Multi-fuel governor drift

[wanderingwillys]

I have been having some issues with my M35a2 (1966 overhauled in 1989 with a multi-fuel and the C turbo) the last two times I have driven it... It seems to get off the line ok and run to 10 - 15 mins with the RPM's able to go to 2850 with no issues...

The last two trips were 200+ miles; and the problem repeats when you stop and let things cool off back to ambient temps ( I had a few stops to make along the way)

Governor acting as it should when cold - boost is normal, no smoke, ect

Then as things warm up and get up to operating temp the RPM limit starts to drift downward and the engine will not run up above 2400 sometimes 2300 RPM regardless of what you try.

I am not too farmiliar with the governor operation and have not adjusted the fueling rates or the governor setting since I got the truck in 2006...

Any thoughts?

Matt

 

[clutch]

whens the last time you changed fuel filters?

 

[Bob H]

2850 RPM

I'd be looking for a big window in the side of the block!
the red line is 2600 rpm.

Anyway, probably an issue with the in tank fuel pump.

 

[wanderingwillys]

It's been a while - ran her dry not too long ago as well... oops?! You thinking fuel restriction?

 

[Massm35a2]

I try never to run it above 2400. but I have 1100's so no need to go over that

 

[wanderingwillys]

I have seen plenty others taken to 3k with no issues - they are way de-rated from the factory... as the average end user is expected to treat the engine very rudely...

2850 RPM

I'd be looking for a big window in the side of the block!
the red line is 2600 rpm.

Anyway, probably an issue with the in tank fuel pump.

 

[clutch]

if you ran it dry you probably sucked all the debris into the fuel filters that was laying on the bottom of the tank which got stirred up by the low fuel sloshing around. may be a in tank pump issue but i would try filters first.

 

[wanderingwillys]

As good a place as any to start... filter and fuel flush... pump was new in 06 when it was resurected from a field in McKenna... had been patiently waiting since 1996 - thanks any other ideas are good too...

Matt

The other thing that seemed odd was the fact that when it went dry there was 4 or 5 inches still left in the tank - maybe the wrong pickup on the pump? Dunno since I didn't source the pump...

 

[clutch]

you really dont want to draw fuel from the very bottom of the tank because thats where the condensation and any debris that may have acidentaly gotten into the tank will lay.

 

[vtach]

I would think fuel filters as well. I don't think the in tank fuel pump would be the problem since the injection pump is strong enough to pull fuel from the tank by its self. Replace your filters one at a time starting with the closest to the tank, then moving towards the motor. It could be just the first one.

 

[SCSG-G4]

Your in-tank pump sits several inches above the bottom of the tank so it does not suck in all the crud. You can lower it, in fact there was a recent thread on how to do it (it's in the -20 manual), but you may be replacing fuel filters 'rather quickly' if you do. Good Luck!

 

[Stretch44875]

Pick up on the fuel pump is adjustable. Moved mine down, it was running out of fuel too soon.

Dennis

 

[zb39]

Try filters first...

 

[Bigred77]

Im having this exact same problem. when its cold it will run up to cruseing speed, then like you flipped a switch it wont budge over 2200 and about 40 mph down hill, about 30mph up hill.
Where can I get some filters locally? advanced, napa, autozone? does anyone know the part number? mine is a 68 m35a2 whistler what is the average top speed? and governer cut out?

 

[JDToumanian]

RPM's able to go to 2850 with no issues...

I have seen plenty others taken to 3k with no issues - they are way de-rated from the factory...

Whoever is telling you this nonsense needs to stop smoking the glass pipe!

These engines may be "de-rated" power-wise, but not RPM. They are not balanced for those speeds.

 

[gimpyrobb]

SWEET pic! Is that from a "certain" yard in Florida?

 

[bottleworks]

I have seen plenty others taken to 3k with no issues - they are way de-rated from the factory...

Part of your problem is that your abusing your engine.

Devilman96 used to have a signature that fits this situation.

 

[JDToumanian]

SWEET pic! Is that from a "certain" yard in Florida?

Yup! That #3 journal has the nicest view on the block.

I get a lot of mileage out of that pic... had it as my desktop image for a while too...

 

[kc5mzd]

Try turning on the power and then loosening the drain on the 3 fuel filters. Use a cup to catch what comes out. If it looks like clean fuel then try it again when it is hot and acting up. If you get a lot of crud then you found your problem. Also it is a good idea to use diesel fuel additive for a few tanks at least once every 6 months. It can extend the life of your filters considerably.

 

[ironworksfab]

I agree with Kc5mzd. If you run the in tank pump and open the drain valve you should be able to see if there is crud and junk in your filters. When I got my truck that is one of the first things I did except when I opened the drain nothing came out. It was that clogged with crap I had to flush the entire line and clean the tank. The Prior owner dumped WMO in without prefiltering the sludge out of it or at least thats what it looked like.