is the best/low-cost mod to do. Good luck with your problem... I know at times something simple can leave you scratching your head till you have done some detective work.

Hope you get it figured out.

Mark