Short on power

[FIREGUY1]

We have a deuce with a Hercules non-turbo multifuel. This truck has been getting short on power, and hard starting for a few months. Idles rough, and sometimes wants to die at idle. Since it's used as a grass fire truck, it doesn't get alot of use until the spring. We changed the fuel filters, tightened all of the lines (had a few loose fittings), bled the system, etc. but still the same. We do notice some air bubbles in the lines going to and from the manifold heater. It has an aftermarket fuel pump (the one in the tank went bad), but that doesn't seem to be the problem. Any suggestions?

 

[Knucklehead]

Check the color of the smoke from the stack. Grey/white is indicitive of an air leak in the fuel system. Pressurize the system with the fuel pump and check for leaks, engine off. If none are detected try it with air. When the engine is running the injector pump creates quite a bit of suction in the fuel lines and will pull in air from the smallest leak. The leaks can be hard to detect as they only leak under suction.

 

[Desert Rat]

FG1,

How about a location in your signature so we can help you better?

Aftermarket pumps don't do the same job as an in-tank pump. Believe me I tried both ways. Also, did you change the primary fuel filter below the alternator (or generator)? Plus the non-turbo will not have the same get-up and go power (based upon my experiences). Did y'all turn up the fuel in the pump too? Don't forget to drain the water from the primary fuel filter too. This will impact the performance as well.

 

[FIREGUY1]

Thanks for the replies. The smoke is somewhat white/gray at idle and light load, turns black under heavy acceleration and load. We have tried checking for leaks with just the pump running, but nothing shows up. We have changed all of the filters, including the primary filter. When we put on the aftermarket pump a few years ago, the performance was as good as new, but it has slowly been going downhill over the past year.

Any suggestions as to a likely place for a leak? Would it be between the tank pump and the injector pump? I'm not all that familiar with these trucks, so any help would be appreciated.

 

[Desert Rat]

If you're close by I'm sure we could scare up some help from Houston..........................

 

[ken]

It sure sounds like to injector nozzles are fouled or they are popping at too low a pressure. That lets them dribble fuel out instead of spraying. Hinch the white and gray smoke. White smoke is unburt fuel. Like when the military dumps fuel in the exaust of armor viehicles to make a smoke screen. Also pull the plug in the fuel tank and make sure there is no water in the tank. Is the original lift pump still in the tank? If so pull it and make sure the pick up screen it clean.

 

[FIREGUY1]

The original pump is still in the tank. We have had two pumps go bad, so we got tired of replacing them and went to an aftermarket type. Do the original pumps have a problem with low voltage? It seemed that every time a pump quit, we had low batteries. This was taken care of with battery maintainers. I have checked for water in the tank, and the in-tank screen is clean. I'm kind of leaning toward an air leak, but not sure where to start. Anything else to look for?

This is a low mileage truck (less than 10K) in super condition. I believe it's a 1976 model, made by AM General. Our fire department has it through a surplus equipment loaner program by the Iowa DNR/State Forestry Service. Also have a 5 ton Kaiser/Jeep with the Mack ENDT 673. Both are great trucks; a blast to drive.

 

[rice]

If you're getting black smoke on acceleration, it sounds like you're getting plenty of fuel. It may be an ijector issue and you're getting too much fuel. Just my.02

 

[Armada]

Perhaps the aftermarket inline pump is failing. I'm not sure what the pre IP fuel pressure/flow specs are, but might be worth checking to rule out the pump performance.

 

[ken]

I'd have the injectors pop tested. And cleaned at the least. You should get black smoke with a N/A engine at lower RPM's. But the gray/white smoke you mentioned is unburned fuel. Do you have #2 fuel in it? Is it cold enough for the fuel to gell? Are you letting it warm up? Is the thermostat letting it get to 190deg? If it's not warming up enough that will cause a incomplete burn. Try driving it for at least a hour, And make it work not just putting around. I've had ours at the FD run like crap for the first hour when they sit for months with out being used.

 

[FIREGUY1]

We will look into getting the injectors cleaned & tested. We are running #2 fuel, but the weather hasn't been cold enough for it to gell. We also run quite a bit of conditioner in these trucks. Temp seems OK, but like you said, they always seem to run better after about an hour. There are about 4 of these in the county in various fire departments, both turbo and NA, and being underpowered when cold is always a complaint. I appreciate all the help guys. Any other suggestions are more than welcome. Like I said earlier, I don't know alot about these trucks, but I'm learning.

 

[ida34]

This brings up a good question. What doe it cost to get the injectors cleaned and tested?

 

[FIREGUY1]

I'll look in to the cost of this. I know quite a few diesel techs that can probably help us out. Another thing I was wondering...Since this is a NA engine, it has a muffler mounted under the chassis. From the muffler, the exhaust comes back up to a stack like the turbo versions. Any chance the muffler is getting plugged from excess fuel? I kind of doubt it would be the problem, but I was just wondering if anyone else had any experience with this.

 

[red devils dude]

cleaned $20EA+- testing is usually free and just so ya know the new tip's cost more then new
injectors from White Owl.

 

[Katch1]

fireguy I'm sure your not gelling in this warm weather, it almost sounds like an air leak. The black smoke at higher rpms could be from soot build up in exhaust, depends on how long you take it out for a drive. The n/a motors were noted for leaving quite a trail behinde them, the turbo was added more to clean this up, than for h.p. In my experience my 1c turbo motor likes to work, too much idling and just putting around = exhaust smoke, for a while. $20. per injector for cleaning sounds reasonable, worth it not just in the process of elimination, but in the long haul. also can you by-pass the manifold heater, just to eliminate that possibility? Do you keep them in the station? If it has been as dry there as its been here, you may need grass fire trucks before spring, its so dry here the gound has big cracks in it, and there are 6-7 counties somewhere around here with burn bans, in mar.! crazzzzy weather