First time posting here We have a truck with a big cam 400 Owned it for 20 years or so Used as a farm truck hauling doubles (Not for Hire) and doesn't see a lot of miles, maybe 5-7k a year Not sure quite how to explain my problem so I will start with back story The first time I started it in cold weather I tried to use the hand throttle and if I bring up the RPMs to maybe a 1000 it will gradually climb to full rpm? It's been doing this since purchased and was never a big deal as it had good power and started good. Does the same thing when holding the pedal and try to maintain any rpm from idle to full. No matter where you put and hold the pedal the RPMs gradually climbs. The only thing that seemed to be an issue was that its takes longer to drop RPMs when shifting? Our other trucks drop quick and allows a quick shift. Now for the main reason for posting here. A few weeks back my brother called and said the truck would not start. He had just drove 20 miles and was waiting to get unloaded so he shut it off. Truck would crank but did not even try to start I told him to check the electric fuel solenoid and try turning the manual bypass in He called back and said he tapped on the solenoid, and it started We have 3 Steiger tractors with the same 855 engine and had the solenoids fail like this Installed a new solenoid and it started. Shut it off and tried to restart, No Start? Turn in the manual screw and it starts every time After starting you can turn the manual out and it stays running Leave the screw halfway and you can start/stop with key With the bypass in tight or the using the solenoid the engine seems lazy when stabbing the throttle Fuel pressure only jumps to 40-50 psi I have seen 100+ psi on other engines Changed filter Checked for blocked fuel supply/return lines and almost no vacuum/in of water on supply line before filter Don't see any air in system Currently installing a new supply pump Any thought would be greatly appreciated Thanks
Did it happen in the middle of harvest?
We had just finished wheat harvest and were hauling straw
For starters. What's the voltage at the solenoid when energized and when cranking? Just because she'll light a test light doesn't mean it'll support the magnet. Did you get the right voltage magnet. I believe they're offered in 24 & 30v in addition to 12. All look the same except for color, I think. If you establish that you have good clean voltage even when cranking, look at the screen forward of the shut-off . It should be domed cap with a straight screwdriver slot to remove. Make sure it's not all gummed up with rust or algae. If that all looks good, then I'd look at the pulse damper at the inlet. It bolts to the back of the pump where your fuel line enters. It houses a thin metal disc. They can sometimes crack causing all kinds of odd grief. Good luck
Correct on damper, fuel screen makes them sluggish. * The issue with idle control by cable is as common as it gets with a PT pump. All because of the type of governor design within pump. Idle will climb when trying to control using throttle shaft. There is a solenoid operated fuel valve {Can't remember the brand, it's changed hands a couple times with different manufactures} that allows for steady high idle.----IIRC a member on here {Pushbroom} will likely remember or know who makes it.
Found it. TR-1001 High Idle Governor For Cummins PT Pump Check out the deal on TR-1001 High Idle Governor For Cummins PT Pump at Apexinds.com www.apexinds.com *
The solenoid is red I will double check the power with a voltage meter, with key on and when cranking The screen was replaced at the same time I did the main filter. Had no effect at all on problems. Filter was a little dark and had some real fine dark stuff in it, when I sprayed brake clean on it the stuff came off and just made the liquid gray colored but did not seem plugged I pulled pump and took it apart, looks great inside. No wear marks Its getting a new pump since I have one already I will check the pulse dampener Thanks
To check for air in fuel---loosen flair nut at fuel line from shut off solenoid--just enough so fuel will crown above the flair nut--fuel should crown clear no foam. * It's sucking air.
There is black soot inside the fuel system? Could it be coming from the heads via return fuel? Maybe the fuel lines are deteriorating? New pump is on and it seemed a little better Adjusted the aneroid out a turn and it really perked up Fuel pressure now jumps to 90psi when you stab the throttle Still giving trouble with starting Going to put a voltage meter on the solenoid so we can see what it is when it fails to start
When she's running, do all 6 holes hit? Could have an injector clamp loose, letting combustion gas up into the fuel rail. Check return flow for aeration.
It would have a miss.
That's what I was getting to.
Check return fuel line for swelling inside.
In his first post--it had/has a issue with slow return to idle and erratic with climbing rpm. Two main things that effect that improper throttle shaft stop settings or air in fuel. A internally swollen fuel can put pressure back to AFC/aneroid and under part throttle cause fuel to be cut back. From pump to injectors the system is all metal--so the black stuff is/was introduced in fuel to tank and or old fuel humbugged from setting or fuel lines deteriorating. There are so many odd issues with a PT pump and air in system, that's why running engine out of a bucket of fuel is the best thing to try first to omit the fuel tanks and hoses. * But he never said after changing pump if all the other items corrected, other than the hard starting.
You were correct Bad ground connection at starter. Small ground wire sandwiched in with the 2 main ground wires from battery on starter Every time I would check voltage it was 12.7v Just kept testing until I finally caught it 10v at fuel solenoid and in cab while 12.7v at batteries Wiggling that wire would make the low air buzzer change tone Always cranked great Voltage at alternator was 14.5v running Only have an amp gage in dash but guessing that if it had a voltmeter, we would have seen it After fixing connection, the amp gage jumped to 75 amps instead of maybe 10amps Truck had been driven at night with lights on several times with no sign of low voltage. Going to add another ground wire from batteries to engine block and cab Between the pump and adjusting the aneroid she runs better than it ever has. Pulls strong all the way to governor Thanks again
Glad you got it sorted, but that doesn't explain the blackened fuel. As Truck Shop mentioned, you might wanna inspect those rubber fuel hoses for internal failure especially if they are the old Stratoflex. I've had them choke off fuel supply before.
Yes we discussed changing lines 1986 truck and lines are cheap
td25c