Cat 3208 troubles

Sorry, this will be long. You guys are the smarties around here, though.

The first day of harvest one of the trucks broke down. I am stumped. The truck is an 88 Ford L8000 if it matters.

I was having troubles getting it started and idling back in the spring. Mechanic said the injector pump was about shot but we could milk it along by putting in a booster pump and setting it at a couple pounds pressure. Did that. It started like a dream for a couple of days so I though that was it.

Put the first load of wheat on it and took out for town. When you get it up to 25 MPH it falls out. There is no response from the foot feed at all. Reminds me of a drive by wire that has gone bad. This is all mechanical though.

If you stop it won't hardly idle - just lopes. Foot feed doesn't do anything and you can't hardly keep it going. Then, like a light switch all of the sudden it has full power and runs fine. It just won't go above 25. It isn't speed sensitive, though, because it did it going up the lane also.

Mechanic says pump. Since it isn't electrical I just can't image it could go in and out. He started by replacing all of the fuel lines and the manual prime pump. I'm beginning to think he's grasping at straws. He's also wanting to gouge on the pump work because he doesn't want it. I only used him on this because he was close. Done with him. I will have to get a day pass to take it to the good guy as he is over the state line so I thought I would try this.

Also, today I pulled it in the shed and after I shut it off I could hear fuel running back into the take from the return. I'm not sure I remember it ever doing that, but maybe it has.

Didn't say - This truck is an automatic but I don't think that has bearing. It idles bad in neutral or drive and then is just fine with no explanation. The trans is all mechanical as well (kickdown, etc).

Have all the fuel filters been replaced?..Every now and then I have luck with issues by looking on youtube..good luck..

On a 3126 they will de-power if the anti freeze is low in the tank. I had one run great down hill, but only 40 up hill.(computer controlled engine)

Check the lift pump pressure. It may have fuel but not enough pressure to the injection pump.

Hello notjustair,

My guess is fuel issue. First thing would be to check the filters; fuel flow quantity; then fuel quality; then air leaking into the pick up side of the pump. Fuel pressure would be next. I would also check to see if you throttle is pushing all the way to full high idle. Old mechanical linkage gets pretty sloppy with age. Air cleaner restriction at 20" of water vacuum or less?
Good hunting......................

Guido.

Shaft seal on transfer pump? (which is on the main input shaft into the IP.)

Install a pressure gauge to monitor transfer pump pressure and a length of clear hose so you can watch for bubbles in the return line (which would be caused by a suction line or filter or transfer pump leak).

Sounds like fuel problem, pumps get worn and leak air, pressure drops. but I have had trucks that lost power and petal didn't make much different. You didn't tell us if you had smoke coming out the exhaust, If your air intake was blocked it would blow black smoke out the exhaust till it got enough air to run again. have found air filters plugged up also rat or birds nest in the intake. engine need air to run full rpm .Only way to check for air in the fuel would be to put a clear test line on , most diesel tecs have one in their tool box,and check for bubbles like the other guy said. Good luck

He did replace the fuel filters at the start of this. Today I rolled up my sleeve and reached down to the bottom of the tank to make sure there wasn't any algae or growth in it. Clean as a whistle.

I put in a fuel regulator along with the pump. It is usually set at 2 pounds but it doesn't seem to matter what it is set at. Mechanic said don't go over three pounds or I will get fuel in the oil.

It does not have any kind of pump before the injector pump - the addition of the pump in there was supposed to fix it. It just acts electrical but the only wire running to the whole engine is to the plunger that shuts it down.

It has a low coolant light that isn't on, and it has never gotten hot. Come to think of it I'm not sure that I have checked antifreeze since all of this started. Oil level is fine and pressure is at 80 so I know that isn't it. I think the low oil shutdown is disconnected anyway (it was an old Pepsi truck with shutdowns on it).

Does it have a sensor in the air cleaner if so replace the air cleaner no matter how good it looks

Check the fuel return line, it bleeds off any air picked up.
Later Bob

I seem to rember an older CAT tech talking about trouble with a centrifugal advance on the front of some 3208 Cat pumps.It may not be your problem but since no one else mentioned it I thought I would.

You have a pump coming apart. I have pulled many of them on generators. Most of the time you will find fuel under the pump. In the valley of the engine. Pump is not that hard to change. But you will need a special tool to remove the drive gear. Early models had a problem with a gear ring.Primer pump has nothing to do with injector pump. Other than priming the system.Find someone that knows what they are doing.

Having had a problem with a 3204, does a 3208 have the strainer before the lift pump? Mine was plugged up with black gunk. Would run good for 20-30 minutes then had no power and would stall.

Did anyone put a fuel pressure gauge on it? What is the fuel pressure? How many miles are on this thing?

The transfer pump is probably worn out, which is built in to the back (gear end) of the pump. Time to pull the pump and have it gone through. The truck is 25 years old.

How do you figure the transfer pump is at the "back" of the IP?????

Actually, the governor hangs out in the back end of the IP!

This was a cummins but had the same thing going on. Lift pump screen. Some jack a$$ threw a snickers bar in the fuel tank. Had to make special tools and clean the screen every ten minutes until I got it all cleaned out.

In Cat terms, the drive end IS the back. In either case, you have to pull the pump to get at it, you have to have the right size fine thread bolt to pull the tapered, one use only hub off the pump shaft to then remove the transfer pump housing and gears and inspect for wear.

I've built dozens of 3208 pumps on the bench.