Starting Issue 350 Diesel

[KenP]

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[Lavoy]

A couple guesses. Replace the fuel filters regardless. If you don't know how long they have been in there, it is too long.
I don't think the fuel tank should pressurize. If it will pressurize, I would think it would hold vacuum. This should not have the effect you are talking about, as it is happening too fast, but still might be an issue that should be addressed in general.
I would check the primary pump for flow, but barring these things fixing the problem, I wonder if you need pump work.
Lavoy

[KenP]

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[Lavoy]

Ken,
Have not looked that close at the cap, I would assume that it has a small vent somewhere, but could be wrong.
Worst case scenario, you can send me the pump and I can have my guys put in on the stand and check it out.
Lavoy

[jdemaris]

Hope its not the injection pump as I can't replace the CBC pump.

You certainly CAN replace the CBC pump. You install a DB or JDB instead and Deere still sells the adpater parts needed.

I'm not saying you need to at this time, just stating that it can be done, and is OFTEN done on machines with C-series pumps.

There are several things inside that pump that can go bad and cause problems like that. Especially the governor piston and rack and pinion gears in the throttle (in the gooseneck that sticks out of the pump). Some shops are still repairing C pumps with a few left-over new parts and many used parts. As of now, you can't even buy a seal and o-ring kit for that pump, so every little seal has to be matched with something.

I'd check the obvious first. You need to make sure fuel is always getting into the pump, and also always getting out. Make sure the exit fitting on the pump is not plugged with something. A partially plugged outlet will make it behave just like a partially plugged inlet.

Also a bad fuel pump will make the injection pump draw air. The machine can run fine with no fuel pump at all, but it cannot with a bad fuel pump. If you check it, do it with the engine cranking and do not rely on the hand primer (if it still has one). A bad fuel pump with a stuck check valve will force the injection pump to draw air.

It would behoove you to find a way to get a clear piece of plastic fuel line temporarly hooked to the injection pump inlet. Then, you can see if it's getting air in the fuel.

Also, check the fuel fitting that screws into the bottom of the fuel tank. On 350s and 450s, it is common for the little port in that fitting to clog, off and on. It only has around an 1/8" or 3/16" hole in it where it lets fuel in , with no screen to hold debris off of it. It was standard procedure on those crawlers to modify it a bit and attach an long narrow screen up inside the tank attached to that fitting. Otherwise, all it took sometimes were a couple of small pieces of leaves or other debris to bounce around and clog that small port, off and on.

[KenP]

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[jdemaris]

jdemaris,
Thanks for the information. I know its possible to replace the CBC pump, but the cost of doing so precludes replacement right now.

Yes, parts prices are nuts. The way to do it, as I see it, is keep your eyes open for a suitable DB or JDB pump and buy one when cheap. I've done it for years, but can't buy every deal I see. A few weeks ago, somebody had a good JDB injection pump from a Deere 2020 ag tractor. Pump, drive gear, and all the lines and it sold for $175 on Ebay. No auction, the $175 was the "buy it now" price. This pump is what is used on a 450 Deere crawler. I was tempted, but was just not in the mood to spend money at that time. I've seen similar for 350 crawlers, 1020 ag tractors, etc. From what I've seen, you can never find a bargain when you actually need it. You have to pre-buy when you don't really need it yet, or you get screwed.

In regard to your machine, I wouldn't be worried about the injection pump until you thorougly check the fuel pump and fuel fitting at the tank. I'll add though that the former CDC pump was much more prone to problems and the CBC had many updates to fix them.
Fuel pumps are cheap. The original with the glass bowl was originally intended to be rebuildable. But, things rarely went that way. The mechancal parts often wore out before the diaphram and check valves did.
One mistake many used to make is - they'd check the fuel pump by moving the hand primer back and forth. That does NOT test the pump. That hand pump over-rides the camshaft driven linkage. So, the normal engine driven part of the fuel pump can be completely worn out - but a test with the hand primer will have the pump working fine. I suspect that, if you pull your pump off, and push on the linkage arm, you'll find it has a lot of free play from wear and hardly does a thing when riding on the camshaft lobe.
It's not really worth discusssing anyway, since fuel transfer pumps are so cheap. Yes, they are mostly sealed tin cans now, but work fine - unless you buy a French-built ag-version pump that is screwed together and has a metal fuel bowl and screen you can clean.
As I said before, besides the fuel pump, the fuel fitting in the 350 and 450 at the bottom of the tank can be a big problem - and when it does give trouble, it tends to come and go. All it needs is some sort of stand-pipe added, or a long narrow screen to fix it.

[KenP]

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[mini kahuna]

sounds like you found your problem.