M715 cuts out over 30mph

Running out of options need some expert advise. Picked up my new M715 on Sat. About 5 miles into the drive home it started running rough. A minute or so later it would practicaly cut out completely and sputter. Push in the clutch and let it idle and it would come out of it. Get back into it and it would happen again.

It idles great and at slow speed and low RPM it runs great.

You can shift through the gears and wind it up with no issues. Once up to 35 or so and on the gas it cuts out again. Some popping and backfired once.

Smells like it is running really rich.

Choke does not appear to be stuck.
Installed a clear fuel filter and it is still clean.
Fuel drained with new fuel in tank
Elec. fuel pump installed in addition to mechanical. (bought it this way)
Carb bowl pulled and very very little dirt particales removed

Engine is the original Tornado but the carb looks newer and is a Holley single barrel. Not sure what they came with.

Is the dist. and rotor an issue on this engine. I don't know much about the setup but right now I'm leaing towards it being the issue.

Any help would be appreciated

had the same problem.... its your ignition points and advance.

replace points and adjust advance and it will run fine..... i replaced with a electronic ignition has never run better i think

Thank you so much in advance...no pun intended. Hope that is my problem too. How difficult was it to replace with the elec. ignition?

it took all of about 30 minutes... or two beers depending onhow you gauge time...

i posted the step-by-step of how i did it.

http://www.steelsoldiers.com/electrical/49136-m715-electronic-ignition-upgrade.html

i usually do this on all my gas engines, never had a problem with the petronix units

If points and condenser don't fix it, it is a not enough fuel delivery to carb problem. But my bet is on ignition like David said.

davidkroberts said:

had the same problem.... its your ignition points and advance.

replace points and adjust advance and it will run fine..... i replaced with a electronic ignition has never run better i think

Click to expand...

Same here also. I fought ignition problems with the stock waterproof ignition. I replaced it with a civilain ignition and all the problems went away. I'm still running points but if they start giving problems I'll go electronic.

Do I have to point this out?

ITS YOUR FUEL SYSTEM............. install a remote fuel tank, clean your filters. if it rund good then pull stock main tank and fing the problem area. bet its the sock at the end of the fuel pickup tube. if it was your ignition syst. it would act up at all rpm,s.

bcowanwheels said:

ITS YOUR FUEL SYSTEM............. install a remote fuel tank, clean your filters. if it rund good then pull stock main tank and fing the problem area. bet its the sock at the end of the fuel pickup tube. if it was your ignition syst. it would act up at all rpm,s.

Click to expand...

Another good idea, Thank you. The fuel delivery option was brought up on the M715Zone as well.

Strike 2 and 3. It's not the condenser or the points, installed brand new ones this AM and it's still acting up. Can't even get it up a hill or over 15mph. Going to start w/ the fuel system next.

It has two filters and the mech. pump an elec. pump, plus the in tank sock. Good Times

get new glass filters one just befor the tank and one just after the fuel pump. then drop the tank and clean it up. is it smoking on uphill?

April 12th, 2010.

Could be the high speed jet in the carburettor is fouled,if your ignition's OK likely its fuel, and if the fuel system is clean(??) then it's the carb. The high speed jets on these often foul when they are not run at high speed frequently enough. Modern gas has a horrible tendency to jell after 90 days or so, and there might be your problem....


Good luck, I love the M715's, wish I had the money to hunt a restored one down....
I'd be a great bookend to my Kaiser Jeep M35A2!

Cheers,

Kyle F. McGrogan

Great ideas guys. Put a glass filter before the carb and it shows clean fuel. Replaced the inline filter right after the tank and b4 the electric inline pump and noticed something right away. The filter was twice as heavy at the other in line filter was. Replaced it and the thing ran great. Ran it around the block for about 5 miles worth and started to run bad again. Must be fuel line and tank crud. Will have to pull and clean. The good news is the problem has been identified now I just have to fix it.

Not sure if it was smoking going uphill.

I will pull the fuel fill cap and see if that helps should there be a vent issue

Thanks for all the pointers and thoughts.
Jason

April 14th, 2010.

There is a turn valve on the vent inside the gas cap used in deep water fording operations, look to see if it is in the "Closed" position. If so move it to the "Open" position and make sure the vent hole IS open. This would cause a vacuum lock if the tank can't breathe, but I'd suspect a lot of CRUD in the system, you may need to get the tank professionally cleaned and resealed.....

Good luck, I still have high regards for the M715 design....


Cheers,

Kyle F. McGrogan

The rubber fuel line between the engine and frame or the rubber lines at the fuel tank may be leaking air causing a power loss. You might check them out. My two cents.

glad you got it worked out..... sometimes these things can be a real bugger to find.

Rigged up the remote fuel supply today. Truck runs good as long as I'm gentle on the peddle. If you hit the gas like you wanted to rev it, it falls on it's face for a second, burps then comes alive. If you take off really easy it will go through the gears pretty well wilth minor hiccups. Try to shift like normal it falls on it's face and burps.

Idles great, revving slowly works great.

I'm guessing it isn't getting the fuel fast enough. I have the mech. pump (status unknown) still installed with an electric pump back by the tank. New fuel filter in the rear and clear filter at the carb which shows clean.

Would this setup have to many restriction points? Two pumps and two filters causing excess restriction to slow the flow?

If there is an air leak in a line there should also be a fuel leak in the same spot correct? No fuel leaks present. Fuel tank vent is open.

They are by nature under powered but I'm thinking you should still be able to give it **** and go through the gears.

Thanks guys
Jason

sounds like carburator problems to me. (kind of like setting the jets on a dirt bike)

Seem to recall a rule of thumb re: backfiring. If it backfires thru the exhaust it's fuel related. If it backfires thru the carb, it's ignition related.

Also recall that a bad ignition condensor can cause the symptoms you describe.

Like others have said, change the points AND condensor. Ought to replace the distributor cap and rotor as well. Also set the timing.

If you do not have a timing light: (a) warm up the engine, (b) loosen the distributor and advance the timing slightly, (c) test drive it and put a load on it, (d) if it does not ping under load then repeat steps b & c, (e) when it is advanced far enough to ping, retard it slightly. This will have it firing just before top dead center.

Regards

Jim

I don't have any first hand experience with these carbs, but, do they have an accelerator pump? You need that working to give it a shot of fuel to get the engine to up the revs so vacuum can increase and suck more fuel etc. Also, I'm wondering if the mechanical fuel pump has a screwed up diaphragm whether the pressure from the electric pump is somehow forcing the diaphragm into a position that will not allow fuel through.
Just some random thoughts.
BC