Hello you pump guys

Texasmark1

Well-known Member
1988 3910, all OEM, 900 hrs when purchased last year, have 75 hrs on it since working it pretty good. Starts in a flash, runs and holds after turned off (gauge on engine) 50# oil pressure, runs up to 2200 rpm about as fast as you can pull the throttle, gooses fast with the foot pedal (advance mechanism in pump working just fine).....not that I do this as a habit but for troubleshooting purposes here....new fuel filters, input lines burped, and I use clean, fresh fuel with PS (gray bottle) additives.

At idle and up to 1200 rpm runs real smooth. Going above that rpm I get enough of a miss to make the exhaust loud and you can tell that something changed. Cracking the injectors, the center has a good pattern at idle and up around 1800....2 data points. #1 and 3 not so much....obviously not as much fuel being delivered, or what is delivered not enough pressure to squirt like #2.

Best I can tell nothing on the engine has had a wrench on it. Timing mark is aligned at 0 and looking at the OEM paint, never been moved since built.

Seems to me something is not providing consistent fuel supplies to all cylinders evenly, especially at the higher flow rates and what could it be but the pump.......butttt the pump supplies enough fuel to the injectors to easily achieve the service manual listed red line rpms.

As usual, thanks in advance.

Mark
 
(quoted from post at 14:52:29 10/07/19) 1988 3910, all OEM, 900 hrs when purchased last year, have 75 hrs on it since working it pretty good. Starts in a flash, runs and holds after turned off (gauge on engine) 50# oil pressure, runs up to 2200 rpm about as fast as you can pull the throttle, gooses fast with the foot pedal (advance mechanism in pump working just fine).....not that I do this as a habit but for troubleshooting purposes here....new fuel filters, input lines burped, and I use clean, fresh fuel with PS (gray bottle) additives.

At idle and up to 1200 rpm runs real smooth. Going above that rpm I get enough of a miss to make the exhaust loud and you can tell that something changed. Cracking the injectors, the center has a good pattern at idle and up around 1800....2 data points. #1 and 3 not so much....obviously not as much fuel being delivered, or what is delivered not enough pressure to squirt like #2.

Best I can tell nothing on the engine has had a wrench on it. Timing mark is aligned at 0 and looking at the OEM paint, never been moved since built.

Seems to me something is not providing consistent fuel supplies to all cylinders evenly, especially at the higher flow rates and what could it be but the pump.......butttt the pump supplies enough fuel to the injectors to easily achieve the service manual listed red line rpms.

As usual, thanks in advance.

Mark
ight try moving injectors cyc to cyl to see if problem moves or not.
 
CAV DPA three cylinder pumps are SOMETIMES phase sensitive, blade rotor slots in relation to rotor outlet port. Your pump MAY have the wrong blade rotor in it causing what you hear. There's a service letter that explains how to check the rotor, sometimes three or four need tried to find the best one. Also as blades and liner wear, transfer pressure can begin to drop which WILL change how the advance curve works.
 
Would that be from the factory? Best I can tell nothing has been touched on the engine fuel system but the filters. Will keep it in mind. Thanks
 
Upon cracking the lines and slowly bringing them back, obviously the engine ran rough with one out but I couldn't detect a difference in any of the 3.

Since I bought this tractor it has been this way and has been terribly loud as compared to my '65 3000 which is only 0.2" smaller in cylinder diameter,
same stroke. I have about determined that the exhaust impulses aren't of the same intensity so as you load up the manifold and muffler, you have impulse
differences making the loud noise. Can't understand what else it could be....resonances in the engine block; being a different casting makeup????
Doesn't sound like a metallic noise; its an exhaust noise. I put a new vertical exhaust system on it thinking that the horizontal was the reason, with the
largest muffler available, and it's still unbearably loud where the 3000 is tolerable with the 18" round OEM type.

Since both tractors are almost identical in fuel systems and most other things, I might just pop all 3 injectors out of the 3000 and put them in it and see if
it runs smoothly. Yes go after injectors. No go after the pump.....or just live with it....problem with that is..... am I looking at a bigger problem down the line
if I don't solve this? Who knows. Thanks J.
 
Yes, it could be. Will have to look up what year the service letter came out that explains the three cylinder only rotor problem. I know it was never mentioned years ago at the CAV DPA service training classes at Troy Michigan.
 
What you are describing is almost always an advance issue. Try advancing the static timing on the engine about 1-1.5 degrees. mark where the pump is now and move it opposite of the direction of rotation. Look at the spec tag and it will have an arrow showing its rotation. Move the pump while the engine is not running about the thickness of a screw driver blade. Most times this does wonders. 3 cyl engines are very sensitive. Sometimes you have to play to find the sweet spot they run the best in. Al
 
I thought about possibly a timing issue but with such low hours didn't figure that would be it. But production lines are built with components which all have their tolerances and assembly testings are sometimes made with green/yellow/red, pass-fail areas on a test meter, maybe not pumps themselves, but other components that can affect timing. The assembly instructions say set the timing at 0 and that's for all the components built to support that assembly line with their tolerances coming down it. Surely makes sense.

Other thing is that this is the least potentially destructive thing I can change as opening up the fuel system and swapping out injectors on both tractors is just asking for trouble. I'll tweak it tomorrow and check back in.

Thanks for kicking in Al.......the pump guy. Grin.
 
When it starts to miss, does it spit white smoke out the exhaust? If so, it's definitely an advance issue, as Al said. Manually advancing the timing as Al described will confirm the problem if it goes away once you do that. Pull the top of the pump toward you to advance. Best solution then is to remove the pump and have a pump shop free up and/or repair the advance mechanism.

If it does NOT spit out white smoke during the miss, and if it only does this under no load (meaning it runs and sounds fine under load), then I would simply call this a "minor irritating flutter" and ignore it myself. Yours wouldn't be the first 3 cylinder Ford tractor that did that.

Disclaimer: The advice above is governed based on what I *think* it sounds like, not necessarily what it actually sounds like. A YouTube video of the problem could be very helpful here.
 
Well Al you nailed it and it took about the blade width of a medium screwdriver.....1* roughly. I jumped out of bed and was on it before the sun crested the horizon. The pump limit allowed the rpms to increase to slightly above where they were telling me that i went the right way besides the smooth and much quieter running......considering a 4.4" diameter pistoned, 3 cyl., 4 stroke diesel.

In reading the A&I serv. manual, it said that some people hook the tractor to a dyno and tune the timing for max output which supports my assumptions about the manufacturing settings being "within a range" and not necessarily right on. Understanding that the production line has to keep rolling to make a profit. One wouldn't expect workers to sit there and play with timing to max out the HP on each tractor.

Thanks,
Mark
 
Later tractors were intentionally timed to sputter, solely for emissions reasons. The first time I called the service department to report this issue, I was told very clearly to not touch it. Soon after that, the "tamper resistant" pumps came out that do not allow a person to change the timing like you just did.
 
So the assembly line built a machine with the mechanic or consumer had no way to vary the timing if the tolerances added up and he had to put up with the rough running or noise in my case? I haven't paid any attention to pump mountings in tractors other than my 3000 when I overhauled it. If the timing is critical, like Al mentioned, that doesn't sound like a good idea for the consumer/mechanic.

From time to time I have read on this forum where some people say that some of these Ford engines are just noisy. Maybe they just need their timing tweaked a bit. Grin
 
EPA emissions regulations mandated that injection pumps be "tamper resistant" to discourage owners like you from doing exactly what you did. To accomplish that objective with rotary pumps, they removed the kidney slots in the pump that allowed for timing adjustments. In addition, the pump was bolted from the inside of the timing cover, requiring the drive gear to be popped off before one could reach the bolts.
 

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